Carb Question - 66k

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Hi Everyone, quick question- summary first:

1. Just rebuilt the carb - runs much better than before

2. The 2nd set of barrells - are not really working - nor did they work before i rebuilt the carb.

3. We did replace the 2nd diaphram.

Any idea's??

Thanks

Eric

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How do you know the secondarys are not working?

secondary venturis will not open when the engine is revved in neutral, there must be a load on the engine.

1. Is the linkage setup properly, diaphragm intact, and all ports/passages free of debris? It is very easy to lodge dirt somewhere during the rebuild process (if you didn't rebuild it yourself then unfortunately you have no idea what really went on).

2. To test the vacuum secondaries, you can put a finger over a certain vacuum port on the underside of the carb while holding the secondary butterfly open (once it's off the engine of course). Let go of the butterfly, and it should slowly close. NOTE - check the shop manual for the exact procedure, I am going from memory here.

Hi,

Check if they work by accelerating very hard,

i.e. gasfoot to the floor and you should feel a

kick in your back when the secondaries open.

/Bo

If it's a 4100 there is a small check ball that is required in the passage between the secondary diaphragm and the body of the carb. If it's not there you'll have a problem. Get a copy of the exploded parts diagram and you'll see it. They tend to be lost out of ignorance (voice of experience) during disassembly. You can buy them from Pony Carbs parts department. See part number 9576 here at the top of the diaphragm (it is mislabeled on page 2 as an accelerator pump check ball):

http://www.ponycarburetors.com/images/pdfs/4100.pdf

Edited by - round2K on 01/09/2007 22:56:35

I know Pony has a monopoly on the minds of Mustangers across the nation, probably w/ some justification; but here is a supplier I have used that has many carb parts at much better prices:

http://www.swapsupply.biz/carbkits.html

The secondary diaphragm check ball is generally not found in carb kits. Plain vanilla carb kits are about $20 at NAPA anywhere in the country.