roller 350 bored 040 over
forged crank, rods, pistons
Comp XE 233/239, .569/.577, 112
vortec heads, suited to match the cam
approximately 9.3:1 compression ratio



not a daily driver, but definitely one that I'd like to be ABLE to drive, ya know? Not go on trips or anything, but at least be able to get around for a bit.

what are your thoughts? concerns? opinions? suggestions?

 

too much lift for the heads, they don't flow as much at .550 as they do at .500, try a XE274 if you want better driveability

 

I'll be porting my heads a bit, just mildly

but why is it too much lift?

 

If you are porting your heads, you won't know how much is too much until they are done.

For the above, it's too much because the heads don't flow as well above .550 as they do at .500" so it's basically choking down at and towards peak cam lift.

 

but will the car be streetable? I mean, <1000 rpm idle, >10 mpg, and fast?

 

It'll be fine on the street.

Why such low compression?

 

72cc heads

i suppose i can mill em

 

Too much cam?

When the lobes wont fit thru cam bearing holes :-)

later
Jeremy

 

Vortec heads have 64cc chambers nominal.

Vortec heads respond VERY POORLY to home porting. About all you can do to the intake side, is just clean up whatever imperfections were left in the casting and machining processes; if the shape of the port is altered significanlty, it almost always hurts flow. Anything beyond casting flash removal and smoothing the steps from seat machining, is a step backwards. The exhaust side is a different matter, it's just like any other stock exhaust port, and can be worked up the same as others. But not the intake. I wouldn't bet on gaining much on top of their stock flow, unless you have a flow bench and work in small steps and check after each step, and have a stack of cores so that when you go backwards, you can throw it away and start over.

If your CR is really 9.3:1, that's too much cam. It will be sort of gutless at low RPMs. You'll need ALOT of converter to get it to launch hard. I'd make real sure to get an accurate calculation of that; AFTER head work if it modifies the chamber, and include the head gasket, and BE SURE to include the ACTUAL deck clearance. Remember, virtually all stock or near-stock pistons, ADD .025" or so of deck clearance to the .025" that's already there from the factory. That's .050" total. Which is a MASSIVE error, if you leave it out; over 10cc in that space.

As far as the head flow being less at higher lifts, the valve will spend VERY VERY LITTLE time anywhere near peak lift. If you have a real steep tall ramp on the cam, then the other 95% of the time, you'll gain flow from the larger opening. I wouldn't be so concerned about the cam's valve lift slightly exceeding the heads' "port stall" lift.

 

induction setup? carb, FI?

xe274 is fine, but you want a roller cam. Perhaps look at the roller variant, xr27x (I forget...).

That cam would idle just sub 1000RPM I'd think, but your CR should be up a bit, do calculate it very accurately, as sofa mentioned.