Ol Classic...305 to 350
07-18-2022, 06:17 PM
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Ol Classic...305 to 350
Hey all, I'm new to the forum and a proud owner of an 85 bird. From all I've seen, I think I'd like to upgrade the engine to a 350. My budget is <5000, and there are plenty of scrapyards around me (fort lauderdale). Ideally, sometime in the future (<5y) I'd like to throw a blower on it as well.
Current specs:
1985 Pontiac Firebird Trans Am
Carburated 305 (rochester 4bbl rebuilt in 2019)
T5 Manual Transmission.
Bone stock, as far as engine components go.
Just what am I getting myself into? What vehicles should I look for to pull the engine from? Or would I be better off spending my money on a crate? What components from the current car will "plug and play" and what will I have to buy? Realistically, how much time can I expect this to take?
I'm sure my inexperience shows so bear with me- getting into all this stuff. Thanks!
Current specs:
1985 Pontiac Firebird Trans Am
Carburated 305 (rochester 4bbl rebuilt in 2019)
T5 Manual Transmission.
Bone stock, as far as engine components go.
Just what am I getting myself into? What vehicles should I look for to pull the engine from? Or would I be better off spending my money on a crate? What components from the current car will "plug and play" and what will I have to buy? Realistically, how much time can I expect this to take?
I'm sure my inexperience shows so bear with me- getting into all this stuff. Thanks!
07-18-2022, 09:08 PM
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Re: Ol Classic...305 to 350
Same as everybody else that asks this question.
96-2000 5.7 Vortec. Comes in trucks & vans. Go to the buzzard nest and scare em off of the most cherry one you can find. Pay whatever it takes to get one that's CHERRY. The idea here is, no matter how much that costs, it's still MILES cheeeeeeeeeeper than any kind of "rebuild" you can do; and it's VASTLY superior to any "rebuilt" motor you can buy.
Remember, 96-2000 Chevy/GMC truck/van.
Same thing re. a "crate"; there's nothing magical that happens when you put a "rebuilt" motor in a box. It's still a ... REBUILT motor. Unless of course you're willing to bite off on a NEW one, which is widely available as well. The ONLY one to get is the NEW GM one, such as this. https://www.jegs.com/p/JEGS/JEGS-Per...0244/10002/-1#
Avoid ANY AND ALL "rebuilt" 60s/70/80s 350s. Quality control was ATROCIOUS in the 70s and earlier 80s, and all the later 80s ones (with the exception of Vette and Z28 / TA ones)) were TBI with the crappiest of the crap heads you can crappily imagine in your crappiest nightmare. 70s motors had unbelievably bad heads also, but in a different way, and possibly even worse. The 96-2000 truck heads are better even than virtually ALL of the old "PowerPack" heads and all that sort of thing; they are quite simply THE BEST heads for 350 that GM has ever offered, BY FAR. As far as the "parts" you want your hypothetical motor to be built out of, those are the best heads to get, period. Smogger garbage and TBI crap doesn't come anywhere near close. Granted, you have the crappiest of the 305s that were available in your year (the wimpy LG4), so almost any 350 might seem like it will be an "upgrade"; but some of the other 305s better than yours, notably the L69, would WAX THE FLOOR with a typical 70s smogger 350. Speaking strictly as someone who traded in a 79 Z28 4-speed on a 83 L69 Z28, and I had a 78 Z28 auto at the same time. The 83 would DRILL either of those older cars so bad it wasn't funny.
Then you will need an intake manifold, which MUST be a "Vortec" one. I think the only one that you can get anymore that fits your carb is a Performer. Not great but not too bad either.
Get rid of every piece of your exhaust from the heads to the street. EVERY PIECE. Replace the manifolds with headers, BUT NOT for LG4. Spend what it takes to get GOOD ones. Get ones for something like a 89 350 TPI. NOT "universal", NOT "block huggers", NOT NOT NOT NOT NOT NOT; and certainly not "cheeeeeeeep". Few things in the world SUCK worse than cheeeeep headers. I'd recommend stainless steel, and have them ceramic coated. Then a 3" cat, and the cat-back of your choice.
If you want to upgrade the motor a bit from the stock truck configuration that it will come in, look at roller cams in the range of 210 - 220° on the intake, and as much as 10° more on the exhaust. ANY cam you get will need better valve springs than what GM used on those motors. I'd recommend LS6 springs https://www.texas-speed.com/p-9573-g...laced-ls6.aspx and the Comp "adapter" retainers https://www.summitracing.com/parts/cca-787-16 with the appropriate keepers from Comp. Using those avoids machine work altogether and makes it all a drop-in. For cams, look at ones like this https://www.summitracing.com/parts/cca-12-412-8 or https://www.summitracing.com/parts/cca-12-422-8.
