I have two Holley carbs list 4313 with 390 CFM each that I want to install on a tunnel ram on a SBC for the street. These are the 4150 models with both primary and secondary metering blocks. Could someone recommend which power valves, jets and squirters to start out with? I also have a pair of 390 CFM double pumpers list 6895 that I want to install on a cross ram for a SBC. The secondary metering blocks on these carbs have no provision for power valves, but do have jets. Could I get some advice on power valves, jets and squirters for these also? Thank you for any info that you can supply.
I'm not a professional by any means, but just did some research on power valves and was told that whatever your vacuum is determines your power valve size needed. In example if your vacuum is over 13 you are safe with the stock 6.5 power valves. if your vacuum is lower divide by 2 and use the next size down.. ex. vacuum of 8 equals 3.5 power valve. I found this same info in several places so I deem it fairly reliable. Hope this helps a little at least.
This used to be the Holley tech line--270-781-9741 ;they helped me a couple of years ago with a problem, and were good folks to deal with. If this # is NFG, look on a Holley product package and it may list an updated one. Good luck with it. Mike from Mass.
http://www.jalopyjournal.com/forum/threads/tunnel-ram-tuning-anybody.694576/ go to post 20, that is my setup. Pete
First off, make sure your ignition system, mechanical and vacuum advance are working and give you full advance around 2500 rpm......THEN work on the carbs. Big squirt nozzles, 37 to start.(get a trick kit) Make sure your accelerator pump cams are working right away. On the dual 4 set up I start with 4.5 PV primary and 2.5 PV secondary. Jets are a crap shoot as every engine is different. Run a plug check and reset accordingly.
I'm not a professional either. I am putting these setups together for sale so I don't know what the vacuum would be. I'm just looking for a starting point. Thanks for your help.
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