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Old 04-10-2018, 06:35 PM
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427 Tall Deck Block

Few years down the road i'd like to drop a BBC in a drag car. Have a line on a tall deck 427 at a sweet sweet price. Freshly machined, magnufluxed, .030 over. From what i've read the biggest difference between the tall deck and short deck is the tall deck is .040 taller in deck height, uses 4 piston rings, and around 60lbs. heavier than the standard deck. My question is if i shaved the deck height on this block .040 or a bit lower for my purposes, i figure this could make a respectable race motor with no intake or distributor problems. Am i correct in that statement? Thanks!

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Old 04-10-2018, 08:35 PM
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Only problem is you’re off a decimal point.
Deck height difference is .40 of an inch. Not .040 of an inch.
Tall block is 10.2 inches.
Standard block is 9.8 inches.
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Old 04-10-2018, 08:41 PM
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You're not correct in the block height difference, it isn't .040" taller, it is .400" taller, more than 3/8" taller than you're thinking it is. You can't mill that much off without making the block deck so weak it won't stay flat and hold a gasket seal.

With that said, lots of guys have used these blocks to make race engines, usually with a longer stroke crank, longer than stock rods and then a conventional 3 ring piston, taking advantage of that extra deck height to get that long rod advantage on a stroker crank.

They need either a dedicated tall deck intake, or spacer plates for use with a standard width intake, and the taller deck requires a distributor either made for the tall deck or one that has an adjustable height slip collar. slip collars are available separately, and a standard distributor can have the stock mounting collar machined off and replaced with the slip adjustable type. Header fit can sometimes be a problem as the exhaust ports are now up higher and slightly wiser apart in the engine bay...depends on header brand and tube size.

Extensive use of the tall deck factory block has somewhat fallen out of favor now that aftermarket blocks with thicker cylinder walls and the bigger 4.460"+ "502" blocks are available.
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Old 04-11-2018, 04:13 PM
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Appreciate the feedback.

Did get a chance to do some more research on the 427 tall deck. I've read those blocks are actually preferred for stroking. I get what you're saying on the distributor which makes sense. Few questions:

1. As for the header clearances.....i assume they make headers out there that would accommodate the 427 TB. Do you have any recommendations on brand or type i'd need to look into.

2. Intake Manifold- Just guessing but doubt there's a ton of TD manifolds on the market. If i was to go the standard deck route and use spacers, what's your experience in using spacers? First thing that came to my mind was longer bolts needed and fear of leaks.

Thanks!

RD
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Old 04-11-2018, 08:05 PM
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As far as I know, not a lot of options on headers if you don't have the space to pull a standard set up a little higher and wider without hitting something in the chassis and steering....the only folks I know using tall deck blocks both have had custom headers built for their car with the tall deck block installed during the fab phase. Header fit is one of the reasons tall deck wasn't more popular than it is.

On the manifold, there are only a few performance intake made specific for the tall deck. All ore BIG single planes - Edelbrock Victor, ProFiler Sniper, Brodix, Dart....no dual planes that I know of.
Brodix has 6 or 7 different single plane Dominator flange manifolds for all the different port location heads they have.

On the intake spacers, they can be just set in place and glued to the head, but most times I've seen them they are either bolted to the head or bolted to the intake using a pair of countersunk head allen cap screws(like a wood screw but with 1/4"-20 machine threads), drilled and tapped into an area on the flange that won't interfere with the regular bolt pattern. Then just longer bolts in the normal holes. Some also have end china wall spacers too, but you may have to make those from scrap aluminum yourself. These are typically screwed on the same way, countersunk flat head allen screws.

B&B Performance, Moroso, Dart, Weiand, RHS, and Brodix all have spacer plate kits.

Pushrods of course are going to be longer too.
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Old 04-11-2018, 08:28 PM
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Quote:
Originally Posted by ericnova72 View Post
As far as I know, not a lot of options on headers if you don't have the space to pull a standard set up a little higher and wider without hitting something in the chassis and steering....the only folks I know using tall deck blocks both have had custom headers built for their car with the tall deck block installed during the fab phase. Header fit is one of the reasons tall deck wasn't more popular than it is.

On the manifold, there are only a few performance intake made specific for the tall deck. All ore BIG single planes - Edelbrock Victor, ProFiler Sniper, Brodix, Dart....no dual planes that I know of.
Brodix has 6 or 7 different single plane Dominator flange manifolds for all the different port location heads they have.

On the intake spacers, they can be just set in place and glued to the head, but most times I've seen them they are either bolted to the head or bolted to the intake using a pair of countersunk head allen cap screws(like a wood screw but with 1/4"-20 machine threads), drilled and tapped into an area on the flange that won't interfere with the regular bolt pattern. Then just longer bolts in the normal holes. Some also have end china wall spacers too, but you may have to make those from scrap aluminum yourself. These are typically screwed on the same way, countersunk flat head allen screws.

B&B Performance, Moroso, Dart, Weiand, RHS, and Brodix all have spacer plate kits.

