Hey, RB, I know you used to have a '79 Camaro (Z28?) so I have a few questions about the engine in my '83, which is a 350 out of a '79 Z28 4 speed.

The engine, I know for a fact, is an L48. I know this because I checked the VIN on the '79 before I took the engine. It appears to be rebuilt, but I'm sure it is a stock rebuild by the engine's previous owner.

Anyway, my questions are these:

1. Do you have any info on the cam specs?
2. Do I have flat top or dished pistons?
3. What size are the valves in the heads? (882's I'm sure)
4. What was the size (cfm) of the factory 4bbl on the '79 and what is the size of my '83 L69s Qjet?

Thanks in advance

 

1. It had the infamous 929 cam.... .390"/.410", 195°/202° 112° LS, extreme POS.

2. Dished... 15cc or 18cc, I never measured them

3. I don't recall exactly which heads they were, some kind of smog crap such as 882s or 624s; I threw them in the trash and put some 186s on it. Made a monstrous difference. Still didn't have any nads, but at least it wasn't quite as embarrassing any more. They had the same valves that nearly all 350 heads come with: 1.94"/1.5".

4. That's the wrong question to ask about a Q-Jet. Their bores are all the same diameter. So their flow is all the same, except for a few certain ones that came on Buick 455s in the early 70s which had larger primaries. A LG4 carb typically has a tang on the sec AV that acts as a stop, to keep the little motor from leaning out on the top end so bad; that's the only difference between a 79 350 one and the 83 305 one, as far as flow capacity goes. Q-Jets flow about 725-750 CFM with the AV all the way open. The tang limited the flow to about 625 or so. But that's not real precise, just a rough ballpark figure.

 

Great... thanks alot RB

 

 

Not to jack your thread Adam, but RB?? I just picked up a 1973 400 sbc cast # 511 it has the stock cam, with no indication or part #'s I have searched many places to find out the specs on this cam, wondering if it is worth keeping. Looks to be in great shape, so.. BTW this is a 2 bolt block, not the 4 bolt. Any help would be great. Oh and would the Q- Jet on this engine possibly be the larger bore you were reffering to also? It also has teh 997 cast heads, ann input on those to please?? Thanks very much.

Keiran

 

Kaz...

The 400 sbc never had more than 200hp (SAE) from the factory, it always came with a 2bbl carb, never a 4bbl carb and never over 9:1 compression..

Since these engines were pretty anemic, and only built to get Grandma to the grocery store, I doubt that cam is worth keeping if its the stock 400 cam.

just my opinion though

 

DSpeaking of Q-jets, I think the older ones came in two flavors, 800cfms and mid 600cfms. My memory is faded a bit, but seem to recall my LS5 had the 800cfm Qjet, which had noticibly larger secondaries than my friends Buick 350 engine, back in the day.

I dunno, just rambling to add to the thread

 

Actually Adam the 400sbc ion this era, came with 265 hp and well over 300ft#'s of torq. I am not sure where you got your info. But it is wrong. sorry.

 

Yea, and every 400 with a rod poking out of it Ive pulled out of trucks had a 4bbl Q-jet sitting ontop, factory.

But The stock cam is for schit. Your way better off replacing the heads and cam with almost anything other then the stock 400 parts. The last couple I bothered to check had 1.88 intakes in them.

 

Really?.. well, i guess i stand corrected. I've never seen a factory 400 with a 4bbl though.

And yes, they were rated at 265hp, but that was gross hp, not SAE (like I said above)

When they changed it over to SAE in '72, it went right down to 180hp, and was the same since '70.