Cam suggestions, please
AJ/FormS, that was a really thoughtful post with lots of new information. Thank you very much for going to the trouble of replying in such detail. I am printing this thread out to keep forever!
However, as IQ52 pointed out, my cam has 244 degrees of duration at .050, not the 236 degrees that I had thought in my original post. (Danged parts house filled the cam card out wrong.)
So I guess that means I have 48 degrees of ramp rather than 56 degrees. Do you think it should therefore idle fairly decently with the right torque converter, timing, etc.?
Yeah 48 is getting there.
As you have discovered,that cam really has too much duration for a street 360, with an automatic, unless you put a big TC and 3.91s,behind it.. It will idle so you know its in there. But in a heavy car, it will be all bark and no bite until it gets wound up some. In a lightweight A, and properly matched, it will haul the mail all right. Been there done that; I'm done with that size cam. It was fun for the summer, but then it was over.And I have never missed it.
So, Because you said you have heavily ported heads, I would order up a custom cam. One to take advantage of the head-flow, but limited in duration, and street-friendly.Ima thinking mid 220s to low 230s; say about 228*@050.
Be forewarned tho, that the TC may still have to go. 2200 is pretty low. With your 10.5Scr, the 228 cam will make plenty of idle torque, and while you can probably tame it some with late timing,that's not really the way to go, nor is standing on the brake pedal.
A quick trip to the Wallace Dcr calculator show that you may have to lower your Scr to run a street-friendly cam.Inputing a 64* ICA, on a 276/110 cam(possible specs for a 228* cam) @ 10.5Scr the calculator spits out 8.4Dcr and 169 psi cylinder pressure. While 8.4 is fine for aluminum heads,as stated here on FABO by experienced users, iron heads have trouble with 8.4; and 8.0 is generally thought to be the high limit for them, and pump gas.This is where a higher stall TC, say in the 2800 to 3200, can help get the engine through the sensitive zone. Not the best idea, but it may work.
Retiming the cam to 108ICL, sets the ICA to 66*, and drops the Dcr to 8.27, and pressure to 166psi
Reordering the cam on a 112 LDA, installed at 110,sets the ICA to 68*, and drops the Dcr to 8.1, and pressure to 163.
So now it's getting really close. The above was using the slow ramps of 48* to achieve 276 from 228.
Faster ramps, like the 44* stated earlier would allow 228+44 = 272 advertised. That puppy ground on a 114LDA, and in on 112, would yield an ICA of 68* again, dropping the Dcr to 8.1/163
But more interesting is the flipside of those 44* ramps. Taking 276 less 44 gets you a 232@050. That's almost a full size bigger cam for the same advertised. Installed with the same 68* ICA gets you the same 8.1/163. But now you have LDA choices. You can order any cam from 110LDA to 114*LDA. But always installed at 110, for a 68* ICA. Hmmmmmmmmmmmm
I know, clear as mud. The point is call your cam guy. Answer all his questions truthfully, and trust him.Order the fastest street ramps for .904 lifters,that he will sell you,and with as much lift as your headflow needs,and you will be golden.