Pushrods of course are going to be longer too.
Thanks for the insights Nova. As to the manifold, i'd be ok there it seems as if i purchase this block, it'd be stroked out for drag racing only so a big single plane is what I'd be getting anyhow which would eliminate me having to go spacer route with a stand. deck intake. Guess my burden to bear would be the headers. I hate fooling with them. The car this block would go in a few years down the road would be in my 72 drag car. I run a stout 383 in it w/hookers. its already tight and a PIA just with the small block. BUT, the price on this 427 ($300) that's freshly machined with allegedly no cracks is hard for me to pass up...
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Old 04-12-2018, 07:51 AM
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Any idea as to it year? GM ran these through 1997. They had the 7.0/427 and the 6.0/366.
Then they dropped them for the medium duty GEN 6 L21 454 with roller cam Coil Near Plug ignition, Electronic Throttle Control and the 24x reluctor.
Then the L18 8.1 GEN VII took over in 01 in the medium duty apps.

Anyone know if the later tall deck truck 427/366 had the OEM roller cam?


Remember that the 2000-2010 GEN VII(7) 496/8.1 BBC was a tall deck engine and came stock with a 4.37" crank. Drop that into your 427 block.


GM now offers that tall deck 488 cube (8.0 liter)BBC engine
Part Number: 19328586
Engine Type: Chevy Big-Block V-8
Displacement (Litre): 8.0L
Displacement (cu in): 488
Bore x Stroke (in): 4.270 x 4.250
Block (P/N 19256820): Tall deck (10.2")

The GM forged steel crank with its 4.250 stroke is Crankshaft (P/N 19300876)for the 8.0/488 BBC..

That engines uses a high resolution 58x crank reluctor and 4x cam reluctor so it can use the more modern ECMs for control.


peace
Hog
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Old 04-12-2018, 04:54 PM
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Quote:
Originally Posted by Hogg View Post
Then the L18 8.1 GEN VII took over in 01 in the medium duty apps.

Hog
When is someone going to make a rod that will withstand what this block will take? I've got a line on a couple of these, but the word is that the rods will not take 800HP. With a decent rod it could be a budget (borderline) big block capable of 1200+ reliably.
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Old 04-12-2018, 05:33 PM
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Quote:
Originally Posted by 64nailhead View Post
When is someone going to make a rod that will withstand what this block will take? I've got a line on a couple of these, but the word is that the rods will not take 800HP. With a decent rod it could be a budget (borderline) big block capable of 1200+ reliably.
I agree with what you're saying.

My thoughts are that a lot of fellows pass on these blocks unless they are going to stroke and race them. Even then some frown. But i've seen plenty of others speak to the plus side of using them. You just don't see 427s, let alone a TD, come on the market very often on CraigsList, at least around here you don't. I want to stroke and race it a few years down the road when i've had my fill of the 383 or it blows up which ever comes first! I won't be hitting the 800 HP mark but my plans won't be too terribly far below that HP mark either when i purchase the block on sat. Block is a 74' based upon Sellers post as well as my numbers run on it. I like to stick to old GM iron for budget reasons until or until i get burned for using these old blocks. A 427 at $300 asking price is just hard for me to let go. I'll have to drive 2-2.5 hours to the sellers house but even if i opted not to use it down the road, i'm pretty dog gone sure i could get my $ back, if not a small profit.
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Old 04-14-2018, 04:01 PM
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Went ahead and bought the 427 tall deck today. Greased it down for storing over the next year or two. Seller was a real cool guy too who's retiring after 35 years of building show cars for the most part. He also gave me an engine stand free of charge

Anyone see any problems with throwing a 4.50 crank in the 427 TD? I figure a 4.25 is any easy fit with little grinding involved but was curious if anyone had experience, thoughts, or advice on putting a 4.50 in it at some point....
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Old 04-14-2018, 05:11 PM
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You made out good... even a free paint job and stable 4 caster engine stand...
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Old 04-14-2018, 07:01 PM
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While I haven't done it, I believe the 4.375" stroke is about the biggest stroke you should consider in a non-aftermarket block, and even then that can be risky too.

Reason is you've got that pesky main oil passage that is buried in the driver side oil pan rail....hit that while grinding and now you've got a large piece of cast iron scrap.
If you grind through, your only hope of saving it is to drill, ream and sleeve the passage, requiring an expensive drill bit and reamer(because of length) and a rethink on your stroke length, you'd have to go to a smaller stroke since you would have to clear that exposed section of sleeved oil passage with no more grinding..
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Old 04-16-2018, 07:50 PM
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Quote:
Originally Posted by rdobbs77 View Post
Went ahead and bought the 427 tall deck today. Greased it down for storing over the next year or two. Seller was a real cool guy too who's retiring after 35 years of building show cars for the most part. He also gave me an engine stand free of charge

Anyone see any problems with throwing a 4.50 crank in the 427 TD? I figure a 4.25 is any easy fit with little grinding involved but was curious if anyone had experience, thoughts, or advice on putting a 4.50 in it at some point....
They make good 540 cu in motors.
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