Holley Jets Opinion
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Racer
Joined: Apr 2005
Posts: 494
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From: Virginia
Holley Jets Opinion
Rebuilding a 650 Holley as part of a 350 engine rebuild for a street/strip 73. The jets are 67 Primaries and 76 Secondaries. This carb was supposedly modified professionally for racing, but needed a rebuild when I bought it. Are these numbers a good starting point for jets for a street/strip setup?
Drifting
Joined: Jul 2001
Posts: 1,418
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Please post the list number for the carb along with intake manifold being used .
I recall that there were three different square bore 650's made through the years . Each used different metering blocks .
One 355 engine with an open plenum manifold using the 650 that did not have a factory secondary power valve ran well with the jets staggered , but close to squared up . I'd have to check notes to be sure but was close to 70/72/ 72/70 or thereabouts .
The engine was hot one though . Thats approaching 750 jetting there .
I recall that there were three different square bore 650's made through the years . Each used different metering blocks .
One 355 engine with an open plenum manifold using the 650 that did not have a factory secondary power valve ran well with the jets staggered , but close to squared up . I'd have to check notes to be sure but was close to 70/72/ 72/70 or thereabouts .
The engine was hot one though . Thats approaching 750 jetting there .
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,390
From: At my Bar drinking and wrenching in Lafayette Colorado
The 67/77 jetting is the stock jetting for list 4777-1. That carb has a power valve on the primary side, and no PV on the sec side, so it's important that you keep about an 8-jet spread between the primary and secondary side. With your open plenum manifold, I'd bump the primary side 2 sizes to a 69 and keep the secondary 77, since this will give you the 8-size differential. The slightly richer primary jetting should maintain good throttle response with the open plenum. 
