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Author Topic:   4412 CARB ?
RACR 73s
Dirt Roller

Total posts: 18
posted March 25, 2005 05:27 PM  
I have bought a 4412 holley that they said was a Blake that C&S had rebuilt and it has 79 jets, 50 Acc pump, stock venturi and choke horn. My questions are: Does the 79 jets seem high? From the others that I see out there have all had 73 jets. Which is better a 30 or 50 acc. pump (why?) and does that effect what jets you use? Any other help would be appreciated?

I am using a .030 over 400 with a 327 crank (352) with large domes and an Elgin 1090 cam(in. 537 / ex. 557 lift and duration is 256/264 @.050 with a lobe center of 106). The cam is dialed in @102.5. It has a set of 2.05/1.6 angle plug Wold Product heads and 134 autolite plugs (I use these because the pistons go way up in the combustion chamber) with headers. It has a victor jr. intake with a turtle in it. I am going to run it on a fast 1/3 mi. track that I was told you have to run the same gear as another local 3/8 mi (6.00-6.20). It is going in a 3500lbs steet stock with a direct drive powerglide. If there is anything else that you need to know, let me know.


unregistered Total posts: 18
posted March 25, 2005 06:47 PM           send a private message to RACR 73s   Edit/Delete Message   Reply w/QuoteBBBBBB
Im up to 81 jet on a 406 flat top motor with humps and useing it all. And a stock 4412 with the power valve.

Dirt Forum Champ
Total posts: 784
posted March 25, 2005 07:41 PM  
on the dyno we ended up with 75's on a flat top 406. we were still a touch on the rich side. dont rely on plugs as a way to set air/fuel mixture. i was running 85's last year and i thought i was on the lean side!! going to 75's was also worth about 15hp.


El Santo
Dirt Full Roller

Total posts: 36
posted March 29, 2005 09:47 AM  
It all depends on how big your power valve channed restrictors are. These are the two holes that are under the power valve in the metering block. A 4412 comes stock with a .055 hole. Different carburetor companies drill these out to different sizes, some even install interchangable jets so you can change these sizes. If you can find out what size these restrictors are, then choosing a jet size will be a little easier. I run a 355 flat top with .150 angle milled double humps and I run a 78 jet in my 4412 and my PVCR's are drilled out to .065.

Dirt Roller

Total posts: 12
posted March 31, 2005 06:34 PM  
Im runnig between 73 and 75 jets according to humidity and temp 358 northeast dirt spts baker carb

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