One of the things making your car slow now is the gears you have. 3.08 if memory serves. I'd suggest 3.42 or 3.73. If you improve the gears, go with the 422 grind or something similar from another quality mfr such as Lunati, CamMotion, etc. NOT the cheeeeeeeepest thing you can find that has "cam" printed on the box and nobody will go to jail for fraud for calling whatever is inside a cam.
96-2000 5.7 Vortec. Comes in trucks & vans. Go to the buzzard nest and scare em off of the most cherry one you can find. Pay whatever it takes to get one that's CHERRY. The idea here is, no matter how much that costs, it's still MILES cheeeeeeeeeeper than any kind of "rebuild" you can do; and it's VASTLY superior to any "rebuilt" motor you can buy.
Remember, 96-2000 Chevy/GMC truck/van.
Same thing re. a "crate"; there's nothing magical that happens when you put a "rebuilt" motor in a box. It's still a ... REBUILT motor. Unless of course you're willing to bite off on a NEW one, which is widely available as well. The ONLY one to get is the NEW GM one, such as this. https://www.jegs.com/p/JEGS/JEGS-Per...0244/10002/-1#
Avoid ANY AND ALL "rebuilt" 60s/70/80s 350s. Quality control was ATROCIOUS in the 70s and earlier 80s, and all the later 80s ones (with the exception of Vette and Z28 / TA ones)) were TBI with the crappiest of the crap heads you can crappily imagine in your crappiest nightmare. 70s motors had unbelievably bad heads also, but in a different way, and possibly even worse. The 96-2000 truck heads are better even than virtually ALL of the old "PowerPack" heads and all that sort of thing; they are quite simply THE BEST heads for 350 that GM has ever offered, BY FAR. As far as the "parts" you want your hypothetical motor to be built out of, those are the best heads to get, period. Smogger garbage and TBI crap doesn't come anywhere near close. Granted, you have the crappiest of the 305s that were available in your year (the wimpy LG4), so almost any 350 might seem like it will be an "upgrade"; but some of the other 305s better than yours, notably the L69, would WAX THE FLOOR with a typical 70s smogger 350. Speaking strictly as someone who traded in a 79 Z28 4-speed on a 83 L69 Z28, and I had a 78 Z28 auto at the same time. The 83 would DRILL either of those older cars so bad it wasn't funny.
Then you will need an intake manifold, which MUST be a "Vortec" one. I think the only one that you can get anymore that fits your carb is a Performer. Not great but not too bad either.
Get rid of every piece of your exhaust from the heads to the street. EVERY PIECE. Replace the manifolds with headers, BUT NOT for LG4. Spend what it takes to get GOOD ones. Get ones for something like a 89 350 TPI. NOT "universal", NOT "block huggers", NOT NOT NOT NOT NOT NOT; and certainly not "cheeeeeeeep". Few things in the world SUCK worse than cheeeeep headers. I'd recommend stainless steel, and have them ceramic coated. Then a 3" cat, and the cat-back of your choice.
If you want to upgrade the motor a bit from the stock truck configuration that it will come in, look at roller cams in the range of 210 - 220° on the intake, and as much as 10° more on the exhaust. ANY cam you get will need better valve springs than what GM used on those motors. I'd recommend LS6 springs https://www.texas-speed.com/p-9573-g...laced-ls6.aspx and the Comp "adapter" retainers https://www.summitracing.com/parts/cca-787-16 with the appropriate keepers from Comp. Using those avoids machine work altogether and makes it all a drop-in. For cams, look at ones like this https://www.summitracing.com/parts/cca-12-412-8 or https://www.summitracing.com/parts/cca-12-422-8.
One of the things making your car slow now is the gears you have. 3.08 if memory serves. I'd suggest 3.42 or 3.73. If you improve the gears, go with the 422 grind or something similar from another quality mfr such as Lunati, CamMotion, etc. NOT the cheeeeeeeepest thing you can find that has "cam" printed on the box and nobody will go to jail for fraud for calling whatever is inside a cam.
Last edited by sofakingdom; 07-18-2022 at 09:18 PM.
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07-18-2022, 11:22 PM
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Car: Resto-Mod 1987 IROC-Z Clone
Engine: Alky fed L92 Vortec Twin-Turbo 6.8L
Transmission: My own built/ design 4L80M
Axle/Gears: Custom 12 bolt (4.10:1)
Re: Ol Classic...305 to 350
The "VORTEC 350" Engine.
One of the few times (in the Modern era) where GM pretty much said to us (GMPT Engineering): just do whatever you guys feel is right.
