I think maybe it has been decked? The car is matching numbers and have checked it is a genuine GS, could it still come from factory being a non SP motor?
Andrew, Welcome to South Florida! I'm on my screen porch in shorts, T-shirt, and flip flops. 74.3 degrees on the electronic temp. gauge. How did I mess myself up? Really? The truth?
It's entirely possible in 48 years its been apart and decked or just been worn away. Only other way to decode that I know of is to remove the timing cover but that's too much of a pita. If you can find a boreoscope and peek in the cylinder you could see what type of piston it has.
Alright, While Andrew is working on his car I'll give more details, because he did ask. I got to go to the Turkey Rod Run at Daytona Beach Speedway this Thanksgiving. What a BLAST!!! I'm partying with my son and a bunch of friends at a buddies house. My son and I laughed our butts off watching 5 guys trip over the owner's garden hose in the driveway. I was the 6th person. What a D.A.!!! I was going face first towards the ground. I put out my arms out and something broke, BAD!!! I didn't go to the hospital for 16 hours. I've got some Buick pics from there if you want to see?
I would have to agree that it is really strange that somebody would waste their time and only swap on a smog intake to a '70 engine. Who would continue to hook up the EGR valve no less? I wouldn't have that hooked up to anything. You can remove that oblong AIR cover plate. Start the engine up and if exhaust is coming out then you also have the smog heads unless the AIR holes were plugged in the heads before the intake was installed. Then the only way to find out is by taking the intake off. The exhaust manifolds were obviously off at one time because they have exhaust gaskets which are not used normally on the Buick V8's. Of course somebody could have installed '72 heads and intake on a '70 block. What are the "numbers matching" you've mentioned? You can do a quick compression test just on one cylinder. Pop one plug out and crank it around a bit. Not the most accurate but it should pretty easily go over 150 lbs. If it doesn't you don't have a high compression engine especially with a stock cam, IMO.
Does the 72 mean the cast year because that casitng is on the head, im confused now because the engine number matches to the VIN, the car is stamped 70.
"Numbers matching" and "Engine VIN." Please provide the proof of these. (chassis and engine) The "Engine VIN" (SIC) will be located on the front of the left side of the block. Your pics of the heads, show them to be "1972" castings, and that along with the intake are where the "questioning" comes into play. (it is easy to "buy the story" with cars, firearms and other such things.)
Or at least the heads. Not looking good... The car may very well be a GS350 but the engine is looking to not be... Unless some Yahoo just put a 72 top end on the 70 short block for some reason.
It appears the egr is hooked up ,and without the tempature vacuum switch, and the vacuum advance doesn’t look like it’s hooked up or not at the right carb port. And egr may be a problem. Opening too much or the wrong time. 36 degrees of timing I feel is too high. I would set to 32 max. . Definitely 72 heads. So you need to confirm the block year, vin number stamped in block. Carb may be wrong also. A lot of not original and questionable stuff there.
Even a 72 with low compression should run better than you describe - Stick with the basics:- compression, fuel and spark. If all three are there, then that car should turn the wheels easy.
My 72 GS350 with all original drivetrain will spin 'em all day long. No reason yours shouldn't. You just gotta diagnose what you have and go from there.
With the correctly stamped block it is looking more like somebody installed '72 heads and induction setup and by its' condition it looks like it was done a long time ago. I can't really see how it was ever done by the factory since that top end is 2 years ahead of the model year. Whatever you do stop with the drilling out of the primary pulloff. The factory hole is .010" or .0125". At the minimum you need a 61-80 drill set. 80 is .0135". No way a stock setup needs to be any quicker. That is not a factory pulloff as far as I can see so who knows what it is at now. How fast the secondaries kick in will not make a difference on how hard it initially gets moving. Plenty of 2 bbl. cars will smoke the tires. The correct rate for the pulloff will make a difference on how it feels as it gets moving as it transitions to the secondaries. To do a quick check on the pulloff push the plunger all the way in with your finger. Quickly move your finger off and count 1001, 1002. If the plunger it completely out by the end of 1002 then it is about as fast as you need. I have seen some crazy slow aftermarket ones so it is possible to be slow. Get that plate off and check for exhaust coming out. I'd even go so far as do a complete compression test now just to confirm that all cylinders are up to snuff even if they are lower in compression than expected. If that is a '70 block then the pistons should be the higher compression ones so even with the '72 heads it will still have "high" compression. There probably would be slightly lower compression than stock because '70 GS 350's would have had steel shim .020" head gaskets(I believe) and whoever did the swap would probably have used thicker .040" composition gaskets that would typically come with a gasket set. Hopefully the engine wasn't rebuilt with later low compression pistons. That picture of the block where the code should be doesn't appear to have any surfacing marks but who knows because it does look like it was all done a long time ago.
I'd casually shop for the correct heads and intake. It will increase the value of your car. I'd also check for a flat camshaft.
