Holley power valve? and blowout protection.
 

Are these things really that easy to blow out??

took my car out for a drive last week when it was 50+ degrees, after letting it 'warm up' to about 185 degrees, i took it for an easy 5 mile drive. on the way back home i stepped it up a bit, and it falls on it's face at about 4600 rpm's no power, just sputters. runs ok from idle to 4600, but nothing after that. I don't recall a carb 'backfire'.

timing was set with a vacuum guage, new distrib, coil, wires, plugs, pretty much everything. only 900 miles on this engine.


don't know what else it could be..

any one installed the holley blowout protection from summit??

is it a new carb? they come with that already if it is... and a blown power valve would make it run rich... I'd check your fuel pump and ignition.. will it run past 4600 at part throttle?

A little off the subject how do you adjust timing with a vacuum gauge?

new carb, new fuel pump... if i gradually run the r's up it'll run out ok, it seems like it happens when the secondaries open. so not sure if it has anything to do with the power valve.. I have tried other secondary springs, but the same thing happens..

maybe i'll just put the stock carb back on..



Sorry, i meant to say; "timing was set and engine checked with a vacuum guage".

You can verify your timing with a vacuum guage, i forget the specifics, but you adjust timing until the needle hit's top vacuum, i'll have to try and find the info. factory timing marks are not an accurate measure of timing (i've seen some 10 degrees off)..

If your fuel pump and ignition check out I would double check the float level. If that is o.k. it sounds like the carb may be jetted too lean. Have you pulled any plugs and if so do they look like you just took them out of the box? If they do that is a good sign that the carb is too lean. I had a stock holley once that did the exact same thing. Put a 650 double pumper on, still had to jet it up and it ran waaay better. Judging from the specs in your sig I would say it is a definite possibillity you are too lean.