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Author Topic:   I stumped KP with a carb problem !LOL
xhubby
Dirt Full Roller

Total posts: 74
posted April 03, 2003 11:21 PM
No offense KP, but I just had to share this with the rest of the guys on this forum.
Here's the problem. I have a new motor, 355,flat top, 50cc Pro Action heads,Torker II aluminum intake(used),Isky 534 cam. Put on newly rebuilt holley 4412 carb,& it will not idle without taking out the float bowl ***** . Replaced carb with a new Braswell with the same results. With the float bowl ***** in place, it runs good for about 3 or 4 minutes, then starts to dump fuel from the boosters. Take out the ***** & it smooths right out. Float is set just below hole level, fuel pressure is 5lbs,I'm convinced the problem is not the carb. KP & I have been pulling our hair out on this one, so have at it guys.

Rick D
Dirt Roller

Total posts: 25
posted April 04, 2003 11:50 AM
Had a similar problem with my 4 bbl but found out we had a few air bleeds plugged up with dirt.


KPLugnut
Dirt Freak

Total posts: 408
posted April 04, 2003 12:36 PM
You ain't lying about "pulling our hair out", xhubby!!! LMAO!
And if any of you know me, I've got none to spare as it is!! :-)

I'm pondering the intake gasket leak theory, currently, just gotta figure how THAT symptom would be how it shows up...

Man, I hope ya find it, so we ALL can learn somethin'.

KPLugnut

autoshop
Dirt Maniac

Total posts: 102
posted April 04, 2003 05:24 PM
check and see if you have the wrong metering plate gasket in the carb. The other problem would be a piece on junk in the metering plate fuel well just behind the power valve.

KPLugnut
Dirt Freak

Total posts: 408
posted April 04, 2003 07:57 PM
Since we eliminated the possibility that it could be actually IN the carb, it can't be a gasket mismatch problem, or "junk in the carb". Those were the first things we talked about checking for.

I got a note from a good friend, and it REALLY enlightened me... Here is what he wrote:

I would suspect it is hanging a intake valve open.......I would guess this is a hyd. cam??? and the valves are too tight. This builds pressure in the intake, messing up the carb.........

I would have Xhubby back off each rocker arm say 1/2 turn.....even if the cam is a solid.

If after backing off the valves the problem keeps going........I would leak the motor down and check the valve seal.

I'll respect the privacy of my friend, but he needs to know that if this IS the problem, he's saved me from losing the rest of my hair. For that I owe him a big ol' THANKS.....

Let us know if that helps, xhubby....

KPLugnut


xhubby
Dirt Full Roller

Total posts: 74
posted April 04, 2003 11:45 PM
Thanks alot KP. Today I changed the intake & plugged the power valve. NO CHANGE! The motor has a solid cam (Isky 534). We have not checked the valves since we got the motor from the engine builder(been too busy trying to get it to idle right), but will do that first thing tomorrow. At this point I'm about ready to say to *ell with it & take up golf. Did I say that? I'll get back to you with the results tomorrow. If it still doesn't run right , I'm going to the nearest bar to get some answers, there's always someone there who thinks they know it all. LOL!

jammin
Dirt Administrator

Total posts: 5556
posted April 05, 2003 07:14 AM UIN: 16262997
RPM change at all when you do this?

jammin

xhubby
Dirt Full Roller

Total posts: 74
posted April 05, 2003 08:50 AM
Jammin, the RPM stays pretty consistant, as long as you don't plug the float bowl ***** hole.

xhubby
Dirt Full Roller

Total posts: 74
posted April 05, 2003 01:11 PM
Valves were all real close. 16 intake & 18 exhaust. Doing a leakdown as soon as we can get a gauge.

rico 08
Dirt Freak

Total posts: 372
posted April 05, 2003 04:56 PM
Thought i'd throw in my 2 cents,have you ruled out that the pressure gauge you are using is not registering right?It really sounds like you have too much fuel pressure from the pump.

xhubby
Dirt Full Roller

Total posts: 74
posted April 05, 2003 06:36 PM
Rico, Not that this makes it 100%, sure but it is brand new . Spent $86.00 at Speedway Mtrs.Thursday so I would like to think it was correct. I'm starting to think that the heads & intake don't match. Wouldn't an engine builder check that out before putting a new motor together? It looks like there is some oil in the right side intake runners. Thanks for joining in.

xhubby
Dirt Full Roller

Total posts: 74
posted April 05, 2003 08:22 PM
Just got the results of the leakdown test & every thing checked out ok. Any more ideas? I'm ready to pull it out & return it to the engine shop & put the old motor back in.

