heads


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By yblock32deuce - 18 Years Ago
hi guys, well the crusin season is almost over here, so time to go to work. have taken my g heads to the machine shop to get worked. anyone have any experience as to size intake valves can be squeeked into these heads, also because with composition head gasket use, isnt a fair amount of compression lost, and if so ,should they be cut (what amount). while i am in the question mode. are y-block zero deck height blocks?appreciate any and all advice.putting these on my 292 plus 40 over 6 deuce 32 3 window cpe. thanks to all
By Pete 55Tbird - 18 Years Ago
Hello; Before you get into this too far, I have a couple of suggestions you may wish to consider. The limiting factor in Yblock is usually the choked up exhaust so bigger intake valves even if the ports could support them(which they can`t) won`t do you much good. TRY A BIGGER EXHAUST VALVE and open up the exhaust ports. Zero deck is a very good idea and if you can do it short of custom pistons go fo it. As to compression, 9 1/2 is good IF YOU CAN AFFORT 93 octane with occasional octane boster. Let us know what you do and how it works out. Pete
By 46yblock - 18 Years Ago
The best CR you can get with the bore and stroke given is 9.15:1 with a zero deck, flat top pistons, comp gasket,  and the heads cut .011 for 67 cc chambers.  Y's came with deck clearance of .015-.020.   The Aftermarket cast pistons commonly used, added another .015-.020 to the deck clearance.  So the point is, achieving that 9.15:1  ratio is a challenge.  OEM steel headgaskets are .023 thick, a savings of .018+.  Most people say they are a bad idea but I still dont know exactly why.  Maybe the Y's have less head bolt clamping than the Chevys.

If you are really getting into the CR stuff, make sure to have each chamber CCd and adjusted as far as possible to equal volumes.

Regarding increasing intake or exhaust valve size:  It seems to me that if you look at some of the other popular motors and their displacements, the intake valve/displacement size of the Y is generous using the 1.92 valves.  Therefore I would also look at the exhaust valves and system first. 

By pegleg - 18 Years Ago
Contact John Mummert @ John Mummert Performance in El Cajon, Ca. You'll find him under links in this site. He can do or tell you all you want to know about y Block heads.