350 timing related to carb setup ?

I'm getting some difference of opinions on some motor and carb issues here locally, so I went to the internet looking for some more opinions. I drove a 79' chevy caprice for 21 years, man I miss that car, but family and lack of funds to put into her, I had to let her go. I'll give you the scenario and info if you folks have a suggestion I'm all eyes.

I'm having some carb issues, so I ordered a rebuild. Wont idle right, really rough. So guy builds another one, different setup per are discussion on the motor, same thing rough idle. In doing a lean idle drop method to smooth it out, idle screws didnt make a difference unless all the way in to stall it. This whole thing had me rechecking timing, plugs, wires, vacuum leak.

I am working on a 77' van with an 83' motor. Supposedly the motor is out of an 83' caprice police car. The manifold, carb and distributor are off the stock 77' van. I have a rochester 4mv carb on it now that idles fine, floods out and bushings leak from time to time. So I have kind of ruled out tune up stuff and vacuum leak. I got 21hg. vac at idle off the manifold, good no ?

Timing and plug types, the 77' specs on the van sticker call for .45 plug gap and 8* btdc, caprice car specs are .35 plug gap and 6* btdc. It's been awhile but I think I tried the .35 plugs and it didnt run right. why wouldnt it if it was in a car before the van. Carb is a different type ? The carb guy built the second one setup for the car I guess, said something about the cam. I told him I didnt know what cam it has but all my 77' parts have worked for many years before I got the van from my dad in 95' when he died. I know he got the motor with 50,000 miles, state police used to pull there motors at 50,000 and put fresh ones in here in Oregon.

I rambled on enough to get the idea of what I am trying to achieve. Any insight why these new carbs are not idling right.

TIA MIKE  

before we go too far...    read up on the Q jet...   A picture is worth a million words...

here is a bunch of Qjet articles that cover several variations...  

you will have to cut and paste the links to open each one..

read up... book mark them ...  then post your question as you will then know a lot more about the carb...    adjusting the electronic feedback versions is not really covered..  so you might also want to post the carb number so someone can check out which version you are working with..

answer this post when you find something..

http://www.circletrack.com/techarticles/ctrp_0607_quadrajet_tech/index.html

http://www.hotrod.com/techarticles/engine/edelbrocks_q_jet_carburetor_replacment/index.html

this one covers the electronic version.. but mostly the mechanicals...

http://www.carcraft.com/techarticles/ccrp_0908_qjet_carburetor_rebuild/index.html

anybody who even thinks of owning a q jet.. needs to read and book mark these articals


http://www.superchevy.com/technical/engines_drivetrain/induction_poweradders/sucp_0012_gm_rochester_quadrajet

http://www.chevyhiperformance.com/projectbuild/148_0403_1974_chevy_camaro_z28_quadrajet

http://www.chevyhiperformance.com/techarticles/49860_rochester_quadrajet_carburetor

http://www.chevyhiperformance.com/techarticles/0606ch_jet_performance_products

http://www.popularhotrodding.com/tech/0802phr_how_carburetors_work


and a huge tip....

copy the entire text... paste it in an email to your self...  the links will be clickable then..


oh.. and somehow...  spaces have been added to the links..  you will have to copy  paste and edit the links for ones that don't show up... i have tried to edit the spaces out..

perhaps an admin..    will make sure that all the posts show up when any of the variations of quadra jet are searched for in the search window of any of the magazines..  it took several hours of searching to grab them all..  how many ways can you type quadra jet..  qjet.  .......  


one other thing...   examine the ignition coil for external high voltage leaks...  

Thanks for the links. I have Doug roe's book on rochesters and a few others. Coil and ignition module are new.

Anyone have an explanation why timing and plug gap between a car and a truck setup are different and why my 350 doesnt like the car setup with .35 gap and 6* timing.

I hand vac the vacuum advance and it held pressure and started to pull in at about 9 hg. and seemed to be all the way in around 12 hg.  

the reason for the timing and gap differences may be because the cop car is designed to idle for long periods of time. The best builder of quadrajets around is JET performance. sent mine there and when i got it back it looked brand new and worked so well i started beating cars in stoplight brawls that previously were untouchable. Many people are sold on holleys and demons (billet holleys) but theres nothing like feeling the secondaries kick in on a q-jet. mine is factory rated at 720 CFM.