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Original Message
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The big-bore gaskets do fatigue as time passes. |
By Dave Shoe - 05/30/2003 12:24:27 AM; IP 216.243.176.34 |
If you drive a lot in performance situations, it's my personal opinion you'll want to think about replacing the head gaskets every few years, as they will tend to relax at the hottest part between the cylinders after being pounded back and forth (by neighboring cylinders) about a hundred million times.
At any rate, I now use the hundred million hard-driven combustion cycles per cylinder as my irrelevant acid test as to whether they need replacing, note:
3000RPM = 1500 combustions per cylinder per minute. Drive an hour a day makes it 90,000 combustions a day. Drive three years makes 100 million combustion cycles.
I'm saving my blown FelPro 1020 as a reminder.
THin gaskets tend to get less side loading from thrusts, less thermal shock, and thend to have more material between cylinders, and thus tend to clamp better.
Also, if you don't mind a little extra compression, don't forget the steel shim head gaskets. They're very easy to find at a good price. Some folk have trouble getting them to seal coolant from the start, but they've done well for me. Beware, there ate two major types of steel shim head gaskets:
1) The round bore version has a reinforcing "rolled over lip" at the bores only, and this helps seal in large bore performance applications
2) The non-round bore (has valve-like reliefs) shim gasket does NOT fit the 427 bore and it does not have a rolled lip at the bores. It is simply embossed and works reliably in stock and mild performance applications.
Minor variations of both types of gasket are abundant.
JMO, Shoe. |
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