AWright I'll tell you what worked for me.
It is totally irrelevant
but shows what can be done. My second iteration;
367 @10.7Scr. Hughes HE2430H cam Specs are 223/230/110. adv;270/276/ installed at 106 with 538/549lift. Running a 4-spd with 2.66low and 3.55s.
Aluminum heads,running 205*F, power timing 32 to 36 on 87E10
The listed Installed centerline yields an ICA of 61*, and a DCR of 8.75, and cylinder pressure of 178psi(Wallace).Mine measured 185psi
This iteration made monster off-the-line SBM torque. Monster! I had to narrow the rear end and install 295s to get a grip on it.The 245s I originally put on it were a joke, and the 275s that followed were not much better.The midrange was very,very strong; stronger than either the 292/508 it had previously had, and stronger also than the following 230@050 cam.This 2430cam would start 275s spinning in 2nd at 45 mph, occasionally 50;they often kept on spinning to 80 mph or more. The top-end was adequate, cuz I didnt really need to go there, as 65mph was 5500rpm(2nd), and I don't usually need to go any faster.I had some nice springs on it that allowed the occasional romp into the high 6000s. This cam would idle at between 650 and 700 with plenty of vacuum for PB, with as little a 12* of initial. The idle was not dead smooth, having a very light lope.The lope was so light, I was actually disappointed;(it following the 292/508). But this beast with a bit of clutch,would idle down to 500/550 and pull itself around the parking lot like that, without any drama, and that with a 750DP/AG feeding it.To get moving I would often just blip the throttle and almost dump the clutch, and let the flywheel do what it was designed to do. It was extremely civil in traffic, and built peak vacuum very early. On one particular trip of about 1000 hiway miles, I installed a 600vac secondary carb and an A833 O/D box with a GearVendor behind it. This gave me 7 usable gears including Double O/D. 75 mph was a tic over 1800 rpm. 32mpgUS was the result. On this particular trip, traffic was booting along at quite a bit more than 75.I cannot recall the DD mileage, except compared to the 292/508 it was stupendous!
Totally irrelevant, except;
If you consider that the aluminum heads might be worth 0.8 to 1.0 in compression ratio, then this theoretically should be able to be done on 9.7 to 9.9 Scr with cast iron and tight quench. If you take out the tight-Q (worth about a half a point), then 9.2 to 9.4 should be doable; theoretically,on,the same 87E10.
So IMHO, one cam-size down(about 264/218@050) might work on one grade up gas, certainly on 91. Keep in mind you only need exactly enough octane to suppress detonation, when the the engine is heavily loaded and forced to spool slowly.And it is usually most sensitive to wrong fuel, at lower rpms. So plan the rest of the combo to match the engine. 2.76 gears and a 1600TC are not gonna like borderline-too-much Scr. A 2800TC and 3.91s will spool thru the Rs so fast it will be on the power-timing in just over an instant, and will never see the troublesome zone.
As for me, I would not sacrifice compression for a DD engine. There are just so many ways to avoid or control detonation below 3000, where most DD driving is done.And I would most definitely shoot for a tightQ. Extra machining costs at build-up will pay big dividends over the life of the engine.
This iteration was by far my favorite. I'm often sorry I moved up just the one cam size.If this cam ever wears out, I'm going back! I've been waiting since about 2005
So there you have it;just as I said,; totally useless information.
Why is that? Cuz the OP wants a smooth idle.
