I am putting a 256 blower on my hp500. I pulled the heads off to have them freshened up (New Valve springs/Valve job). I am pretty sure I am going to go with a Cometic or the good FelPro gasket. Does anyone have a part# for the right gaskets to use? What is the gasket thickness you guys use? Thanks.

Go with the cometic. The standard thickness is .040. You can go as small as .027 if you want to raise the compression or as thick as .120 if you want to lower the compression. Use a C5333-040 for a .040 thick gasket. Change the last 3 numbers for a different thickness. It has a 4.540 bore size. The Fel-Pro number is 17048. Hope this helps, Eddie.

Thanks for the info Eddie. How thick of a gasket would you recommend for my engine? I would like to run a 7# pulley on pump fuel (93 Oct.) Do you know what the actual comp. is on a hp500? I was 8.5:1 and 8.75:1 so i'm not sure which one it is for sure? How about intake gasket? Sorry for all the questions. Doing this on my own and just want to make sure I put it back together with the right stuff. Thanks again!

Stock is 8.75. If you use a .060 head gasket it will lower it to about 8.5.

I like the Felpro printoseal intake gaskets. Felpro part #1211.

The felpro MLS head gasket is 1075.

Keith Eickert offers a top of the line multi-layer cometic head gasket. By using "multi-layer" technology individual sealing sheets withstand engine loads that until now were never capable of containing. Here is a quick link to the cometic gasket.http://www.keitheickert.com/products...skets-head.htm You can p.m., e-mail me at [email protected], or my phone number is (386) 446-0660.

Happy Holidays

Tony

You might want to consider an exhaust valve upgrade.

Blown85,

I would keep the compression around 8.75, where it currently is. Cometic has a .040 gasket that is readily available and usually in stock. This will allow you to spin that small blower a little slower and not generate as much heat. You could even go with a little higher compression, but you MUST run premium fuel. At 8.75:1, 7#is not a problem. It's still not a problem at 9:1, but the motor must be tuned right. The intake gasket that Griff recommended (1211)is perfect. I have not run the Fel-Pro MLS or the Eickert, but I have beat the snot out of Cometics and NEVER had a failure. I've run over 14# of boost on a 9plus:1 engine with 50 lbs of water pressure and had no problems. They are also able to be reinstalled should you have to lift the head for some reason. You can remove and replace them up to 5 times. When it's time for a rebuild, you should replace them, but if you need to remove the head before that, they can be reused. Hope this helps, Eddie.
PS: definetely do the exhaust valve upgrade to a set of Manley Inconel valves. Give me a call if you need any parts.

Did a lot in the past with this blower, keeping the compression stock as Young recomended is a good answer. Do not run over 6 lbs of boost with pump gas. It seems to detonate after that. It least it did on mine. The 256 is a good low boost blower on the 502. I like the 420 better as it did not generate as much heat. Keep the engine cool and make sure you add extra valve to guide clearance on the exhaust. BTW, 502 heads have some exhaust seat issue with a blower. They only have a coule of thousands press fit. They also are very thin heads and tend to lift some. Low boost, 5 lbs they seem to do OK. Make sure the carb is rich to start.

What valves are currently on the exhaust side? I took a magnet to the exhaust valve and it is not magnetic? I would assume that it is a stainless valve? I was trying to find some info on all the internals of the hp500 but wasn't very successful. What valves come in them from the factory?