Thread: Compression is too high on my '71 460 Lincoln...

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Originally Posted by 71LincolnCoupe

and I am getting a lot of what I'm thinking is pre-detonation 'gas' clatter when I step on it.

This isn't the original motor that came with the car but one that I had rebuilt. We had the '71 heads from that original motor rebuilt, and they were ported and polished a bit before we put them back on.

The block was bored 60 over, has an Edelbrock Alum. manifold, new Edelbrock 625 cfm carb, Pertronix II elec. ignition, full roller rockers, dual exhaust, and a double roller timing chain.

I wish I could tell you all what cam is in it, but the motor builder won't give me any of the info I need. Long story with a crappy ending, but anyway I do know he had the cam custom ground to HIS specs, but I have no idea what they were.

I had a local car guy do a compression check on each of the cylinders and he said they were all running very close together pressure-wise, but that it was pretty darn high. High enough to cause him concern.

We took the car out today for a run and worked on the timing and adjusted the carb back and forth to try to get rid of the clatter, but while it is a little quieter the noise it is still there. The car cruises beautifully as long as I don't hit the throttle, it seems to be quick and responsive.

So now we are thinking about going ahead and rebuilding a set of later-model(75-84?) 460 heads to possibly try to bring the compression down to more manageable levels.

Does anyone here recommend a particular year of 460 head cores for me to start looking for in the boneyards? Any help would be appreciated greatly.

You need to ask your local car guy what the "cranking compression" is.

What were your pistons like........flattops or dished slightly? I assume you are running premium gas?


Don

Don't know if they are flattop or dished, I can't get any more info from the motor guy. They were Keith Black's, but that is really all I know. I will ask the new guy about cranking compression when possible.