Ok guys, I need a little input. I'm purchasing an 850 Holley from a member for my 401. The carb originally came with 80 and 78 jets, and currently has 76 and 78 jets. He's offered to put in any jets I want before it ships. Any suggestions as to a good starting point? When the motor goes back into the car it will have the specs listed in my sig, in addition to a Pertronix Ignitor III kit. Also, it currently has #37 squirters. Any suggestions as to where I should start with those too? Thanks!
Anybody? I know it's kinda difficult to say what jets to run, but someone has to be running a Holley. Doc, any suggestions? Your the resident Holley guy.
I'd get a jet kit from Jegs or Summit and start with stock jetting. Then jet down or up by two sizes front and rear until you get best MPH (most likely down in size). Use your G-tech if you do not go to the track and back up all results. Jet up by 7-10 in the rear if you block off the rear power valve. Remember to set the float level using the back throttle rod when adjusting the float. Cheryl
As a base line,,, go with what Holley says... if i remember right my original 850 had 80's in the front and 81's in the rear.... but that was back when you could buy real gasoline not cat pee gas like we get now.... it is better to be slightly rich ,than lean ..... then adjust and fine tune.... be sure to go thru each adjustment , [throttle setting, accelerator pump lever adjustment, linkage adjustment, choke , ect...] and set them just like holley says to set them... Holley wants you to get the most out of your holley carb because it boosts their reputation... and is good for sales.... remember that as a carb tends to lean out at high rpm...so the secondaries need to be a little richer... but most later carbs have secondary plates not the old style1/4'' thick jet plate that had replaceble jets... but you can get richer late model plates from holley... I usually take the choke assembly out to gain a few more cfm.... and fine tune every thing .... keep a log of what you do ,,, that way you can see what difference each change makes and remember what you did later....
Thanks Cheryl and Doc. I'll start back at the stock configuration (jets at 80/78 and squirters at # 31's) and work from there. Thanks for the info!
Nylon washers for the bowl bolts and a nonstick metering block/bowl gasket set are reusable when tuning. It will save you quite a bit in gaskets and anoyance over time. Have a cup ready to catch the gas when removing the lower bowl bolts. Gas on a hot engine or headers is not a good thing! Cheryl
