427 questions - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Bayouboy · 02-12-2005, 12:10 AM

Hey guys I haven't posted in a while, but its come time to start the buildup of my engine. My question is I have the oppurtunity to buy a 427 out of a flat bed truck. I am guessing its a tall deck, but I have no clue. If it is would it be worth putting it in my 72 and what would have to be done to get it hotrodable and what would have to be done to put it in. Thanks

GMC1tondually4dr · 02-12-2005, 01:19 AM

The tall deck (10.20" centerline of crank to deck) block is identical to the short deck (9.80" cl. crank to deck) block. The tall deck is that way because GM put a 4 ring piston in it.

Everything else is the same, pan, heads manifold, waterpump, everything external and internal.

All tall decks have 4bolt mains and usually have very thick cylinder walls. You may get the cylinder walls sonic checked, very often the will allow a very large overbore. Our race car has a .125" over bore and the machinist said that it could go to a 4.44" bore. very thick walls!!

When you build a tall deck for the street, the decks are .400" taller which puts the cylinder heads further apart, (the short deck manifold will not fit unless you put tall deck spacers on,these are available from the aftermarket.) and higher in the chassis. The cylinder heads are higher in the chassis. You may be able to fit regular headers or manifolds in. It's a try it deal.

The crankshaft is the same tall vs short deck. 454- 4.00", 427- 3.76"
you must make the .400" up with a longer connecting rod and the correct compression height piston. This can be done with a 5.385 center to center
connecting rod. They are available from numerous places, Scat has a stock type rod .400" long that is made out of 4340 material, and it is less than $300.00. Ohio crankshaft also make a 4340 rod that is 6.385 I think that it is less than $200.00. SRP makes a number of pistons that fit this combination.
KB and I think TRW/Speed pro have a hyperutectic piston that is really cheap
(less than $300.00?)

Or put an aftermarket crank and the correct rod /piston combination in it for street use or track use.

Do not be afraid of this combination, just call a piston and /or crank shaft manufacturer and ask them about your combination.

I run a tall deck engine in my drag race altered. I have a somewhat stock crank and .400" long Bill Miller rods 6.385" cl to cl.
493" 750hp @ 7000rpm, 633ft/lbs. of torque @ 5800 rpm.
Car weighs 1800# wet with my son in it. 8.28 @ 164 and change. That was with the wrong gears (4:56 have 4:10 in now)) leaving on a 5,000 rpm chip, should leave at 5,800 and the single carb on a mechanical throttle stop.
This was the first car my son had driven at the drag strip!!!

I may be putting a tall deck block in my CCDually that tows my race stuff.
If I do I will go .100 over which ends up at 505" with a 4.25" Scat cast crank.

Can you say stump puller!!!!

It isn't that hard to over come the small stuff you may encounter.
If you can't fab stuff it, is available aftermarket

If you don't want or need the tall deck block I am always looking for TD BBC's

Sorry to be so long winded, but I didn't want you to take advice that has no experience behind it.

Yes to putting it in a '72PU, if it would fit,(most likely) and if it's cheap!!!
It would be a torque monster!!

Just my .02

CCDually

4x4Poet · 02-12-2005, 02:41 AM

Great info, GMC1tondually4dr.

I very much appreciate the detailed info because I'm considering swapping a tall-deck 427 in my K20 Burb. I only envision two drawbacks: Firewall fit and mpg. Don't be surprised if some months from now I pester you with a pm containing some questions I couldn't resolve on my own.

And zoom, zoom on the 8-second drag car.

LONGHAIR · 02-12-2005, 06:57 AM

I believe that is 6.385" rod length.

1976Scottsdale · 02-12-2005, 09:28 AM

My dad is about to begin to rebuild his old 427 tall deck. He stuffed it into a 1967 Chevelle SS with a 4.11 rearend and a muncie rockcrusher 4spd. He an that for a very long time, then he found a 327 375 horse factory engine and ran that until he pu the car in cold storage( a friends barn 20 years ago). We got word yesterday that his friends dad had passed on and that the car and 427 were still sitting in that barn, untouched for the last 20 years, as was a 66 chevelle SS with a 454 4 bolt. Dad owns the 67 and I am going to try to buy the 66 to build for the next few years. The 427 was indeed a monster according to my dad.

Mike76251 · 02-12-2005, 10:57 AM

I love the truck 427's because some people just want the easiest route to power and avoid the tall decks.
This makes those tall decks cheap and they are some of the best engines (short of $$$$ Bow Tie blocks) that Chevy ever made.
You can score cheap tall deck stuff off eBay if you got the time.
I scored a tall deck 427 block for $75 off there but let it go for more $$.

