well fellas, im new to the group and thought i could find this site useful, im in the process of buying a '84 trans am. its got the L69 w/ a 5 spd. i know they started doing a lot of that electronic engine control junk them years and i diddnt know if it had one of them electric carbs? the engine is no good but im ging to put in a freshly rebuilt 305 (pretty much stock) and i was wanting to bypass all that electric engine control crap and and go manual carb (quadrajet) and set it up simple w/ no computer stuff. also did these cars alredy have that electronic timing junk or a distributor? the 305 im putting in is going to have the dist. of course as im trying to keep it simple as can be. so how hard would this be or what problems can i look forward to? also, lots of people say to run a 350 cause their better and so on, they are better but im trying to stay simple and there would be more things to do to run a 350 and the 305 is there handy and cheap w/ only 7000 miles on it. any help is greatly appriceated,

D.

 

Welcome aboard thirdgen.org.

Now, we need to straighten out some misunderstandings.

First, yes, the L69 had the "computer command control", as we abbreviate it around here, computer controlled or "CC" quadrajet. The computer controls mixture in the primaries (until wide open throttle), timing, and has knock sensing capability (all L69's - the lower performance LG4 didn't get the knock sensor until 1985).

Now, to address all of the pejoratives and biases: The CC q-jet is the best possible street/performance carb/ignition system out there. Without exception. The only "excuse" for putting something else on is the manual transmission, and you're headed absolutely the wrong way with a non-computer q-jet. The only excusable carb replacement, and only because of the manual transmission, is a mechanical secondary Holley (double pumper) or Demon (dual squirter). What you are proposing is silly, bordering on stupid (to be frank).

Now, about your replacement 305 - you'd better understand exactly what it is. The L69 had higher compression due to flat top pistons than the vast majority of 305's out there. It's almost 2nd nature for rebuilders to put dished pistons in when they rebuild an engine, especially 305's. The cam is another important component, and the typical rebuild cam is pretty lame.

With that rebuilt 305, you could be putting in a real clinker.

So, that's my take on your plan.

 

thanks for the info. the thing is im wanting to stay easy and cheap. the car has no carb and the guy wants the heads off it and the other engine im sure had flat tops in it. it was going to be put in a derby car but was never used. i have no "CC" q-jet and im not buying one as i alredy have a manual q-jet from a '75 trans am 400. its had some work done to it, its got the bigger 72 primaries and i cant remember what the secondaris are but its had a couple hundred dollars worked into it. i was told that that carb would be to much for that little 305 and it probly is but i will see. and as im goung to be short on any cash this will be done myself w/ some help and im not taking it to no shop and spending thousands of dollars to get that computer stuff set back up. i know what its like having an electric carb, i have a '85 nissan 720 2wd and i like it but i would rather adjust my own carb than rather having a piece of plastic under my seat do it for me. i going to run it w/ no A/C. there is wires under the hood everywhere and im not going to trial and error them for days trying to get the electric stuff put back together and im not paynig someone to do it. you see, im not trying to restore this thing back to showroom floor standards, but have a easy to work on and fun to drve car and mostley not spending very much money exept on essential things that i dont have (and not a CC q-jet).this car is going to be simple. and for the 305 replacement, this is a guy i know and he's not going to rip me off and its probly just a 305 out of a truck or something thats been rebuilt. as i said, this will be a simple car build up whether whoever think its dumb cause i dont have money to pay for, fix up, and maintain all the nice cars you show on this site.

 

Well, there's nothing like having all of the information. Sounded like you were getting a complete car with a bad engine, not no engine and no carb.

The Pontiac carb isn't going to be that much of a problem. Jet size is only half the story, as they have rods sticking down in them that together determine the fuel flow. Unless deliberately jetted up, '75 was smack in the middle of the smog-dog era, so probably wouldn't be overly rich on a well-tuned 305. The secondaries adjust themselves to the flow needed by the engine (when properly adjusted the first time), so that isn't a big issue, either.

Why you would "want" a carb that needs retuning when the weather changes or you go to a higher/lower elevation is beyond me. You don't have to be doing a restoration to benefit from it, and I don't think low-13's out of a daily driver is anything to sneeze at.

But, to each his own. To get the mechanical q-jet (or other non-computer carb) running, you'll need a vacuum/mechanical advance distributor, and that's all there is to it. The car having been equipped with an L69 may have an in-tank electric fuel pump, and I'm not completely clear what will have to happen with that once the ECM goes brain dead.