Keep in mind, this was a "Work Truck" Engine Program, and NOT a Corvette or "Performance" Engine Program.
This Engine was to be the finest Small Block Chevrolet Engine ever produced... and it actually was.
GM let us do almost everything that we asked for; short of designing completely new Technology/ Parts.
The 'Last 350 Chevy" is without a doubt, the best 350 Chevy!
One of the few times (in the Modern era) where GM pretty much said to us (GMPT Engineering): just do whatever you guys feel is right.
Keep in mind, this was a "Work Truck" Engine Program, and NOT a Corvette or "Performance" Engine Program.
This Engine was to be the finest Small Block Chevrolet Engine ever produced... and it actually was.
GM let us do almost everything that we asked for; short of designing completely new Technology/ Parts.
The 'Last 350 Chevy" is without a doubt, the best 350 Chevy!
The Vortec-350 Engine was GMs "last-hurrah" with the Gen-1 SBC.
It is by far the best Factory/ Production Gen-1 SBC Engine that GM ever produced.
The manufacturing quality leaves a bit to be desired...
However, the Roller-Camshaft/ Lifters, and the Cylinder-Head design (well at least the Intake-Runner and Combustion-Chamber designs)
...make it the best Factory/ Production Gen-1 SBC Engine that GM ever produced.
... and if you would be happy with 300 HP; just refresh (or if need be, rebuild) a stock Vortec-350 (260 HP Stock) from the Scrap-Yard.
They will make a solid 300 HP with Headers and an Edelbrock Vortec Performer (non-RPM) Air-Gap Intake-Manifold and Carburetor...
...beyond that, a Camshaft (corresponding valvetrain) will produce 400 to 500 HP for very little money...
Until the Gen-3/ Gen-IV Engines became plentiful and grew massive aftermarket parts/ high-performance parts support...
I was building TONs of the Vortec-350 Engines from a near stock 300 HP to 550 HP normally-aspirated...
and 600 HP to near 1,000 HP via forced-induction.
It is by far the best Factory/ Production Gen-1 SBC Engine that GM ever produced.
The manufacturing quality leaves a bit to be desired...
However, the Roller-Camshaft/ Lifters, and the Cylinder-Head design (well at least the Intake-Runner and Combustion-Chamber designs)
...make it the best Factory/ Production Gen-1 SBC Engine that GM ever produced.
... and if you would be happy with 300 HP; just refresh (or if need be, rebuild) a stock Vortec-350 (260 HP Stock) from the Scrap-Yard.
They will make a solid 300 HP with Headers and an Edelbrock Vortec Performer (non-RPM) Air-Gap Intake-Manifold and Carburetor...
...beyond that, a Camshaft (corresponding valvetrain) will produce 400 to 500 HP for very little money...
Until the Gen-3/ Gen-IV Engines became plentiful and grew massive aftermarket parts/ high-performance parts support...
I was building TONs of the Vortec-350 Engines from a near stock 300 HP to 550 HP normally-aspirated...
and 600 HP to near 1,000 HP via forced-induction.
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07-19-2022, 12:21 PM
#5
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Re: Ol Classic...305 to 350
One other detail with the vortec block is that it may or may not be drilled for a mechanical fuel pump. Some are drilled and have a block off plate and others are not. Not a major thing either way as if it's not there you can either have the machine shop do it for you or add an electric pump if you find a good running engine.
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T.L. (07-19-2022)
07-20-2022, 11:03 PM
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Car: 1983 G20 Chevy
Engine: 305 TPI
Transmission: 4L60
Axle/Gears: 14 bolt with 3.07 gears
Re: Ol Classic...305 to 350
Same as everybody else that asks this question.
96-2000 5.7 Vortec. Comes in trucks & vans. Go to the buzzard nest and scare em off of the most cherry one you can find. Pay whatever it takes to get one that's CHERRY. The idea here is, no matter how much that costs, it's still MILES cheeeeeeeeeeper than any kind of "rebuild" you can do; and it's VASTLY superior to any "rebuilt" motor you can buy.
Remember, 96-2000 Chevy/GMC truck/van.
