holley carb help
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Joined: Aug 2003
Posts: 94
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From: virginia beach va
holley carb help
my 77 came with a holley streat avenger 770cfm carb. i would like to play around with the mixture because i think it is running a bit rich. how do you adjust this? is there a web site explaining this?
thanks
thanks
Safety Car
Joined: Aug 2001
Posts: 3,685
Likes: 202
From: Waterford Mi
Re: holley carb help (ray77vette)
Check out this from Lars.
http://www.corvettefaq.com/redir.asp?site=25
Lars is a great forum member and has helped many here.
http://www.corvettefaq.com/redir.asp?site=25
Lars is a great forum member and has helped many here.
Drifting
Joined: Jan 2002
Posts: 1,645
Likes: 11
From: Schaumburg IL
Re: holley carb help (ray77vette)
Follow the tips in the article, but adjust your floats first before messing with the jets. BTW, in all honesty the 770cfm may be a bit too much for a basic stock 350.
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,390
From: At my Bar drinking and wrenching in Lafayette Colorado
Re: holley carb help (bigvette1)
Hi bigv!
Regarding the subject of carbs that are too big, I had a great opportunity to really try this out last week. I was at Westech Performance - the dyno test place that does all the dyno testing for Hot Rod, Car Craft, Hi Perf Chevy, etc. I had a chance to do some dyno testing with Matt King - Senior Editor for Hot Rod. We took a 302 Ford and ran it with a 650DP Speed Demon. With the dyno, it's obviously possible to set the carb up nearly perfectly. We then slapped on a 750DP on the little 302 and set it up to the same mixture. The 750DP on the little engine picked the engine up about 10 horses across the rpm range with no degredation in idle or low-speed performance. No bog or hestition slamming the 750 mechanical secs open at low rpm. In talking to the Westech guys and the engine builders at Dougan's Racing Engines, they have consistently the same results: the 750 will run great on engines 302 and above.
A few weekends ago, we yanked a 750DP off of a CCC SB Vette and slapped on "lavetteman's" 850DP. The car picked up power across the rpm range.
About a month ago, a friend running an 850DP Holley on a 363 drag car borrowed a 1050 Dominator. The 1050 cut 3 tenths off the car's 1/4-mile ET, and that's after verifying that the 1050 mixture was set up the same as the 850.
Other discussions with noted Pontiac NHRA Engine Builder & National Record Holder Ken Crocie reveals the same experiences - for best power, he preferers to err on the big side and disregard the "manufacturer's recommendations" for sizing.
So the 770 is certainly not to big for a 350, especially since it's a vacuum secondary carb that will never allow the secondaries to fully open anyway... (I've tried them on the dyno even with the lightest springs - the sec's never go wide open even on the best day).
Regarding the subject of carbs that are too big, I had a great opportunity to really try this out last week. I was at Westech Performance - the dyno test place that does all the dyno testing for Hot Rod, Car Craft, Hi Perf Chevy, etc. I had a chance to do some dyno testing with Matt King - Senior Editor for Hot Rod. We took a 302 Ford and ran it with a 650DP Speed Demon. With the dyno, it's obviously possible to set the carb up nearly perfectly. We then slapped on a 750DP on the little 302 and set it up to the same mixture. The 750DP on the little engine picked the engine up about 10 horses across the rpm range with no degredation in idle or low-speed performance. No bog or hestition slamming the 750 mechanical secs open at low rpm. In talking to the Westech guys and the engine builders at Dougan's Racing Engines, they have consistently the same results: the 750 will run great on engines 302 and above.
A few weekends ago, we yanked a 750DP off of a CCC SB Vette and slapped on "lavetteman's" 850DP. The car picked up power across the rpm range.
About a month ago, a friend running an 850DP Holley on a 363 drag car borrowed a 1050 Dominator. The 1050 cut 3 tenths off the car's 1/4-mile ET, and that's after verifying that the 1050 mixture was set up the same as the 850.
Other discussions with noted Pontiac NHRA Engine Builder & National Record Holder Ken Crocie reveals the same experiences - for best power, he preferers to err on the big side and disregard the "manufacturer's recommendations" for sizing.
So the 770 is certainly not to big for a 350, especially since it's a vacuum secondary carb that will never allow the secondaries to fully open anyway... (I've tried them on the dyno even with the lightest springs - the sec's never go wide open even on the best day).
