Fuel regulator/bypass

[ZERO25]

Which one are yall using on a 602 with the rear mounted fuel pump?

After chasing carb problems for the last 2 weeks, our local crate builder believed we had the wrong regulator, too small he said.(it came with the car)

[brad hibbard]

rear mount belt pumps deliver quite a bit of volume and a crate engine does not use much volume so the regulator and return line are critical ---also do not forget the fuel cell vent needs to be adequate and clear

as for the pump---do you know what size it is 300-400-500?? this is determined by the length of the gear
for crates we use the 300

if the pump is bigger than a 300 definitely use a a regulator with a bleed

the aeromotive stuff is real nice but the universal bypass regulator from them does not have a bleed---it works well with a 300 pump but if you are larger I recommend something with a bleed

make sure there are no dips or kinks in your return line (-8 minimum -10 is better)

Brad

https://www.race-1.com

[ZERO25]

Thanks Brad! This is kinda baffling us. It was a 3 race old Hendren 602, tuned on his dyno. We've adjusted the floats both ways and adjusted the front squirters, but nothing seems to help. We've checked the filter and lines and there were no issues. Our local builder adjusted the fuel pressure from 6.5 to 7.5 to no affect.

[brad hibbard]

OK lets get more specific---originally you just asked about a regulator
What is the actual on track problem?
What fuel are you using?

Brad

https://www.race-1.com

[ZERO25]

Yeah, because our local builder said we were using the wrong one.(it was changed tonight)

Our car has been stumbling at the end of the straightaway.

We are using VP x85.

[brad hibbard]

did changing the regulator fix your problem?
I am going to interpret your "stumbling" as a misfire
on E85 a high end misfire is a rich condition
we do not like dead head regulators for E85 that have 3/8 pipe fittings as they will go lean at high end---and I am going to assume that is why your local builder didn't like the regulator you were using but I do not think that was the "stumble"

I hope your problem went away but I am guessing that it did not

Brad

https://www.race-1.com

[ZERO25]

Dont really know as it doesn't do it until it has a load on it.

We had the regulator with the return on it but our local builder said it was too small, so we purchased a bigger one.

I just find it odd that it had 3 races on it with no problem or at least according to the prior owner ( we did verify that it was dynoed by Hendren)

[brad hibbard]

have you called Steve Hendren to ask specifically about the situation?
he is pretty easy to talk to

Brad

https://www.race-1.com

[ZERO25]

have you called Steve Hendren to ask specifically about the situation?
he is pretty easy to talk to

Brad
www.race-1.com

Yes, he helped us sort out the regulator.

[north louisiana dirt]

we are trying to sort out a similar problem with our 604 crate LM.... the WRC /aeromotive mech drive pump Part number is 250250LM..... does that mean it is a 250 size or 250 gph pump ? car was bought with the fuel set up on it.... pump has a check valve on top looped back into the incoming fuel line, a deadhead Reg between the pump and fuel log. ( no bypass back to the tank. so I assume dead head reg) .... never seen a set up like this.....got a stumble at corner exit... then clears .... E85...carb did not come with the car.... got to sort out and pinpoint if it is the carb or the pump / check/ reg set up.... Aeromotive / WRC web site is about the worst I have come across in a while...for finding info easily....

[Lizardracing]

Stumble on Exit, When does this happen? When you pick up the throttle?

[north louisiana dirt]

yes Sir, we raised and lowered the float level , raising it seemed to make it worse, lowering it helped a little... driver "thinks" it's carrying 6psi fuel pressure down the straights , but not for sure

[JustAddDirt]

might be too big or small of a squirter, or a cam issue or adjustment to the squirter.
are you matting it, or rolling into throttle? does it do it when the you are on the way down with the throttle, or once at WOT?

[north louisiana dirt]

I will have to get with the driver and get more detail for you...... and pinpoint exactly what is going on.... It looks like, from where I was hanging in the fence... it would rotate on entry and when he would pick the gas back up it would go... but when it was in the center of the arc in the middle and really needing to GO... it would stumble / bog / not accelerate.....till it got a little way out on the exit...

[north louisiana dirt]

directly from the driver...>>>>>>>>>>>>>>>..Sure. During the feature, when I run the bottom and drive off into the corner, and go to pick up the throttle at the 1/4 mark or so of the corner, the car stumbles and hesitates repeatedly through the duration of the corner. When i get onto the straightaway, it will clean up about at the flag stand and run smoothly. It was the same symptoms at and did it intermittently in practice at Boothill, but seemed to be at its worse when really throwing the car into the corner. The biggest change we had was when we raised the floats for the feature at Vivian. It actually made it worse. When we adjusted them back down for hot lapping after, it was back to where we were in the heat race and hot laps. It makes no sense, but it does appear to be better when I run around the top versus trying to roll the bottom.