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Big Block chev 706

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Big Block chev 706

Postby Tom bene » Wed Jan 16, 2008 8:15 pm

Was wondering if some one at this site could help me out.Im a novice engine builder/racer that has a problem.I current have a 665 ci bbc.The block is aluminum and has a deck height of 11.6250 with 4.605 bore and 4.90 bore spacing a 400 thou raise cam,stock bbc cam journals.It has sonny brynt crank with 5.00 stroke,and has bill miller 7.200 aluminm rods.My problem is i need to buy a new crank shaft,so i want to change the stroke to 5.300 to make it a 706.I do no if the 5.300 stroke crank will fit and dont want to buy if it wont fit.Is their a special way to check for clearence
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706

Postby speedracer » Wed Jan 16, 2008 9:35 pm

What brand of block is it?

Most 11.625 blocks were built for 706+ motors and are clearanced for the 5.3 stroke and some advertise they will clear 5.5 - 5.6 strokes. You might have to grind the block near the pan rails for rod clearance and the best way to do that now is see how much you have with the 5.0 stroke. The stroke difference between the 5.0 and the 5.3 crank is .150, so you can gauge off of that. Also check the rod to cam clearance before you disassemble or just mock it up. Hope this helps.
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Postby highVE » Wed Jan 16, 2008 10:37 pm

Be sure to cam it accordingly, along with tune-up, and possibly if the heads still meat the demand!

Mike Theroux
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Postby Tom bene » Thu Jan 17, 2008 7:48 am

The block say sonnys automotive racing on it but im not shure who manifactured the block for him
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Postby Ron C. » Thu Jan 17, 2008 11:45 am

You might want to post for some help on the www.promodzone.com board. This is a common motor there and there pretty helpful in general.

Have fun............blessings..............Ron.
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Postby Ed-vancedEngines » Thu Jan 17, 2008 4:59 pm

If your block is showing a logo with a funny looking A & R on it with an arrow trhough the AR and some very strong strengthening ribs across the valley area, you have a strong and Bad to the Bone Block made by Allan Root. With working the underside it should easily take a 5.300 crank if it is using the DRCE/Merlin Pan Rails and not the Chevy Pan rails. It will take even bigger.

Why not make a phone call to Sonny Leonard and speak with him and find out. Sonny is a very nice guy to speak with and will help you with what you need to know.

Ed
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Postby speedracer » Thu Jan 17, 2008 6:59 pm

Not to get off the Sonny's block topic, what about the Merlin 11.625 aluminum block with the massive ribs running across that block? Anybody run or have any knowledge about that block? That one looks a little more beefier than others I have seen. I haven't seen to many around, I heard they don't make those any more? Why did they stop making the Merlin Pro 11.625 cast iron block?
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Postby highVE » Thu Jan 17, 2008 9:38 pm

Not sure if there still made or not, but we used back for a Offshore deal. 653 cid supercharged motors. Very nice blocks, but also VERY HEAVY!!

Mike Theroux
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Big Block 706.

Postby jimivice » Mon Jan 21, 2008 7:15 am

If you have 11.625" deck and a 4.605" bore, you probably have a Donovan block. In the early Pro Mod days there were no other aluminum blocks available. 5.300" stroke and a 4.600" bore was the popular combination. There were inherent problems. The blocks would always crack between cyls. because there was not enough material to suppoprt the sleeves. When Jon Kaase was involved with Pro Mods, he tried to remedy the problem by replacing the aluminum between the cyls. with billet aluminum to try to eliminate cracking and support the sleeves. At a finished size of 4.600" the wall thickness of the sleeve was only .074", any movement in the block would transferred to the cyl. This was ampllified with spreading the bore centers from 4.840" to 4.900". The Donovan casting wasn't revised but only made thinner to accomadate the dimensional change. Donovan is now offering 5" bore spacing within their existing casting design. I have seen the Donovan 5" blocks and I'm not impressed. There is only one block that I have seen that has been properly designed for 5" bore spacing by Gary St. Dennis of Dart. It not only allowed 5" bore spacing but the bore size was 4.675" with a .120" wall sleeve. The 704"s now used a 5.125" stroke with a 4.675" bore. I did not know Gary personally but my understanding he was underminded and was forced to sell his design. It is my understanding that Chuck Nuyten has the rights to manufacture these blocks. I often wonder if the posts by CNC are Chuck Nuyten. If Chuck Nuyten does not have the rights to the design,Allen Root might have. I have worked on the original blocks and would like to see if Chuck Nuyten or Allen Root has acquired the design.
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Big Block 706.

