Holley Carb Problem

[Clarkson]

Originally Posted by Warren

Hee, hee, hee, it's not, I've had it in bits today but you made me laugh.

Anything more helpful David?

Cheers
Warren

Remove the mixture screws and blow some compressed air down them and try again?? Are the orings ok on the mixture screws??

[Warren]

Originally Posted by Clarkson

Remove the mixture screws and blow some compressed air down them and try again?? Are the orings ok on the mixture screws??

'O' Rings looked good, plenty of bounce in them, not hard and perished but then again the Carb came from a 'dynoed only' engine......we can trust our fellow members can't we...

I really have found very little crap knocking about the system. Pump was new, feed lines new, tank new at beginning of the build, I'm not even that sure what the piece of crap in the float bowl was. It was rubbery but not silicone maybe a shard or cut hose but then again I was really careful.

Odd that buggering around with the idle screw on boths side was a little inconsistant but I am no pro and reluctant to go more than 1/4 to 1/2 turn either way after having things set up by Bogg Brothers. AND I must say it ran like a peach up until the other day when the float needle got crap in it.

Hopefully I will pick up another length of fuel hose, after Craig's warning, and take it for a spin tomorrow evening to see how it runs under load.

Cheers
Warren

[Purple AK]

Warren. Looking at things logically. It was fine until the other day when it picked up some crap in the needle valve. It is now better, but not totally. So.. Either there is still some crap in there somewhere. Or..The Float height is not quite right

[mikey]

Originally Posted by Warren

'O' Rings looked good, plenty of bounce in them, not hard and perished but then again the Carb came from a 'dynoed only' engine......we can trust our fellow members can't we...

I really have found very little crap knocking about the system. Pump was new, feed lines new, tank new at beginning of the build, I'm not even that sure what the piece of crap in the float bowl was. It was rubbery but not silicone maybe a shard or cut hose but then again I was really careful.

Odd that buggering around with the idle screw on boths side was a little inconsistant but I am no pro and reluctant to go more than 1/4 to 1/2 turn either way after having things set up by Bogg Brothers. AND I must say it ran like a peach up until the other day when the float needle got crap in it.

Hopefully I will pick up another length of fuel hose, after Craig's warning, and take it for a spin tomorrow evening to see how it runs under load.

Cheers
Warren

Screw the mixture srews in until they seat and write down the number of turns. This will give you the datum setting that warren ended up with.

Check a couple of thimgs if the carb has stopped backfiring. Set the primary butterfly so that when you see the transfer slot in the throttle body it appears as a square hole - ie butterfly obscures the rest. Open up the secondary butterfly the same amount. From fully closed unscrew the mixture screws say 2.25 to 2.5 turns open - no more. Start and warm the car up. Put a vacuum gauge on the full vacuum port (manifold side of the butterfly) and adjust slowly and evenly each screw until you get the highest vacuum reading which should also give the best tickover.

If you have to increase the screws to more than 2.5 turns out you are coming too far out of the calibration of your needles on the mixture srews and should be looking at the bleeds - but dont worry about that for the moment as it is likely you wont be.

When you get the highest vacuum if your tickover is too high then close the secondary butterfly in preference.

If you have a fuel regulator check that you are not too high in pressure as this can cause leakage past the float needle valves 6psi is more than enough for most aplications. Also set float level through the sight plugs - about 1/4 way up if they are glass or until just dribbling out if you just have the hole.

Also have you checked the bowl srews and metering block/plate gaskets. These can cause havock if fuel seaps by. A neat rick for you when you fit new gaskets even if non stick is to spray with WD40 allows a perfect gasket on dissasemblt - its what the racing fraternity do.

Have a go at the above and then let us know it will help zoom in to what the problem may be by eradicating the simple stuff and allowing a baseline stiing to be achieved.

Regards
Mike

[Naumoff]

Warren,
It sounds like a plug or two were fouled out do the the rawl fuel being dumped into the engine.

I would change all the plugs and start from there.
The carb was adjusted fine before the trash in the needle and seat. I would not be messing with it until I looked at other things that don't involve messing with the carb adjustments other than reseting the float level of the rear bowl.

[mikey]

Originally Posted by Naumoff

Warren,
It sounds like a plug or two were fouled out do the the rawl fuel being dumped into the engine.

I would change all the plugs and start from there.
The carb was adjusted fine before the trash in the needle and seat. I would not be messing with it until I looked at other things that don't involve messing with the carb adjustments other than reseting the float level of the rear bowl.

I agree with changing the plugs - thought you had. Check you are not on a seven grade and if you are on a six if tou are changing try a five as often 6 is too cold for anything but track use if you want an efficient bur.

Unfortunately leave alone - the reality is that settingsdo not behave that way - mine was set up on Tim Adams Rig and I kept the original settings. Car has sat for over a year and the carb cleaner had to come out. Logged it on the Innovate with the laptop this weekend as it was tickling the back of the troat. Way off to say the least - only 1/8 turn on the primaries were needed to bring it back. On the Holley rig set up is done to set the idle, intermediate and high power circuits. This is where you need to be clear that the needles do absolutely bugger all in setting and mixing the mixture, This is done with the bleeds, jets and emulsion tubes . If that hasn't been done then its either been uneccesary or the guy dosent know how to set up a Holle and should leave well alone. Idle screws are simply that and are just for tinkering and tickover/low cruise - as soon as you primary circuit kicks in they are all but irrelevant.

The important thingis to check the startup circuit - calibrating the butterflys against the transfer slots an dcleanthlines.

Setting up the idle screws really is something goofy with a vacuum gauge could perform

No direspect meant but it is that simple.

Mike

Webbers are the worst - I used to do the DCOE's and IMP series on the twin cams. Fantastic when set up, but within a season they were way off.

Timing is the same you set it up and it should never change - ye right.

[conrod]

Originally Posted by Naumoff

Warren,
It sounds like a plug or two were fouled out do the the rawl fuel being dumped into the engine.

I would change all the plugs and start from there.
The carb was adjusted fine before the trash in the needle and seat. I would not be messing with it until I looked at other things that don't involve messing with the carb adjustments other than reseting the float level of the rear bowl.

Also, the original problem was a stuck needle valve on the **secondary** fuel bowl, so was independent of primary side settings such as the idle mixture screws etc. So I agree - the residual problems are probably due to very fouled plugs.

BTW Warren - the bolt arrrived yesterday, and I've managed to source some from Repower. Thanks again, and I hope you finally get this sorted!

[Warren]

Didn't even get near the office today and most of the evening has been taken up by work so this will have to wait for tomorrow now.

Thanks for all the pointers.

I let you know how it runs when I get chance.

Cheers
Warren