snork Posted October 25, 2009 Share Posted October 25, 2009 stupid question. the gt40 heads wont work on a non roller block, will they? Im just tryin to figure out a way to raise the compression on my late '70's 302 with out doing any machining. I think it would be pointless to do that on a non roller block. Any suggestions? Quote Link to comment Share on other sites More sharing options...
Just Jim Posted October 26, 2009 Share Posted October 26, 2009 Not sure how much more compression will be gained, if any, but the heads will bolt onto a non roller block with no problems. Quote Link to comment Share on other sites More sharing options...
V8INtheZ Posted October 27, 2009 Share Posted October 27, 2009 Just need to be careful with piston to valve clearance. Search the mustang forums like corral. net or stangnet. com Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted October 28, 2009 Share Posted October 28, 2009 I bought some GT-40 heads for my father-in-law's 1968 302 that we put in his 1964 comet convertible. The heads were a straight bolt on. The later model heads utilize a pedestal mount rocker arm, while the older heads use the rail type rocker arms. The newer rocker arm design is much better, but you need to be particlular about which push rods you use. For his application (hydraulic flat tappet cam) we ended up using push rods for a 1982 Mustang. The 1982 Mustang had a hydraulic flat tappet cam and the new style rocker arms. If you are going to use aftermarket rocker arms, then ignore the above, but be sure to get the proper length push rods. Quote Link to comment Share on other sites More sharing options...
snork Posted October 28, 2009 Author Share Posted October 28, 2009 for some stupid reason, i was thinking the heads had a smaller combustion chamber, but that wouldnt make sense if they flowed better than the stock late 70's head Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted October 28, 2009 Share Posted October 28, 2009 After doing about two minutes of web research, I came up with the following: The GT40 heads have a nominal combustion chamber size of 64cc and the early 302 have a nominal combustion chamber size of 58.2 cc. So the downside would be that you would lose compression ratio. The upside is that you would get bigger valves and better flowing ports. Why not go to an aftermarket aluminum head? They are available with small (58cc) combustion chambers and even better flow rates. Currently, I am using the Edelbrock P/N 60379 aluminum heads on mine. They are great heads for a stock bottom end. They were worth 10 mph in the quarter mile over the stock heads. Recently, I upgraded my bottom end to a stroker, so I plan to remove the Edelbrock heads sometime in the future and go with either an AFR185 or the new Ford Z302 head. Quote Link to comment Share on other sites More sharing options...
V8INtheZ Posted October 28, 2009 Share Posted October 28, 2009 Another option is an aluminum GT40 head, they are a little over $900 bucks at summit. Considering it would cost 300-500 for a set of iron GT40 heads I think thats a good way to go. They are available in either 64cc or 58cc so you can still have the better compression ratio.... 64cc http://www.summitracing.com/parts/FMS-M-6049-X306/ 58cc http://www.summitracing.com/parts/FMS-M-6049-X307/ They wont make as much HP as a set of AFR 165's but they are almost 500 bucks cheaper too Quote Link to comment Share on other sites More sharing options...
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