Holley Carb on 455 Olds

[Fournbr3]

I have a Holley 4160 (list 3310) on a 455 Olds. The engine has been freshly built to run 6000-6500 RPM. I can't get any more than 4000 out of it at a meager speed of 40-50. This is a vacuum secondary carb that has also been recently rebuilt. After running the engine for a while the plugs are very black but it doesn't seem to be flooding at idle at all. I would really like to find out what size primary jetting I should use to begin, (the secondaries are through a metering plate), and the color spring I should use on the vac secondaries. The secondaries do not open at all, and I can't find anything wrong with them. The timing has been checked at 16 BTDC and the ignition sys has also been taken out and tested by Performance Distributors. I think my next step is to down size the jets, install a new power valve (what size...) and a new spring in the secs. ANY help would be appreciated.


Gary R.

[78Vector]

I had this same carb on about a 525 to 550 hp Ford 460....in stock form it sucks ! Double-pumpers are Much better on boats...get a 750 or 800 cfm.
If you are dead-set on the vac-sec carb, put a quik-change kit on the secondary diaphragm body....it makes changing springs much easier. You should run either the white (lightest) or yellow (second lightest tension) spring. With these springs, they WILL open. The stock #72 primary jets are most likely WAAAAY too rich for your application. Try #69's to start & read the plugs....if they read 'lean' go to #70s & if they are still black go to #67's.
Also, your power valve may be opening too soon. What is your vacuum level when cruising ? The power valve number should be at least 1 number below your cruise vacuum your motor makes...example if cruise vacuum is around 9.5 or 10 inches, you should run a #85 power valve.
for 7.5 inches you need a #65 power valve.
Hope this helps.

[DAVE BICKHAUS]

timeing should be at 31 deg. av

[J Lamb]

I had to run a 3.5 power valve in my 700 double pumper with 72 primary jets. Motor only made 5 inches of vacumm at idle. Course this was a street motor may be different in a boat. Check the vacumm at idle and go at least 1 number below that. You said it was built to turn 6000-6500 rpms, that's a a LOT of rpms for a bigblock Olds. Not like a BB Chevy. I never turned mine over 5600. You can go up to about 36 degrees on your total timing with good gas but you got to work the distibutor to get it. Your idle timing sounds close to mine.

[mrcrsr]

you turn that olds over 5000 and you had better keep a box handy for the scattered parts!!! you can go to the holley website for original carb specs and it usually gets you fairly close, the metering plates are numbered for size and can be changed- also- if yo use the wrong metering block gasket on the primary side-it will have a u shaped cut in it- it can pull fuel from there amd make it run rich above idle

[Rickracer]

....but I would go at least 1.5" below idle vacuum with your power valve. Might not be a bad idea just to pull the carb back apart to see if any parts are missing and make sure all the right gaskets have been used. :cool:

[150aintenuff]

you will never see 6000 and live in an olds.... they pump the oil pan dry and the oil will all be in the top of the engine... skatered parts can happen at 5500 and WILL at 6000.. they are not a high reving engine due in part to their overly small drain back holes and restrictions throought therir oiling system.. good luck most 455's ran about 60MPH on a good day..