need help with a Holley carb

-
trudysduster

trudysduster

FABO Gold Member
FABO Gold Member
Joined
Aug 24, 2009
Messages
5,033
Reaction score
224
Location
Corinth, Ky.
I thought I would put this in the right forum. I have stated several times while on FABO that I am no Holley guy. Me personally, I wouldn't have one on my car if it was given to me. That doesn't made me a bad person because I have had better results with Edelbrock, This goes back to 2002 right after I put the Duster together. I had a 650 double pumper on it. I had a stroke in 2001 and wasn't getting around very well. I was going to the dr. office that day and I was going to drive the Duster. Started it up and it coughed. Burnt the top of the engine bad. Had to replace the intake, dist., wiring and hood before I managed to get it out. So that is why I don't like a Holley. bad time. Now I have this 67 GTO sitting in the garage with the same problem. Holley poured fuel and caught the engine bay on fire.
Spent last week doing the wiring, installing ignition module, dist. cap, hot tanking intake, detailing top of engine etc. etc. etc. Had the carb rebuilt by reputable guy from a machine shop who races his own dragsters and such. Put it all back together. Started right up, sounds good at idle and even sounds good if you bring the RPM's up slowly but if you rap on it from an idle, it has a dead spot in it. same thing my Duster did before it coughed. when you run the car for awhile and let it idle down and then shut it off, the engine wants to keep running some and it seems like there is a mist of fuel coming out the top of the carb when this is happening. I don't know very much about a Holley. On another thread I mentioned this problem so I brought it over here.
One member said it was called " run on ". said he thought it may be throttle blades open too wide at idle. maybe need need to set floats. One said to check timing.
This is what I have. Engine is a 455/467 CID putting out 515 HP. Motor was built by Butler Performance in 2012. everything was new in engine. carb is a 4781C Holley Chromate 850 CFM double pumper. Has Edelbrock D port 87 CC heads. Has an Edelbrock Performer RPM dual plane intake. It has a M6907 Carter fuel pump. I don't know if the guage on it is correct but it showed 8 PSI of fuel pressure on it when it was running. Timing is set at 36* according to the timing marks. That is also what Butler set it at when built. car ran great until the fire.
Would this be some simple adjustment on the carb causing this or do you think it would be something he missed when he rebuilt it. Do you think someone who hates a Holley could do this LOL. I put a call in to the guy who built it and was going to see if he could come over and adjust it. What do you Holley guys think. Thanks, Bill

Oh, I also put an Edelbrock # 9266 heat insulator gasket on it instead of the thin one that came with the kit.
 
carb leaked some fuel on the manifold and it had a fire on the back of the engine. burned wiring harness, dist. cap. not a big fire or anything. was put out fairly quick. Carb wasn't really hurt but had it rebuilt just in case. Posted this in General Discussions under have you ever seen this before.
 
run on is timing, I would get a timing light on it . usually its because the timing is too advanced. get that sorted out first and then go to the carb. ive seen this so many times to where the run on will cause a pop and spit raw fuel out of the carb. I stopped using holleys myself because they are notorious for leaks and flooding. Ive actually had 2 that started fires in 2 different cars.
 
Thanks Lance, I will try that. It was a long day yesterday and really didn't have more time to mess with it. What has me puzzled is that when Butler put this on the dyno, they set the timing at 36* according to the paperwork I have here. It ran fine since 2012. would changing things like the ignition module and rebuilding the carb cause the timing to change that much to cause these problems. I don't know as I said I am no mechanic. I know enough to get by.
 
bad spark plugs could cause that couldn't it. I pulled a couple of plugs and they didn't look too good to me. maybe I should put a set in there before I go on.
 
if you are feeling ambitious , slap an eddy on there and see how it runs and what it does when you shut the car off. is that the same carb used on the dyno? fuel fouled plugs will be black and sooty. oil fouled will be black and wet. Ive pulled some ugly plugs out of engines that were running fine, I don't think that would cause it to pop out the carb
 
the Holley is the same carb that was used when it was on the dyno. these plugs are black and sooty. I tried to post a pic but the camera didn't get a good shot. I may try later. have to get ready to bowl this morning. I mean these plugs are caked with soot. I personally think that 850 is too much carb. I may when I get back from Cruisin the Coast slap on my 650 Thunder series carb and check it out. I called Jegs and the tech guy said 750 CFM would be great on there. But who knows. I am going to order a set of plugs and put them in anyway. just thought they weren't burning the fuel properly.
 
trudysduster said:
the Holley is the same carb that was used when it was on the dyno. these plugs are black and sooty. I tried to post a pic but the camera didn't get a good shot. I may try later. have to get ready to bowl this morning. I mean these plugs are caked with soot. I personally think that 850 is too much carb. I may when I get back from Cruisin the Coast slap on my 650 Thunder series carb and check it out. I called Jegs and the tech guy said 750 CFM would be great on there. But who knows. I am going to order a set of plugs and put them in anyway. just thought they weren't burning the fuel properly.
Click to expand...

it sounds like it is definitely running rich. could be float level and/or flooding , weak spark or timing. if the timing was set on the dyno and running good , I would be looking at the carb because it sounds like that's the only thing has been messed with. just a guess but I bet that eddy will make all the difference.
 
