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427 tall deck help

General engine tech -- Drag Racing to Circle Track

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PFC 1
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427 tall deck help

Post by PFC 1 »

Hi, new to the forumand looking for some advice. I've been doing some research here and other places on building a 427 tall deck motor. My son and I will be using it in a classic truck build so we're not going racing but we are looking for some ground thumping torque and moderate HP. We have a line on a cheap engine that's been sitting for a while so we thought it would be a good candidate. The heads will be replaced, they are obviously a drawback, intake and maybe FI instead of a carb......maybe. I've read that the blocks and cranks are heavy duty if they are in good condition but the rods and pistons are in question? 400 plus HP would be a decent target, building on a budget. Anyone have any suggestions, they would be appreciated.

Thanks Paul
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Re: 427 tall deck help

Post by Schurkey »

The OEM pistons are tall, heavy, and have four rings instead of the more usual three. They're a waste of effort. Don't even consider using them. You can use all sorts of different combinations of piston, rod length, and stroke to make normal 3-ring pistons work. When it was GM doing the mods to the tall-deck in the late '60s--early '70s, they used a 4.25 stroke crank, 6.405 rods, and ordinary 454 pistons. That's not the hot set-up any more.






Buy a dedicated tall-deck intake manifold so you don't have to dick with manifold spacers and slip-collar distributors.
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Re: 427 tall deck help

Post by ProPower engines »

With all the parts on the market today and the wide number of choices scrap the tall deck idea.
Back in the day that was the way to go but not now.
You can get a rotating assemble and make you common short deck 427 or 454 into a smooth idling 600 HP cruiser
for much less time and cost then doing a tall deck.

The largest crank that will fit is a 4.750" stroke and with some grinding. Remember next is the rod length issue and then custom pistons and a funky intake. Yes spacers can be had but regardless a dedicated intake is also out there and the whole build is costly.
Even if it is a 4 bolt block so what. Big old 2 bolt will do just fine. And less aggravation!
And with taller comes wider so exhaust is a nightmare as well cause its up higher in the chassis and further towards the out side of the engine bay closer to the frame. Yup custom headers can be made if you have the talent and all that time.
Purpose off the shelf stuff is easier and fit better based on application and build requirements.
I have done many builds over the years and every engine has its problems to over come regardless so if its a balls out boosted race deal then fine do it but for a fun to run N/A street project............don't do it! [-X

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Re: 427 tall deck help

Post by FC-Pilot »

When you say budget what are you thinking for the actual Budget? If I wanted a budget bbc engine that made good solid torque I might start with a late model 454 (gen 6). They are four bolt main and it’s cast crank and rods would do just fine in a well built “torquie” truck engine. You can use the factory roller lifter setup and with a good cam and have well over 550 lb/ft of torque and close to the same hp if matched to a good head. If you used the factory heads you could save more cash but loose some power. But honestly, 500+ of torque could still be within reach.

So now, the question is how much are you looking at spending?

I am also I the camp of “skip the tall deck” as it will cost you more in the long run.

Paul
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Re: 427 tall deck help

Post by Little Mouse »

How is it having to spend $600.00 plus for a new crankshaft and buying another block saves him money. Assuming the 427 steel crank in good shape just buy some 6.535 rods SIR around $300.00 and new standard deck 427 pistons you don't even need forged pistons for 400 hp.. Stock heads no problem only wanting 400 hp less the 1 hp per cube. Hell even the stock intake manifold, carb, dist. could do the job. 427 with a decent tq converter for that low gear tq will do the job.
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Re: 427 tall deck help

Post by racear2865 »

This will show my age. Ive built many tall deck 427 blocks. They are not a expensive project. Most Ive built are 4.250 stroke for approx 496 C.I.. The next is 4.375 stroke works real well but has to be clearanced a little bit. Do not attempt a 4.5. Yes it can be done but chances are u will hit into the oil galley on drivers side. Ive never seen a 4.750 in one but I would like to see it. We bore them .060 to help head breath but although I have bored several .090. Adding a slightly longer rod does not cost any more money unless u wanted to use stock rods and I wouldnt do that any time. A standard shelp piston will fit. Just use a slip collar on distributor. Ive turned down many stock distributors and got $10 slip collar from Jegs. The adapter plates are not bad at all to install but all to their own and u can purchase a tall deck intake. Again not expensive. I have one here in the shop now.
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Re: 427 tall deck help

Post by lefty o »

a half decent set of modern pistons, and a decent little cam will easily exceed his goals. no need for fancy stuff. 400+hp out of 427 inches just doest require much. #-o
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Re: 427 tall deck help

Post by PRH »

Use +.400 rods....... then proceed as you would if it weren’t a tall deck.
Somewhat handy with a die grinder.
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Re: 427 tall deck help

Post by piston guy »

There is a tall deck ( marine) rectangular port , aluminum GM intake for this application usually fairly cheap at swap meets
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Re: 427 tall deck help

Post by pdq67 »

I personally like my 496", but a tall deck block should bore to 4.375",, sonic check to be sure.

