Are head and cylinder gaskets compression gaskets? |
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Are head and cylinder gaskets compression gaskets? |
stevegm |
Oct 22 2016, 01:04 PM
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#1
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Advanced Member Group: Members Posts: 2,111 Joined: 14-July 14 From: North Carolina Member No.: 17,633 Region Association: South East States |
I need to remove the heads off of a newly rebuilt engine (4-cylinder) I built (never run). They have already been torqued. Are the head gaskets and gasket between the cylinder and block, compression gaskets that should be thrown away (i.e., replaced with new one) after I untorque the heads?
The head gaskets will be easy to replace. But I'd have to pull the cylinders to replace the ones between them and the block. |
stugray |
Nov 14 2016, 11:37 AM
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#2
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Advanced Member Group: Members Posts: 3,824 Joined: 17-September 09 From: Longmont, CO Member No.: 10,819 Region Association: None |
Ok, I stayed out of this conversation towards the end because I had just finished my last race of the year.
During that race I was hearing a loud "Brrrrrrrrrppppppp!!!" whenever I exceeded 6200 RPM. I thought it was an exhaust leak, found one leak, fixed it, and the noise did not go away. I was worried it was a head leak. SO I decided to pull the motor at the end of the season and have a look. First compression test just before pulling the motor was bad - 60-70 PSI cold, 75-80 PSI warm - Not good results. So I pulled the engine Saturday and got the heads off yesterday. This engine is a 9.5:1 CR and I routinely rev it above 6200 RPM during hard racing (20 minutes at a time). During disassembly I DID find at least one exhaust leak between the stubs and the headers, so that was probably my "Brrrrp!!" noise. I assembled this engine with no head gaskets jugs were brand new and heads had just been machined down to decrease comb chamber volume. I did NOT hone these heads or do anything other than bolt them up. When I took the engine apart I checked the torque on all the bolts and some were a little low (~20 ft-lbs). I can detect ZERO leakage or blowby on the sealing surfaces. My valves are a different story. (IMG:http://www.914world.com/bbs2/uploads_offsite/i366.photobucket.com-10819-1479145075.1.jpg) (IMG:http://www.914world.com/bbs2/uploads_offsite/i366.photobucket.com-10819-1479145075.2.jpg) (IMG:http://www.914world.com/bbs2/uploads_offsite/i366.photobucket.com-10819-1479145075.3.jpg) (IMG:http://www.914world.com/bbs2/uploads_offsite/i366.photobucket.com-10819-1479145076.4.jpg) And here is my home made spring compressor (IMG:http://www.914world.com/bbs2/uploads_offsite/i366.photobucket.com-10819-1479145076.5.jpg) SO long story short: No head gaskets, no special prep (other than GOOD mating surfaces), normal torques, 9.5:1 CR and engine routinely reved above 6200 RPM. No discernible leaks after 2 race seasons. The engine looked like new inside. So run head gaskets if you want, I dont, and I am fairly certain that I beat on this engine more than your average DD. |
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