My '74 LS4 has a matching number Engine and Tranny (TH400), but has an edelbrock 1406 mated to the original intake with an open element air cleaner. The engine is a fresh rebuild, but in spite of what seems to be a solid setup/rebuild it's still not running/sounding quite right.

I have my suspicions that the carb just isn't right or not cutting it. I did notice that gas was 'puddling' in the back two bores on the side as well as just the overall crappy idle/power. Timing is all good it seems and everything else up so thinking its time to go ahead and flip the carb.

My goal is to go back with a year matching/model Q-Jet for that engine and an original air cleaner assembly - thanks to Lars' information and spreadsheet I believe the Q-Jet model I'm looking for is 7044225, but where I get lost is these date codes - so long as I find that model do I need to worry about date codes to match things up well, or do is there another lay of specificity that I need to watch out for in these date codes to match up? If so, how do I know what date ranges I need?

Oh, and of course if anyone has one out there to let go for cheap that I can send to Lars for a rebuild, feel free to PM me

 

Guess it depends on how authentic you want to be, do you know when your car was manufactured. If so you need a date code prior to that date but not more than 6 months.

 

Actually, had another question, on the list that Lars sent, I noticed that there were actually two number that seemed like they referenced what I should be looking for on my LS4, 7044223 and 7044225 - is there any reason I should match one over the other - I don't quite follow the differences and/or how I would know what was originally in my car.

 

If your car was 49 state compliant, it came with a 7044225. If it started life in CA, it had a 7044505. Finding a carb with the correct numbers and date is nice but it's just the tip of the iceberg. Who knows what Bubba might have done to the carb in the last 40 years?

If you're not worried about judging I'd sooner start with a decent core and have Lars go through it making sure it's 100% functional.

 

Its honestly not my plan to make it a true show car. Mostly a weekend driver and maybe the occasional small 'show for fun'. I just figured I'd attempt to see if I could find a fair/matching carb that Lars can work his magic on first, but if not then realistically I will most likely just grab up the best bang for buck shape one I can find and send it to him to go through and dial in. He did wonders with the QJet I had in my 76 - the man is definitely worthy of the praise he gets!