So 110 cc heads, plus it looks like the cylinders are double-chamfered for early and late heads so that probably takes another 5 CC out. That would put that engine at less than 6:1 CR, dipping into the 5's. Your absolute best bet would be a set of the smallest chambered heads you can find. The 140's are ideal. and have the biggest valves that head would hold. Port the 140's and get back that lost compression.
@@Nostradamus_Order33 I agree. I have a set of 197s, (71 455 HO round port), that have nasty 110ccs. If I can't find domed pistons, then a blower or turbo follows that. (Only on a punched 455)
1967 was a transition year where both open and closed chamber heads were offered, as well as both 20 and 14 degree valve angle heads. 68 and on all are 14 degrees
Unfortunately, the closed chamber heads restricted the flow around the valve above 0.420" - 0.425" lift or so, even with the big valve 14 degree heads. The open chambers really allowed the RA II cam to work. The 14 degree heads got matching high rise intakes with Q-Jet carbs, due to the improved ports. The 1965 camshafts had 75 percent cam lobes, except the 2 barrel engines. The 1964 camshafts had old 70 percent cam lobes. That is, the 0.050" lift duration was 70 percent of the SAE 0.006" duration. The 1964 GTO camshaft is a bit of a mystery camshaft. It has the same specs as the 1964 automatic transmission cam on paper, but has a different part number and was used with automatic, manual and tripower 1964 GTO's. Some speculate that it might have been an early 75 percent cam lobe cam. In 1965 the intake ports were improved and the camshafts updated and the engine blocks were cast using thin wall casting technology for the first time.
Years back my 69' gto that ive had since 94'-95' also. I blew the head gasket on a fresh 400 because the machine shop reversed one of the center head bolts with an outter one thats a longer bolt and it bottomed out instead of torquing head down
Bolting on a set of 110cc heads on a 326 is total nonsense. You get something in the neighborhood of 6:1 CR. Somebody had no idea of what they were doing.
I think I’m in the same boat. Car overheats in minutes and there’s coolant in the oil. I’m hoping I can do the job with the engine in the car (1978 TA)
Wow I bet that ran terrible, performance wise. 455 heads with huge combustion chambers on a 326 would net you 6:1 or lower compression. I would buy a closed chamber head for sure.
I had them deck the block. I had the port and polish the heads. Should be 10:1 compression. Found out the old shop milled the heads, but left the compression at 8.5:1. So, I should see a huge difference between the compression, head work, new performer rpm intake, roller cam, and so on. There will be a follow up once I get the motor back.
enjoyed your video, im also going through a 326, have #46 heads , in the process of installing rocker studs to make the valve train adjustable. My plan is to put a 68 cam in and retard it 2% and put a 66 389 4 barrel intake on it, hopefully this setup will work, not much info on a 326
I think you need to cc your heads, can be done with a 50 cc and a 10 cc syringes. Then get on a calculator and figure out what your actual compression ratio is.
I have a question you might be able to help me with,, i have a 1967 pontiac firebird with a 326 ,engine was rebuilt quite a few years ago before i bought it from a friend .yesterday i went to start it ,and i was surprised to hear what sounded like a really bad exhaust leak from back of engine, turns out rear of passenger side head has like a small freeze plug next to big freeze plug blown out .looking at your video i spotted same kind of 2 plugs ,one large on small..anyway my question is there a way to replace that small plug without removing head., it is kind of a tight spot . I really would appreciate your help. Thank you
Hi, my 326 Pontiac of the 1966 start to lost a lot of water of the radiator by exhaust, i can see the leak of water fall in final part of the exhaust, and the radiator gets empty in only few minutes, what do you think it is the problem? 😩😭
@@Driven2Compete Even W/ "0" deck height, and heads milled to the water jacket, you still won't make anything logical. If you put a 2bbl on it, and never spin it faster than 2500 RPMs, you probably won't care. And if gas quality deteriorates worse than it is now, you could run a total advance of 45°, all in at 900, and never have ta worry about detonation. But if you want some kinda decent mileage, power, and throttle response, ditch those heads for "anything" would be better. It looks like you have other options in your garage. Take advantage of it. By now, you've probably rectumfied the issue. Curious about a follow up.
I strongly disagree with you the deports are higher compression Which will make more power And flowing that 140 or whatever you said it was that's not good you want something that flows at 2:20 intake runner You want a closed chamber for high compression those that The head cylinders you want Number 62 13 14 Head There's a lot more than just those ones just a name a few I think the X6 head cylinders are good as well I don't know enough about them but high compression 220 or 215 intake runner flow is what you want to look for like that is what I'd be looking for I'm not a professional but this is what I've been told
Amen, I’ve been building Pontiac engines for 40 years. Nothing about that 326 makes any sense.. so much I could say but it would take hours to educate 😅
