289 problems advice needed...

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Dec 5, 2008 | 07:48 AM

#16

MBDiagMan

Cargo Master

Joined: Dec 2004

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From: NE Texas

Yes, preignition is certainly a possiblity. That's why I need to hear and maybe drive the car. In these days of knock sensors and EFI, there are probably lots of young people who have never heard preignition before, thus they don't recognize it for what it is.

Dec 5, 2008 | 01:23 PM

#17

85e150

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On the trail of pre-ignition.

First, what is the timing set to? Should be between 6 & 12, the stock specs for 2bbl or 4bbl.

Now, if you have the casting numbers off the old heads and the new heads, we might be able to see what the combustion chamber volume is. It is possible you have gone from a 54.5 cc to a 53.5 cc chamber.

Those pistons have valve reliefs in them, so that might compensate. Does the piston info say the volume of the reliefs? The old pistons, were they dished or flat?

Head gasket thickness?

You might have 3 little things adding up here. Even if they did, it doesn't seem like it would cause this level of trouble, but all things need to be examined methinks.

Plug in those numbers here:
CUBIC INCH CALCULATOR and COMPRESSION RATIO

Dec 10, 2008 | 04:35 PM

#18

gearhed1971

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From: Little Falls,New York

Out of curiosity,how did everything fare?I have one 289 head and one 302 head on an engine I've just bought,It'd be good to know what I'm in for.

Dec 10, 2008 | 05:48 PM

#19

85e150

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If they are the same style rocker and valve size, no big deal. But I bet they are not. You should match them.

And yes, I'd like to hear more about the tale of the 289 here.

Dec 10, 2008 | 08:37 PM

#20

Beanscoot

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From: British Columbia

"I have one 289 head and one 302 head on an engine I've just bought, It'd be good to know what I'm in for."

Well if you provide us with casting numbers then we can determine valve size, combustion chamber size etc. and advise you what you are in for.

Dec 11, 2008 | 12:59 PM

#21

85e150

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Quote:

Originally Posted by Beanscoot

Thanks for pointing that out--But if I'm reading this chart correctly:

Cylinder-Head Casting Numbers

And if it's correct, he is probably mismatched for both combustion chamber size and intake valve size. One side of the engine run better than the other?

Dec 11, 2008 | 05:33 PM

#22

gearhed1971

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From: Little Falls,New York

Yeah,I've already checked that,but haven't miced the valves yet.Hpoefully some one machined it to match.But yes,according to the numbers,they're a mismatch.