Fast355

iTrader: (2)

I just want to show what a good running 305 build can do. We are only scratching the surface with this setup. The shortblock has over 100K miles on it, the cam is still 4* advanced from pulling around my leviathon of a fullsize G20 conversion van and the Q-Jet is the functional equivalent of a DualJet. The truck still ran a 9.15 @ 73 1/8 mile with a 2.41s 60' time. Although it is in a 1980 C10 that my dad bought new in 1980. It had a 305 which got swapped for a 350 Goodwrench. The 350 Goodwrench engine spun a couple of rod bearings. The Vortec head, Crane 272 H10 cammed, 10.5:1, .040" over 305 that powered my 1983 G20 van came off the engine stand in the garage and went into the truck. We recently swapped it from a Saginaw 3spd column shift to a TH350 with a 2,600 stall and floor shift. Truck still has the original highway gears in it, witnessed by the fact it runs 65 mph @ 6,000 rpm in 1st gear. It runs suprisingly well with the old (now higher mileage)312 in it.

The Truck


312 TPI in Van


We swapped the 312 into his truck with a Q-Jet and a GMPP Vortec Q-Jet intake using the tweaked Q-Jet original to my 1983 G20 Van.









The Q-Jets secondary fuel cam fell apart during the swap which prevented the secondary hangers from raising the metering rods. Creating a huge lean bog when the secondaries opened. We have a new cam on the way, but it is still a few days off. To make the truck driveable we blocked the air valve linkage from opening at all.



Despite having the functional equivalent of a 325 CFM @ 3.0 in/hg Dualjet on the truck it moves and runs quite well.

The KEY to how this thing runs so well...PORTED 059 305 Vortec heads with 1.94/1.60" valves and .484" valve lift from the 1.6:1 roller rockers.



We are really thinking of tossing my modified for TBI, Edelbrock 2912 Victor Jr 2bbl Vortec intake onto it with a 454 TBI unit.

Startup and a few quick revs
http://www.youtube.com/watch?v=sWlqAgpEyhc

WOT acceleration on the primaries only
http://www.youtube.com/watch?v=9S8A6nD0WMI

Doom86

Yeah do the TBI it will be right at home in the truck. I also have a personal interest in how it runs too.

After seeing what you did with them on that TPI 305 I wanted to try my hand porting some for my TBI 305 in my RS and use EBL to tune.

What was your focus in the head porting? You obviously didn't just do a standard mindless hogging to get the results you did.

When you get those secondaries fixed it's going to feel like a new motor I bet. It sounds great though, gotta love them air-plane gears too (120mhp in second gear? )

Fast355

iTrader: (2)

I did spend a good amount of time cleaning up the heads and the casting. Although these heads really responded well to the larger valves. I got atleast 50% of the gains from the 1.94/1.60 undercut valves and reworked valve seat angles alone.

TBI and a single plane intake like an edelbrock victor jr 2bbl 2912 would really wake the top-end of this engine up even more without hurting torque. It would be interesting to run this setup with the EBL Classic I have hanging around.

We are building the Q-Jet tonight for the truck.

We have discussed putting the L30/L31 injection setup I have kicking around in my garage on it and running it with a 7730 TPI ecm. The small cap HEI will clear and the sensors are just everyday GM specifications. With 22 lb/hr worth of injector per cylinder the Vortec injection setup will not be a limitation on a NA 305.

The airplane like gears really seem to hurt acceleration, but they are somewhat of a blessing cruising down the highway @ 70+ mph with no OD.

Doom86

That is very true about the gears I have to say that. I have the same problem. It's the only thing I don't mind about the pathetic TH200C + 2.73 combo in my Z28. (the highway cruise RPM)

The secondaries will make a huge difference with this though you may not want to do any swapping once you get that sorted out. Do you plan to modify the secondary air valve?

That made a huge difference on the transition from idle to WOT on my Z28. Mine just had a small slot cut on each valve above where it shoots fuel into the secondaries. I know you understand what I'm talking about, I copied from your CCC Qjet a while ago, just explaining so others understand. Even with a good choke pull-off there's still a noticeable transition from idle to WOT but with the valve modded like this it just flows right into it.

Did those valves in the heads have the margins cut as well? It looks that way in the picture is why I ask. My plan was to make the port taller by raising the roof and trying to not widen the port as much as I can help. And cleaning the casting up and the valve guide. That may change once I get a good look down the runner though.

As soon as I get this 305 done in my Z28 I'm going to start searching for good 059 cores to port and build for next summer. Thanks for sharing all your info.