Same thing re. a "crate"; there's nothing magical that happens when you put a "rebuilt" motor in a box. It's still a ... REBUILT motor. Unless of course you're willing to bite off on a NEW one, which is widely available as well. The ONLY one to get is the NEW GM one, such as this. https://www.jegs.com/p/JEGS/JEGS-Per...0244/10002/-1#
Avoid ANY AND ALL "rebuilt" 60s/70/80s 350s. Quality control was ATROCIOUS in the 70s and earlier 80s, and all the later 80s ones (with the exception of Vette and Z28 / TA ones)) were TBI with the crappiest of the crap heads you can crappily imagine in your crappiest nightmare. 70s motors had unbelievably bad heads also, but in a different way, and possibly even worse. The 96-2000 truck heads are better even than virtually ALL of the old "PowerPack" heads and all that sort of thing; they are quite simply THE BEST heads for 350 that GM has ever offered, BY FAR. As far as the "parts" you want your hypothetical motor to be built out of, those are the best heads to get, period. Smogger garbage and TBI crap doesn't come anywhere near close. Granted, you have the crappiest of the 305s that were available in your year (the wimpy LG4), so almost any 350 might seem like it will be an "upgrade"; but some of the other 305s better than yours, notably the L69, would WAX THE FLOOR with a typical 70s smogger 350. Speaking strictly as someone who traded in a 79 Z28 4-speed on a 83 L69 Z28, and I had a 78 Z28 auto at the same time. The 83 would DRILL either of those older cars so bad it wasn't funny.
Then you will need an intake manifold, which MUST be a "Vortec" one. I think the only one that you can get anymore that fits your carb is a Performer. Not great but not too bad either.
Get rid of every piece of your exhaust from the heads to the street. EVERY PIECE. Replace the manifolds with headers, BUT NOT for LG4. Spend what it takes to get GOOD ones. Get ones for something like a 89 350 TPI. NOT "universal", NOT "block huggers", NOT NOT NOT NOT NOT NOT; and certainly not "cheeeeeeeep". Few things in the world SUCK worse than cheeeeep headers. I'd recommend stainless steel, and have them ceramic coated. Then a 3" cat, and the cat-back of your choice.
If you want to upgrade the motor a bit from the stock truck configuration that it will come in, look at roller cams in the range of 210 - 220° on the intake, and as much as 10° more on the exhaust. ANY cam you get will need better valve springs than what GM used on those motors. I'd recommend LS6 springs https://www.texas-speed.com/p-9573-g...laced-ls6.aspx and the Comp "adapter" retainers https://www.summitracing.com/parts/cca-787-16 with the appropriate keepers from Comp. Using those avoids machine work altogether and makes it all a drop-in. For cams, look at ones like this https://www.summitracing.com/parts/cca-12-412-8 or https://www.summitracing.com/parts/cca-12-422-8.
One of the things making your car slow now is the gears you have. 3.08 if memory serves. I'd suggest 3.42 or 3.73. If you improve the gears, go with the 422 grind or something similar from another quality mfr such as Lunati, CamMotion, etc. NOT the cheeeeeeeepest thing you can find that has "cam" printed on the box and nobody will go to jail for fraud for calling whatever is inside a cam.
96-2000 5.7 Vortec. Comes in trucks & vans. Go to the buzzard nest and scare em off of the most cherry one you can find. Pay whatever it takes to get one that's CHERRY. The idea here is, no matter how much that costs, it's still MILES cheeeeeeeeeeper than any kind of "rebuild" you can do; and it's VASTLY superior to any "rebuilt" motor you can buy.
Remember, 96-2000 Chevy/GMC truck/van.
Same thing re. a "crate"; there's nothing magical that happens when you put a "rebuilt" motor in a box. It's still a ... REBUILT motor. Unless of course you're willing to bite off on a NEW one, which is widely available as well. The ONLY one to get is the NEW GM one, such as this. https://www.jegs.com/p/JEGS/JEGS-Per...0244/10002/-1#
Avoid ANY AND ALL "rebuilt" 60s/70/80s 350s. Quality control was ATROCIOUS in the 70s and earlier 80s, and all the later 80s ones (with the exception of Vette and Z28 / TA ones)) were TBI with the crappiest of the crap heads you can crappily imagine in your crappiest nightmare. 70s motors had unbelievably bad heads also, but in a different way, and possibly even worse. The 96-2000 truck heads are better even than virtually ALL of the old "PowerPack" heads and all that sort of thing; they are quite simply THE BEST heads for 350 that GM has ever offered, BY FAR. As far as the "parts" you want your hypothetical motor to be built out of, those are the best heads to get, period. Smogger garbage and TBI crap doesn't come anywhere near close. Granted, you have the crappiest of the 305s that were available in your year (the wimpy LG4), so almost any 350 might seem like it will be an "upgrade"; but some of the other 305s better than yours, notably the L69, would WAX THE FLOOR with a typical 70s smogger 350. Speaking strictly as someone who traded in a 79 Z28 4-speed on a 83 L69 Z28, and I had a 78 Z28 auto at the same time. The 83 would DRILL either of those older cars so bad it wasn't funny.
