Visit The Dirt Forum for More Information

Author Topic:   Carb ? for KP
Racer8c
Member
posted July 02, 2003 03:59 PM
I have a Holley 600 vac. secondaries on a 355 chevy engine with a .552 lift cam, I was having problems with it idling, I was having to ***** the idle adjustment out a whole lot to get it to idle fast enough so it wouldn't die when I put it in gear(stock converter). It was letting too much of the transfer slot show and it was getting too much fuel, I drilled a .100 hole in the primary butterflies on the same side as the transfer slots like one of your posts had said, and it still didn't help, so I enlarged it by about twice the size it was and this helped, but I still can't get a high enough idle(I'm needing about 1500 rpm or so, without exposing more of the transfer slot, the idle mixture screws bring it down to 900rpm all the way closed and that's it, they don't make too much difference in rpm or vacuum as I ***** them out(about 2Hg difference), any suggestions?


KPLugnut
Member
posted July 02, 2003 08:44 PM
Sounds to me like the primary idle bleeds are too large maybe? If not that, then I'd like to see why your situation could ever need a .200" hole in the butterflies....that's just out of the ballpark, if ya ask me..
I'm wondering is there any fuel being pulled over thru the boosters? The proverbial "pullover" messes with an idle circuit something fierce (tho, you didn't mention having any).
Also, what sort of fuel pressure are you running at idle, and exactly what is your idle vacuum reading when you get it tuned as best you can?
If your idle skrews won't stall the motor when closed, then there is fuel being pulled from somewhere else (it has to, or the thing will stall).
Are the secondaries opened any? (just another thought...)

Let me know what ya can, and I'll do some more digging as soon as I get back to the shop on Sunday..

KP

p.s. - sorry i took so long to answer, i've been on vacation.

Racer8c
Member
posted July 02, 2003 10:19 PM
As long as I only have the .25 opening in the butterflies I don't have any fuel being pulled from the boosters, but when I open them up more I do, as far as fuel pressure...it's it's somewhere between 6 and 8, the needle bounces alot, it's not liquid filled, I need to get one, but it doesn't go below 6. As far as the secondaries, I tightened the ***** until it touches the linkage and then another 1/4 turn past that, the transfer slots aren't explosed. The vacuum stays about 8 to 8.5 the best I can get it, but that's with the screws turned out about 3/4 turn. I'll check to see if I still have pullover from the boosters again tomorrow, but it wasn't happening when I checked it last night.


Racer8c
Member
posted July 03, 2003 09:57 PM
Well, I checked it tonight for "**llover" and I was getting a little drip everyfew seconds. I had to adjust the idle ***** down where it was idling at about 600rpm before it stopped completely, and then I turned my idle mixture *****s all the way in and it still ran, it eventually stalled about a minute later. I don't know what to do except try another carb. I had to make this one out of parts I had from two different carbs, and it had been awhile since I had built one(about 13 years), so I may have ******* something up somewhere, but I'm getting really ****** at this thing.


KPLugnut
Member
posted July 04, 2003 03:41 PM
Dunno what to tell ya unless there's a mismatch of parts (i.e., wrong metering block, baseplate, etc).
I'd have to see the actual carb to be able to fix it, but I can say with fair certainty that I've never ever seen a carb that needed to have 1/4" bypass holes in the butterflies. Something is fishy in Denmark....

KP


Racer8c
Member
posted July 04, 2003 07:13 PM
I'm going tomorrow morning to have a local guy who's pretty good with Holley's to look at it for me, I may even buy a different one and try it, I'll let you know what I find out. Thanks for your help though, I know you are very knowledgeable with carbs!!!


Back to the Archives