Add a 4.375" crank and you make like a 526" engine..

I really like a 598" low deck engine, 4.6" x 4.5" jobber...

Rod ratio isn't all that bad and you can say it is a stock 396!!!

This big an engine and I will not have to rpm it...

And again, if I don't feel that I have enough power, then I will blow it...

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Re: 427 tall deck help

Post by ProPower engines »

Little Mouse wrote: Fri Oct 09, 2020 8:56 am How is it having to spend $600.00 plus for a new crankshaft and buying another block saves him money. Assuming the 427 steel crank in good shape just buy some 6.535 rods SIR around $300.00 and new standard deck 427 pistons you don't even need forged pistons for 400 hp.. Stock heads no problem only wanting 400 hp less the 1 hp per cube. Hell even the stock intake manifold, carb, dist. could do the job. 427 with a decent tq converter for that low gear tq will do the job.
The OP has to buy the core to start with. No savings there compared to a easier to find 454 core.
Less time trying to find old obsolete parts and everything is just less money all the way around and less work.
Yes it can be done. Been there many times but I would trade a 4" stroke 454 for a 3.760 TD 427 any day for a build he has described.
It would fit a chassis better and have more then enough power for what he wants and be half the cost.
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Re: 427 tall deck help

Post by PRH »

Sure, I’d rather have a std deck 454 core too.

It might come down to how cheap and easy one is to come by in the area where the OP lives.
Somewhat handy with a die grinder.
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Re: 427 tall deck help

Post by PFC 1 »

Well obviously I have come to right place for information, thank you all for your replies. How much money do we want to spend?, not sure but enough that it will run well. If the crank is good, it sounds like rods and pistons will be the most economical combo plus all the rest. We are not concerned with space because it will be going in a older truck. We are not looking for a super stroker motor, just a solid big block that will take us cruising into the sunset and have some fun building it as well.......that's the best part :)
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Re: 427 tall deck help

Post by Little Mouse »

ProPower engines wrote: Fri Oct 09, 2020 3:27 pm
Little Mouse wrote: Fri Oct 09, 2020 8:56 am How is it having to spend $600.00 plus for a new crankshaft and buying another block saves him money. Assuming the 427 steel crank in good shape just buy some 6.535 rods SIR around $300.00 and new standard deck 427 pistons you don't even need forged pistons for 400 hp.. Stock heads no problem only wanting 400 hp less the 1 hp per cube. Hell even the stock intake manifold, carb, dist. could do the job. 427 with a decent tq converter for that low gear tq will do the job.
The OP has to buy the core to start with. No savings there compared to a easier to find 454 core.
Less time trying to find old obsolete parts and everything is just less money all the way around and less work.
Yes it can be done. Been there many times but I would trade a 4" stroke 454 for a 3.760 TD 427 any day for a build he has described.
It would fit a chassis better and have more then enough power for what he wants and be half the cost.
JMO
Sure there were gillions of two bolt 454s put in pickups can be bought and makes no difference on the caps at power level he wants. But then 4 bolt standard deck blocks generally not cheap. He said what sounded like he had a cheap buy on a complete truck engine lying around. Already a steel crank in it and 4 bolt mains and putting it in a pickup has plenty of room for anything he wants. No reason for a bunch of expensive parts needed at 400 hp or settling for a cast iron crank pickup engine because of a .400 taller deck. If the engine is all there it will easly do what he needs to do with nothing more then a modern flat tappet cam change.
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Re: 427 tall deck help

Post by ProPower engines »

I see guys want ridiculous money for a tall deck block where a std. deck block can be had for lass then half the money.
He already has 781 heads and to get the comp. up to 9.5-1 for reg. pump gas it would cost less over all.
Sure same bore as a 454 but much shorter stroke == more cost just to get the squeeze up to snuff.

We sell them all the time out of our wrecking yard and guys pay a premium for doing race stuff but any
hot rodder that wants a basic BBC will go std. deck purely because of cost.
Yes you can scrounge used hard to get stuff to make it run but from a purely KISS situation the std deck is easier and cheaper.
Hell you can use a GM dimple rod and regular LS-6 copy .100 dome Hyper piston and be at 9-5.
Cast crank will live at 450 HP for ever intakes and distributors are a dime a dozen. No bastard length/type pushrods like the tall decks use. And off the shelf headers are an issue with the taller and wider locations. Then theres the water pump thats a bastard piece and the pulleys and balancer again spaced totally wrong and too far towards the rad so no stock brackets line up and the PS pump is fun as well.
Having put tall deck engines in various trucks for customers its not as easy as it appears .
Really its up to the OP to decide what he wants. And based on all the suggestions he's a big boy so he can decide himself.
But I think cost is the biggest concern for him

JMO
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