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73-87 Chevy _ GMC Trucks => Performance => Topic started by: 1984k30 on February 15, 2010, 07:31:54 pm

Title: holley carb question
Post by: 1984k30 on February 15, 2010, 07:31:54 pm

I have a holley carb on my truck and it leaks fuel.  It is coming from the bottom of the front float cover.  I think the piece is the accelerator pump not sure though.  It is about 1 inch by 1 inch and has 4 screws holding it on.  can I purchase this gasket or do I have to buy the whole kit.  Trying to find out what model it is.  The list number says 8700 and then 1571.  Any one know how I can find out the model it is.

Title: Re: holley carb question
Post by: Josh454 on February 16, 2010, 08:07:16 pm

I think you'll find that is an old school 600-650.  The date code is for 1971 so I full on rebuild kit would probably be a good idea anyhow...

Title: Re: holley carb question
Post by: eventhorizon66 on February 18, 2010, 03:15:04 pm

The leak source that you described is the accelerator pump.  The gasket is integral to the pump diaphram.  They are cheap to replace and come in 30cc (the one you should have) and 50cc versions.  Full rebuild is not a bad idea.  If I were running a Holley, I'd probably rebuild it once a year (in an ideal world where I'm not so lazy).

Title: Re: holley carb question
Post by: 1984k30 on February 18, 2010, 05:24:14 pm

Got a hold of holley today and said it was a q-jet replacement model 4175.  Summit has a rebuild kit for 80 bucks.  I going to order the kit but not sure if I am going to rebuild the whole carb.   I hate to tear the whole thing apart because it works perfect now. 

Title: Re: holley carb question
Post by: ohio hab on February 18, 2010, 05:51:56 pm

Jeg's has just the accelerator pump, 30cc- 2.99, which is more likely what you have, or 50cc- 13.99, if carb is working fine I would just replace the accelerator pump. Part # 510-135-5 for 30, and 510-135-7 for 50.

Title: Re: holley carb question
Post by: 1984k30 on February 18, 2010, 06:56:52 pm

thanks for the info.  I always forget about jegs.  I will check it out tonight.

Title: Re: holley carb question
Post by: TexasRed on February 18, 2010, 09:00:12 pm

Most part stores have the accelerator pump. Unless you get the big rebuild kit from summit, it won't have the dual stage power valve, just the single stager. So you'd have to reuse your old one.

Title: Re: holley carb question
Post by: Josh454 on February 19, 2010, 08:42:03 pm

Is the carb a square or spreadbore?

Title: Re: holley carb question
Post by: 1984k30 on February 19, 2010, 08:47:30 pm

It is a spreadbore.  I am thinking it is a older model.  All of the 4175's that I see on summit and jegs have a electric choke.  Mine uses the intake manifold.

Title: Re: holley carb question
Post by: Josh454 on February 20, 2010, 02:49:39 pm

I'm sure you could convert it to electric if you wanted to.  The 4175 is really a great carb.  It's has many of the benefits of a holley and a Q-jet.