| Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | The Siamese intake runners and ports on GM 6 cyl. engines do not lend well to increasing HP and torque, made for long life and torque. Some have put a Ford 300 6 cylinder head on a GM 6 for more power.
Wayne, etc., single port cylinder heads were a significant improvement to pre. 62 GM cyl. heads.
Ed
Last edited by EdPruss; 07/20/2020 9:43 PM.
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
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