Post some more videos when you get that thing running right.

Fast355

iTrader: (2)

Consindering the air valves came from the CCC Q-Jet that was on my 1983 G20 van, it has modified air valves. Nice little transition slot cut into the leading edge around the transition port. Keep in mind Pontiac did this from the factory.

The margins were not cut, but the valves are .050" longer than stock and it has a 5 angle valve job, also often called a radius angle. I can actually run a .600 lift cam on these if I felt like it.

I have some additional jets ordered for this carb. I have found the metering area is TINY on the primaries at the moment. Somehow I ended up with 70 jets and a 50 metering rod. To put this in perspective a 1977 L82 350 in a Vette ran 76 jets and 46 metering rods.

I have jets coming...73, 75, 76, 77 and primary metering rods 48 and 52, secondary rods CE (.0410) and CC (.0300), a B hanger, and Power valve springs in 4, 5, 6 in/hg. Should be plenty to get it dialed in well. The primaries are a little lean @ WOT at the moment.

Here is a little video clip as my brother pulled away tonight after we tweaked on it a little. Unfortunately with the gears and the distance to the next stop sign the secondaries really didn't even get a chance to open. I have the air valve tension set at 1 full turn at the moment. Eventually we will tweak it to open sooner they open around 4,000-4,500 rpm now.

http://www.youtube.com/watch?v=sDzZqIz7_eY

Things left to do

A.) Fix the exhaust leaks he has at the shorty header to exhaust pipe flange.
B.) Tweak on the timing, its still an un-touched GMPP HEI distributor from a 330 HP 350 Vortec HO
C.)Tweak on the jetting of the primaries
D.)Find the right secondary metering rod/hanger

Fast355

iTrader: (2)

This is for the few of you that are following this build.

I did a little more work to the distributor today and also added the EGR setup back onto the engine. We also added an air cleaner housing and air duct from a late 80s TBI suburban.

Notice how clean the Q-Jet came out!! EVERYTHING about it works exactly like it should. When its cold, press it once to the floor, the choke sets and it fires right to life, stays running, and idles down as it warms up. When its idling, tip into the throttle even a little and it wakes right up. Floor it and the secondaries kick in and it goes...Although the air valves are a little loose and it will bog a little if you punch it at low rpm.







Right now the setup is as follows.

Carb---hybrid M4ME Q-Jet (17083226 body and 17084226 base and airhorn)

Primary Jets = .070"
Primary Rods = .050M... All Q-Jet Primary Rods have .026" power tips.
Secondary Rod = DR
Secondary Hanger = B
Air Valve = 5/8 turn

All other carb adjustments STOCK

Distributor = GMPP HEI

Centrifical Weights = 41
Center Plate = 369
Springs = One Moroso Light and One Moroso Medium
Centrifical advance is 22*, starts at 1,200 and is full in by 2,900.
Initial timing is 10*
Vacuum advance starts at 5 in/hg and gives 10* crank by 10 in/hg vacuum...Classic 10* @ 10 in/hg
Vacuum advance hooked to MANIFOLD vacuum

I am still waiting for the FedEx truck to drop off the tuning parts I need for the carb. I worked with the secondary opening rate and they are actually opening a touch too quickly when you actually get the pedal to the floor. We found that his throttle pedal trave would not quite reach WOT, so we bent the pedal arm up some. We were then able to reach WOT.

Listen to this sucker SCREAM when the pedal is floored half-way through first gear.

http://www.youtube.com/watch?v=VxJmvWAlIQQ

Doom86

Sounds awesome man I love to hear them Qjets scream it sounds nice.

That motor really wakes up on the top end you can hear it.

Fast355

iTrader: (2)

Yes it does pull VERY well up top after the secondaries open...On that run he was on the primaries up till around 3,500 then smashed on it (you can hear the distinct secondary scream when he finally hammered it). I had a wideband on it logging it and it was showing about 15:1 air/fuel ratio at heavy part-throttle when 13:1 is more appropriate. The larger jets and smaller metering rods I have on the way should take care of that and make it more responsive through the low-midrange where only the primaries are being used. I have learned PRIMARY jetting makes or breaks the 60' times with a Q-Jet. Shifts were happening somewhere in the 5,800-6,000 rpm range in Drive after tweaking the governor. The truck lags a little from the 2.73 or 3.08 airplane gears, then gets up on cam and moves out. I really want to pull out the 4* cam advance and set the cam to its specifiend 105 ICL.

http://cranecams.com/?show=browsePar...52&lvl=2&prt=5

I LOVE the way it sounds too....The sad thing is with my little rivalry on our trucks my brother and I have, I built his too fast. Now his little 305 runs with my cammed Hemi in my 06 Ram. I am going to have to make the Hemi faster to stay out in front of him.

