Chevy V6 questions

Started by GPster, November 16, 2006, 09:17:47 AM

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GPster

I have an even-fire V6 that is probably out of an '85 Astro van. It was fuel injected with a / that bolted on a quadrajet looking intake manifold. This engine is made to take a regular style fuel pump and I've changed the distributor over to where we think it will work as a normal HEI. Now the only quadrajet I have is off that '79 350 truck engine I have and it's been in the 2003 flood so it will need rebuilt and then I feel it would be "Over-Kill". Also the V6 manifold has the "Smog Pump" devise on it. Now,I know that Chevy used these 90 degree V6s in the '70s in their trucks and the'70s trucks where excluded from the smog pumps--------SO------will an "odd-fire" intake fit on an "even-fire" V6, what carbs did they use and did those manifolds have the "smog pump" stuff on them? If everything else fails, point me at a site that tells how to make a quadrajet work on 3/4s of the intended  application? Now for part 2: My V6 came with a flexplate on it. I was going to make it all one "lump" with my '79 350 turbo and starter. The '79 engine is still on it's engine stand and the flexplate is captured on it. Are the flexplates the same for torque converter and starter or do I need the '79 flexplate or nothing will work? The Jeepster is schedualed to go back in the garage the day after Thanksgiving so I'm trying to put lumps together. GPster

model a vette

Quote from: "GPster"I have an even-fire V6 that is probably out of an '85 Astro van. It was fuel injected with a / that bolted on a quadrajet looking intake manifold. This engine is made to take a regular style fuel pump and I've changed the distributor over to where we think it will work as a normal HEI. Now the only quadrajet I have is off that '79 350 truck engine I have and it's been in the 2003 flood so it will need rebuilt and then I feel it would be "Over-Kill". Also the V6 manifold has the "Smog Pump" devise on it. Now,I know that Chevy used these 90 degree V6s in the '70s in their trucks and the'70s trucks where excluded from the smog pumps--------SO------will an "odd-fire" intake fit on an "even-fire" V6, what carbs did they use and did those manifolds have the "smog pump" stuff on them? If everything else fails, point me at a site that tells how to make a quadrajet work on 3/4s of the intended  application? Now for part 2: My V6 came with a flexplate on it. I was going to make it all one "lump" with my '79 350 turbo and starter. The '79 engine is still on it's engine stand and the flexplate is captured on it. Are the flexplates the same for torque converter and starter or do I need the '79 flexplate or nothing will work? The Jeepster is schedualed to go back in the garage the day after Thanksgiving so I'm trying to put lumps together. GPster
The 200 and 229 earlier Chevy V6 manifolds will bolt up. There is no reason not to use the manifold you have if a Q-jet bolts to it. I think the only smog part on it is the exhaust gas recirculation valve. You could get away with just leaving the vacuum hose off it to keep the valve closed or you could remove the valve and make a block-off plate to seal the holes.
The 85 Astro van manifolds are usually hi-rise cast iron (heavy!) manifolds. The hi-rise allows more clearance for the aircleaner to clear the distributor. There are some boat manifolds that are similar. I'm using a Weiand or Holley (can't remember which) that was for the earlier engines. Edelbrock made manifolds for both the early and late engines. The only real difference is a cut between the left and right sides of the chamber under the carb pad. The later manifold has the cut, I suppose to even out the distribution between the two sides. The 200 V6 came out in 1978 and used a Q-jet which only had primaries and undrilled secondaries. I think they started using a semi-computer controlled Q-jet in 1980-81 when they went to 229s. They are expensive and were a patch to meet smog rules at the time.
The Buick 231 or 3.8 V6 was made for years and had Q-jets also. One before 1979 would work ok for your application. I lent a 307 SBC 1968 Q-jet to a rodder having problems with his Holley spreadbore carb so he could get home from the Streetrod Nats. He sent it back to me with a note saying that it got better mileage than the Holley. I suspect that Q-jets with their small primaries and somewhat vacuum controlled secondaries are more forgiving if used on smaller engines than they were designed for.
On any 86 & up 4.3 you have to use a flywheel or flexplate designed for either a 4.3 or a SBC with the later small crank pattern. These engines use external balancing (kind of like a 400 SBC but a different flywheel). I'm not sure about '85 engines. I have a Chevy Power Manual that says only '86 and up have the one piece rear main seal and small crank flange. I think the '85s had them also. You should be able to see if the crank flange is the small pattern even on the engine stand.
The starters are the same with the only difference being straight across bolt noses for the 153 tooth and staggered bolt nose for the 168 tooth flywheels. Both 153 and 168 tooth flywheels and flexplates were/are available for the small pattern crank flange. I don't know if the bolt patterns for the converter are the same between the early and late flywheels. You can redrill the flexplate if you need to change the pattern.
Ed

GPster

OK, the crank is the large flange style with the two piece main seal. I pulled the 350 out from the wall (why do we stow stuff backwards) enough tocompare O.D,s and they are probably the same tooth count so thats one thing. Your explanation of the high rise intake was excellant for making me look at the clearance around the HEI which makes a good reason for keeping it. The breathing of an even-fire vs. odd-fire might make a differance but I'll keep it in mind when I go visit the engine pile at the junk yard and see what's laying there. I'm going anyway to start a collection of pulleys to try to put a short water pump on it. That's going to be real funas the 4.3 has a big recess on the front of the crank damper. My biggest reason for not wantting the smog pump diaghram on the front of the intake would be if we ever got in the position wher they would order you to pop your hood and ask "How come this isn't hooked up". I might just block it off for now as it doesn't leave many choices where the top radiator hose will be. One more question, How long is the dipstick? GPster

sirstude

Joe,

Just put a BB in the vacuum line to the EGR and they will never know, and it will look like it has all the smog stuff to keep them happy.

Doug
1965 Impala SS  502
1941 Olds


Watcher of #974 1953 Studebaker Bonneville pas record holder B/BGCC 249.945 MPH.  He sure is FAST

www.theicebreaker.us

model a vette

I used a "universal" V8 chrome dipstick and tube I got at a parts store. I had to cut 1" off the tube to make it match the reading on the original three foot or so long dipstick. I actually had to buy a second tube and dipstick because I bent the first one getting it to clear the stock chevy headers that came with the engine from the '86 MonteCarlo.
What kind off exhaust are you going to use?
I think you can use the entire pulley setup from a short waterpump V8. They used the short pump up to 71 on most SB V8 trucks and up to 68 on cars.
Ed

GPster

Quote from: "sirstude"Joe,Just put a BB in the vacuum line to the EGR and they will never know, and it will look like it has all the smog stuff to keep them happy.Doug
With the pump not there and different pulleys on the front I like the looks of an intake manifold that doesn't have a strange plate bolted on the front of the intake manifold. This vehicle will be licensed as a 1948 Willys and Ohio doesn't require any change to the title for engine changes. If it ever comes to that I'd rather it look like a '77 229.GPster