Holley power valve? and blowout protection.

jerrys84 · 02-26-2002, 11:56 AM

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??

Dark Knight · 02-26-2002, 01:25 PM

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?

bosco · 02-26-2002, 03:49 PM

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

jerrys84 · 02-26-2002, 04:51 PM

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)..

nitrousdave · 02-26-2002, 08:38 PM

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.

02-26-2002, 11:56 AM	#1
jerrys84 Registered Member Join Date: Feb 2002 Location: minnesota Posts: 129	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?? __________________ 91 LX 'work in progress' previous stangs; lightly modded 84GT 81 2.3 converted to 302 auto

02-26-2002, 01:25 PM	#2
Dark Knight Registered Member Join Date: Oct 1998 Location: Az Posts: 854	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? __________________ 84 convt,roller 302,AFR's, performer 3.55's, underdrives BBK shorties stock cam, 1.7's 13.58@102.84 and a '68 stang .. project 8 sec street car... 557 big block + N20 :-) http://members.cox.net/darkknight302/68nwrear.jpg

02-26-2002, 03:49 PM	#3
bosco Registered Member Join Date: Nov 2001 Location: austin TX Posts: 115	A little off the subject how do you adjust timing with a vacuum gauge? __________________ '87 coupe, 308, world product windsor jr. heads, comp cams 220@.050/.512 @110 deg., roller cam,crane full roller rockers, 4bbl 600cfm holly carb,1 inch spacer, wiend aluminum intake, pullies, msd distributer/ignition, 1 5/8 bbk shorties, off road h-pipe 2 chamber flows, 3.73 posi rear end, P.S.T control arms, steeda tri-ax shifter, t-5, auto meter guages, and more to come (hopefully )

02-26-2002, 04:51 PM	#4
jerrys84 Registered Member Join Date: Feb 2002 Location: minnesota Posts: 129	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).. __________________ 91 LX 'work in progress' previous stangs; lightly modded 84GT 81 2.3 converted to 302 auto

02-26-2002, 08:38 PM	#5
nitrousdave Registered Member Join Date: Dec 2001 Location: south bend, indiana Posts: 24	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. __________________ 85 GT 10 pt cage 11.68 to 1 408 windsor ported dart sr's super victor 9 inch w/4.11's bigshot plate turbo 350 trans etc etc