Well I finally got one, a 1975. Oh my she's very pretty but soooooo slow and all over the road. Man this thing is borderline dangerous what the heck was I thinking buying this! The person I bought it from told me she was a numbers matching vehicle. I don’t think it is. I found a stamping on the rear of the drivers side of the engine and found out it actually came from an early 80s vehicle. Dipstick was on the passengers side - I didn't know these things prior to buying it but I’m learning now! So the original engine for this car would have been a L48 according to the vin. I think this may be a L82? The bore size is approx 4.000". The pistons are flat. The cam is stamped 260H. As far as the heads they are heavy cast iron. It has a Quadra Jet carb. Original exhaust manifold and a Weiand intake. Again this machine is slow and loud. Can’t even peel out if the road is wet. I’m attaching some pics to see if you can help me figure out what engine I have and if it’s worth saving.

1975 C3


Rochester Carb

Cylinder heads

Flat pistons

Weiand Intake

Front numbers on engine block

Numbers on engine block rear driver

Numbers on heads

Approx bore size

260H Comp Cam ?
I also would like to get some advice on how I can get some more HP out of this engine. Nothing crazy I’m not going to race - just want to keep up with cars under 300HP.

 

I was going to say to get rid of that extra fuel filter and rubber line leading to the carb, but as I scrolled down it looks like you removed a little more than that!

Many small blocks were made with pistons like that. I don’t think it’s an L82. The 624 heads come back as some of the worst heads ever put on a 350, however with that comp 260H cam you should be able to make somewhat decent power. You could put it all back together the way it is and worry more about your ignition timing and exhaust to up the power.

However, since you already have it apart…

Some 180cc runner 64cc combustion chamber aluminum heads would really liven it up.

 

Yup, 64cc aluminum heads would be a big improvement. The stock exhaust manifolds aren’t that bad, but headers are better.
the cam is decent, obviously you can go bigger if you want more power.
The big things, was your timing set for performance or emissions?
and is your Qjet in good shape? A neglected Qjet easily gets the quadrabog reputation.
a higher stall converter(if auto) and or bigger rear gears really helps too.

 

Thanks for the advice. I'll purchase those size heads you recommended. Should I keep those pistons or replace them? No idea how many miles the engine has but title says 224K. This engine is not from this car so it could have less could have more. I can say that the engine wasn't smoking or knocking when I drove it. Just lacked power.

 

I didn't check timing since it was idling great around 650-700. But now that you mention Quadrabog, when I floored it there was some serious hesitation. I didn't think much about it since I'm strongly considering EFI.

 

Yeah, that's not the original engine. The square-ish stamp pad on the front passenger side of the block should be a long rectangle. The square-er pad came out in '77ish.

What kind of hot idle oil pressure did the engine have prior to tear-down?

Is that a crack on the #8 cylinder going down to the piston?

 

Omega Roger,

There are two terms tossed around in the automotive market that are overused & abused:
(Barn Find)
Matching Numbers
To thousands of buyers today, those terms don't mean diddley squat. Do those references make the vehicle worth more? Seldom.

But anyway, your cars seller thought that numbers matching (original) term would be a sales clincher.
But went on to add different front end and a rear spoiler, not original looking.

Those valve reliefs in the pistons look strange to me that high on the piston, when actually the valves heads are lower in the cyl head.
Somebody has been in there, chisel marks on freeze plugs to hold them in place. Double timing chain. Maybe a shim under the valve-spring?

Your first observation should be lifter bottoms and cam lobes condition. Not everybody used Zinc in their oil.

Passenger side front numbers pad is indeed strange. Zooming-in, numbers not showing and no indication there ever were numbers.
Replacement block perhaps? Truck block? Milled deck? IDK

 

The seller told me that he installed new lifters, rods, valve stems, springs etc. Please see the pics of the bottom of the heads thanks.


Why do a couple of those valves look almost white?

 

A white valve usually means the cylinder was running on the leaner side.

The hesitation could be from many different things. From retarded ignition timing to a bad accelerator pump. That Quadrajet looks to be from the early 80’s too, and probably has jets and rods more suited for a pickup truck. The correct carb number for your 1975 L48 automatic is 7045222, and would work wonderfully with your engine combination for hundreds less than an EFI conversion.

But if you do want to go the EFI route I would recommend ACES with their Killshot II or Fusion kits.

 

I cleaned the block tab where the passenger head was and uncovered some numbers. I’m also attaching the Quadrajet part number that’s on the carb. Thanks again for all your help.

 

The car itself looks good from here. Replacing worn suspension parts will probably fix the wandering condition.
If the cylinder wall isn't cracked, do as tnothe member advised and buy quality aluminum heads---you'll notice a huge difference in performanc. Rebuild your carb or buy a4-barrel Edelbrock/Holley/Etc.

DO NOT DISASSEMBLE THE INTERNALS OF THE ENGINE IF THERE IS NO GOOD RESON TO DO SO.

You can turn it into a decent running nice looking car with a little DIY work using members advice.

 

That carb is a service replacement for '75 trucks,vettes, and novas.
It looks as though it's been commercially rebuilt, so quality is questionable.

The best thing you could do is 64cc heads, with runners no bigger than 180cc, headers with free-flow exhaust system, and a modern roller cam system. Also you should recurve your distributor so mechanical advance is all in at 28-3000 RPM and limit total advance to 48*
That will wake up the beast....

 

Thanks for all of the replies. The cylinder doesn't seem cracked. I went over that mark with a fine scuff pad lightly and that mark came off. Maybe it was some residue from the antifreeze?

I'm getting ready to order the heads today. Are 180CC 64CC Flo-Tek heads decent? It was under 1K for the set assembled. Do I need special rocker arms and rods or can I reuse the ones off my head since those were fairly new? BTW the new Flo-Tek heads are angled plugs for that price. For the straight ones they want a little more. I noticed that some of my spark plugs wires were burnt. So I was thinking that maybe the angled plugs may be better? Also I think I should buy a new distributor since this one has lots of rust on the mechanism. Do you think a MSD distributor is a good choice for this engine? Thanks again.

 

Rag joint I think I should replace it

Front shock

Broken bushing lower control arms

 

Once you get close to the car you’ll see paint blisters -


Previous owner fiberglassed the front bumper to the body - it’s starting to crack

Previous owner put these tabs to open headlights

 

Once you change out the bushings, rag joint, and shocks it will help a lot. I may also suggest changing the tie rods, drag link and ball joints. Mine had the original 50 year old parts and once it was all replaced it was night and day. Tight steering and handles very well and responsive. I also did the body mounts since they were pretty much toast. Get rubber ones and not poly. Good luck and don't get down on it. Yours just needs some TLC that it wasn't getting. As far as the paint, mine is doing the same thing. My paint guy told me it's because they didn't let the primer cure out long enough before the top coat.

 

Found a pdf called "The Lime Book" The Complete Chevrolet V-8 Engine code 1955-1991. Here's a link in case anyone is interested http://www.camaros.org/pdf/LimeBook.pdf

According to the ZFK code on my block the engine in my 75 Corvette is actually from an 84 Corvette 350, 205HP AT, TBI.

 

ZFK is a 1984 Corvette application:


Again with the yellow arrows... What am I seeing here? (looks like serious pitting)

 

The velcro light pull tabs is a new one, but how do you close them?

 

I think it’s just carbon deposit and grease