Fast355

iTrader: (2)

Most of my carb tuning parts arrived today on the FedEx truck, although my 77 jets and 48 primary rods have not arrived yet. In that same box came a little surprise I ordered myself to go along with the tuning efforts.

Once I get the primay jetting a little closer, I am going to install a 2* advance limit bushing in the centrifical advance to drop the centrifical advance to 20*. Then I will advance the initial up to 12. I also have a thicker 4* bushing that I may try as well, with 14* initial advance.

My brother and I are really thinking of installing a spare engine harness we have from a 94 CPI S10 Blazer and putting in a 7427 TBI PCM with a small cap HEI EST distributor. With that installed his leaking longtail TH350 will come out and in its place will be a Stock Rebuild 4L60E with a S10 converter and Transgo HD2 shift kit.

bluers91

A nice thread you have posted once again Fast. You give me hope with my 062s sitting in the garage. Once I collect a few more parts ill be doing a similiar upgrade to my 305 TBI.

basiccamaro

Cool thread! I'm interested in seeing how those 059 heads run, I've got a stock set laying around the garage.

As for putting 062's on a 305, you're going to lose a lot of compression if you don't mill them pretty far. 062's combustion chambers are 64cc's and 059's are about 58cc's.

Fast355

iTrader: (2)

If you use flattop pistons with 6cc reliefs standard compression height and a .015" rubber embossed shim, it will give you around 8.9:1 compression at standard bore. Oversize bores bring the compression higher.

bluers91

I plan to have them milled first to keep compression. I'd like to shoot for a 10:1 using the shim gasket to have a nice quench. I also have an LT1 cam and carb to tbi adapter. The cam looks a bit thrashed so i plan to find another. Still need intake, timing set, gaskets, time, EBL, etc.

Fast355

iTrader: (2)

Well I need to take a couple of pictures and maybe see if I can get a better video.

The first thing I did was install the additional experimental part that I obtained for the truck. This was the secret that I didn't mention.



I then tightened the air valve and additional 1/4 turn. As you may recall we had some WOT bogging previously. You might also notice that that is 7/8 turn windup, which is factory specification for this carburetor number.

The headers on the truck were designed for a L31 Vortec and have dual oxygen sensor bungs installed into them. I do alot of EFI tuning and have an Innovative LM1 with dual sensors. Out came the LM1 and we hooked it up to the truck. Turns out that in the near stock configuration the Q-Jet is very much an emissions carb. The banks were fairly even and here is approximately what we got for air/fuel ratio.

Coasting = 16:1
Idle = 14:1 (Set for highest vacuum)
60 mph Cruise = 16.5:1
Light Acceleration = 15:1
Moderate Acceleration = 15.2:1
WOT Primaries = 14.9:1
WOT x 4 >3,500 rpm = 13.5:1

The Q-Jet parts came in on the FedEx truck today. I swapped the 70 jets for some 73s and installed 52 metering rods in place of 50s.

Here are the metering areas with 70 jets and 50 rods.

Cruise = 0.00188496"
Power = 0.00331752"

With 73 jets and 52 rods.

Cruise =0.00212372"
Power = 0.00365446"

That works out to....

Cruise = 12.667% Larger = Richer
Power = 10.156% Larger

Back on the road the truck was definately crisper on the primaries. The very slight hesitation the truck had on minute throttle openings was greatly reduced.

Coasting = 16:1
Idle = 14:1
60 mph cruise = 15.8:1
Light Acceleration = 14.5:1
Moderate Acceleration = 14.4:1
WOT Primaries = 13.8:1
WOT x 4 >3,500 rpm = 13.2:1

I felt the idle mixture was a little rich and leaned both sides out to 14.5:1. Here is how the truck responded.

Coasting = 16.4:1
Idle = 14.5:1
60 mph cruise = 16.2:1
Light Acceleration = 14.8:1
Moderate Acceleration = 14.5:1
WOT Primaries = 13.8:1
WOT x 4 >3,500 rpm = 13.2:1

As you can see the idle mixture screws have NO effect over about 1/2 throttle on the primaries. I was shocked at how much those two screws affected the whole fuel curve under 1/2 throttle at all rpms.