Then you will need an intake manifold, which MUST be a "Vortec" one. I think the only one that you can get anymore that fits your carb is a Performer. Not great but not too bad either.
Get rid of every piece of your exhaust from the heads to the street. EVERY PIECE. Replace the manifolds with headers, BUT NOT for LG4. Spend what it takes to get GOOD ones. Get ones for something like a 89 350 TPI. NOT "universal", NOT "block huggers", NOT NOT NOT NOT NOT NOT; and certainly not "cheeeeeeeep". Few things in the world SUCK worse than cheeeeep headers. I'd recommend stainless steel, and have them ceramic coated. Then a 3" cat, and the cat-back of your choice.
If you want to upgrade the motor a bit from the stock truck configuration that it will come in, look at roller cams in the range of 210 - 220° on the intake, and as much as 10° more on the exhaust. ANY cam you get will need better valve springs than what GM used on those motors. I'd recommend LS6 springs https://www.texas-speed.com/p-9573-g...laced-ls6.aspx and the Comp "adapter" retainers https://www.summitracing.com/parts/cca-787-16 with the appropriate keepers from Comp. Using those avoids machine work altogether and makes it all a drop-in. For cams, look at ones like this https://www.summitracing.com/parts/cca-12-412-8 or https://www.summitracing.com/parts/cca-12-422-8.
One of the things making your car slow now is the gears you have. 3.08 if memory serves. I'd suggest 3.42 or 3.73. If you improve the gears, go with the 422 grind or something similar from another quality mfr such as Lunati, CamMotion, etc. NOT the cheeeeeeeepest thing you can find that has "cam" printed on the box and nobody will go to jail for fraud for calling whatever is inside a cam.
Last edited by Fast355; 07-20-2022 at 11:08 PM.
07-21-2022, 06:59 AM
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Car: 1989 IROC-Z 305 LB9 AT Convertible
Engine: LB9 305
Transmission: AT
Re: Ol Classic...305 to 350
RE My 1989 IROC Z Vert, LB9 305/AT , Will my OE TPI upper and lower, exhaust manifolds, distributor, engine mounts bolt on the the 96-2000 Jeg's L31? What about injectors, knock sensors, ESC and "Prom"? Thanks.
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07-21-2022, 09:01 AM
#8
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Re: Ol Classic...305 to 350
Will my OE TPI upper and lower, exhaust manifolds, distributor, engine mounts bolt on the the 96-2000 Jeg's L31? What about injectors, knock sensors, ESC and "Prom"?
No (base)
Yes but why would you do that? They choke the 305, think what they'll do to a 350.
Yes
Yes
Yes but they're too small (305 vs 350)
Yes but it's wrong (305 vs 350) and there's only 1
Yes but since tuning benefits even totally stock motors, that's not the same as saying "it's as good as it can be"
07-21-2022, 12:53 PM
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Car: 1989 IROC-Z 305 LB9 AT Convertible
Engine: LB9 305
Transmission: AT
Re: Ol Classic...305 to 350
Yes (plenum & runners)
No (base)
Yes but why would you do that? They choke the 305, think what they'll do to a 350.
Yes
Yes
Yes but they're too small (305 vs 350)
Yes but it's wrong (305 vs 350) and there's only 1
Yes but since tuning benefits even totally stock motors, that's not the same as saying "it's as good as it can be"
No (base)
Yes but why would you do that? They choke the 305, think what they'll do to a 350.
Yes
Yes
Yes but they're too small (305 vs 350)
Yes but it's wrong (305 vs 350) and there's only 1
Yes but since tuning benefits even totally stock motors, that's not the same as saying "it's as good as it can be"
So I guess I'd need a Scogin Dickey (SP) lower?
I'm not fond of headers, are there suitable OE cast exhaust manifolds, that fit and flow better? ? Or, headers that leave some "power on the table" , to provide OE qualities? Like FIT, not impeding of service operations(starter R&R, plug changes, etc.) The my Lincoln Mark VII had factory stainless steel headers that presented no problems in 288,000 miles)
24# Injectors?
Knock sensor(s) ESC, Prom for a L31? or L98?
Thank you!
