Reason for constant timing?

MalcolmV8 · Post by **MalcolmV8** » Mon Aug 16, 2010 6:19 pm

Thanks for the tip. I found the PDFs on his carb finally today and went through and taught myself a bunch on the carb. I think the Holley spec on what you're talking about is 0.15 clearance at idle. Kinda cool when you press the gas pedal you can actually see gas squirt out those nozzles above and into the throttle bodies of the carb.

After reading through the whole manual on the carb its not nearly as intimidating as it seemed at first. It's actually a lot simpler than I was expecting. Now that I know what all the parts inside do (mostly lol) we're ordering a jet kit and are going to try and get this carb dialed in.

Will keep you guys updated.

Thanks
Malcolm

plowboy34 · Post by **plowboy34** » Mon Aug 16, 2010 8:55 pm

Hey Malcolm, the Holley is the simplest carb out there. There was a time I would do one in my sleep. Probably couldn't do that anymore but they are very simple. If you have some good reading and with your intelligence you are on your way. just a walk in the park my friend.

MalcolmV8 · Post by **MalcolmV8** » Tue Aug 17, 2010 12:00 am

Thanks Dave. Hopefully I'll get it figured out. As soon as I get stuck I'll be on here picking all the carb guru's brains lol. I figured it must be a simple carb because I've seen some carb tear downs on Horsepower TV and it seemed like a bucket full of parts came out.

v8ranger · Post by **v8ranger** » Tue Aug 17, 2010 3:14 am

Ya, there are not to many moving part on them that's for sure. Its all in holes, power valves and accelerator pumps. And of coarse. your foot, lol

MalcolmV8 · Post by **MalcolmV8** » Tue Aug 17, 2010 5:49 pm

OK first real question here. There are four idle air mixture screws on the carb. One for each throttle body (is that the correct terminology?) of the carb. From reading the docs on Holley's website I see each screw must be adjusted the same as the other. The part I don't understand is how do you get a baseline to start with them?
Do you turn the screws all the way in and then back them out say two full turns? or how do you get a baseline to start at? We ordered the jet kit today and I assume you want to baseline the idle air mixtures screws each time you swap out the jets?

Also I wasn't entirely clear but do the idle air mix screws have any affect on the air fuel ratio of the carb while driving? or do they strictly affect idle only?

Thanks
Malcolm

MalcolmV8 · Post by **MalcolmV8** » Tue Aug 17, 2010 6:00 pm

Here's a few pics of the carb I'm working with.

v8ranger · Post by **v8ranger** » Tue Aug 17, 2010 7:19 pm

They will affect how its driven off idle. Not as bad as at idle but they do under low rpm's when your foot is hardly on the gas, about 1/4 throttle or less. After that, then not so much. At least not to my knowledge or in my experience with them. I have mine only turned out about 1/2 to 1 turn on all 4 corners. I know with the old Q-jet carbs you turned them out about 2 turns to get you started. Most of the time that's about where they stayed. I think the Holleys are more sensitive to adjustments. Now my Edelbrock adjusted about the same as the Q-jets. I think its because these two carbs only has two mixture screws instead of 4 like the Holley's do.

plowboy34 · Post by **plowboy34** » Tue Aug 17, 2010 8:47 pm

We always set ours at a 1/4 turn out to start. that will be real close then just start from there but we found most times that is where we would end up. v8ranger is correct in the fact that they only work 1/4 throttle or less. May actually be less on such a big carb. They really have nothing to do with performance

MalcolmV8 · Post by **MalcolmV8** » Wed Aug 18, 2010 8:51 am

Great thanks guys. I'll set them to 1/4 turn out to start. I was wondering how they affected various cruise conditions so that when we get it running and cruise down the highway and pull over and pull plugs and read them. He doesn't have a wideband yet so we'll be tuning this old school way. Seat of the pants and reading plugs. A wideband is on his list of things to get though.

v8ranger · Post by **v8ranger** » Mon Sep 13, 2010 4:26 am

So what happen? Did you get it figured out yet???

MalcolmV8 · Post by **MalcolmV8** » Mon Sep 13, 2010 6:23 am

Getting close. The carb was indeed extremely rich. I don't have my notes with me now but primary jets were 88 I believe. I've been dropping them down two sizes at a time and I believe I'm at 82 now and it's still missing some but actually runs now. Secondary jets where a 92 and a 93 and both are at 90 now.

However as luck would have it. No sooner than we get the car drivable and go for a test drive his tranny over heated something horrible. Had to pull over and let it cool and limp it home. The oil was so burnt it smelt horrible. I'm not sure what happened. It's an $1800 built TH400 he got from Redneck performance I believe. He pulled the tranny this weekend and is taking it so some performance shop Tuesday. We'll see what they say went wrong.

Once he gets the tranny back I'll keep tuning the carb.

v8ranger · Post by **v8ranger** » Mon Sep 13, 2010 9:03 am

That sucks to spend that kind of money on a transmission and then to have something go wrong with it.... Someone would be paying, and it wouldnt be me... lol...

MalcolmV8 · Post by **MalcolmV8** » Mon Sep 13, 2010 9:18 am

Yeah problem is that tranny was built almost two years ago, maybe longer. This has been project car for a while so I think he's hosed. I have a feeling its coming out his pocket but we'll see.

v8ranger · Post by **v8ranger** » Mon Sep 13, 2010 11:29 am

man, that makes it suck twice as bad then.....

rojam18801 · Post by **rojam18801** » Thu Sep 23, 2010 3:55 pm

redneck proformance is where i ordered my c-4, and like you had it over a year before installing it. i got about 200 miles before it dumped. i dont think we should go to redneck again....the old trucker

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