GMC1tondually4dr · 02-12-2005, 02:45 PM

Thanks LONGHAIR, it was a brain fart!

6.135 is stock, 6.385 for a 4.25" crank, and 6.585 is .400 long..........and up from there.

Just my.02

CCDually

Bayouboy · 02-13-2005, 03:25 PM

I dunno I have a 350 block right now I thought about turning it into a 383. The guy gave it to me a while back said it came out of a 95 pickup. Is there any sure fire way to tell if its got a roller cam? Also what kind of machine work would have to be done to turn it into a 383 if I bought a rotating assembly? Thanks

GMC1tondually4dr · 02-13-2005, 05:57 PM

Pull the intake and see if you have roller lifters. Think a '95 would be a hydraulic roller cam. I could be wrong. (my wife says I am all the time.)

You can get rotating assemblies from all the mail order houses and a street one would not be that expen$ive.
The cast 3.75" cranks come in a two piece or a late model one piece seal.

If you use the 400 block stock rods, (shorter than a 5.70", 350 rod) there will be no machine work needed on the 350 block.
If you use the 5.70" rod you may need some clearancing on the big end on the sides of the block.
Check the clearance on the top of the big end where the cam lobes come close to the con rod.

A quality machine shop can tell you exactly what to do.

This is one of the most popular swaps in the history of the small block. It seems everyone does it, and it is easy and inexpensive too.

Machine work depends on if you do any additional work, block blueprint, overbore, ect.

Just my .02

CCDually

Mike76251 · 02-13-2005, 07:10 PM

Look to see if the block has three bosses for this retainer spider,

02-12-2005, 12:10 AM	#1
Bayouboy Registered User Join Date: Oct 2004 Location: Kennesaw GA Posts: 44	427 questions Hey guys I haven't posted in a while, but its come time to start the buildup of my engine. My question is I have the oppurtunity to buy a 427 out of a flat bed truck. I am guessing its a tall deck, but I have no clue. If it is would it be worth putting it in my 72 and what would have to be done to get it hotrodable and what would have to be done to put it in. Thanks __________________ 72 long wheelbase Stock 350/th350 hugger orange

02-12-2005, 01:19 AM	#2
GMC1tondually4dr Registered User Join Date: Jun 2004 Location: Rosemount, MN Posts: 341	The tall deck (10.20" centerline of crank to deck) block is identical to the short deck (9.80" cl. crank to deck) block. The tall deck is that way because GM put a 4 ring piston in it. Everything else is the same, pan, heads manifold, waterpump, everything external and internal. All tall decks have 4bolt mains and usually have very thick cylinder walls. You may get the cylinder walls sonic checked, very often the will allow a very large overbore. Our race car has a .125" over bore and the machinist said that it could go to a 4.44" bore. very thick walls!! When you build a tall deck for the street, the decks are .400" taller which puts the cylinder heads further apart, (the short deck manifold will not fit unless you put tall deck spacers on,these are available from the aftermarket.) and higher in the chassis. The cylinder heads are higher in the chassis. You may be able to fit regular headers or manifolds in. It's a try it deal. The crankshaft is the same tall vs short deck. 454- 4.00", 427- 3.76" you must make the .400" up with a longer connecting rod and the correct compression height piston. This can be done with a 5.385 center to center connecting rod. They are available from numerous places, Scat has a stock type rod .400" long that is made out of 4340 material, and it is less than $300.00. Ohio crankshaft also make a 4340 rod that is 6.385 I think that it is less than $200.00. SRP makes a number of pistons that fit this combination. KB and I think TRW/Speed pro have a hyperutectic piston that is really cheap (less than $300.00?) Or put an aftermarket crank and the correct rod /piston combination in it for street use or track use. Do not be afraid of this combination, just call a piston and /or crank shaft manufacturer and ask them about your combination. I run a tall deck engine in my drag race altered. I have a somewhat stock crank and .400" long Bill Miller rods 6.385" cl to cl. 493" 750hp @ 7000rpm, 633ft/lbs. of torque @ 5800 rpm. Car weighs 1800# wet with my son in it. 8.28 @ 164 and change. That was with the wrong gears (4:56 have 4:10 in now)) leaving on a 5,000 rpm chip, should leave at 5,800 and the single carb on a mechanical throttle stop. This was the first car my son had driven at the drag strip!!! I may be putting a tall deck block in my CCDually that tows my race stuff. If I do I will go .100 over which ends up at 505" with a 4.25" Scat cast crank. Can you say stump puller!!!! It isn't that hard to over come the small stuff you may encounter. If you can't fab stuff it, is available aftermarket If you don't want or need the tall deck block I am always looking for TD BBC's Sorry to be so long winded, but I didn't want you to take advice that has no experience behind it. Yes to putting it in a '72PU, if it would fit,(most likely) and if it's cheap!!! It would be a torque monster!! Just my .02 CCDually Last edited by GMC1tondually4dr; 02-12-2005 at 02:43 PM.

