Another Head Thread...
Searched without a solid answer....what kind of power increases, if any, could be expected if you started with the following, all in good working order:
Stock '69 340 "10.5-1" short block
Stock cast intake and exhaust manifolds
Stock 340 or mild cam (450ish lift, 215-220ish @050 duration)
650-750 AVS or Eddy carb.
....and replaced the X heads with a mild aftermarket OOTB head (and i'll define that as Eddys
that have been checked and corrected if needed but no porting, LAXs from IMM, maybe a Magnum-style, etc.) The gasket thickness and chamber volume could be optimized for compression.
Obviously headers, better intake, and more cam would lead to bigger increases. Not really looking for an exact HP#, just wondering what the return would be on a stockish engine.
Thanks...Matt
You wanna know the answer?
The flow difference between the x heads and the eddys all the way throughout the lift range will be the diff in hp.
So if you keep all else but change heads, and the eddy heads on average do 15 cfm better than the x heads ...then you made about a 25-30 hp increase over stock, with stock cam.
Add a 750 and you may see an average 10+ more, add headers and you may have another +12-15 hp.
So...you spend on ready to go eddy heads
- 1700 or so
A 750 carb -500
Headers -200
Stock cam still...
And you made around 50 +/- more hp.
So a 275hp/305hp 340 , depending on who rates it, goes to about 355 hp with a stock cam by adding the heads, carb, header.
Now if you just changed the cam from stock to something in the .500 lift range...you can expect more, You would be in the 400hp range.... but realizing the potential of all the other parts will eventually fall on the camshaft.
Going about it this way is expensive, you could change the cam, add the headers and carb and make the same increase without buying the heads.
Spend 700 or spend 1700 for 30 or so hp, it's all how you go about it.
