How far in the hole 318 pistons
Instead of a 340 cam 64* how about something like a Comp xe250h it's got something like a 51* even better get a similar cam cut on a 107 lsa for a stock 48* ? But still be able to gain a good 30-50 hp over stock cam. Probably starting at least 2500 rpms and up.
Wait; 30>50hp from nothing but a cam-change of ; 10* extra intake duration, and 19* additional overlap, that is only meaningful with headers and a free-flowing dual exhaust? I'm just not seeing it unless the rate of lift goes off the chart, or
unless
you are including the 4bbl, the headers, and the dual exhaust.
And besides;
friend;
yur still dealing with a measly 140psi ccp. Put a 4bbl on that and watch it get soggy. Sure you could do it but why?
Just to brag on your 1000rpm powerband 318?
That combo is gonna need about a 3500 stall and 3.91s for sure.
at Extra cost.
My guess is that Over 95% of the miles a 318 ever turns are gonna be under 3500 rpm, and what you're thinking is gonna give it all away, I mean, there is already nothing there at 140 psi. and now with a 3500 TC, it's all but disappeared.
You know the 1-2 split on the TF is .59 right, meaning that the revs drop to 59% on the shift. The 250* cam is gonna power-peak around 4500, so reving to 5000 is already going down the back of the power curve. Shifting at 5000, the rev's will drop to ~2950, with the stock 2000 or less, stall. With the stock rear gears, that are likely to be 2.76s, can you say sucked out? That's a hole yur 140psi cammed-up 318 is NOT gonna like. Put her in Drive and go home, cuz yur goose is cooked.
That combo is gonna need about a 3500 stall and 3.91s for sure.
at Extra cost.
For about the same money, you could bore it out and install some decent pistons, to get the pressure up to ~160, get a valve job, and reinstall the stock cam with better springs, and top it off with a small 4bbl, no headers, and finally, hang a 2800 on the back, and leave the rear-gears alone; then go have a blast.
And while yur at it, install a fresh air kit, cuz she's gonna need all the help she can get.
Yes you can make modest power with the short pistons; just not with 318 heads, a 250* cam, log manifolds, etcetera, and NOT at 140psi, and for sure not with a modicum of bottom end., not to forget the wet-noodle throttle response.
I'll say it again; IMO; the stock pistons have got to go! Notta chance would I leave them in there for any performance 318 in my stable.
I'll tell ya another thing, for a low-compression 318, here's a game changer;
4.10s with a valve spring swap, leave the 2bbl and factory convertor; or
a small 4bbl, a 2800 convertor, and 3.55s, is a reasonably good alternative. If you put a 4bbl on it, it needs more than the teeny weeny, 3-pass muffler, single-exhaust.
These are my opinions, based on my experiences.
Don't get me started on big-valve heads, and a 340 cam, on a low compression 318. I'll never do that again!