KPLugnut
Dirt Freak

Total posts: 408
posted April 05, 2003 08:37 PM
With a tight lash cam the advance of the cam becomes extreamly important.......if the cam is off say 2 degrees.....it could cause this problem.....I would try to back the valve lash off half a turn or basically make both .026" and start the motor. This will show if the problem is in the cam timing.

The other thing that could be going on is the machine shop might have a intake valve too tight in the guide. When the motor builds enough heat, one or more valves can "hang" a bit and cause the problem.
Now, doing a leakdown test on a cold motor with the rockers backed off (valves closed) may not necessarily show this.

I'm kinda stabbing in the dark here (also relaying this advice which was given to me by a friend).

Xhubby, I hope you don't have to yank the motor. That would be the absolute last resort, I assume.

BTW, has your engine builder been any help?

Boy, I hope we solve this...
KPLugnut

7jdwmod
Dirt Roller

Total posts: 11
posted April 06, 2003 01:55 AM
i had the same problem...adjusted this adjusted that.. nothing worked.....bought new carb....fixed it all...carb had trouble with was a c&s...replaced it with a willeys

[This message has been edited by 7jdwmod (edited April 06, 2003).]

madmodshoe
Dirt Forum Racer

Total posts: 89
posted April 06, 2003 05:50 AM
lets test some known quantities here. Put both carbs on someone elses motor or your pickup or any carbed motor. That will tell you whether it is in the carb or motor. If it is in the carb it may be something that needes to be done or is being done incorrectly. For instance, How do you set your idle air bleeds? There is a given process and it doesn't take much pressure to mess the idle air screws. Is your shop particularly dusty? Maybe you have dirt that gets stirred when you fire the car and the fan puts that dirt into an area where it can be ingested into the carb. Have you ruled out the fuel pump? How much pressure does the gauge read with the float bowl screws in? Sometimes, because of harmonics, the fuel pump pushrod can actually bounce between the cam and fuel pump. Maybe this added pressure with screws in place is causing this. That is, if you don't have a regulator and return line. Is the fuel actually coming out of the boosters? Or the bowl vent? If it is the boosters then there would be a signal problem. That could be anything from a cracked aluminum spacer to cracked baseplate. Baseplates can also warp if not tightened properly. Sorry to be so long, just trying to help! Let us know if you get any more "research" done. Thanks Steve.

rico 08
Dirt Freak

Total posts: 372
posted April 06, 2003 08:34 AM
Oil in the intake runners?Whoa that is not right,you may have some angle milled heads/intake,which will make it pull oil/air from intake valley. area.

xhubby
Dirt Full Roller

Total posts: 74
posted April 06, 2003 04:22 PM
KP, I heard a rumor that there have been some 50cc Pro heads that were found to be bad. I'm not sure what the problem was exactly. Maybe somebody on here could shed some light on this or verify whether the rumor is true or not. To your question about the engine builder, no. As far as pulling it out, We start our season next weekend ,and we've gotten behind on other parts of the car dealing with this headache,& need to get in a motor that runs right. We did get to check vacume yesterday, & it was about 10 - 12 at idle & dropped to around 5 when it started to load up.
Madmod, good to hear from you. Just in case you didnt make the connection, this troubled motor is in your old DW6. How would a person tell if the fuel pump rod was bouncing? We do have a regulator & guage & it holds a steady 5lbs. The fuel starts dumping from the boosters, but it's done it with two diff carbs & one of them is new.
Rico, The heads are brand new & I know the intake has never been milled. Like I said earlier, I'm wandering if this type of intake just does not fit this brand of head, or maybe the rumor is not a rumor.(about the 50cc Pro heads having some problems)That would be my luck. Thanks guys for all the ideas.

racerwilson
Dirt Full Roller

Total posts: 56
posted April 07, 2003 10:45 PM
Did you check your fuel lines? From the pick-up in the tank to the carb. Had same problem with any carb on my engine. Checked all lines and found one loose and was sucking air that didn't show on the fuel guage only messed up the carbs and pushed fuel through the boosters. Just a thought mybe someting simple or over looked.

xhubby
Dirt Full Roller

Total posts: 74
posted April 07, 2003 11:07 PM
Racer, Yes we checked the fuel lines, all were good to go.

