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Old 07-21-2011, 09:54 PM   #1
Dave
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Smile 454 BBC 781 heads

I saw a pair of 781 heads f/s in stock form. I've heard these heads have good air flow characteristics and compression comes in around 8.5-9.0
What has anyone heard about them good, bad, indifferent. LMK
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Old 07-21-2011, 10:38 PM   #2
SCOTI
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Re: 454 BBC 781 heads

One of the best 'bang for the buck' bbc heads offered.

Mild port work & a good valve job & they'll flow as much as high dollar aftermarket heads. I don't recall typical compression ratios but I believe the 781's on my RetroRod combined w/a forged flat-top yielded 9.5:1. It will mainly depend on deck height, if the heads have been milled/surfaced, & what pistons are used.
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Building a small, high rpm engine
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like a highly skilled Morrocan sword fighter with a Damascus Steel Scimitar.

Cubic inches is like Indiana Jones with a cheap pistol....
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Old 07-21-2011, 10:53 PM   #3
Dave
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Talking Re: 454 BBC 781 heads

Thanks SCOTI.
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Old 07-22-2011, 07:01 AM   #4
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Re: 454 BBC 781 heads

You ain't gonna be anywhere near 9.5:1 with flat tops and open chamber heads, period.
With 119cc chambers and 3cc valve reliefs with a decked block and .040 quench, you'll be at 8:1. It'll take a small dome to get you up to 9 or 9.5:1.
With a good bit of port work, large valves, etc., you'll be as good as entry level aluminum heads, I've seen well done ones flow in the 340cfm range. They won't hold a candle to a good race head which are all well over 400cfm, but will be great for daily driver or mild racing.
Don't get too tied up in big port work...stock valves with a good bowl blending and a bit of short turn work, good 3-angle valve job and some necked-down valves plus some small dome pistons will get you a very good head, capable of 600hp or so on a 454.
Or forget the domes, go with a forged and studded bottom end and add forced induction, that's a perfect compression ratio for a hairdryer or huffer!
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Old 07-22-2011, 09:10 AM   #5
Moostifer
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Re: 454 BBC 781 heads

what they said...

I'm running 781's... larger valves, bowl blend, 3 angle, ports matched to intake runners, etc..

good heads stock...

great heads if they are given to the right machine shop...

but, as cheap as uluminum heads are now, for a few hundred more...
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Old 07-22-2011, 02:04 PM   #6
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Re: 454 BBC 781 heads

Quote:
Originally Posted by Moostifer View Post
what they said...

I'm running 781's... larger valves, bowl blend, 3 angle, ports matched to intake runners, etc..

good heads stock...

great heads if they are given to the right machine shop...

but, as cheap as uluminum heads are now, for a few hundred more...
Ditto...781's seem to perform well.
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Old 07-22-2011, 02:12 PM   #7
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Re: 454 BBC 781 heads

Quote:
Originally Posted by Moostifer View Post
what they said...

I'm running 781's... larger valves, bowl blend, 3 angle, ports matched to intake runners, etc..

good heads stock...

great heads if they are given to the right machine shop...

but, as cheap as uluminum heads are now, for a few hundred more...
Post up links to aluminum heads that are "a few hundred more".
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All Fleetsides

Building a small, high rpm engine
with the perfect bore, stroke and rod ratio is very impressive...
like a highly skilled Morrocan sword fighter with a Damascus Steel Scimitar.

Cubic inches is like Indiana Jones with a cheap pistol....
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Old 07-22-2011, 02:28 PM   #8
Desert1957
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Re: 454 BBC 781 heads

http://www.profilerperformance.com/bbc-heads-184.html

http://www.pbmperformance.com/store....randparent=339
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Old 07-22-2011, 03:49 PM   #9
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Re: 454 BBC 781 heads

No pricing on the Profilers that I could find on that link.
The Brodix listed on the PBM site site are $950 each + shipping so $1800 minimum. That's a little more than purchasing & rebuilding some 781's.

Go to Summit or Jegs & the typical price for standard, street use oval ports are around $850ea on up regardless of mfr.
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89CCDually-Driver/Tow Truck
90SWB Driver
All Fleetsides

Building a small, high rpm engine
with the perfect bore, stroke and rod ratio is very impressive...
like a highly skilled Morrocan sword fighter with a Damascus Steel Scimitar.

Cubic inches is like Indiana Jones with a cheap pistol....
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Old 07-22-2011, 09:57 PM   #10
77BBGMC
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Re: 454 BBC 781 heads

I looked at the receipt for the machine work and parts on my 781’s, I have less than $900.00 for the pair (that’s not counting roller rockers). I did the bowl blending and cleaned up the runners to save a little money.
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