Postby jimivice » Mon Jan 21, 2008 7:16 am

If you have 11.625" deck and a 4.605" bore, you probably have a Donovan block. In the early Pro Mod days there were no other aluminum blocks available. 5.300" stroke and a 4.600" bore was the popular combination. There were inherent problems. The blocks would always crack between cyls. because there was not enough material to suppoprt the sleeves. When Jon Kaase was involved with Pro Mods, he tried to remedy the problem by replacing the aluminum between the cyls. with billet aluminum to try to eliminate cracking and support the sleeves. At a finished size of 4.600" the wall thickness of the sleeve was only .074", any movement in the block would be transferred to the cyl. This was ampllified with spreading the bore centers from 4.840" to 4.900". The Donovan casting wasn't revised but only made thinner to accomadate the dimensional change. Donovan is now offering 5" bore spacing within their existing casting design. I have seen the Donovan 5" blocks and I'm not impressed. There is only one block that I have seen that has been properly designed for 5" bore spacing by Gary St. Dennis of Dart. It not only allowed 5" bore spacing but the bore size was increased 4.675" with a .120" wall sleeve. The 704"s now used a 5.125" stroke with a 4.675" bore. I did not know Gary personally but my understanding he was underminded and was forced to sell his design. It is my understanding that Chuck Nuyten has the rights to manufacture these blocks. I often wonder if the posts by CNC are Chuck Nuyten. If Chuck Nuyten does not have the rights to the design,Allen Root might have. I have worked on the original blocks and would like to see if Chuck Nuyten or Allen Root has acquired the design. Yes the block will accomodate a 5.300" stroke. I have notched enough of these blocks to that stroke. If you need to know the proper angles, just post your questions.
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Postby Ed-vancedEngines » Mon Jan 21, 2008 7:36 am

Jim,
The Nuyten Block is begun from a solid hunk of billet.
The Root block was a cast block with much beefy ribbing in the valley area.
I think the Trick Flow block was also a cast block.
I know at times Sonny had used both the Root Blocks and the Trick Flow blocks.
I also think the new Dart Aluminum block is begun as a casting and then machined to spec. Not positive yet on that though.

His question has been asked on several different boards, and I know I have replied to it on three of them.

I also suggested to him on one board that buiding a 706 cu in engine is not a wonderful idea for the novice builder. It can be done but there are lots of things different and much more time consuming. You better be up to snuff and dod all your i 's and cross your t's and use the spell check several times, if you get my meanings. ;)

Ed
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Postby Tom bene » Mon Jan 21, 2008 8:50 am

This engine was together and ran 4 a couple years.I damaged the crank and i wanted to know if the 5.300 crank would fit.I have check the clearance now with the 5.00 stroke crank and i have lots of room(.300-.400)thou .Thanks for all the replies
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Postby speedracer » Thu Jan 31, 2008 12:22 am

Hey jimivice, or any that wish to comment, in these 11.625 blocks with the cam .400 higher, is there a problem with cam to rod clearance?

Can you put a 55mm cam with or w/o roller bearings?

Or do you have to run a small base circle cam?

Can you possibly run a 5.375 stroke with alum. rods and not run tit. rods?

What's the max?

I also have talked to racers that have run these w/o nitrous and have had good luck still making n/a power.

Appreciate any info.
speedracer
 


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