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Hi All,

I have a Holley 750DP which I bought second hand but in great condition with very few hours on it which I will shortly be fitting to my new 393 stroker build. Further investigation of the carb throttle bores, venturi areas & butterflies has revealed a number of rough edges which are not damage but manufacturing casting lines & minor defects. Can anyone advise if it is worthwhile smoothing these surfaces & in general cleaning up these areas to promote air flow. In addition to this I have read that replacing the butterfly securing screws for smooth dome heads & trimming the excess thread length off these screws also assists carb performance. Obviously I do not want to create excessive work for myself but are there HP gains to be had by blueprinting the carb this way? In addition what additional blueprinting should I be doing to get the best out of this carb?

Any advise greatly apreciated.
Martyn.
 

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I believe that there would be gains in airflow after flashing removal, and blending the carb body into the throttle plate.

After an hour's worth of work to my 850, it sure did look nicer, but I didn't run any faster at the track.

Still, I believe that making all parts fit together properly is a basic part of high performance engine building. I would do it again to my next carb for that reason alone!

Greg

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'71 Torino GT - 545 stroker, Edelbrock CJ heads w/ 11.8:1 compression, victor intake with 850 DP, C6 w/TCI streetfighter converter, 4.56 detroit locker, a/c with full interior

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<font size=-1>[ This Message was edited by: GregP on 7/26/06 4:43am ]</font>
 

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Just a regular razor knife and some work on those ruff areas will help by leaps and bounds. Blow everything clean with compressed air, tape up the air horn holes and other things that will not be in your way.

Be very careful anything you scrape clean does not get into the air bleed holes. But yes, remove every ruff surface you can. The knife will gey most of it, then maybe a small round file for the places that are a little deeper. Get around the booster venturies too, inside and out, but be carefull not to change the outside diameter. I think this web sight has a great artical on cleaning up the carb like you want to do. You will have to hunt around for it, maybe on the tech board.

Jegs sells a proform kit for the throttle shafts, and shorter screws. If you go that route, then take the throttle plate base off and get a new gasket, it will let you get into the deep parts of the venturis easier.
 
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