Pump Shot Help
The LS3 dual plane isn't your average dual plane. Just imagine the huge ports on your single plane, then more than double the runner length and you have the GMPP dual. It shouldn't need quite as much pump shot, but the runners are massive and move a ton of air.
I know the runners are plenty big, thats why I was stating he needs plenty of squirter. Or i guess you could take the time and fix it like you did. I prefer the single plane because it fits my needs. I think anytime you try to carb these motors like a old traditional sbc, thats where you make mistakes. What I have found is this motor loves lots more fuel, more timing and all around more anything than any sbc I have ever had. I have had lots of faster cars in my life, but this one just keeps surprising me. Once you start giving these motors what they like, it sounds illogical.
I picked a single because I dont need any more low end power. I was actually trying to aid my traction, and the single plane still almost over powers my drag radials.......not because duals are garbage. I always preferred a dual plane before this engine build.
My reasoning behind the dual was my need for drive ability at very low RPM with the setup I built this time around. What I didn't expect was for the GMPP dual to buzz straight to 7K and hitting the limiter before I felt the engine want to start nosing over. Traction is a big issue with mine now, with a tiny 220*at .050 cam and that intake, but I will take it! Mid 11s at 118 and excellent low RPM drive ability, even with a pedaling , spinning 1.8 60ft, is way better than I expected.
LOL, no, not even close to gramps SBC. I posted up in the other site I visit a lot, NastyZ28, that I was going to make a trip to the track and challenged them to guess what it would run on their "Competition Camaro" forum. I gave them my specs....3485lbs race weight, crate GM LS3 with only a 220-230 at .050 cam, dual plane intake, Fast EZ efi, 1 7/8" long tube headers, 2004R trans w 2800rpm lock up converter, 3.42 gears and 25.7" Nitto NTO5R tires and stiff road racing suspension. Most of the old school drag racers guessed I would run between 12.6 and 13.10 . That would be a great guess on a SBC ,based on the mods and the car setup. It blew their minds that it went 11.65 at 118, blowing the tires off ! 10.9x to 11 flat with a 1.5 60ft, if it hooked ?! Its not even grandmas hot BBC!!! LOL. These LS engines RULE!!
I also think buying the cheaper carb and drilling them for home made restrictors is a better option then paying for the a top end carb with replaceable every things. Those predrilled airbleeds and metering block restrictors can really add up in price by the time you buy enough of them to have some flexibility in tuning. Mc Master Carr sells bags of blanks for few bucks. The carb you have can be made to work. You have the wideband so all you need now is the patience to dial it in.
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Verdad Gallardo I posted this link in the FAQs for this forum. Has some good info on tip in stumble
http://www.aedperformance.com/tuning-tips.html
http://www.aedperformance.com/tuning-tips.html
This wasnt aimed at you in particular, just seems to be the norm on here
I still have tons of holly parts left over from god know when. Started tuning @ 17yrs old on my still under warrantee 1970 440 six pack Challenger. Then to 4 barrel holleys on my vettes. I used to get all sorts of different types from guys who thought there carbs were junk. They would sell them to me for 20.00. I once traded a 750 dp for am 850 db because it wasn't allowed in his class of racing. So I have tried all of the different versions. I just would hate to see this guy not have the awesome reaction time and feel of a dp over vacuum secondary's. I have tried them with the lightest spring pressures and the secondary's are just never going to get open in time. You can also tune dp carbs to be just as fuel efficient.
Last edited by handyandy496; Nov 14, 2013 at 08:53 AM.
100% agreed ! Unless you just want the avenger for what ever reason, find someone who just needs a 770 and unload it. Get a 750-850 DP and start tuning! Its just my opinion , but Id go with the 850. With your cam and those heads, I think the idle circuits will work better, out of the box, than the 750. May be able to get away with the 750 because of the better signal from the dual plane, but I still think 850 for the win.
