Holly carb help
I'll tell you what I for sure know, because I spent nearly a year with that cam.
You cannot run 36* of Idle timing, on the street, and here is why;
1) there is no reason to idle that cam over 800rpm, unless your oil-pressure is low, and then you have other issues.
2) The higher you idle it, the more idle-power she will make, and the harder she will bang into gear and the more rpm-drop you will get, and you will end up with two feet on the brake pedal.
3) at the current setting; your engine has way too much power BECAUSE;
A) of the 36*Idle-Timing, and
B) the high idle rpm, and
C) all the fuel she is inhaling, thru the 4-corner idle system.
4) IMO, that cam is not big enough to require a 4-corner idle system. Mine sure didn't need it.
Humor me;
set the Idle-timing to 14*,
set the T-slot exposure to like I said; a little taller than wide
Set the Primary mixture screws to, in the range of 3/4 to 1 turn.
Make sure the fuel-level is correct and stable
Then get your idle-air bypass worked out, to set your idle-speed to ~800, but DO NOT CHANGE the T-Slot exposure! Set your idle speed with bypass air.
You will know that you are getting close by:
A) when the rpm drop from Neutral to in-gear is ~100rpm or less, and
b) it doesn't want to explode the L/R band or over-running sprag, and
C) when you roll into the throttle, you do not get a hesitation, a sag, or nose-over. and
D) she tics over in gear at 650/700ish, and you can hold her back with just a lil toe on the brake-pedal.
Now; because of the small amount of Idle-advance;
1) to get the off-idle power back, you will need to use two strategies; You will need a two-stage advance curve with a kink in it at around 2800 +/- 200; very fast at the start, then slowing right down to keep your VERY HIGH compression ratio engine out of detonation. and
2) you will need a lot of vacuum advance at Part-Throttle to clean up the exhaust, and make her peppy again, and fuel-efficient at cruising speed. BTW, this cam sucks gas big-time and the more you advance it the worse it gets. This is partly because of the very modest duration of the power cycle. Because I already had 11.3 Scr and big cylinder pressure, I ended up running this cam at a few degrees retarded, but to no avail; with 3.55s it just sucked.
Right now, your engine is getting 36* under all circumstances.You are getting away with 36* of Power-Timing because of the 3000TC. So under power that may be fine (unless it detonates). But at rpms less than stall and under part throttle, there may be times your engine is wanting 40 to 50 degrees, but all your current system is allowing,is the 36*.
Mine liked at least 20* MORE under various circumstances; up to 60* of cruise timing at 2800rpm!
But at 3000 and Cruising, yours might like 56* for best torque and then can be leaned out for a modicum of fuel economy. The only way to get those high numbers (40 to 50) is with a good working modified vacuum advance system.
>>Lets say your engine likes 44* at 2000 just accelerating normally; and lets say your idle-timing is 14*@800; and lets say she does Not begin advancing until 1000 rpm. So that means, from 1000 to 2000rpm, the advance systems have to bring in 44 less 14=30degrees. Make a note of that.
>I said to install a 20* cam into your distributor. At 14* of idle timing, then, your Power Timing will be; 14 + 20=34* leaving you a 2* window to play with at some future date.
> I said to modify your V-can to 22* ( I think I did) that means the very maxim cruise timing can be is 34 +22=56* after the Advance is all in, which is perfect for your 3.91s.
> Lets go back to Cruise timing at 2000rpm. We already know that the V-can will be bring in up to 22*, so 30less 22= 8 degrees required in the mechanical.
so then 8 degrees from 1000 to 2000 is .8* per 100rpm , which is easy to get with One light spring and One HD spring that has a long-loop on one end. These are the stock 318 smogger springs.
So that's how I get 44* at 2000rpm for cruising on. But as you roll on the throttle, the 22* of vacuum advance will diminish and eventually disappear. Thus you might think that leaves you with just 14*plus 8= 22*, but simultaneously, your engine rpm is climbing to it's stall so picking up about .8* per 100rpm, so by 3000 it has climbed to 22* plus another 8, is 30 degrees, IMO, this is perfect to stay out of detonation. Then from 3000, to 3400/3600, the final 4* will come in.
> I would try this for a few weeks monitoring for detonation. I guarantee you that on the street, you can NOT feel the difference by azz-dyno of 34* or 36*. So don't be in a rush to dial those last two degrees in; ESPECIALLY with cylinder pressure over say 170psi. You are just looking for trouble on pump-gas with pressure higher than that.
Please note;
Unchecked detonation will destroy your engine and must be avoided at all costs, especially with cast pistons, hypers included.
Ok I've said my piece.
BTW, I am not insisting that you have to do it my way, as some members occasionally mention. I only care about your engine surviving detonation. So you are free to follow whatever advice you get. But if she drops the skirts into the pan, or holes a piston, maybe on the next go-round, you will tame it down.
Happy Hot-Rodding,
lol