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Old 11-16-2009, 09:50 PM
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Blower motor set up questions

I am putting a 468 BBC blower motor together for my Anglia

I have a set of Gm cast oval prrt heads #3336 (781) 118cc chambers and the blower is a 420 B& M with rect ports,,
I read a article about the matching the oval ports to the rect blower ports,, using 1211 flopro gaskets and got better flow # up to about 6K rpm, here
http://www.maliburacing.com/patrick_budd_article.htm

flow comparason here http:// www.maliburacing.com/ovalvsrect.htm
The cam I have is a comp #11-414-8 blower/ Nitrious, 566 In and 575 ex with a lobe sep of 113* duration 242 int and 254 ex

and 8'5 comp full hyd roller

any ideas from you blower guys aboutwhat size and type of Carbs would be best for this motor? also have a carb plate nitrous kit for it
this one http://www.summitracing.com/parts/NO...S/?image=large
any ideas please,, I posted over on a existing thread on blowers but it got so far down the list that it got no replys,, Thanks bIll

Last edited by Bad Rat; 11-16-2009 at 10:07 PM.
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Old 11-17-2009, 12:39 AM
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blower carbs

Search "backfire blower" within the HBB websit, and it will tap you into a thread 471A began with nightmare problems in setting up the carbs on a Weiand/Holley 250 blower atop a SBC 355. The info I received through HBB solved problems that had me close to giving up. You will find in that thread three or four regular HBB contributors with superb knowledge about carb setups for blowers. In my particular case, I run dual four-corner boost referenced Holley 600s where the key proved to be ignition timing. Once I went locked in 34 degrees, backfires no longer were a problem and the SBC fires reliably in weather cold or warm.
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Old 11-17-2009, 01:26 AM
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There was nothing in the referenced Patrick Budd article link about grinding the oval intake ports to the rectangular shape??? Just a test of two entirely different heads, one Rect port LS-6 heads (026 casting) and the other just common '70's oval ports (781 casting).
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Old 11-17-2009, 01:36 AM
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Quote:
Originally Posted by ericnova72
There was nothing in the referenced Patrick Budd article link about grinding the oval intake ports to the rectangular shape??? Just a test of two entirely different heads, one Rect port LS-6 heads (026 casting) and the other just common '70's oval ports (781 casting).

Eric,, That infromation is in this link,,

www.maliburacing.com/ovalvsrect.htm


the 781 oval ports are the same as the 049 cast heads except for the 781 have 118 cc chambers and the 049 has 122 cc chambers and slightly larger ports by 2 cc. at 256/114 to 255/119 for the 049 susposeably these are the desired heads for a stock cast head,,,

Last edited by Bad Rat; 11-17-2009 at 01:55 AM.
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Old 11-17-2009, 02:24 AM
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Bad Rat, I think you are misreading that article. It is a comparison of home ported Oval heads vs home ported Rectangle heads. The oval kept their oval shape, and the rectangles kept their rectangle shape. They are both gasket matched to their respective stock port gasket sizes, bowl blended, and have larger than stock valves added(which are a different size between the two heads, which kind of invalidates the results, IMO). The ovals have not been ground out to the rectangle port gasket, which is what you said in the first post.
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Old 11-17-2009, 12:48 PM
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Quote:
Originally Posted by ericnova72
Bad Rat, I think you are misreading that article. It is a comparison of home ported Oval heads vs home ported Rectangle heads. The oval kept their oval shape, and the rectangles kept their rectangle shape. They are both gasket matched to their respective stock port gasket sizes, bowl blended, and have larger than stock valves added(which are a different size between the two heads, which kind of invalidates the results, IMO). The ovals have not been ground out to the rectangle port gasket, which is what you said in the first post.
Thats very possable but what I am getting at is when matching the oval ports to the felpro 1211 gasket, [not to the rect port head not enough meat there] and porting the ovals to blend into the rect heads, you get a better flowing CHEAPER set of heads that will flow better than the rect up to around 6500 rpm, better bottomend torque, and ideal for street use,

heres another article from Chev performance Mag on the same subject,, maybe I'm reading this all wrong,, but this is how I am trying to build my

http://www.chevyhiperformance.com/te...ads/index.html


blower motor, and it too late now, i'm down to carb selection ideas now,, this is susposably what this thread is all about,,,
But I certainly appreciate this discussion and looking forward to more,, Thanks guys ,,appreciate the input

Last edited by Bad Rat; 11-17-2009 at 12:54 PM.
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Old 11-17-2009, 12:56 PM
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I would not use smaller than two 750 cfm blower carbs.

750 to 850's will work well.

You're going to need a higher rpm capable street solid roller to get any use from the nitrous system on this motor. The girlie cam hyd roller is going to give up on you way too soon.

Get some 110-116 octane race gas also if you plan on spraying this motor.
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