My 318 dyno results
So I haven't been able to get the idle quality where I want. I did try the Holley Ultra Street Avenger 670, but it didn't improve anything so I'm back to the Holley Street Avenger 570.
Cold starts during winter time are terrible. I also get hesitation driving around at low RPM all the way until the thermostat opens and the engine is up the temperature. I'm thinking I need to increase the idle feed restrictor?
Anyways, when I built this engine the Whiplash camshaft was chosen for being used with the OEM 302 cylinder heads, which I later found out were cracked. Since I know have the Edelbrock Performer RPM cylinder heads and I'm unhappy with the idle quality, I'm considering replacing the camshaft. What do you guys think about the Lunati Voodoo 20200710?
Hang on Olei
What are the specs on that cam, I found two whiplash cams, and neither of them have the advertised specs listed.
Ok I went to the Hughes site; it appears you may have the 1326 cam, with 213/226, or who knows cam, and it may be on a 109 LSa who knows.
But if it is a 213/226/109 cam and if you installed it at plus 5 or at 104, then if I gross that roller up by 53 degrees for typical roller acceleration ramps, then I get
advertised numbers of 266/280/109, and an ICA of 57*. Now, that will get you a Dcr of 8.2@165psi and a VP of 135, and that is a nice place for an aluminum headed teener to be.
So we know the engine design is fine
But here's the deal; with the effective starter gear of 2.94x2.74x12/31=6.24 is really taxing your combo. I didn't see the Stall-spec on your XTM, so,I went to the Hughes site and found that the XTM has a design stall of 2500 to 2700.
So;Your problem isn't carb nor cam, nor stall.
Yes you can get rid of that cam, but that Voodoo ain't the answer either. And
Yes you can put 3.55s in there, but that ain't the answer either with 31s. That will only increase your starter gear to 3.55x2.74x12/15.5=7.53 normalized to a 24" tire. Your combo is begging for a starter closer to 10/1...... and that would take 4.30s at a minimum. 4.3x2.74x12/15.5=9.12 normalized.
IMO your problem is strictly in the tune, and specifically in the T-port sync.and pump-shot. That cam has just 55* of overlap, so you may be trying too hard to hear the lope;check this out;
AJ's guide to Transfer Port Synchronization
Additionally, you probably have a reason to be running just 9.5Scr,with aluminum heads, but that is holding back your low rpm performance, a bit.
Just for kicks, I ran the Wallace at 10.5Scr and got a Dcr of 8.79@181psi, and that would really wake your combo up, to the tune of VP=144.That's a 7% improvement. This would allow you to run a bit more cam without a penalty in low rpm performance, but not the Voodoo you listed; that is a retro-fit roller for an LA block. 180psi might sound like a lot, but I run that in my combo ....on 87E10 gas. I have run more. Other guys are running 200 and a bit more, but not in a pick-up truck with 2.94s,lol.
