New to forum need carb advise please...

[DUB]

2300, 6" rods, big valves, tons of porting, big cam... This is a pro 4 motor, not a mini..

My son ran a ton of practice laps this weekend and has developed a huge flutter off corner (sounds like flooding fuel out of acc pump), engine cleans righ up and makes great rpm until next corner. This is a Dorton 500 and has stock #25 squirter, 30cc pump and orange cam... Thinking about lowering the float level a bit more and going to a #21 squiter and pink cam.

This only happens when he is really getting after it, this is a high banked 1/4 mile track!

I have done a ton of searching on pull over but I'm not convinced that is my problem?

Any suggestions would be great. Thanks!

[car62]

what do the plugs look like? 30cc seems kinda odd for that setup,i think id put a 50cc pump in it

[DUB]

Plugs look perfect actually... we are still hitting 8,200 at the end of the straightaway, he is of the throttle for around 1 second..

[let-r-eat]

Cranking compression numbers per hole. How many laps on engine.

[DUB]

I don't have the cranking compression numbers, this is a new engine with a little over 100 laps. Brand new Johnson's motor full tilt boogie!

We are headed to the same track this weekend for a big race... I have found that my float level was just a bit high and the transfer slots were open a little far. I hope this is the problem, could mean the difference of .010 or more per lap. Any suggestions to look at would be good though.

[Big E tech]

My recomendation is to set the float level to the bottom of the hole with the engine NOT running, and then raise the float level 2 flats. Most likely your problem is not float level too high, but could be from running too low... Sometimes when the float is set too low, the fuel can slosh and allow air to be sucked into the main jets. That is still probably not the problem in your situation though.

Do yourself a favor and loosen the locknuts that hold the carb tight so that you can just barely slide the carb around. This minimizes the vibration transfered to the needle & seat, and the accelerator pump diaphram. Don't worry about a vacuum leak, the vacuum under the carb with the butterflies shut is enough to suck the carb down and seal against the gasket. At full throttle there is still enough vacuum to hold it down enough to not worry about a vacuum leak altering the jetting more than about 1 size.

Post up your findings after you run the car this weekend!

[7uptruckracer]

Power Valve if its as soon as he cracks it, stuck needle and seat maybe, Or high idle can sometimes. If it takes gas then dies its too little fuel if it never clears it can mean to much. Check your timing too.....To check the PV count your turns on the idle mixture screws till they are gently closed if the motor dies its not the PV if it runs it is.....Could be so many things check fuel pressure as well could be blowing the needle and seat up if its too high and causing it to overfill the bowl

[7uptruckracer]

I wouldn't change the pump the Dorton Series comes with a 30cc pump, and a wedged float. Bring the extra squirters but don't change them yet sounds like a part problem like a broken PV or seal. I ran 75 Jets 25 squirter white cam, a 4.5 PV even with the blow out check ball they go bad and check the float like he said! It should end up about 1/3 a way up the sight hole after you do what he said which is right! Thats a very very good tuneable carb Don't mess with it too much just bring replacement parts!

[DUB]

Thanks guys for all the help! I have replaced all critical componants like PV and acc pump, ruling this out. Loostening the acc arm actually created the same condition with a hicup, so I don't think it needs less fuel, based on that anyway... The float level was set just below the sight, where only a trickle would come out when running, of course these engines move the chassis quite a bit... This is going to kill me if I can't get it fixed, we only have 4 short practice sessions before the race!

Also We are only off the throttle for just a split second..

[car62]

running at WVSO?

[DUB]

Yes we are...

[car62]

heard there was 1 engine that let go...hopefully it wasnt yours

[DUB]

Not our engine... Our strans jammed above 3rd again, second race that we didn't finish because of this..

The pink cam fixed most of our issues, I think I need a smaller squiter as well to top it off. I did everything you guys suggested but still stumbled, did get better though. Thanks to all very much!

Now I need to figure out a bullet proof tranny for this (not a nice word)(not a nice word)(not a nice word)(not a nice word) thing!

[car62]

are you running a quick change rearend? or what rearend and rear gear are you running?

[DUB]

Yes we run a Speedway mini QC. Right now I have the FOG mustang trans, jams all the time.

[7uptruckracer]

I ran the White Cam in mine Could be squirter issue if less cam helped. Nothing to do but play with it!!!

[7uptruckracer]

We never asked what your Power Valve actually was????? Let us know fords like a 3.5 or 4.5

[DUB]

Stock Dorton carb, 3.5 PV!

[7uptruckracer]

All your stuff sounds right actually on the leaner side.....What is your needle and seat. 110? Wedged Plastic float or old brass? What Jets?

[DUB]

Wedged platic float, .110 needle & seat, 73 mains....

[7uptruckracer]

Make sure the wedged float is the correct wedge shape too. They make one that turns either way depending on application.... I've dealt with enough carb problems I know most of the tricks, but this one has me stumped a little. With those rods you need to be around 38-40 on timing. Long rods like more timing. Make sure you pump arm isn't maxing out or has excessive slop. 7.5 fuel psi. Good Plug gap and a cold set of plugs. Make sure you base plate and throttle body (two halves) gasket is good and your using fresh metering block gaskets. You can also look into an anti pullover squirter (hooded) Four Cylinders have bad bad pullover problems with some cams RPM ranges and soild motor mounts. Make sure the idle is as low as possible 1300-1500 so its not drawing fuel into the carb off the gas....I wouldn't go any lower the 71 jets. That has the adjustable metering block and all the tuneable plugs thats worth a look to. Hope this helps you narrow it down some....

[DUB]

Thanks very much! I will check all your suggestions next time out.