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| | | | Joined: Mar 2015 Posts: 57 'Bolter | | 'Bolter Joined: Mar 2015 Posts: 57 | a wile back i read chevy 307 pistons are the same size as 250 pistons except they dont have the dish on the top.... if this is true what does that due to hp and compression | | | | | Joined: Feb 2004 Posts: 29,742 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,742 | Yes, the diameter, compression distance, and wrist pin is the same, even the weight is in the ballpark. You'll gain about half a ratio on compression. I've built several engines that way. While you're at it, install a set of screw-in rocker studs and guide plates and a set of big block V8 roller rocker arms, and shave the head about 50 thousandths. Just don't get too radical on the cam profile - - - -a Comp Cams 260-H cam works well with the increased compression without making the idle get squirrely.
Claim whatever HP gain you think you can get away with- - - -most modified engines never see a dyno, so horsepower claims are mostly pipe dreams.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Mar 2015 Posts: 57 'Bolter | | 'Bolter Joined: Mar 2015 Posts: 57 | thank you i live in a very small town and the guy at the local parts store has not been very help full.. i have a 51 3100 and put a 250 in along with a 5 speed from a s10 and 323 gear camaro rear end i have only put about 150 miles on the set up i realy like it just not quite enough power | | | | | Joined: Feb 2004 Posts: 29,742 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,742 | Ditch the 3.23 rear end gear for something in the 3.55 to 3.73 range, and forget about doing internal engine modifications. You're way over-geared and the engine is suffering from a lack of RPM.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Feb 2000 Posts: 5,190 'Bolter | | 'Bolter Joined: Feb 2000 Posts: 5,190 | When shopping for the 307 pistons, be sure to get a true flat top piston, there are some universal pistons with a heavy chamfer around the top and four valve reliefs per piston. These work out to about the same CC as the dish pistons, the true flat top raise the compression, the universals will, but just slightly.
Joe | | |
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