351 Cleveland swapped MII

[Blackhawkxx]

Agree, but those numbers are not in Holley terms. The 86/93 jet sizing is for Proform carbs. They use a different numbering system for their jets than Holley. You can't directly cross over the sizes between the two manufacturers... a Holley 70 jet is not the same size as a Proform 70 jet.

Well there is a reason I wouldn't buy one, parts. Holley stuff fits many other carb brands and are available everywhere.

 

[78 Mach1]

I pulled all 8 plugs after taking it for a drive and shut it down and coasted to a stop. All 8 plugs actually looked spot on. Not to rich, not to lean. But the weird thing is, I still have that potential vacuum leak at the modulator. It should be here’s this weak. I guess once I replace that I will be able to get a true reading.

I also found a slight leak in the intake manifold. Where the top bolts to the bottom. I made a set of gaskets and sealed that today. I’m very surprised it ran as well as it did with two known vacuum leaks.

Once all vacuum leaks are sealed. I’ll go back and readjust the carb. Should see even better results.

 

[78 Mach1]

I just tried to search for a cross reference sheet of Holley jets as compared to Proform jet sizes. No luck. Anyone have the conversion on this?

 

[85GTStangGuy]

Don't know of a cross reference for them, but I believe Holley jets range from 64 to 99, and Proform jets range from 70 to 100. (Dunno, but there may be larger jets available for "huge" carb applications.)

 

[LILCBRA]

Best thing I can help with you've probably already seen or found, but if you happen to have a complete drill set (letter, number, fractional) you could use them as gage pins to find the hole size in your Proform jet and cross reference it to the equivalent Holley jet.

 

[78 Mach1]

I did see where people have done that. Apparently even Holley jets can very in size with the same number identified on them. I may buy a drill blank set to verify.

 

[78 Mach1]

I got the new modulator installed. Had to adjust the shift points to my liking. With that and the leak fixed in the tunnel ram. This car now idles and drives very well. Surprisingly street able considering all the mods done to it.