602 blubbering in high gear

[jasonsensational80]

Ok im needing some help. Just put a brand new 602 crate in my b-mod. Fresh Willey's carb... all directly off the dyno.. When we took it to the field to test high gear it started blubbering under initial throttle in high gear... it will clear after a couple seconds.. but every time you slow back down to simulate a slow rolling start it does it on take off...Changed 4 carbs from 750 to 650 to 390 all with the same result. Changed fuel pumps, changed regulators, put new battery in, put new solenoid in, put new module in the HEI... re-wired the car where it literally only has power to the switch and then to the distributor. None of which fixing it. The car will not blubber if the RPMs stay up, but if you try a slow start and gas it, it does it. Its also turning all the spark plugs black and dry (no fuel on them)

Any thoughts or suggestions? I feel like we've changed everything but the number the last 2 days!

Also.. from the dyno the builder set the timing at 36
using NGK R5724-8 plugs gapped at 40

I know everyone's first move is to the carb.. but we've put 4 different carbs on it.. 1 of which came off a 602 that ran last weekend with no issues and all 4 had the same exact problem.. which tells me its likely not with the carb.

Also we are using piston style race pumps for fueling... has anyone used these on crates? We've ran them for years on our other engines.

Its carrying 6 lbs of fuel pressure and never falling off that (even when its blurbbing in high gear).. 60 lbs of oil pressure.. constant as well.

[brad hibbard]

what is your timing curve-----you said the timing is at 36 but is it locked or advancing to 36

if it is NOT locked or advancing quickly-----that would be where I would start

also are you just rolling along and then hitting the pedal or are you power braking?

power braking the engine on slow speed starts is crate racing 101

last suggestion (for now) is what carb spacer are you using-----the dual plane on a 602 is kinda fussy about what spacer it likes

Brad
www.race-1.com

[jasonsensational80]

what is your timing curve-----you said the timing is at 36 but is it locked or advancing to 36

if it is NOT locked or advancing quickly-----that would be where I would start

also are you just rolling along and then hitting the pedal or are you power braking?

power braking the engine on slow speed starts is crate racing 101

last suggestion (for now) is what carb spacer are you using-----the dual plane on a 602 is kinda fussy about what spacer it likes

Brad
www.race-1.com

Brad-
Thanks for your reply.

It wasn't locked, but we locked it yesterday with the same result.

Just rolling a long and going to throttle as you would say at the start of a race.. no braking. But it does do the same thing if you let off the throttle then go back quickly.

Wasn't familiar with power braking on these? (this is our first crate)

Moroso part #64940 is the spacer we have to use per our rules. Now that being said. It was dyno'd with Speedway's 54564940 carb spacer.. which seems to be the same, but it isn't the "Moroso" as specified by our rules.

[Egoracing]

What fuel pressure do you have? What jets in the carb? Have you checked the float levels? We run them slightly high in the rear and slightly low in the front. I found this setting in an old Holley Tech manual for off road racing.

[jasonsensational80]

What fuel pressure do you have? What jets in the carb? Have you checked the float levels? We run them slightly high in the rear and slightly low in the front. I found this setting in an old Holley Tech manual for off road racing.

running 6 lbs of fuel pressure on a regulator... not sure on the jets in the carb.. but the carb currently on it just came off a 602 last weekend so it should be close.. floats are exactly as you mentioned..

[Egoracing]

running 6 lbs of fuel pressure on a regulator... not sure on the jets in the carb.. but the carb currently on it just came off a 602 last weekend so it should be close.. floats are exactly as you mentioned..

Our car started doing this one cool night racing at East Bay in Tampa, we ended up going down 1 or 2 jet sizes and the problem went away. There are a ton of things that can cause this condition and you have to be lucky or really really good to find it some times.

[mudeater18]

Also.. from the dyno the builder set the timing at 36

Recommended timing for a 602 and 604 is 32 degrees. Have you tried that ?

[jasonsensational80]

Recommended timing for a 602 and 604 is 32 degrees. Have you tried that ?

Yes... no luck though.. Next move is I'm switching plug wires... it recommends 8's I believe.. I put solid core big boys off an MSD ignition on it... possibly too much???

[1LTMDL]

We had a similar problem a few years ago on a 602 and the button under the coil had burnt into the cap.

[Dirt Knife]

Turn up the Regulator to 10psi. and see what happens.

[Egoracing]

Turn up the Regulator to 10psi. and see what happens.

He is getting to much fuel and you want him to go up? We typically ran at around 4 if we could keep it steady at all RPM's. 10 is to high, 8psi is about normal.

[jasonsensational80]

Our car started doing this one cool night racing at East Bay in Tampa, we ended up going down 1 or 2 jet sizes and the problem went away. There are a ton of things that can cause this condition and you have to be lucky or really really good to find it some times.

Yeah we are kind of at our wits end... Seems if a few things we try tomorrow don't work (i.e. changing plug wires, taking timing out) the next move is to sell everything and start over. lol

[Dirt Knife]

You tried 4 carbs. even a little 390 eye dropper?
changed plugs wires ect ect.

How hard is it to turn up the regulator and try it?

Maybe the fuel pres gauge is bad.

Dose the fuel press hold or does it blead down right away??

My mod runs 8-10 psi even my s stock runs 8-10 vortec 355

never had a car with 4 psi or id be replacing the pump along with the carb but you had 4 on it already.
just saying

2-3 turns on an alen wrench is easy to put back.

[jasonsensational80]

You tried 4 carbs. even a little 390 eye dropper?
changed plugs wires ect ect.

How hard is it to turn up the regulator and try it?

Maybe the fuel pres gauge is bad.

Dose the fuel press hold or does it blead down right away??

My mod runs 8-10 psi even my s stock runs 8-10 vortec 355

never had a car with 4 psi or id be replacing the pump along with the carb but you had 4 on it already.
just saying

2-3 turns on an alen wrench is easy to put back.

yeah its not hard to change fuel pressure with our regulator.. we set it at 6 because thats what we've always ran.. fuel pressure stays constant the entire time..

[Egoracing]

It would not matter what the gauge is showing or if he did not have one, the plugs are black which is a rich condition. 10psi is at the pressure where it can start to foam the fuel in the bowls when it sprays into them, this will lift the floats and starve the engine of fuel and lean out the engine which can cause meltdown.

[jedclampit]

Stale fuel?
Engine temp too low?
Spark plugs too cold or gaped too wide?
Have you changed out the fouled plugs ?
Is this a completely stock crate motor?
I don't believe an HEI and solid wires play nice together.

[MikeC1969]

Any updates on the problem? Did you fix it?

[hot rock]

we had a simular problem last year with a 604,it ended up being a grounding problem.we ran a wire from where battery was grounded to frame up to where every thing else was grounded. fixed our problem.good luck.

[jasonsensational80]

The dealership ended up taking the engine back and trading me out for a new one... bolted the new one in and it worked perfectly... still unsure what caused the other one to act that way.