which carbs to get

[tomsfe64]

got my 427 hi riser 2 carb engine running with 2 holly 600 carbs. its running way too rich and these carbs dont have replaceable secondary jets.  its only getting about 330 hp at 5k. i think 1200 cfm may be too much ? would quick fuel 450's be a better choice ?

[Barry_R]

Wrong direction.  It wants more - not less.  A pair of 750s

[tomsfe64]

1500 cfm?

[Drew Pojedinec]

I don't see why the 600's can
t work.  Would need more info on where it is so rich.

[tomsfe64]

its running rich the  whole rpm range. got a oxy sensor on chassis dyno. these carbs dont have removable secondary jets. the tuner says he cant lean it

[Heo]

To big carbs runs lean, not rich  and another carb
don't doubles the flow

[Falcon67]

Then get tuning parts for the back end:

http://www.jegs.com/p/Quick-Fuel/Quick-Fuel-Billet-Secondary-Metering-Plates/750660/10002/-1

You can also modify stock metering plates for jets, lots of info on the web.

I run two 600 Eds on a 302 - actually had to bump fuel up 4% on both primary and secondary of both carbs to get best MPH on the track.  No reason a pair of 1850s can't work well.  Seems to me except maybe for idle depending on the air bleeds, should be close to lean out of the box with stock jetting.  Make sure you are not feeding fuel from unknown sources like cross leaking metering block to main body gaskets or power valve gaskets.  Also consider that you do not have "1200 CFM" on the engine.  You've basically got 600 CFM until you wind that bugger up.  Would you run a 600 vacuum secondary on a 4 cylinder motor - sure, no problem and should not necessarily be fat out of the box.  Have run a 600 DP on a 302 for several years, ran great.  You've got two 4 cylinder motors with a common block - or a big motor with a bitty 600 DP on top of it.


Holley 450s are mechanical secondary carbs without a rear accelerator pump - run away.  Would just make for more problems IMHO.

[Stangman]

Can a 427 high riser motor only make 330 horse power, I mean you should be able to make 400 by accident

[andyf]

got my 427 hi riser 2 carb engine running with 2 holly 600 carbs. its running way too rich and these carbs dont have replaceable secondary jets.  its only getting about 330 hp at 5k. i think 1200 cfm may be too much ? would quick fuel 450's be a better choice ?

Twin 600 carbs should be fine for a 427. Not sure why you can't tune the carbs, if you have a screwdriver you should be able to tune them. You can drill the secondary plates or buy new ones. It isn't rocket science, just holes in a plate.  Smaller carbs might work better if it is a mild street motor but the 600's should work.

[tomsfe64]

oh well. i guess i will ask some chevy guys what to do. not much help here.

[jayb]

All the right answers are here.  Go to an adjustable secondary plate so you can change jets, or go to bigger carbs.  Don't get hung up on the cfm numbers, the engine will take what it needs.  Ford used 600+ cfm carbs on their dual 4 setups, with a factory 425HP 427.  They ran great.  Carl's Ford Parts sells reproductions of those factory carbs, by the way...

[blykins]

Fuel pressure too high?  Blown PV?

There’s nothing wrong with the size of the carbs and the engine could actually use more.

[Heo]

Leaking float ?

[cammerfe]

oh well. i guess i will ask some chevy guys what to do. not much help here.

Tom---With all due respect, I believe your comment above suggests, perhaps, getting off on the wrong foot. You have a significant mass of information/suggestions above, and your comments suggest you DO need help. The plates inside the secondary bowls can be changed, or drilled, and plates set-up for replaceable jets are also available. It seems to me that your local help is likely a bit deficient in knowledge also. Please accept what's said, above, as gospel. It comes from some VERY knowledgeable sources.

My '64 427, new, came from the factory with a pair of 540s.

KS

[ntheogen]

oh well. i guess i will ask some chevy guys what to do. not much help here.

That will end up with you with an LS instead of actual tuning information.