454 to 496: Which block? 1pc vs. 2pc main seal? - Chevelle Tech
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  #1  
Old Feb 8th, 06, 10:21 PM
MillerTime MillerTime is offline
 
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Default 454 to 496: Which block? 1pc vs. 2pc main seal?

Sorry for the newbie question, just joined the board.

I did search, but nowhere is a definitive Yes or No to which block to have, which one to avoid, to do a 454 buildup to a 496 for my Chevelle.

I like the idea of a 1 pc rear main seal, for leak sake. But the pre-Gen V blocks appear to be everywhere, and cheap.

I would like to use a Hyd. Roller cam, don't know if some blocks can or can't accomodate it. And any head compatibility issues with different Gen/Mark blocks?

Any info would be appreciated. And if anyone has one for sale, let me know.

Matt

ps, if you live in the Bay Area, stop by and say hi at my bar.
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  #2  
Old Feb 9th, 06, 6:11 AM
tuffss tuffss is offline
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Default Re: 454 to 496: Which block? 1pc vs. 2pc main seal?

Hi, I am currently building a 496 using a new Gen VI block, which as we know will accommodate a roller cam, as for the Gen V & Mk 4 blocks these will also take roller cams but need to use the lifters that are manufactured in pairs with retaining straps to prevent lifters rotating. As for cyl heads Gen VI blocks will take early & late cyl heads but if using a Gen V block with early heads then a special head gasket is required. Couldn't say which block to avoid but why use 20-30 year old block some with helicoils, some already 060" over, when new improved blocks are readily available, good luck with your project.
Tuff SS
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  #3  
Old Feb 9th, 06, 11:15 AM
MillerTime MillerTime is offline
 
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Default Re: 454 to 496: Which block? 1pc vs. 2pc main seal?

Tuffss,

Thanks for the info...that's along the lines I was thinking.

So will ANY Gen VI 454 block work? I see a bunch of truck vortec type engines cheap. Are they all 4-bolt as well? And from what year did the Gen VI originate from.

It sounds like you've done the research already, and I appreciate the info.

Btw, who's stroker/rotating assembly kit did you go with?

Matt
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  #4  
Old Feb 9th, 06, 2:17 PM
tuffss tuffss is offline
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Default Re: 454 to 496: Which block? 1pc vs. 2pc main seal?

Hi, Yeah i think any 454 bbc Gen VI will do thats what my block is based on, it's just the cyl heads that are different thats why the name vortec is used & they are all 4 bolt, if i remember correctly the Gen VI was introduced in 1996.
I used Eagle 4.250 stroker crank along with 6.385 H beam Eagle rods & .060 SRP pistons but during a dummy assemble had issues with counterweights brushing piston skirts & pin bosses so i had the counterweights machined down now everything is fine.
Tuffss.
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  #5  
Old Feb 9th, 06, 3:42 PM
MillerTime MillerTime is offline
 
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Default Re: 454 to 496: Which block? 1pc vs. 2pc main seal?

Tuffss

I just looked on the GM Performance website for the 454 Gen VI block, and it says it has a .060 max overbore, can that be?

Did you buy yours new, or from a take out?

What heads are you going to run?
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  #6  
Old Feb 9th, 06, 3:53 PM
boarhunter boarhunter is offline
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Default Re: 454 to 496: Which block? 1pc vs. 2pc main seal?

I use a gen 4 block for my 496 with scat 9000 crank, scat 6.385 h beam rods and srp 13 to 1 piston and i had to clearance the bottom of the cylinders walls because the rods just niped the lower cylinder wall. after that it was a breeze
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  #7  
Old Feb 9th, 06, 4:12 PM
Schurkey Schurkey is offline
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Default Re: 454 to 496: Which block? 1pc vs. 2pc main seal?

Quote:
Originally Posted by tuffss
why use 20-30 year old block some with helicoils, some already 060" over, when new improved blocks are readily available
Quote:
Originally Posted by Miller Time
I just looked on the GM Performance website for the 454 Gen VI block, and it says it has a .060 max overbore, can that be?
'Cause the old blocks are stronger? 'Cause the old blocks have thicker cylinder walls?

I have heard, but not experienced, that the Gen 6 blocks are quite weak. I would expect about the same from the Gen 5. Probably not an issue at lower power levels, though.

NEW heads will bolt onto OLD (Mk IV) blocks without issue, provided you use a head gasket that matches the BLOCK. Mk IV heads can be a problem on Gen 5 blocks. Victor/Reinz makes a pair of special head gaskets to ease that problem, though. There is a different part number for the left and the right side.

The 2-piece neoprene seal works just fine. I think the REAL reason the factory changed to the one-piece seal was to make an easier/faster/cheaper installation, not so much as to "fix" an oil leak problem. Mind you, if it DOES leak, the one-piece seal is much simpler to change than the 2-piece.
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  #8  
Old Feb 9th, 06, 7:49 PM
Johnny O Johnny O is offline
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Default Re: 454 to 496: Which block? 1pc vs. 2pc main seal?

