Tall Deck 427

[66lemans]

Alright, here is another question for yall. I can get a 4-bolt 427 block for 200, std bore. I know that a 427 and a 454 are the same block, but what is the deal with a tall deck. I would have to get longer rods to have decent compression right, but if I did that wouldnt that limit how much I could turn it up? Also i hear the intake is wider, does that mean a regular set of heads wont fit? How bad of clearance problems would I have? Thanks again for any and all help guys. Steve

[techinspector1]

The tall deck block is 0.400" taller measured from the centerline of the main bearing bore to the surface of the block deck. Use rods that are 6.535" instead of 6.135", then just use the proper piston for the crank, 427 or 454.

Several companies make spacer plates that sandwich between the heads and the intake manifold, allowing you to run a standard big block manifold. Use any big block Chevy head.

[76GMC1500]

Tall deck blocks are worth considering. They all came with forged cranks but used short rods to make room for 4 piston rings. You can use longer rods with the stock crank and some normal pistons to make a very torquey engine. You can also use the rods that came with the block and a stroker crank with some normal pistons to make a very torquey very large displacement engine. It is the same block that GM uses to make the 572. Normal intake manifolds will not fit, but there are many manifolds for tall deck blocks available as well as adapters.

[66lemans]

O.K. how bout all the pulley's, and brackets, etc., will they all bolt right on? And Does any one know exactly how much wider it is at the exhaust ports?

[76GMC1500]

Didn't think about pullies. There will be no difference with the actual pullies, but the belts may have to be slightly longer if you have accessories bolted to the heads.

[pat mccarthy]

my 66 gto has a 10.200 tall deck donovan in it what do you need to know have put 3 tall decks in 66 gtos

[BLOWN 502 MONTE]

Thats gonna be my next motor, tall deck chevy with about a 4.5" bore and a 4.750 stroke crank if memory serves me right that would put me somewhere around 600 cubes...yeah thats the next motor im building. if you can pick up a tall deck block for 200 bucks your getting a decent deal....

[66lemans]

Pat, that is great to know, although I knew you had a 66, didnt know you had put a tall deck in them. My question is now is will I have any major clearance issues to deal with. I have a big block 396 now, and the headers are pretty tight now. I was wondering how it will be when I put in a tall deck block if were to go that route. any help is appreciated, thanks, Steve.

[pat mccarthy]

yes header will be a problem and if you use a after market head it dose not help some ex ports are 3/4 hi and things get in the way like the steering shaft you will have to cut it down and use u joints and make a set of headers and make a new alt brakets this is not to bad but it is time and money a good built 396 will out run a stock tall deck . here are some things to think about you need a msd or cut a distributor for a slip collar if you use a stock deck type intake with plates if you use tall deck intake some are cut down for a stock distributor .i can not recommend this for a stock type 427 talldeck .but if you want a big engine this is the type of block you will have to use you can get 526 out of the stock block and some more but the wall will get thin. i could write a book on all the things i had to do to get the tall deck to fit in the gto s I did this so i could put a 572 big block in them and now i have a 630+ in the one i drive on the street this is a lot of work but it can be done .if you want more cubes than a 526 you need tall deck bow tie or world or dart . the donovan is what i use but to put a bigger engine in you need a bigger oil pan and then you have to cut the front cross to get room for pan and you have to move the center link and make new pitman arm and idl arm or put a rack in i had to make my oil pan for my donovan i had to make a lot of stuff so you need a small michine shop and a tig and a mig welder would help

['68LT1Camaro]

What's the biggest stroke you can do in one of these 427TD blocks? Can you cram a 4.5" stroke crank in one? Thanks guys.

Raymond

[pat mccarthy]

yes i have done a 4.500 in the stock 427 truck block

[pat mccarthy]

yes i have done a 4.500 in the stock 427 truck block

['68LT1Camaro]

Hey Pat, thanks for the reply!

It looks like your the only one on this forum to build this bore/stroke combo with a 427TD block. I've got some questions for you if you don't mind helping me out. I could really use your advice, and would greatly appreciate it. Thanks!


1) Does any clearancing need to be done to the block to fit a crank this big? (4.50" stroke)

2) Was this your motor, or was it a build you did for someone else?

3) Can you give some pro's and con's that you've experienced with this motor?

4) So how well did you like this motor once you got it running in a vehicle?

5) Any reliability, or overheating issues?

6) Could you tell me which heads and cam you used on this motor, and how much power it made?

7) How high were you able to rev it?

Thanks Pat!

Raymond

[pat mccarthy]

Originally posted by pat mccarthy
yes i have done a 4.500 in the stock 427 truck block

the engine was for a customer and it was for a air boat the block need some work on the bottom of the block but not alot i use a 400 longer h beam rods and a srp pistons it was bored to 4.310 0.60 over the block was a new block before the one pices rear main seal blocks mark 5 and6 and had some clearance in the block from gm if you have and old block this may not be the same. i use a mildon pan and it worked out of the box .the heads were edelbrocks rpm the intake was a air gap the cam was a howards hyd roller 577/576 222/234 at0.50 i think and was 10 to 1 cr no dyno time on this engine it would have been nice but it did not happen .the customer is very happy and it was not built for hi rpm max rpm was6500 it dose most of its work at 2500 rpms any more questions on this tall deck build you can ask me. but a lot of this stuff is on old threads this may help you .would i build the same thing ?yes. how much rpms will it take ? this has a lot to do with cam the bottom ends are rock soild on big block chevys i do not know what you are putting this in but the add deck can be a pain and custom headers will be needed

['68LT1Camaro]

I plan on building this motor for my '68 Camaro. This car was a daily driver with a 355 cubic inch supercharged LT1, T56 6-speed tranny, and a 3.73 8.2" 10-bolt rear end.

Due to current gas prices, it's not realistic to use this as a daily driver anymore. Now that the Camaro will only be driven ocasionally, and on weekends, I've decided to put a real motor in it. I will ditch the T56 in favor of a 4L80(non electronic) with a manual valve body and trans-brake. I'm undecided on a 12-bolt or a 9" for the rearend.

I believe I read somewhere else that it would require hammering a few spots on the headers if you were to use a TD block.

Is it as simple as that? How bad would I need to beat up the primaries for clearance? Will collector clearance against the floor board give me any trouble?


Thanks.

Raymond