305 to 350
10-03-2006, 01:15 PM
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Car: 1991 z28
Engine: 5.7L
305 to 350
I own a 91 z28 305 TPI with a borla cat back exhaust system, I need to replace my engine and was thinking of replacing it with a rebuilt 350. I want to get this done and overwith as quickly as possible. I want to keep as much stock as i can due to costs.
I have a few questions though:
1. Is it a straight swap or will i have issues trying to get the new engine in?
2. Is it easier to take the engine and transmission out together or separately?
3. Is it easier to put the engine and transmission back in assemebled or separately?
4. Will my current automatic transmission fit on the new 350?
5. Will i need to purchase anything or will all the stuff from my 305 work with a 350?
6. I was thinking of purchasing some headers since I will have easy access to the engine, does anyone have any suggestions for some headers?
7. Will my rear end and transmission be able to handle the extra power from the 350?
I have some family that will be doing most of the work. Is there any tricks or tips we should know before doing this?
I have a few questions though:
1. Is it a straight swap or will i have issues trying to get the new engine in?
2. Is it easier to take the engine and transmission out together or separately?
3. Is it easier to put the engine and transmission back in assemebled or separately?
4. Will my current automatic transmission fit on the new 350?
5. Will i need to purchase anything or will all the stuff from my 305 work with a 350?
6. I was thinking of purchasing some headers since I will have easy access to the engine, does anyone have any suggestions for some headers?
7. Will my rear end and transmission be able to handle the extra power from the 350?
I have some family that will be doing most of the work. Is there any tricks or tips we should know before doing this?
10-04-2006, 09:39 AM
#2
Supreme Member
You shouldnt have any issues getting the new motor in but are you going to keep the computer or scrap it?
take both engine and tranny out together and put them back in together way easier doing it that way. Just make sure you have a engine lever it will come in very handy.
Yes your tranny will fit on the 350. 305 and 350 block are pretty much the same.
If your going to get headers I would get some long tubes.
Depending on your hosrepower and the way you drive the tranny and rearend
might hold up or maybe not.
And make sure you label everything before you disconnect it makes life alot easier when putting it back togehter.
take both engine and tranny out together and put them back in together way easier doing it that way. Just make sure you have a engine lever it will come in very handy.
Yes your tranny will fit on the 350. 305 and 350 block are pretty much the same.
If your going to get headers I would get some long tubes.
Depending on your hosrepower and the way you drive the tranny and rearend
might hold up or maybe not.
And make sure you label everything before you disconnect it makes life alot easier when putting it back togehter.
10-04-2006, 11:47 AM
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Car: 1991 z28
Engine: 5.7L
Do you think it would be better to get a new computer or get mine reprogrammed? I read online that I can get it reprogrammed but I havent really decide what I want to do just yet.
Im not going to be racing my car or anything just the odd street race here and there. When peopel in honda think they have a faster car than me I need to teach them a lesson. Other than that the car would be driving to get me from point a to point b.
Will my alternator, starter, fuel injection and etc work on the 350?
Im not going to be racing my car or anything just the odd street race here and there. When peopel in honda think they have a faster car than me I need to teach them a lesson. Other than that the car would be driving to get me from point a to point b.
Will my alternator, starter, fuel injection and etc work on the 350?
10-11-2006, 01:37 PM
#4
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I would get it reprogrammed and as for the rest i am not sure with the newer motor that you have now to another motor. I think you might want to look into a year specfic block but i could be wrong.
10-11-2006, 01:50 PM
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Car: 1991 z28
Engine: 5.7L
I haven't purchased the 350 yet, but I was going to get a 1991 350, the same year as my 305, I thought that would simplify things as much as possible.
10-11-2006, 02:34 PM
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Car: 82 Berlinetta/57 Bel Air
Engine: LS1/LQ4
Transmission: 4L60E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
The year of the 350 makes practically no difference. You would want to get one with '87-later heads, and roller cam is preferred, but those are minor considerations with regard to getting it to work. What is important is that it have good heads (not truck or swirl port), proper compression, and a TPI-friendly cam.
If the engine/heads are '87-later, everything will transfer over from your 305. Externally, the longblocks are identical, and that's what you're talking about replacing. What won't work (or at least won't work well) are the 305 knock sensor and module, 305 injectors, and 305 PROM tuning. The first 3 you just get the proper 350 parts. The PROM tuning can be done by getting a 350 PROM, but just putting headers on or having a slightly different cam can throw that off. The ultimate solution would be to get your own PROM burning equipment. You could start with a basic 350 tune and work from there.
3rd gen rear ends didn't change based on the engine that was installed. A V6 and a 350 could have the very same part. Similar story with the transmission, although there were slight differences between 305 and 350 with regard to stall speed, shift points, and the like. It wouldn't be a bad idea to have the transmission gone through while you're at it to freshen it up and put a Transgo shift improver kit in.
Personally, I think it's easiest to pull the engine and transmission together, especially if you're going to do something with both of them. I've done it both ways, and just getting the bellhousing bolts out takes about as long as unhooking the rest of the transmission to pull it out with the engine, and it's one less operation when you do them together.
Hooker 2055HKR are very good headers. They are made for the '86-'90 TPI single cat application, meaning they fit to a 3" inlet single cat. You'd have to change the cat(s), and probably at least modify the cat-back to get them to work, or modify the y-pipe that comes with them if you have dual cats. But, they are quality headers, and one of the best out there for our cars. Whatever you do, do NOT get headers for the '91 single cat application, since you would be retaining a major restriction with that small stock single cat by doing that.
If the engine/heads are '87-later, everything will transfer over from your 305. Externally, the longblocks are identical, and that's what you're talking about replacing. What won't work (or at least won't work well) are the 305 knock sensor and module, 305 injectors, and 305 PROM tuning. The first 3 you just get the proper 350 parts. The PROM tuning can be done by getting a 350 PROM, but just putting headers on or having a slightly different cam can throw that off. The ultimate solution would be to get your own PROM burning equipment. You could start with a basic 350 tune and work from there.
3rd gen rear ends didn't change based on the engine that was installed. A V6 and a 350 could have the very same part. Similar story with the transmission, although there were slight differences between 305 and 350 with regard to stall speed, shift points, and the like. It wouldn't be a bad idea to have the transmission gone through while you're at it to freshen it up and put a Transgo shift improver kit in.
Personally, I think it's easiest to pull the engine and transmission together, especially if you're going to do something with both of them. I've done it both ways, and just getting the bellhousing bolts out takes about as long as unhooking the rest of the transmission to pull it out with the engine, and it's one less operation when you do them together.
Hooker 2055HKR are very good headers. They are made for the '86-'90 TPI single cat application, meaning they fit to a 3" inlet single cat. You'd have to change the cat(s), and probably at least modify the cat-back to get them to work, or modify the y-pipe that comes with them if you have dual cats. But, they are quality headers, and one of the best out there for our cars. Whatever you do, do NOT get headers for the '91 single cat application, since you would be retaining a major restriction with that small stock single cat by doing that.
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