07-22-2022, 12:34 PM
#10
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Re: Ol Classic...305 to 350
Yes
Yes but still highly restrictive; L69, LB9, or L98
Not sure, never heard of any such
As far as fit, I've had both Edelbrock TES and SLPs on my car, and had no problem with any of that
Yes, or maybe even 26, such as stock LS1 ones
L98; L31 electronics are completely different
Yes but still highly restrictive; L69, LB9, or L98
Not sure, never heard of any such
As far as fit, I've had both Edelbrock TES and SLPs on my car, and had no problem with any of that
Yes, or maybe even 26, such as stock LS1 ones
L98; L31 electronics are completely different
01-13-2023, 01:03 PM
#12
Re: Ol Classic...305 to 350
Hello.guys, hopefully soon I will be going to.a.350.from a 96 k1500, roughly 20k miles. It's a jasper rebuild! Not sure if the block is drilled for a mechanical pump, or.just has a.block.off.plate. In the event it isn't drilled what kind of electric pump would you recommend to fuel my carb---edlebrock 600cfm
! Any input would be greatly appreciated
! Any input would be greatly appreciated
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04-17-2023, 04:33 PM
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Car: 1985 TransAm
Engine: 4bbl 305
Transmission: Automatic
Re: Ol Classic...305 to 350
Hello All.
I am at a crossroads here as I don't know to much about motor swaps and trying to determine what else I will need.
I have a 96 Vortec block that I had rebuilt that I want to swap out the current 305.
Will Everything else typically bolt up?
I am at a crossroads here as I don't know to much about motor swaps and trying to determine what else I will need.
I have a 96 Vortec block that I had rebuilt that I want to swap out the current 305.
Will Everything else typically bolt up?
04-19-2023, 01:47 PM
#14
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Re: Ol Classic...305 to 350
Define "everything else". Not necessarily tell us "everything" down to the last bolt and tie-wrap, but at least, give a hint at what concerns you.
04-19-2023, 05:13 PM
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Re: Ol Classic...305 to 350
Fair enough.. Thank you.
I guess my primary concerns are the oil pan, flywheel the Harmonic Balancer and the pulleys/accessories system?
I suspect that I will grab a new oil pump as well.
As mentioned, I have a 96 block that I had rebuilt, added a mild comp cam.
I have a 1996 from a Express 3500 van, aVortec to Quadragjet intake, and the Edelbrock Quadra jet 750.
The block had the manual fuel pump bore.
All of this has just been sitting around for 2 years now as the car still had a running 305 I can pull what is needed from.
Thx
I am in need of the exhaust
I guess my primary concerns are the oil pan, flywheel the Harmonic Balancer and the pulleys/accessories system?
I suspect that I will grab a new oil pump as well.
As mentioned, I have a 96 block that I had rebuilt, added a mild comp cam.
I have a 1996 from a Express 3500 van, aVortec to Quadragjet intake, and the Edelbrock Quadra jet 750.
The block had the manual fuel pump bore.
All of this has just been sitting around for 2 years now as the car still had a running 305 I can pull what is needed from.
Thx
I am in need of the exhaust
04-19-2023, 06:01 PM
#16
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Re: Ol Classic...305 to 350
Well, since you don't say what you're starting out with, I'll just have to "assume". We all know what the component parts of that word break down to. Butt, let's "assume" you're starting out with the 85 305.
Oil pan: No it will not fit. Your existing pan is for the old 2-piece rear main seal, but 86-up has the newer 1-pc RMS.
Flywheel: You don't have one. You have a flex plate. But, the answer is the same: No. Same deal, same year-model break. Bolt pattern diameter is different, and the newer motor will need the last little bit of INTERNAL balance, that used to be part of the oddball shape of the crank flange, mounted on the flywheel. That DOES NOT make the newer setup "external" balance; it is still "internally balanced", even though even the vendors of crankshafts and whatnot have given into the morons that think that just because the balance weight is on the other side of the crank/flywheel interface it's "external"; but IT'S NOT. Be VERY CAREFUL of this distinction while buying parts. IGNORE the "internal/external" NOISE and MONKEY SPANK, and instead, concentrate on the word "stock". You will need the flex plate with the STOCK balance for 86-up 305/350. Best in fact not to even mention the word balance: just stick with "stock".
Crank damper: Yes either the 96 or your 85 one will work.
Pulleys/accessories: Depends on your definitions of "fit" and "work". Yes, yours will bolt up, with the possible exception of having to drill & tap one bolt hole. Whether that's really The Best Thing, or The Way To Go, is a whole other question.
Oil pump: get a Melling M55, the Mr Gasket "high-pressure" spring, and a Melling M55E drive rod. The E drive rod replaces the pathetic plastic coupling between the dist and the pump with a metal collar.
As to whether the Eddie 1406 will "work", will depend on how "mild" the cam you got is.
Same for everything else about the heads. Those heads are well and widely known to have (a) very low clearance between the top of the guide and the bottom of the retainer (probably no more than .460"), and (b) the ABSOLUTE CRAPPIEST valve springs GM ever used on a SBC head. Incorrect setup of this part of the motor can result in INSTANT CATASTROPHIC DESTRUCTION of the valve train, shedding metal into the oil, and EATING the bearings. I cannot overemphasize the importance of this: hopefully the use of words like "destroy" and "eat" will instill the appropriate respect for the situation. Again, tell us what cam you have, and we can talk about how to set up the heads for it, at minimal cost & effort.
