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Old 05-20-2013, 09:15 AM
gearheadslife gearheadslife is offline
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Originally Posted by toddalin View Post
I run a 600 dp so it is not exactly the same. The carb's PO could not get it to work right. It had a stumble and would backfire, much like you allude to.

The PO had changed the stock shooter (which is a 25) to a 31 chasing the problem thinking, as most people do, that it was a "lean bog."

Dyno testing showed the opposite and it was a rich bog cause by too large of a pump shot. I believe this lets fuel puddle in the manifold that eventually backfires. I changed the squirters to 21 and that cured most of the problem. I then moved the pink cam from position 1 to 2 on the secondaries to get a smaller pump shot and that seems to have done the trick.

BTW CarCraft had a similar problem with their 600 dps and filled the 25s with epoxy and drilled them out to 22s before realizing that Holley sold 21s. It fixed their bog too.

not a holley guru, but didn't holley tech line basicly say the same thing?
and you brushed it off..
have you even tried a smaller shooter than the first one??
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