8psi is too much. Could be the reason for your fire. Knock it down to no more than 6psi for that car. Change plugs,those are probably gas fouled. Give em a good whiff. Smell like gas they're fouled.
 
hangn0ut said:
8psi is too much. Could be the reason for your fire. Knock it down to no more than 6psi for that car. Change plugs,those are probably gas fouled. Give em a good whiff. Smell like gas they're fouled.
Click to expand...

I over looked the 8 psi , deifinitely too high , 5.5 is where I run all my 4 barrels at
 
Not trying to be a dick, but there's nothing wrong with Holley carbs. The work awesome. It's the people who don't know what they're doing that causes the problem. If it leaked and caught fire, it's because someone didn't do something right. If it coughed, and caught fire, it's because someone didn't tune the car correctly. If it has a hesitation, the timing, and carb aren't tuned properly. The one issue that I feel they have, is the need for excellent filtering. The needle and seat gets stuck on the smallest of particles. Sometimes we need to look in the mirror to find the problem. Including me.
 
36° timing? How did you check/set this?

Also, yes, fuel pressure is to high. Check the float levels too.
 
I got a call back from my friend that built the carb and he loaned me another 850 Holley to put on here that may fix the problem. It is a carb he uses to dyno engines with. If it fixes the problem, he is going to set this up the same way. Going to change the plugs and get the pressure down some. see what this does. He said if this doesn't cure it, he will come here and get it right. cant ask for better than that.

69 340 GTS, as far as the timing goes, the 36* was set by Butler Performance when it was built. I never moved the dist. and they marked the damper with a mark. I have not put a gun on it yet but with #1 piston up it is right on the mark. And if someone is going to tell me that the timing has changed on this, be prepared to explain how the timing could change if the dist. hasn't been moved. All I did was replace the ignition module with the same one and fixed some burnt wires in the harness and have the carb rebuilt. I may learn something here. This isn't my best field.
 
Lance, as far as the fuel pressure is concerned, I don't know if the guage is bad, weak or what. I don't know how accurate it is. It has a Carter M6907 pump on it and it says the range I believe is between 5.5 and 7.5 max. It is less than 3 years old and only has about 3000 miles on it .What do you check the pressure with other than a new guage. It is probably a good idea to get one.
 
trudysduster said:
Lance, as far as the fuel pressure is concerned, I don't know if the guage is bad, weak or what. I don't know how accurate it is. It has a Carter M6907 pump on it and it says the range I believe is between 5.5 and 7.5 max. It is less than 3 years old and only has about 3000 miles on it .What do you check the pressure with other than a new guage. It is probably a good idea to get one.
Click to expand...

I have a temporary gauge I T-d up in a spare piece of rubber line that goes between the pump and the carb specifically for testing fuel pressure . after I test it I put my regular fuel line back on. my stock pump is almost exactly 5.5 right where it should be. if the pressure is too high the pump can force fuel past the needle/seats and flood the float bowls. you could try another gauge. I would definitely look into the fuel pressure, that may be where your initial problem started. you could always get a regulator to knock the pressure down, or look into a different fuel pump.
 
I have a vacuum gauge and my son has a fuel pressure gauge. I replaced the gauge on the fuel line and checked the pressure and it was bouncing between 7-9 PSI. I ordered a Holley regulator. It will be here tomorrow. Get that on and regulate the pressure down to 6 PSI and then I am going to change the carb and put this 850 Quick Fuel on that my friend loaned me and see if that cures the problem. With the pressure bouncing back and forth it may be the fuel pump acting up. According to Holley tech support when I talked to the guy Sat. it looks like Lance hit the nail on the head according to him. Get this
 
I believe the old goat is gonna make it. I finished the engine bay and got the motor back together tonight. I installed the regulator and the PSI is sitting at 6.5. Started it up and it still had the dead spot in it. It didn't do the " run on " after I shut it off so the pressure problem is fixed. So I swapped the carb that my friend gave me. He said he uses it to dyno the engines they build. It is a Quick Fuel 850. WOW, what a difference. This engine has very good response. So, I am going to take that carb back and have him set this one up like the other one. He told me he could but he needed to know what my engine liked. I can tell you it liked the new carb. For a minute there I thought I liked a Holley. Maybe, just maybe I one day might own one. Now that I found someone who know what they are doing. I cant believe I just said that. I will have him change this carb while I am on vacation next week. thanks for the help guys.
 

Attachments

  • DSC08593.jpg
    39.2 KB · Views: 111
  • DSC08594.jpg
    55.1 KB · Views: 132
  • DSC08595.jpg
    52.7 KB · Views: 137
trudysduster said:
Maybe, just maybe I one day might own one. Now that I found someone who know what they are doing. I cant believe I just said that. I will have him change this carb while I am on vacation next week. thanks for the help guys.
Click to expand...


Old dog, new tricks Bill, lmao.

I've never been a fan of Holleys either, but that's what's going on my new build. I will give it a fair shot, but if it irritates me it will come off.
 
You must log in or register to reply here.
-

Back
Top