02-12-2005, 02:41 AM	#3
4x4Poet Registered User Join Date: Nov 2004 Location: "Under Montana skies." Posts: 1,836	Great info, GMC1tondually4dr. I very much appreciate the detailed info because I'm considering swapping a tall-deck 427 in my K20 Burb. I only envision two drawbacks: Firewall fit and mpg. Don't be surprised if some months from now I pester you with a pm containing some questions I couldn't resolve on my own. And zoom, zoom on the 8-second drag car. __________________ '71 GMC K20 Suburban, '71 GMC K10 Suburban, '72 Chevy C10 CST Suburban, '72 Chevy K20 clunker pickup.

02-12-2005, 02:45 PM	#7
GMC1tondually4dr Registered User Join Date: Jun 2004 Location: Rosemount, MN Posts: 341	Thanks LONGHAIR, it was a brain fart! 6.135 is stock, 6.385 for a 4.25" crank, and 6.585 is .400 long..........and up from there. Just my.02 CCDually Last edited by GMC1tondually4dr; 02-12-2005 at 02:48 PM.

02-13-2005, 03:25 PM	#8
Bayouboy Registered User Join Date: Oct 2004 Location: Kennesaw GA Posts: 44	I dunno I have a 350 block right now I thought about turning it into a 383. The guy gave it to me a while back said it came out of a 95 pickup. Is there any sure fire way to tell if its got a roller cam? Also what kind of machine work would have to be done to turn it into a 383 if I bought a rotating assembly? Thanks __________________ 72 long wheelbase Stock 350/th350 hugger orange

02-12-2005, 06:57 AM	#4
LONGHAIR just can't cover up my redneck Join Date: May 2004 Location: Columbus OH Posts: 11,414	I believe that is 6.385" rod length.

02-12-2005, 09:28 AM	#5
1976Scottsdale Registered User Join Date: Aug 2004 Posts: 76	My dad is about to begin to rebuild his old 427 tall deck. He stuffed it into a 1967 Chevelle SS with a 4.11 rearend and a muncie rockcrusher 4spd. He an that for a very long time, then he found a 327 375 horse factory engine and ran that until he pu the car in cold storage( a friends barn 20 years ago). We got word yesterday that his friends dad had passed on and that the car and 427 were still sitting in that barn, untouched for the last 20 years, as was a 66 chevelle SS with a 454 4 bolt. Dad owns the 67 and I am going to try to buy the 66 to build for the next few years. The 427 was indeed a monster according to my dad.

02-12-2005, 10:57 AM	#6
Mike76251 Senior Member Join Date: Mar 2003 Posts: 2,499	I love the truck 427's because some people just want the easiest route to power and avoid the tall decks. This makes those tall decks cheap and they are some of the best engines (short of $$$$ Bow Tie blocks) that Chevy ever made. You can score cheap tall deck stuff off eBay if you got the time. I scored a tall deck 427 block for $75 off there but let it go for more $$.

02-13-2005, 05:57 PM	#9
GMC1tondually4dr Registered User Join Date: Jun 2004 Location: Rosemount, MN Posts: 341	Pull the intake and see if you have roller lifters. Think a '95 would be a hydraulic roller cam. I could be wrong. (my wife says I am all the time.) You can get rotating assemblies from all the mail order houses and a street one would not be that expen$ive. The cast 3.75" cranks come in a two piece or a late model one piece seal. If you use the 400 block stock rods, (shorter than a 5.70", 350 rod) there will be no machine work needed on the 350 block. If you use the 5.70" rod you may need some clearancing on the big end on the sides of the block. Check the clearance on the top of the big end where the cam lobes come close to the con rod. A quality machine shop can tell you exactly what to do. This is one of the most popular swaps in the history of the small block. It seems everyone does it, and it is easy and inexpensive too. Machine work depends on if you do any additional work, block blueprint, overbore, ect. Just my .02 CCDually Last edited by GMC1tondually4dr; 02-13-2005 at 05:59 PM.

02-13-2005, 07:10 PM	#10
Mike76251 Senior Member Join Date: Mar 2003 Posts: 2,499	Look to see if the block has three bosses for this retainer spider, Attached Images



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