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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
What changes in motor characteristics can I expect if I change camshaft as illustrated, and keeping everything else as is?
Engine is a Chevy small block 350 factory roller block.
Holley carb.
Vortec heads modified for increased lift.
Compression was 9,3:1 with stock GM gasket. Have changed to 0,015" shim gasket that should pump it up to app 9,8:1
Manual transmission T56 w/ overdrive.
2700 lbs car.
4,09:1 rear axle ratio.
It works pretty well today, but I want to optimize it up to the maximum lift that the heads are cleared for ( around 0.525)
Is this change worth the effort?
I could of course change to a GM HOT cam as well, but to reach 0,525" lift with that one, I would have to change to 1.6 rockers as well.
And I already have a nice set of 1.5 full roller rockers.
I don't want higher lift than around .525" because the total clearance is .571.
Safety margin app .040 - .050" = max lift app .525.
From what I have read, the Vortec heads respond very well on lift up to app .525.
Tests show noticeable hp increase when changing from 1.5 to 1.6 rockers on the GM HOT cam and Vortec tops.
That's a change from .495 to .525.
I don't want to change to 1.6 rockers on my present combination. That wil be too much lift for my safety margin.
That's why I thought maybe my suggested cam change would make a difference.?
I know lift isn't all that matters, but my knowledge is limited when it comes to camshafts.
I would go with something more along the lines of 224/232 on a 108 or even 106. Between those other two cams you will not be able to tell the difference.
Not worth the work and $$$ to do that cam swap. IMO, you'd notice zero change in the 'butt dyno.' Any substantial performance increase over what you have now (that engine with a 4:1 rear and only 2700 pounds should already be a rocket ship) will require changing a lot more than just the cam you propose to go to.
07-08-2021, 01:17 PM
