holley carb problem *DELETED*

[hotrod 84 lesabre]

Post deleted by hotrod 84 lesabre

[Reatta Man]

Sounds like a classic accelerator pump problem.

If the plunger can be adjusted, you may try adjusting it up or down. Moving it up may allow it to pump a larger surge spray of gas into the venturi, while moving it down may cause it to react faster to throttle movements, but inject a smaller spray. There is also the possibility that the float is set too low to allow an adequate amount of gas to get into the accelerator pump chamber inside the carb. It has been a looong time since I worked on a Holley, so you might want to talk to a wrench at a local speed shop that works on Holleys on a regular basis for better advice.

You may also try advancing the timing in SMALL increments to see if the hesitation goes away, but without creating "ping" or detonation knock.

Joe

[2seater]

I concur with Reatta Man in the pump shot being to small, or it is shot in too quickly to cover the fuel needs until the main fuel system kicks in. Raising the float level will quicken the response of the main system starting to flow, but it can be overdone. I would start by verifying the fuel level is correct. Check to be sure the accelerator pump shot starts as soon as you crack the throttle. If it is shot in too quickly, the car will probably launch and then bog until the mains start. There are all sorts of different accelerator pump cams and "shooters" available, but if the carb. is fresh from the box, I would start with the basic things first. The suggestion on advancing the timing, a couple of degrees at a time, is also a good way to snap the car off the line, as long as pinging is avoided. I do not know what your fuel octane requirements are, but if you are running more octane than required, the engine will most likely want more ignition advance.

[hotrod 84 lesabre]

i am running 34 degrees total timing.dist is a msd pro billet,with a msd 6a box.

using 91 octane fuel.

[Reatta Man]

I've heard of problems with MSD ignitions. If you don't have any luck with external adjustments and advancing the distributor, I would try a conventional HEI distributor, or if the MSD has a bypass switch, go into bypass mode before tearing open a new carb.

Holleys tend to come from the factory set properly, so I would check everything before opening the carb.

[2seater]

Ditto on the MSD box. The total timing sounds about right, but what rpm is it all in? You could probably tolerate a bit more timing, but it may be more helpful to bring it in faster, or possibly more initial timing and slow down and/or limit the curve. Really a matter of experimenting but only one step at a time. Easy to bump the initial timing a few degrees and see if it helps the bog. If not, the problem likely lies elsewhere.

[hotrod 84 lesabre]

thanks!!

i'll check that all out!

[hotrod 84 lesabre]

talked to a holley tech today,was told the accelerator pump squirters were too small(#25's from factory) was told to jump to a #31 size.

and,since my plugs show a rich condition after adjusting(plugs are correct heat range) was told to use a#69front jet,and a #71 rear.(factory ones were #71 front,75 rear) charging problem is solved,had fan switch wired wrong

[2seater]

Great! Thanks for letting us know on the possible resolution.