750cfm

Automan · #1 (**permalink**) 08-22-2007, 11:29 AM

WOW!! Thats all i can say. Been driving around (only a couple of days because of the weather) but what a thrill. The sound of this 427 is amazing. Need to get use to the solid lifters tapping though.

The problems that i have been experiencing during my test runs havn't been too bad. Lost the fuel pump during my second test. Cost me a 80 tow. Found that one of the fittings got blocked by some crud. The shifter was rough until today. Took it to a tranny shop and they got her changing fine. They were really surprized to see a hydraulic clutch though. They found the pedal to be alot harder then they expected.

My biggest problem is the carbs. They are idling very inconsistant. I have to stomp on it when it is idling to bring it down. It is deffinately running rich. So far quite a few people have said that i have way too much carbs for my engine. Did anyone else use 2 750cfm carbs on thier 427? Or what size should i have used. I'm getting it from everyone. Lowest ive heard are a pair of 390 cfm carbs.

Any suggestions.
Thanks
Automan.

Man, is she loud!!!

sharpe 1 · #2 (**permalink**) 08-22-2007, 01:19 PM

You need to think about a couple of 600 cfms for that engine. They should be a matched pair.

lineslinger · #3 (**permalink**) 08-22-2007, 02:35 PM

Quote:

Originally Posted by Automan

. They are idling very inconsistant. I have to stomp on it when it is idling to bring it down. It is deffinately running rich. So far quite a few people have said that i have way too much carbs for my engine. Did anyone else use 2 750cfm carbs on thier 427?

If you have to stomp it down to idle properly you may be getting some linkage bind somewhere.
I am running two Holley 750's and love em'. I did tweak them out on the dyno. The cam I am running asks for every bit of mixture they deliver. A stingy air filter will cause rich mixture to the point where you have to de-tune them to a level where performance is sacraficed.
Once you get them properly tweaked properly you will be happy.

The 3" tall air filter supplies the carbs with required air volume.

WildBill3 · #4 (**permalink**) 08-22-2007, 02:59 PM

i had wonderd if that short oval air claener wasnt fouling things up a little on ours trouble is im already against the bottom of the hood now may have to try to make a custom drop base so we can run a bigger element ,we run a single 830HP on our 408 works good.

WildBill3 · #5 (**permalink**) 08-22-2007, 03:02 PM

what part # is that larger filter from k@n???

lineslinger · #6 (**permalink**) 08-22-2007, 03:15 PM

Quote:

Originally Posted by WildBill3

what part # is that larger filter from k@n???

I need to look it up, I think I paid around $70 for it.

lineslinger · #7 (**permalink**) 08-22-2007, 03:20 PM

The receipt I have says.......
Part# KNN-E-1963... unit price was $70.95 (that was in 05')

DavidBetts · #8 (**permalink**) 08-22-2007, 05:39 PM

I've been running Holley 750's for three years now. My engine is a 427 side oiler stroker built by Bill Parham at Southern Automotive in Atlanta. I've also heard that this is too much CFM's but, you can't proof it by me. Unless you are under 2500 rpm's, it launches without hestitation. My understanding is that you must have vacumm assisted secondaries to eliminate lag. The 750's have that. I had dual 450's prior ( adifferent 427) and the hesitation was annoying. Bill's people know what thy're doing.

Automan · #9 (**permalink**) 08-22-2007, 07:08 PM

Any danger in burning out the rings running alittle rich untill i get someone to look at this. Maybe i should run without the air filter?

Automan · #10 (**permalink**) 08-23-2007, 12:59 PM

I tightened up the linkage alittle more. I also ordered a new set of linkage for the carbs. Origional style. I am going to get rid of this universal style setup. After the adjustment it ran much better. Did 20 miles today and even took it on the highway. What a sound. idling was at 1100rpm and sometimes at 900. Switching gears was great.

Automan.