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Old 02-12-2003, 09:22 AM   #1
HYPERMAN
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353049 Casting Bb Head?

Are the big block heads with casting number 353049 any good of a head? I have a set to put on a 402 bottom end that are in better condition than the original 402 ones.

Thanks,
Peter
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Old 02-12-2003, 10:23 AM   #2
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122cc chamber will kill your 402s compression. Won't run worth a flip.
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Old 02-12-2003, 11:28 AM   #3
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They are some of the most looked for big port oval heads out there. Those and 781's [I think?]
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Old 02-12-2003, 05:12 PM   #4
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Tom , you are 100 % right
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Old 02-12-2003, 07:18 PM   #5
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Re: 353049 Casting Bb Head?

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Originally posted by HYPERMAN
Are the big block heads with casting number 353049 any good of a head? I have a set to put on a 402 bottom end that are in better condition than the original 402 ones.

Thanks,
Peter
Unless you have a BIG dome on your 402 pistons, you DO NOT want 049 heads. On a flat top 454, the only yield around 7.8:1 compression. I HAD 049 heads on my flat top 454, and I took them off and put a set of closed chamber 396 heads on it. From a seat of the pants evaluation, I'd say I picked up about 50 horsepower and 50 foot pounds of torque. And the 049 heads MAY have even flowed a little better.

The 049 head is a killer head for a domed piston 454. And pretty much useless for a 402. With the normal small dome on a 402 piston, you could end up with a compression ratio of 7.5:1 or less. If you are going to put an 8-71 blower on it with about 16% overdrive, you might be okay.
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Old 02-12-2003, 10:32 PM   #6
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Does anyone know what the usual cc's are for 1970 402? Just want to compare.

Thanks for the input so far.

Peter
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Old 02-13-2003, 01:41 AM   #7
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Talking

Check this link out. http://www.chevyhiperformance.com/te...98/index9.html
049's are a good factory head. The flow well for small and big cubes. Everybody has their opinions on whether closed chamber or open chambers are better.
Also check out www.chevelles.com and do a search. They have alot of useful information regarding these heads.
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Old 02-13-2003, 11:39 AM   #8
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Post your stock head casting number, but it is most likley either 101cc (like my 290's) or possibly 109cc.

I have not confirmend, but rumor has that the 99cc Vortec 7.4L heads combined with proper Gen VI head gaskets will work on the Mark IV motor, and they claim performance on a big block compareable to the Vortec small block heads. Give Scoggin Dickey a call.

When I get around to doing heads, If I can confirm this, I'll buy the Vortecs instead of R&Ring my 290 castings. Combined with a flat top on a 402, should be about 9:1 compression, and with a flat top 427, about 9.5:1
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Old 02-14-2003, 02:24 AM   #9
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Hyper those are as said some very sought after castings. However like the boys said CR will go to heck in a handbasket unless you use some MAJOR domes... they sell them but it's something to think about. As for open chamber versus closed there isn't much comparison. Opens allow for a cleaner more efficient burn with a better overall shape to the chamber. The problem of course is you lose CR and CR is where you gain efficiency.

Get the most CR you can handle for whatever fuel you're running and some great flowing open chamber heads you've got killer combination.

As mentioned a blower would be an option.... assuming you've got time money and skill to invest. My favorite is turbocharging but that's another subject good luck dude
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Old 02-14-2003, 05:13 PM   #10
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781's come in at 113.5cc, at least my set did. With the particular slugs I have in my 402, which were actually milled to drop the compression a bit, it comes in at anound 10:1.
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Old 02-16-2003, 03:10 PM   #11
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What heads would have come on a 68 396? or where can i find the casting #?
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Old 02-16-2003, 04:11 PM   #12
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'68 396 heads

330864
330865
3856260
3917215
3919840
3919842
3931063
3965198
3975950

Are among the possible few...
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Old 02-16-2003, 05:08 PM   #13
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vortec 7.4L heads are normal penaut port heads, no good for flow. Both ovals [the best all around] and rectangles flow better. No idea on the 8.1L heads though....
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Old 02-17-2003, 10:26 AM   #14
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7.4L Vortec heads are NOT peanut port heads. The following is straight off of Scoggin Dickeys site where 7.4L Vortecs are $429.50 each.

The L29 Vortec big block head was used on 1997-99 pick-ups with 7.4L engines. They are the best kept secret of GM. The small 99cc combustion chambers raise compression by 1 full point from the stock 119cc heads. The large oval port design flows better than any factory oval port head. If you are looking for a good head to put on your tow rig to help you haul the load, then the L29 Vortec big block head will do the trick. Sold as bare castings. For use on 1991 and later Gen V and VI engines only. Price is per head.

Notice here it says only on gen V and gen VI, but I have been told it will work on older motors as well with the appropriate gaskets. Confirmation from anybody?
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Old 02-19-2003, 07:48 AM   #15
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Re: 353049 Casting Bb Head?

Quote:
Originally posted by HYPERMAN
Are the big block heads with casting number 353049 any good of a head? I have a set to put on a 402 bottom end that are in better condition than the original 402 ones.

Thanks,
Peter
Nope, they are junk, send them to me

Tom is right, they are very good heads (oval) for port velocity which equalls effective torque on a street engine. If you have a flat top piston, and if the 049's are open chamber you will not have an effective compression ratio for any kind of power. If they are closed chamber, most early BBC oval's were (pre 71) you are golden with your flat tops. Open chambers require at least an .180 dome on top to build compression.

A closed chamber will look like a bathtub in shape, and open will be a half circle shape.
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