Oil pan: No it will not fit. Your existing pan is for the old 2-piece rear main seal, but 86-up has the newer 1-pc RMS.
Flywheel: You don't have one. You have a flex plate. But, the answer is the same: No. Same deal, same year-model break. Bolt pattern diameter is different, and the newer motor will need the last little bit of INTERNAL balance, that used to be part of the oddball shape of the crank flange, mounted on the flywheel. That DOES NOT make the newer setup "external" balance; it is still "internally balanced", even though even the vendors of crankshafts and whatnot have given into the morons that think that just because the balance weight is on the other side of the crank/flywheel interface it's "external"; but IT'S NOT. Be VERY CAREFUL of this distinction while buying parts. IGNORE the "internal/external" NOISE and MONKEY SPANK, and instead, concentrate on the word "stock". You will need the flex plate with the STOCK balance for 86-up 305/350. Best in fact not to even mention the word balance: just stick with "stock".
Crank damper: Yes either the 96 or your 85 one will work.
Pulleys/accessories: Depends on your definitions of "fit" and "work". Yes, yours will bolt up, with the possible exception of having to drill & tap one bolt hole. Whether that's really The Best Thing, or The Way To Go, is a whole other question.
Oil pump: get a Melling M55, the Mr Gasket "high-pressure" spring, and a Melling M55E drive rod. The E drive rod replaces the pathetic plastic coupling between the dist and the pump with a metal collar.
As to whether the Eddie 1406 will "work", will depend on how "mild" the cam you got is.
Same for everything else about the heads. Those heads are well and widely known to have (a) very low clearance between the top of the guide and the bottom of the retainer (probably no more than .460"), and (b) the ABSOLUTE CRAPPIEST valve springs GM ever used on a SBC head. Incorrect setup of this part of the motor can result in INSTANT CATASTROPHIC DESTRUCTION of the valve train, shedding metal into the oil, and EATING the bearings. I cannot overemphasize the importance of this: hopefully the use of words like "destroy" and "eat" will instill the appropriate respect for the situation. Again, tell us what cam you have, and we can talk about how to set up the heads for it, at minimal cost & effort.
Last edited by sofakingdom; 04-19-2023 at 06:10 PM.
04-20-2023, 07:35 AM
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Car: 1985 TransAm
Engine: 4bbl 305
Transmission: Automatic
Re: Ol Classic...305 to 350
Well, since you don't say what you're starting out with, I'll just have to "assume". We all know what the component parts of that word break down to. Butt, let's "assume" you're starting out with the 85 305.
Oil pan: No it will not fit. Your existing pan is for the old 2-piece rear main seal, but 86-up has the newer 1-pc RMS.
Flywheel: You don't have one. You have a flex plate. But, the answer is the same: No. Same deal, same year-model break. Bolt pattern diameter is different, and the newer motor will need the last little bit of INTERNAL balance, that used to be part of the oddball shape of the crank flange, mounted on the flywheel. That DOES NOT make the newer setup "external" balance; it is still "internally balanced", even though even the vendors of crankshafts and whatnot have given into the morons that think that just because the balance weight is on the other side of the crank/flywheel interface it's "external"; but IT'S NOT. Be VERY CAREFUL of this distinction while buying parts. IGNORE the "internal/external" NOISE and MONKEY SPANK, and instead, concentrate on the word "stock". You will need the flex plate with the STOCK balance for 86-up 305/350. Best in fact not to even mention the word balance: just stick with "stock".
Crank damper: Yes either the 96 or your 85 one will work.
Pulleys/accessories: Depends on your definitions of "fit" and "work". Yes, yours will bolt up, with the possible exception of having to drill & tap one bolt hole. Whether that's really The Best Thing, or The Way To Go, is a whole other question.
Oil pump: get a Melling M55, the Mr Gasket "high-pressure" spring, and a Melling M55E drive rod. The E drive rod replaces the pathetic plastic coupling between the dist and the pump with a metal collar.
As to whether the Eddie 1406 will "work", will depend on how "mild" the cam you got is.
Same for everything else about the heads. Those heads are well and widely known to have (a) very low clearance between the top of the guide and the bottom of the retainer (probably no more than .460"), and (b) the ABSOLUTE CRAPPIEST valve springs GM ever used on a SBC head. Incorrect setup of this part of the motor can result in INSTANT CATASTROPHIC DESTRUCTION of the valve train, shedding metal into the oil, and EATING the bearings. I cannot overemphasize the importance of this: hopefully the use of words like "destroy" and "eat" will instill the appropriate respect for the situation. Again, tell us what cam you have, and we can talk about how to set up the heads for it, at minimal cost & effort.
