781 BBC heads - Chevelle Tech

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post #1 of 15 (permalink) Old Jun 13th, 09, 10:59 PM Thread Starter
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JOHN
 
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781 BBC heads

I aquired a 454 this weekend that has 781 heads on it. I'm looking to build a 450 HP bigblock and was wondering if these heads could possibly get me there? Thanks
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post #2 of 15 (permalink) Old Jun 13th, 09, 11:14 PM
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Jeff
 
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Re: 781 BBC heads

yep no problem just gonna need the right cam and other related parts.

78 Malibu 402, 4L60E, 3:70 9"
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post #3 of 15 (permalink) Old Jun 13th, 09, 11:30 PM
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Re: 781 BBC heads

It would be hard NOT to make 450 HP.

The car doesn't have an engine . . . the engine has a car.
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post #4 of 15 (permalink) Old Jun 14th, 09, 12:02 AM
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Re: 781 BBC heads

Absolutely, good find.
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post #5 of 15 (permalink) Old Jun 14th, 09, 12:27 AM
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Re: 781 BBC heads

They are a great street head, and will work pretty well on everything from a mild cruiser to a hot street car. They respond well to bigger valves and basic head work. But you should be able to get to the 450hp level with them being pretty much stock. Just pick the right cam and intake.

Mike
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post #6 of 15 (permalink) Old Jun 14th, 09, 1:58 AM
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George
 
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Re: 781 BBC heads

John,

Use SEARCH
thousands of posts on BBC builds, 049 and 781 heads

George Kettler
o 70 Elky 496 #074 AL heads with porting, 10.3:1 CR, Straub HR 237/241* .617/.570 107 race weight should be 3895#. 3500 or better stall, 3.90s
o 68 Vette 427/M-20/3.36 23 year owner
http://public.fotki.com/kettbo/gearhead/
o 68 Camaro Vert 327 project, painted, assembly stage http://www.camaros.net/forums/showth...183654&page=55
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post #7 of 15 (permalink) Old Jun 14th, 09, 7:50 AM
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Gene
 
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Re: 781 BBC heads

Vortec Pro uses these almost exclusively. I just finished putting a coat of POR orange enamel on a set in my garage. Next is ss screen in the oil drainback and off to the Serdi machine for some seat opening.

Gene
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post #8 of 15 (permalink) Old Jun 14th, 09, 7:59 AM Thread Starter
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JOHN
 
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Re: 781 BBC heads

Quote:
Originally Posted by Twins Fan View Post
Absolutely, good find.
We were talking about the 215's I have, but I'm not sure they are useable. A couple of exhaust ports are extremely rusty to the point of losing material. I picked up a 76 3+3 truck with a 454/400 that has the 781's on it. I only gave $200 for the whole truck and it was advertised for the world to see on the internet. Couldn't believe the add when I seen it.
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post #9 of 15 (permalink) Old Jun 14th, 09, 9:21 AM
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Rod
 
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Re: 781 BBC heads

Quote:
Originally Posted by TRANNY SMOKE View Post
We were talking about the 215's I have, but I'm not sure they are useable. A couple of exhaust ports are extremely rusty to the point of losing material. I picked up a 76 3+3 truck with a 454/400 that has the 781's on it. I only gave $200 for the whole truck and it was advertised for the world to see on the internet. Couldn't believe the add when I seen it.
Good score! Craigslist?
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post #10 of 15 (permalink) Old Jun 14th, 09, 2:43 PM Thread Starter
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JOHN
 
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Re: 781 BBC heads

No. http://www.hoosiertopics.com/
Here is a link to the specific add.http://www.hoosiertopics.com/cgi-bin...req=26w6a0749a

Last edited by TRANNY SMOKE; Jun 14th, 09 at 3:47 PM.
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post #11 of 15 (permalink) Old Jun 14th, 09, 3:14 PM
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Paul
 
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Smile Re: 781 BBC heads

Great heads, but remember that you will need to cc them b/c they can vary from 113 up to 119 cc's or so! -049 heads can go above 122 cc's here....

I'd use stock type GM .020" thick steel shims to set the quench at .035" to .045" and then order a set of forged pistons to get the CR up to at least 9.75 to 1 CR, if not right at 10 to 1 WITH the cc of your -781 heads!!

Please don't try to run the cheaper hyper pistons, only b/c you are starting to be up in the forged piston power range and I figure that once you get her going, the dreaded, "More power, Scottie" bug will bite you just like it did me!! This way, your new pistons will be FINE!!

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post #12 of 15 (permalink) Old Jun 20th, 09, 12:51 AM
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Re: 781 BBC heads

Quote:
Originally Posted by 68chevelle533 View Post
They are a great street head, and will work pretty well on everything from a mild cruiser to a hot street car. They respond well to bigger valves and basic head work. But you should be able to get to the 450hp level with them being pretty much stock. Just pick the right cam and intake.

What Cam and Intake would you all recommend. I am in the process of cleaning up my 454 but was just planning to put a Cam and Intake in myself to beef it up a little. What about changing the Valve Springs as well? Also would a Holley 750 work on this engine for daily driving?

Thanks

Jacen
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post #13 of 15 (permalink) Old Jun 20th, 09, 3:31 AM
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Paul
 
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Re: 781 BBC heads

Imho, no more than CC's old 282s solid flat tappet lifter cam will do you fine,.

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post #14 of 15 (permalink) Old Jun 20th, 09, 10:31 AM
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Paul
 
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Re: 781 BBC heads

Get them cut for 2.19/1.88 valves and some port work done. Probe -18cc dome top forged pistons are cheap and will bring up you compression to 9.6-9.8 but cc your heads....my 781's were 116
You should be able to get 500/550hp with a good matching combo

454/T400/9" in a 67 Beaumont
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post #15 of 15 (permalink) Old Jun 20th, 09, 1:32 PM
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Paul
 
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Re: 781 BBC heads

Right, use the springs recommended for your cam here, not the low lift stock type.

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