need help to find good baseline jess for my holley 650 spreadbore dubble pumper

[moparjoe3604]

I'm going to install it on my 360, it's bored .030 with 10.5/1 KB sivolite pistons 1.88 valve heads crane .454 lift 216 duration cam and edlbrock performer 318/360 intake. I need to figure out a good base jet for the front and rear I'm not sure what the jets it has in the front are but the ones in the rear are #83's. The fronts are a weird # not like normal.Any help would be awesome.

[wilks3]

Call Holley or find a speed shop. Either way they can tell you the stock jetting for a base line, then drive it and keep an eye on the plugs.

[turbododge]

When I ran a spreadbore dp on the tt340, I was using 63's in the front, rears were way big for the turbos. My bet is that you could start out at 65 or 66 in front and leave your secondaries alone. Get an AF meter or read your plugs and go from there.

The odd numbering on the primaries is probably what they called their higher accuracy jets for polution purposes. I don't remember exactly the way it worked, but I think the regular jet size is within the larger number.

[Crank]

64 84 stock is 62 82

[moparjoe3604]

thanks for all the advice guys I kinda figured that 63-65 would be the right jets but I wanted a second opinion

[451Mopar]

Never had a spread bore, I just checked my truck Avenger and it was #68 front and rear.