hesitation with acceleration

my cj seems to hesitate when I 'floor' it. When I accelerate slower if seems to be fine.

Is that a timing advance problem ? ('79 cj5, 258 with 4.0 head, HEI and Holley 390 cfm)

thanks,

Ron

Reply to
csdude
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Reply to
L.W.(ßill)Hughes III

diaphragm

Reply to
L.W.(ßill)Hughes III

It sounds like the accelerator pump on the carb. On an Edelbrock you can adjust the pump linkage. I had the same problem and I adjusted the link and no more hesitation. Not sure about Holley.

Anyway, heres the link for edelbrock manual. Might be the same for a Holley.

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Link takes you here: (in case your paranoid)

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Reply to
Jo Baggs

Since it's a carb the first thing that comes to mind is fuel. How's the accelerator pump? Is it sticking or not pushing enough fuel?

Reply to
DougW

These should help.

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Reply to
DougW

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Thanks Doug, I guess there is a pretty big difference between a Holley and an Edelbrock.

Reply to
Jo Baggs

uhm, the Holley is brand new, I don't think it needs rebuilding

however, manifold vacuum is higher (more vacuum) then with the old 258 that is why I thought it might be the advance

R> Hi Ron,

Reply to
csdude

whoops. . . .

I think I messed with the 'accelerator pump lever' one time when I was messing with the curb idle. (the first link says to not do that)

how can I get that back to the default setting? Is there a measurement I can take ? What is the effect of tightening or loosening the nut (spring) of that lever?

Reply to
csdude

(I'm working from foggy memory here, been a long time since I did any work on a carb and then it was mostly the Rochester 4M4 Quadrajet)

There should be just enough clearance in the pump lever at WOT to prevent mechanical binding. (.010 to .005) Since the piston is working against pressure, the spring just prevents binding when the pedal is floored. The tighter the spring the more pressure is put on the piston, but more pressure is not always better.

You might be better off simply dropping by a carb shop and asking. Some times the better shops will do a quick check/tweak for beer money.

Reply to
DougW

I looked up accelerator lever clearance for a holley , it seems to be factory set at 0.015".

thanks!

Reply to
csdude

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