Matt....I built my stroker last summer. I went with a Mk IV block, 4 bolt. I only used a 4 bolt block, cause my machinist had one available. A 2 bolt block is plenty strong enough for most applications. I had it bored .100, there was plenty there. That gave me 505 cu.in. I went with Scat crank and rods only because my shop will not use any Eagle products, he says the quality control just isnt there. You will get many opinions on this Eagle/Scat controversy. They both sell tons of stuff. Anyway, Im very happy with the results. Dont get hung up on using a newer block when you can get a Mk IV for lots less. Just have it checked out before you invest money. I have built several big blocks, and have never once had a two piece rear seal leak. John
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  #9  
Old Feb 9th, 06, 9:55 PM
ratengine ratengine is offline
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Cool Re: 454 to 496: Which block? 1pc vs. 2pc main seal?

Hi all I just used a Mark VI block they are not by any means weaker all come 4 bolt main and I went .70 over and used a Scat 9000 series 4.25 crank 2 piece rear seal and used adapter Does not leak a drop. Used Eagle 6.385 rods H beams. Note did not have to grind any where on block swallowed the rods and crank with plenty of clerance. Used a gear drive and solid roller .675 lift
By the way even with a .70 bore had plenty of meat left around bores. These blocks also have the taller lifter bosses for the roller lifters. I used the special head gaskets for cheap insurance with my 781 heads they are sold thru napa
auto parts if any one needs the part numbers let me know. I got cheap and assembled the pistons and rods my self with the spiro locks. I took out for a hrad run up to 6700 rpm and have a little light knock above 2000 rpm so moral of my point have machine shop assemble pistons and rods my pins were a little tight on the rods brass bushings.Either block will do I got mine cheap. Good luck Dave
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  #10  
Old Feb 10th, 06, 7:30 AM
tuffss tuffss is offline
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Default Re: 454 to 496: Which block? 1pc vs. 2pc main seal?

Hi Matt, Yeah i bought my block new from an outlet here in Melbourne Australia, GM only ever mention .060" over on their blocks but sometime ago i had a early 2 bolt that was sonic tested & could have taken a .125" thou bore & still have reasonable meat around the cylinders, from what i've heard & read plenty of guy's are running larger than .060" oversize with success. Also depending on finances i intend to use 315cc AFR cyl heads but at this stage not convinced to run a solid roller probably because of all the maintenance issues that go with large solid rollers so i am still a bit of a solid flat tappet fan & recently built a 502 Gen V for a friend using std stroke, factory large port heads with mild port work and early victor manifold with a quite large solid flat tappet 272/280 @50 & that engine made 610hp @6000 & 608ft lb @ 4500 with only 30 degrees total timing knowing that the distributor had 37 degrees in it but we had to finish up on the dyno, needless to say he was real happy & his Camaro is a lot of fun on the street. Hope this is of some help. see ya, Tuffss
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  #11  
Old Feb 10th, 06, 11:12 AM
MillerTime MillerTime is offline
 
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Default Re: 454 to 496: Which block? 1pc vs. 2pc main seal?

Thanks for the advice everyone!

There is a place in my area that is selling Shor Block 496's for $2550. I'm sure it may be cheaper to build one myself, but this looks like all the leg work has been done. Of course it's not a Gen VI, but does it seem like an ok deal?


http://cgi.ebay.com/ebaymotors/CHEVY...10687002QQrdZ1

Thanks again, I'm sure I'll be back with Head questions.

Matt
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  #12  
Old Feb 10th, 06, 11:54 AM
Schurkey Schurkey is offline
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Default Re: 454 to 496: Which block? 1pc vs. 2pc main seal?

Be very careful. They advertise that they use CAT crank and rods...
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  #13  
Old Feb 10th, 06, 5:06 PM
Johnny O Johnny O is offline
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Default Re: 454 to 496: Which block? 1pc vs. 2pc main seal?

I agree with Schurkey....Cat crank?? I have seen them only on Ebay, no where else. They are really low priced, and lets face it, you still get what you pay for.
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  #14  
Old Feb 10th, 06, 6:59 PM
Davec43 Davec43 is offline
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Default Re: 454 to 496: Which block? 1pc vs. 2pc main seal?

Talk to mike he can give you a deal on a rotating assembly. I'm a firm believer in doing things once and this dosnt have a warranty and do you know the seller?
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  #15  
Old Feb 11th, 06, 9:56 AM
Whittaker Whittaker is offline
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Default Re: 454 to 496: Which block? 1pc vs. 2pc main seal?

I bought my Eagle stroker kit from Jegs it was suppossed to be balanced but I never double checked. It also had the clearance issue at the bottom of a few bores. I would now probably lean towards Scat. They also have cast crank stuff for lower priced 496s. If you are not spraying it or really pushing the power limits of one. If I had not had a 454 all ready I would have gone with a Gen VI motor that a local yard had for $700. It had the stock Vortec heads but it would have had the roller lifter set up as well and being a 4 bolt block. Not that my 2 bolt studded block isn't fine. Check with local machine shops for stuff. I have gotten a few good deals from the local shop on stuff he kept that people never paid for or didn't use. I found that Gen VI engine on http://car-part.com/ .

I am also in the middle of swapping in a hyd roller cam into my Mark IV block and it is not cheap. But always wanted to do it so what the heck.
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