Ok, we pulled the mill that we had in the car last year and sealed it up for use as a spare. The motor ran well and consisted of the following:

440, 4.15 stroker crank, Ross flat-top pistons (12-1 calculated ratio), ported Indy 440-1 heads, Indy 440-25 intake (with mods to reduce volume), twin Edlebrock 750 carbs, custom Comp roller cam, 268 deg Intake, 272 deg Exhaust, 114 LSA, 0.690" lift, installed at 106 deg intake centerline, 32 degrees timing (not locked out, but advances immediately at startup).

Starting manners were very good. Fired right up hot and cold. One of the issues with this motor is that it made a lot of low end torque. Tire shake was an issue on well prepped tracks. Best ET was 9.82 at 137 mph.

My goal this year was to tame the combo down (especially at the low end) to alleviate tire shake. Using an identical combination as above with exception of the camshaft, the car is very hard to start both hot and cold. Cranks about 3-4 times longer than before, is difficult to light (stumbles a bit), but once it fires runs fine. It is a Lunati 53712, 276 deg Intake, 284 deg Exhaust, 108 LSA, 0.690" lift installed at 104 intake centeline, however, I did retard the cam 2 degrees to kill a little bottom end. At 104 deg ICL, the cam is advanced 4 degrees. Timing started out at 32 degrees, but the engine felt a bit lazy. Upped it to 35 degrees and it responded with more mph. ET was 10.15 at 133 (heads do not flow as well as the set on the other engine.) Jetting is the same; with this cam may be a little rich (haven't had time to fine-tune it).

So, this cam, when run with the stock cross ram started fine. I realize that the tighter LSA is probably bleeding off compression when cranking, but I have not run a compression test (on either engine; we only do leak-down tests) so I can't compare engines. It is doing what I want; killing some bottom end and tire shake is gone, but the long and difficult cranking is not good for both the starter and increases the possibility of backfire (these intakes do not do well during a severe backfire. I know 3 people that have lost intakes due to this).

We can advance the cam while it is in the car and I am wondering if advancing it 2-4 degrees will help build cylinder pressure during cranking making it easier to start. Anyone have any ideas?

Did you verify that both lobes(Int. and Ex.) are ground on 108 LSA? If not do that first Normally a closer LSA builds more bottom end HP and torque and gives up top end HP and torque The widest LSA I have ran on any Mopar RB/B wedge was 110, that was with a 5000+ RPM converter behind a 526 C.I. wedge with M.W heads for drag racing only I have ran a bunch of different cams that had from 110 to 101 LSA, the narrower the LSA the more tire spin occurred when traction was limited and the lower peak HP RPM also I would look for a vacume leak now

Cab - No I did not. The Lunati started OK with the stock intake but did not seem well matched to the restricted runners when used with close to 500 cu-in. The Comp cam was designed to alleviate that and it worked very well, but we decided to go with the 440-25 intake and the car picked up about 0.3 sec using that Comp cam. Went back to the Lunati (degreed it the same as before, except retarding it 2 deg) using the 440-25 and this problem started. We were very careful seating the intake so I am 99% sure that a vacuum leak is not the issue.

Best fix is to spin the engine for a few sceonds and then hit the ignition switch to start it



Russ

Since you retarded the cam,try advancing the timing to 38 degrees and see what happens.

the tighter LSA is probably bleeding off compression

The Lunati IVC is only 2° later than the Comp, but it's because of your ICL, not the LSA.

The Lunati has about 70% more overlap window area, which means the charge quality at cranking speed is much worse.

Thanks for the replies. We do spin it over first and then hit the ignition. Same procedure as before. We will spray the intake and see what happens and possibly advance the timing (but an effiicient combustion chamber should not need a whole lot of timing). The car started fine with the Lunati using the old cross ram. The only thing that changed between last year and this year is the cam. We have never run this cam with the 440-25 intake.

This is just a feeling, no data.

I think the large plenum and the large overlap of the 108 LSA cam are the prime reasons starting isn't so snappy. But more ignition timing might help, especially if you can adjust the distributor to get the timing to come in at cranking speed rather than idle.

You have the cam in at a 106 ICL if I read everything correctly. Installing back to 2* or even 4* more advanced from the 2* advanced now will help build cylinder pressure.

I dont know much about the 440-25 intake but I figure its plenum area and ports are bigger then the stock intake you were running. I see you stated you took steps to reduce some of that area, as I read it.

Between the extra area of that intake and the combined lower Quality,and Slower speed of the intake charge with the extra overlap, that would make it harder to fire. You may have other issues going on as well, maybe a vac leak as well.

Id go at least back to a 104 ICL maybe even a 102, but dont expect it to help to much. You may see a increase in cranking PSI around 10' per each 2* advance. Definately more then you have right now, whatever that is.

We can advance the cam while it is in the car, so I may give that a try. I was trying to kill a little bottom end torque to alleviate tire shake (which it did), but the rpm range where it wants to make power is higher (6500-7500) and I don't want to spin it that high. It goes through the traps at 6800 now with a 29" tire and 4.10 gears.

The car ran very well for what little testing we did. In 10 runs over 3 days it ran 10.15-10.18. Slower than with the other cam, but that doesn't bother me. It's just a pain to start.

I agree, try more spark lead during cranking even if it has to drop off when idling.

I run this same intake . The cam is larger but ground on a wider LCA. 285/292@112 in at 108. it is 572" so I have not reduced the plenum. The timing is crank trigger fixed at 32-34. While it starts fine warm it is very difficult to start at 50 degrees or less. By accident last year I stumbled on to something. I have a set of machined aluminum carb covers to keep debris out when it's parked. Getting ready to make a run the engine started quickly, than went pig rich. You guessed it, forgot to take the covers off. In the fall again it wouldn't start. I was afraid I flooded it so I pulled the plugs, 6 were dry , 2 were wet. Swapped plugs still didn't want to start. Put the caps on, fired right up. I used to crank it first w/o spark. This resulted in hard starting. One time it resulted in this.
Doug

That's exactly what I don't want to happen. We did try a locked out distributor a couple of years ago and it seemed like it wanted to backfire and cranking was labored when he hit the ignition. I only run one spring in the advance so timing comes in right after it fires. I don't think I want to go back to a locked out dizzy. May try more initial/total timing. It's at 35 now.

Like Doug said... he had the covers on the carbs and
it fired right up.. thats 2 big choke plates.. it
wants more fuel