Cam for this 340 ?

[rebeldart]

In my Swinger :.030 over, Air-Gap intake, Street Avenger 770, mild ported X heads and may go Eddys, TTI headers, 3000 stall, 3:91 gears and manual brakes. The XE268 seems highly recommended but can I handle a little more ? Still wanna be street friendly but I want a noticeable lump to it (does a 268 have that or are we talking 274?) Plan to purchase some parts this week before the wife finds the stash ! Oh yeah - I dont know my compression ratio yet, but I'll be shooting for 10-10.5 (It's a 68 motor w/original heads so I'm probably there).

 

[AdamR]

With that compression I would look at the XE274

 

[rumblefish360]

YEP! Me too. Also, since you allready have mildly done "X" heads, I'd look into further work on them rather than go aluminum.

If you have not yet gotten pistons, I would look at a max of 10-1 with adecently sized cam to bleed some pressure off. A good example would be the KB107's. with a "X" head chamber at approx. 72 -74 cc's, your qatio will be 9.8-1 (W/ a 74cc chamber) This is with a Fel-Pro .039 thick gasket. You can get a Fel-Pro gasket at .050/.055 thick as well to take the edge off if needed.

 

[AdamR]

Stock replacement High compression 340 pistons will put the piston at around +.018 above the deck. with the shorter stroke of the 340 he should be right around 10:1 with a .040" gasket. Mines at 11:1 with milled heads and a decked block

 

[rumblefish360]

Your not quibbling over .02 are you.. LOL
Just kidding.
What heads R U running now Adam?
Pining/timing advancement problems?

 

[AdamR]

They're ported 597s. Still havent fired it yet so Im not sure if pump gas will work.

I do know the pistons are .020" out of the deck and its exactly 11:1. I think I figured the chambers would have to be around 62ccs

 

[rumblefish360]

Whew! You cam is large aint it?

What did you get away with on the pump gas engine and iron heads? (Comp and cam specs)

 

[AdamR]

The cam is a crower solid, 260/265 .050 on a 108lsa. I had a iron head 440 with about 10:1 and a 509 cam that wouldnt run on pump gas because of the poor quench so I have my doubts about this one.

 

[D-mailman]

YEP! Me too. Also, since you allready have mildly done "X" heads, I'd look into further work on them rather than go aluminum.

If you have not yet gotten pistons, I would look at a max of 10-1 with adecently sized cam to bleed some pressure off. A good example would be the KB107's. with a "X" head chamber at approx. 72 -74 cc's, your qatio will be 9.8-1 (W/ a 74cc chamber) This is with a Fel-Pro .039 thick gasket. You can get a Fel-Pro gasket at .050/.055 thick as well to take the edge off if needed.

Nice work Robert.