let us know 
327 Holley vs Edelbrock
Thread Starter
Le Mans Master
Joined: May 2003
Posts: 8,877
Likes: 3,556
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
327 Holley vs Edelbrock
Fresh rebuild 327 .30 over aprox 10.1 compression
RPM performer intake
Brodix Track 1 heads
Comp Cam XR 270 Hyd. Roller
Alum Roller Rockers
electronic ignition
Currently running a Holley 80457 600CFM carb w/ vacuum secondaries. But seems to be way too rich. Was running rich before rebuild- so I knew I was going to have to mess w/ it. Nothing has been changed as far as jets or powervalve. I was told to step up the power valve to an 8.5 (comes w/ 6.5)
I'm getting about 12+inches of vacuum at idle.
I've tried to fine tune - runs bad till warmed up-SO it looks as though I'm taking it apart -OR do I chunk it and switch to an Edelbrock 600CFM 1406?
RPM performer intake
Brodix Track 1 heads
Comp Cam XR 270 Hyd. Roller
Alum Roller Rockers
electronic ignition
Currently running a Holley 80457 600CFM carb w/ vacuum secondaries. But seems to be way too rich. Was running rich before rebuild- so I knew I was going to have to mess w/ it. Nothing has been changed as far as jets or powervalve. I was told to step up the power valve to an 8.5 (comes w/ 6.5)
I'm getting about 12+inches of vacuum at idle.
I've tried to fine tune - runs bad till warmed up-SO it looks as though I'm taking it apart -OR do I chunk it and switch to an Edelbrock 600CFM 1406?
Pro
Joined: Oct 2001
Posts: 621
Likes: 1
Uhh... why haven't you changed the jets? That is the main mixture adjustment on Holleys.
No need to change the power valve, unless you are getting a lean stumble at part throttle.
One thing at a time. Get the cruise and WOT mixtures right, then attack the power valve in the unlikely event it is needed.
The power valve number tells you the vacuum at which it opens, nothing more. 8.5 is generally for a mild cam.
No need to change the power valve, unless you are getting a lean stumble at part throttle.
One thing at a time. Get the cruise and WOT mixtures right, then attack the power valve in the unlikely event it is needed.
The power valve number tells you the vacuum at which it opens, nothing more. 8.5 is generally for a mild cam.
Thread Starter
Le Mans Master
Joined: May 2003
Posts: 8,877
Likes: 3,556
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
I guess more of my question is- Do I spend the time and money to get the Holley right( even after reading an article where drilling a hole in the throttle blades was required to idle correctly)- buying the jets and gaskets?
Or do I go w/ the Edelbrock-which from my reading/understanding is a little more forgiving and will work well w/ the intake I have.
Or do I go w/ the Edelbrock-which from my reading/understanding is a little more forgiving and will work well w/ the intake I have.
Pro
Joined: Oct 2001
Posts: 621
Likes: 1
Yes, tune the Holley. Either can be made to work. With your setup, either one is going to need work.
I'd also dump the vacuum secondaries with a semi-radical engine like that. I have the 650CFM Holley 4150HP race carb. Very tuneable.
I'd also dump the vacuum secondaries with a semi-radical engine like that. I have the 650CFM Holley 4150HP race carb. Very tuneable.
Thread Starter
Le Mans Master
Joined: May 2003
Posts: 8,877
Likes: 3,556
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
Well...that's what I was thinking about the vacuum seconds. When I was having the motor built- I thought 5grand -maybe every once in a while. BUT after driving it, it's seeing 5k every chance I get!
SO you think the 4777 650CFM mechanical would be a good choice? AND get my buddy the carb expert to tune it - I'm trying to keep it streetable.
Thanks for your thoughts!!
Richard
SO you think the 4777 650CFM mechanical would be a good choice? AND get my buddy the carb expert to tune it - I'm trying to keep it streetable.
Thanks for your thoughts!!
Richard
Pro
Joined: Oct 2001
Posts: 621
Likes: 1
Yes, I think the 650CFM mechanical is an excellent choice. With the right tune, it will respond instantly under any conditions.
The only thing that would compromise streetability would be if you went way too big on the carb. A 750 would not be too big, by the way. An 850 would be pushing it.
Be prepared for awful gas mileage with the double pumper, but it's probably already not stellar. I get 11MPG at 80MPH with mine, but I've got a big cam and deep gears. Who cares??
The only thing that would compromise streetability would be if you went way too big on the carb. A 750 would not be too big, by the way. An 850 would be pushing it.
Be prepared for awful gas mileage with the double pumper, but it's probably already not stellar. I get 11MPG at 80MPH with mine, but I've got a big cam and deep gears. Who cares??
Last edited by L79vette; Aug 21, 2004 at 11:17 AM.
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Le Mans Master
Joined: Oct 2000
Posts: 8,897
Likes: 1,357
From: Santa Ana CA
If you want to try a 650 dp with mechanical secondaries, I have one sitting on the shelf with an electric choke that works fine. (I replaced it with a modified 600 dp.) Yours for $100 plus shipping.
Thread Starter
Le Mans Master
Joined: May 2003
Posts: 8,877
Likes: 3,556
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
Toddalin-thanks for your offer. Looks like my carb expert buddy has one he's going to "give" me (he'll still owe me...)
Gas mileage? I just put gas in it when it gets to a quarter tank!
Gas mileage? I just put gas in it when it gets to a quarter tank!
