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 Holley 4777-2 upgrade? 
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Joined: Tue Apr 07, 2015 10:13 pm
Posts: 3
I have a SB mopar 4.03x4 408 ci street and mild bracket truck. It is 10 to 1 comp,pump gas,3.73 gears,28" drag radial, auto with 3800 stall converter,Performer RPM intake manifold,headers etc. I had a borrowed Holley HP 750 on it for a few weeks and got it to run reasonably well,best 10.87@122mph,driven to and from the track. I recently gave the carb back to it's owner and need to decide what to replace it with. Given that this is not a very serious build I'd like to avoid spending more for bling than performance. I have an old 4777-2 that has been in the shop for years but is in good condition. Would it be practical to upgrade this carb for my application? Thanks for any help or suggestions.


Thu May 04, 2017 8:39 pm
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Joined: Fri Feb 08, 2013 5:50 pm
Posts: 2357
A 650 will work, but will slow performance a little. If you want to conserve money look for a used 950 to rework, or annular 1000HP. A new custom carb would start at $850 for cast, $900-$1100 for billet.


Fri May 05, 2017 10:02 am
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Joined: Fri Feb 08, 2013 2:37 pm
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The early 650 double pumpers are a good basic carb. No reason not to use this carb if you have it. Measure the orifices and reply, let's see what you have and give it some love. With some effort in tuning it is usually an excellent street carb for most engines. The original 650DP primary metering block has an emulsion tube like the best OE HP carbs. If the main wells have a flat plug, rather than the cup plug which is in the idle wells, they are probably the original blocks.

Some of the early 4777s have unusual jetting as manufactured, too-large MJ and too-small PVCR, perhaps because the intake manifolds of the period, Edelbrock Torquer and Taratula, etc, have very small volume compared to today's intakes.

Because it is smaller it won't have as much WOT power as a 750, though If you were short-track circle racing it would probably outrun a 750 on tracks 1/2 mi. and smaller.


Fri May 05, 2017 2:39 pm
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Joined: Tue Apr 07, 2015 10:13 pm
Posts: 3
I'd love to run one of your carbs Jmark but its not realistic at this time. I may freshen this 4777 and use it for the engine run stand or use it on a milder build. Another friend offered to donate a Proform 950 that he really liked but isn't using at this time so I have some testing to do. Thanks guys


Thu May 11, 2017 10:14 pm
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