Oil pan: No it will not fit. Your existing pan is for the old 2-piece rear main seal, but 86-up has the newer 1-pc RMS.
Flywheel: You don't have one. You have a flex plate. But, the answer is the same: No. Same deal, same year-model break. Bolt pattern diameter is different, and the newer motor will need the last little bit of INTERNAL balance, that used to be part of the oddball shape of the crank flange, mounted on the flywheel. That DOES NOT make the newer setup "external" balance; it is still "internally balanced", even though even the vendors of crankshafts and whatnot have given into the morons that think that just because the balance weight is on the other side of the crank/flywheel interface it's "external"; but IT'S NOT. Be VERY CAREFUL of this distinction while buying parts. IGNORE the "internal/external" NOISE and MONKEY SPANK, and instead, concentrate on the word "stock". You will need the flex plate with the STOCK balance for 86-up 305/350. Best in fact not to even mention the word balance: just stick with "stock".
Crank damper: Yes either the 96 or your 85 one will work.
Pulleys/accessories: Depends on your definitions of "fit" and "work". Yes, yours will bolt up, with the possible exception of having to drill & tap one bolt hole. Whether that's really The Best Thing, or The Way To Go, is a whole other question.
Oil pump: get a Melling M55, the Mr Gasket "high-pressure" spring, and a Melling M55E drive rod. The E drive rod replaces the pathetic plastic coupling between the dist and the pump with a metal collar.
As to whether the Eddie 1406 will "work", will depend on how "mild" the cam you got is.
Same for everything else about the heads. Those heads are well and widely known to have (a) very low clearance between the top of the guide and the bottom of the retainer (probably no more than .460"), and (b) the ABSOLUTE CRAPPIEST valve springs GM ever used on a SBC head. Incorrect setup of this part of the motor can result in INSTANT CATASTROPHIC DESTRUCTION of the valve train, shedding metal into the oil, and EATING the bearings. I cannot overemphasize the importance of this: hopefully the use of words like "destroy" and "eat" will instill the appropriate respect for the situation. Again, tell us what cam you have, and we can talk about how to set up the heads for it, at minimal cost & effort.
My apologies, you are correct the original engine is the 85 305 with Carb ... I think its called the the LG4 with a electronic 4 barrel carb.
It has the automatic 700 R4 transmission.
In checking my parts that came with the 96 vortec engine This came from a Express Van 3500) - I have the OE Flexplate and the OE Oil Pan, just needs to be cleaned up.... glad they were returned back form the engine builder.
I also have the original brackets and pulleys from the 96 block as well. If you have a recommendation of a particular set I should use/search for , I am all ears.
The block was built by a reputable shop about 3-4 years ago, and at the time they installed the Comp Cams part number 08-422-8 with a grind of "XR270HR-10" that I had received the spec sheet for.
I have the Vortec to Quadra jet intake, but do not have the gasket set for it or picked out a HEI distributor yet ... I have been told I will need a vacuum advance one.
I do realize allot of this sounds silly, but in context I lost connection with a good friend a while back that was my go-to guy for things like this.
I am trying to find someone local in my area on another thread here with knowledge of this stuff, and I can pay to install as well.... I know when I am a bit over my head...lol
Appreciate the direction, and will look to order the oil pump you recommended... my build sheet shows a Melling "M155" and a Melling "155S" as the pump pickup, but no mention of a drive rod....
04-20-2023, 01:26 PM
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Re: Ol Classic...305 to 350
96 OE flex plate will work.
96 OE oil pan probably won't. It will likely hit the K member. You'll need one that fits 86-92 Camaro/Firebird.
That cam will be fine. In fact it's one that I often suggest for this swap. Search this forum for posts about it. You MUST replace the springs. Again, I've given part #s and sources for what you should do, many times.
Yes you will need a dist w vac adv, unless you use a CC Q-Jet. I'd suggest one from Performance Distributors. I'd also recommend a Holley 6210 carb
96 OE oil pan probably won't. It will likely hit the K member. You'll need one that fits 86-92 Camaro/Firebird.
That cam will be fine. In fact it's one that I often suggest for this swap. Search this forum for posts about it. You MUST replace the springs. Again, I've given part #s and sources for what you should do, many times.
Yes you will need a dist w vac adv, unless you use a CC Q-Jet. I'd suggest one from Performance Distributors. I'd also recommend a Holley 6210 carb
Last edited by sofakingdom; 04-20-2023 at 01:33 PM.
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