rebuilt carb, now it has hesitation

[haven]

1998 Volvo 5.7 gs 2 bl holly carb
I had a leaking acc pump diaphragm. Ordered rebuild kit and seperate diaphragm part # 3854257. The old diaphragm was about 1/4 inch deeper than either of the two new diaphragms. Now the acc pump linkage on the side of the carb does not contact the cam until about 1/4 throttle, so I have a hesitation until that point. the adjusting bolt is not long enough to adjust so that contact is on the cam before 1/4 throttle. Can I just put in a longer bolt, or bend the tab on the lever down to make contact on the cam. There seems to have been a change in the parts dimensions since new. How is the best way to make this adjustment?

Thanks in advance.

J

 

[Haut Medoc]

Re: rebuilt carb, now it has hesitation

Sounds like you have the wrong parts to me......​

 

[haven]

Re: rebuilt carb, now it has hesitation

I thought that also. I have checked the part # in many different places. My parts catalog, here on Iboats, at the dealer, and doug russell. All places point to the same part #.

 

[Haut Medoc]

Re: rebuilt carb, now it has hesitation

I'm not a Volvo guy, but.....
Is it possible that you are looking/ordering by the year & not the serial # or actual part # on the carb?.....
Just a thought......​

 

[Maclin]

Re: rebuilt carb, now it has hesitation

Those cams have two mounting holes, appropriately designated #1 and #2. Remember, Holleys are high perf carbs and are designed to be run on all kinds of engines in all states of tune, and the 2bbl is just the front half of one of those types of high perf carbs.

The #2 position is for engines that need the idle screw way high, like ones with a big overlap cam that will not idle without the plates open some, or maybe it is race engine that can idle at 1500 or so and needs a full pump shot..... the purpose of the #2 hole is to not hit the pump arm until "later", that way you get the whole action of the pump cam against the lever.

I would try the other hole first, should be easy to do while on the engine with the right small screwdriver.

 

[haven]

Re: rebuilt carb, now it has hesitation

Thanks for the advice. I just checked the hole positions for the cam. It is already in the top hole. the one that would raise the cam up closer to the lever. dag nabbit. Any other good ideas?

 

[haven]

Re: rebuilt carb, now it has hesitation

Any other suggestions before I have to break down and buy a new carb?

 

[Maclin]

Re: rebuilt carb, now it has hesitation

Is the pump diapragm spring in correctly?

There are larger 50cc pump housings available, wonder if yours has one of those. The diaphragms are different, the 50cc one has to have more travel. The 50cc housing hangs down a lot farther than the standard pump housing.

Got any pics?

 

[haven]

Re: rebuilt carb, now it has hesitation

Sorry I don't have pics. But it sounds like I may have the 50cc housing. the old diaphragm is at least 1/4 inch deeper than any of the two replacements. Where would I get the larger diapgragm, if everything at the dealer, the parts books etc point to the smaller one part # 3854257

thanks

 

[marunr]

Re: rebuilt carb, now it has hesitation

You might try these people:
http://www.thecarburetorshop.com/

Or you could contact Holley

 

[haven]

Re: rebuilt carb, now it has hesitation

Thanks for the replies. After it wsa mentioned that it might be a 50cc diaphragm, google was my friend and I found the 50cc at advanced auto parts. Had to order it, but that is better than a new Carb. Should be here monday. Thanks folks..