KP, we backed rockers off to 26 & still had the same problem. Put the carb on another motor,( this one had KP Carbs on the carb we took off,Hmmm,I wonder whos motor that was) & ours ran perfect. SOOOOOOOO we pulled the motor & have the old one ready to stick in. The new one is going back to the engine shop tomorrow. There was alot of oil in the front & rear ports of the right side head.

madmodshoe
Dirt Forum Racer

Total posts: 89
posted April 08, 2003 01:20 AM
X-hubby, good to see you still got the goods! Sounds like one heck of a problem! I am glad that you figured it out! Good luck with your season. Keep kickin' those jets arses with your DW. Let me know if have any chassis Q's. I ain't the brightest bulb, but sometimes I flicker on and off! Good Luck!

xhubby
Dirt Full Roller

Total posts: 74
posted April 08, 2003 05:49 PM
Madmod, We still have,nt figured out the problem,we just gave up. Actually we just plain ran out of time & need to get in a motor that runs right. I'll let the man who built the possessed motor figure it out.We named it Christine(after the movie about the car that was possessed)Out of the 18 cars preregistered in our class,13 of them are Jet mods so we've got our work cut out for us. Have a great season!

2nd2none
Dirt Freak

Total posts: 368
posted April 08, 2003 07:14 PM
xhubby, let us know what the engine builder finds. We are putting together a flat top 50cc pro action head motor with a bow tie intake..........hope i dont have same problems knock on wood....

madmodshoe
Dirt Forum Racer

Total posts: 89
posted April 09, 2003 07:35 PM
X-hub, actually won't be racing this year. Been out of work for a while after back surgery. Had to sell out to pay bills. But I will be back. Thanks.

xhubby
Dirt Full Roller

Total posts: 74
posted April 09, 2003 10:53 PM
Well guys, so far we still have our problem!! As of tonight, we have changed carbs, fuel pumps,carb adapters,motors(everything on this motor is different than the other motor), added a fuel regulator & gauge, checked all fuel line fittings, & fuel filter. Tried the carb on another car the other night & it ran perfect. Tonight we added a return line(temporary fit) & the carb idled ok, but the fuel coming out of the return line was real erratic & came out in spurts. The fuel pressure gauge jumped from erratically back & forth from 1 to 6.(yes we bled the line to the gauge) Tomorrow I'm changing all fuel lines from the fuel cell forward. So far this bug has cost me about $1000.00. $200.00 on parts & $800.00 on therapy & sleep aids.

2nd2none, I'll get back to you on the motor as soon as we get an answer from the engine builder as to why were getting oil in the runners.
Three days till our first race.Hope we make it.

Flatlander
Dirt Freak

Total posts: 310
posted April 09, 2003 11:40 PM
sounds like foam or something in the fuel line or a line sucking together also take pickup out of fuel cell make sure hose has no pin holes in it or clamp is not loosetry feeding it fuel from an indepentdent source

Eljojo
Dirt Freak

Total posts: 273
posted April 10, 2003 07:56 AM
I'd originally suspected the intake and wondered why you didn't pull it and replace it with a different one. My guess was that someone had, in the past, matched it to a set of angle milled heads and your motor man missed it. But this isn't a guessing game so I kept the pie-hole shut.
I found one like this: remove the pick up from the call and plug it at the end. Remove the fuel line from the carb and attach a line from your compressor. Run 'er up to about 50psi and that leak will show itself! Mine was at the bulkhead fitting at the top of the cell. Darn thing would not idle and had that "I'm starving for gas" sound. Blamed fuel pump. Convicted fuel line fitting. Good luck!

flywheel
Dirt Roller

Total posts: 9
posted April 10, 2003 03:22 PM
Vent hose or valve maybe clogged.

madmodshoe
Dirt Forum Racer

Total posts: 89
posted April 10, 2003 10:38 PM
Check your pm.

[This message has been edited by madmodshoe (edited April 10, 2003).]

xhubby
Dirt Full Roller

Total posts: 74
posted April 11, 2003 12:23 PM
Well gentlemen, the search may be over.(I hope so).I found a fitting that connected the fuel line to the fuel cell that was probably sucking air. It was tight, but when we applied some dish soap & blew air into it, bubbles appeared. Replaced it with a new fitting & seemed to fix the problem. We'll find out tomorrow night. I don't yet understand the theory on this though. I figured if it was sucking air, it would get less fuel, kind of like trying to get pop from a tall glass through a broken straw.
Anyway, thanks to all of you. As you probably figured out, I'm no MR. Goodwrench, so it's nice to know there are people that are willing to take the time to offer their assistance.
Good luck to all of you in 2003.

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