402 just not running right(frustrated)... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**68350** · 10-20-2011, 10:19 PM

Ok, I guess I'll start off with what the engine is...

1970 402 truck block
1965-1967 396 car heads
1970 BB truck quadrajet rebuilt
HEI with aftermarket cap
rest unknown but all looked good when engine had new gasket set installed

Timing is set at 12 below TDC
Idle set at roughly 700 in park

Ok, here are my issues. It doesn't seem to want to run worth a crap when you put it in gear. By this I mean it has a slight stutter if you gas it after its in gear. It will rev up in PARK perfectly fine. If you get on it, it has alright power(nothing like my other big block truck) until about 2000-2500 RPMs, then it feels like it loses almost all of its power until it shifts, then it regains a decent amount of power. The truck has a 4.11 rearend, so I would think it should have way more snap than my 68 which has a 402/400/3.08 rearend.

Can anyone shed some light as to where to start. Also, can anyone tell me how to properly set mixture screws on the q-jet? What should the idle be at in gear, too? thanks

10-20-2011, 10:19 PM	#1
68350 Senior Member Join Date: Jan 2002 Location: Williston, ND Posts: 2,999	402 just not running right(frustrated)... Ok, I guess I'll start off with what the engine is... 1970 402 truck block 1965-1967 396 car heads 1970 BB truck quadrajet rebuilt HEI with aftermarket cap rest unknown but all looked good when engine had new gasket set installed Timing is set at 12 below TDC Idle set at roughly 700 in park Ok, here are my issues. It doesn't seem to want to run worth a crap when you put it in gear. By this I mean it has a slight stutter if you gas it after its in gear. It will rev up in PARK perfectly fine. If you get on it, it has alright power(nothing like my other big block truck) until about 2000-2500 RPMs, then it feels like it loses almost all of its power until it shifts, then it regains a decent amount of power. The truck has a 4.11 rearend, so I would think it should have way more snap than my 68 which has a 402/400/3.08 rearend. Can anyone shed some light as to where to start. Also, can anyone tell me how to properly set mixture screws on the q-jet? What should the idle be at in gear, too? thanks __________________ 68 Chevy CST/10, 50th Anniversary, 327/th400, 373 posi, buckets 68 GMC Shortbox Stepside, 402/th400, Tilt, Tach, Bucket Seats, 3.08 Positraction 69 Chevy Camaro SS, 383, 4 speed, positraction 70 Chevy El Camino SS396, Triple Black, 454/th400, Tach 70 Chevy Shortbox Stepside 4x4, 350/th350, Tilt, Tach, Cab Lights, Bumper Guards, Tow Hooks 70 Chevy 3/4 Longbox, 350/auto, 70k, SURVIVOR 71 Chevy Blazer, CST, 350/auto 71 GMC Sierra K2500, 454, 4 speed, 4.10 posi, 37s 71 Custom/30, Open Road, 350/th400, tilt 72 Chevy Shortbox Fleetside, 496 Stroker/th400, Tilt, Tach, Bucket Seats, 3.42 Posi 72 GMC Sierra Grande 2500. 427/th400, tilt, a/c, tool and stowage, buckets/console, 3.54 posi



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.