Pump gas and nitrous

502SS

502SS

Forum Member
Ok, here's what I have for motor...
383 Small block chevy
Callies crank
Carrillo 6” rods
JE/SRP pistons (10.5-1 compression)
Comp Cams custom solid roller (.571/.577 lift)
Comp Cams lifters
1.5 rollers with stud girdle
AFR 195 heads
Edelbrock Super Victor intake
Pro Systems 780 carb
MSD 6AL
MSD Dist/coil


What I added this year...
NOS Cheater kit with an HVH plate and 150HP jets in it.
MSD retard/start box
Everything is the "out of the box" setup

Max I want to run is 180HP, but the 150's are in it (not sure if the 180 would make that much of a difference?).
I REALLY want to run pump gas if possible on the bottle. What are some thoughts here? If it's feasible, how much timing do I need to pull? It has 38* total right now (not locked out, it's all in by 1,500RPMs). What plugs/etc. should I run? Any other info I should know?
Keep in mind this is in my Jeep, so the runs take place at the sand dragstrip. The tracks are 300'. The MAX I might run would be 400' at the dunes, so for the most part, I'm on the bottle for 5 seconds or so at the very most (usually mid 4 seconds).
 
I've sprayed a 250 on my 421 with 10.8:1 compression on pump gas and pulled 9.9* of timing out. Didn't hurt a thing!
 
Would it be worth it to pull 10* of timing out though for a 150 shot? At some point I would think you're starting to taking away more than you're gonna get out of that 150?
 
Start at taking out 10 and just read the plugs. Do all your timing adjustments from the plugs (straps) but remember if you add timing to add fuel and vise versa
 
Start by locking the timing out, this will get rid of possible timing related issues caused by the mechanical advance. Rule of thumb is 2* for every 50. I start there and start adding timing back. I only run 32* total on my motor to start with though and don't pull anything out for 180. Obviously every motor is different so start safe and slowly work into it. Also make sure you run a separate regulator for the nitrous fuel. This will give you a lot more tuning control.
 
Thanks guys. I may wait until this year is over to mess around with pump gas. As of now, I'm only running 1 regulator but plan on switching to 2 with a dedicated cheap Holley for the nitrous this winter. Once that's done, I'll feel a little "safer" about it.
 
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