The truck is still a little lean on the primaries for my taste and probably a 1/2 point lean on the secondaries for best power. The float level is perfect, so I am not going to play with that. I think the next step is to increase the main jet size to a 75, keeping the 52 rod. I may also put in the 6 in/hg power piston spring in place of the stock one that looks to have been a 4 in/hg spring. I may also installed the B-hanger on the secondaries to pull the secondary rods up sooner, delivering more WOT fuel. It is currently a F-hanger. If the 75 jets and B hanger don't make the WOT mixture rich enough, I will try either the DA (.440") or CE rods (.410") power tips...As opposed to the DR (.570"). Whats sad is on the same engine from 1983 to 1984 GM reduced the secondary rod from a DR (.570) to a DP (.686)...That HAD to kill power because the whole rod is fatter at every air valve opening%.

This is my goal and I am going to see how closely I can get to it. Keep in mind these values are also all with a stock GM NOS 1983 305 G20 Van EGR valve installed.

Coasting = 16.5:1
Idle = 14.5:1
60 mph cruise = 15.6:1
Light Acceleration = 14.3:1
Moderate Acceleration = 13.8:1
WOT Primaries = 13.0:1
WOT x 4 >3,500 rpm = 12.7:1

I should also mention the engine accidentally buzzed 6,900 rpm today for a seconds in first gear. Oops! The engine had a noticeable missfire above about 5,000 rpm. I closed the plug gap from the .060" vortec spec to .035" and it went away. I am fairly certain the culprit is the stock GM ignition control module. I guess its time for a MSD 6a with the HEI pickup coil triggering it directly. When the MSD goes on I will probably open the gaps back up to .050".

Doom86

Do you think that spacer helped at all? I've always had a feeling they were a waste but you never know.

Are you using a stock mechanical pump with this?

Fast355

iTrader: (2)

The spacer seems to have helped at part-throttle and throught he mid-range. Maybe a few HP as well.

The mechanical fuel pump is stock spec for a 1983 305 G20 van. Has not seemed to be inadequate yet.

Doom86

I agree that's why I asked it sounds great on the high end and it gives me hope for my stock pump too.


try to get a better video lucky for you you're a better engine builder then a camera man

Fast355

iTrader: (2)

I will get a better video soon, once we fix the damage we caused to the driveline hammering on the setup. The carrier bearing completely fell apart and the driveshaft was flopping around in the carrier bearing mount.

Doom86

You get this thing dialed in yet Fast355?

Damon

Sounds like a great low-buck combo.

One thing about the primary rods in that QJet...... since it's a "truck-style" QJet it probably uses "M" style primary metering rods. They are the same length as older "K" style rods but the power tip isn't .026", it's .036". That's the difference between M and K rods. If you run the math again you'll see the difference in WOT metering area (jet area - rod area) vs. what you calculated.

You've obviously put in the effort to calculate things out before you make a change so I thought I'd just point this out to maybe save you a little time banging your head against the wall.

Your stock calibration (50M rod/70 jet) is a little leaner than most truck engine QJets. They would more commonly have a 72 jet with those 50M rods, but it's not radically different than most stock calibrations. My usual advice is to go up 4 jet sizes from stock and keep using the existing rods as a starting point for a mild performance application.

That's close to what you've already done, but also explains why you're a little lean at WOT on the primaries. It's that difference of .010" on the primary rods' power tip that's causing what you're seeing. So you might want to jet up a little more and then lean out the primary rods to bring the cruise A/F back down. If your carb has an APT screw don't be afraid to use it as part of your tuning efforts.

Given that K rods are getting pretty rare but M rods are still readily available it would probably be advisable to keep using M-style rods during your tuning. I've been experimenting with them in QJets that originally used K rods for that reason. They work fine, just that the jetting on those earlier QJets often has to be in the range of 80+ to make them work.

In your case you might want to think about doing the reverse.... putting in a set of similar number K rods. Like a 48-49K, if you can get your hands on them. That would keep the cruise A/F close to where it is now but fatten up the WOT mix. Just something to keep in mind if you want to try it later on.

Fast355

iTrader: (2)

Its dialed in pretty well, but we are going to make some changes soon. It has a small front crank seal leak and a leak at the timing cover/oil pan junction. The timing cover is junk as well. When we get the time, we will change it out and while we are in there, pull the cam back to TDC. We also have a set of 1.6:1 full roller rockers we put on the truck not too long ago.

Damon,

Thanks for the tips...I completely forgot that the trucks had .036" power tips on them.