Thread: 427 tall deck

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I'm going to get a working 427 tall deck from a friend, and i have been looking for performance parts like heads, pistons, intake manifolds, distributors , and i don't know where to look, i understand the tall deck is a truck motor heavy crank lots of torque. so this is why i want to make it a awesome hot rod motor. so if anyone can make suggestions to me or link me to performance pars that will fit this motor it would be very appreciated and any suggestions, comment, and opinions will also be appreciate.

Originally Posted by joede870

I'm going to get a working 427 tall deck from a friend, and i have been looking for performance parts like heads, pistons, intake manifolds, distributors , and i don't know where to look, i understand the tall deck is a truck motor heavy crank lots of torque. so this is why i want to make it a awesome hot rod motor. so if anyone can make suggestions to me or link me to performance pars that will fit this motor it would be very appreciated and any suggestions, comment, and opinions will also be appreciate.

Sorry to burst your bubble, but the tall deck BBC motors were designed to move dump trucks and such, very heavy loads at low speeds. The 4-ring pistons are very heavy and not suitable for hot rodding, so they need to be slung over the fence. The block deck height is 0.400" taller than the production big blocks that were designed for cars and light trucks, so there are no performance manifolds that will fit the heads without using spacer plates, which are not acceptable by many fellows because of their failure to seal up in all applications. The 0.400" taller decks put the heads higher on the block, so that headers may not fit the car/truck like they are supposed to. Speaking of heads, the stock 427T heads were meant to make power up to about 3500 rpm's, so they will not work in a performance application.

Here's a paper build I put together several years ago that may give you a heads-up....
Cheapo BBC 505 tall deck grunt motor - Hot Rod Forum : Hotrodders Bulletin Board


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Well actually---------------use a 454 crank and pistons, get rods that are .400 long (fairly common part), there are manifolds made(Dart) for the tall deck motors except if you want to maybe run dual dominators on tunnel ram use spacer plates--again very common-----use open chamber heads and with raised exhaust ports---------
This was what the combo was in the Monza in my avator pic----

Originally Posted by jerry clayton

Well actually---------------use a 454 crank and pistons, get rods that are .400 long (fairly common part), there are manifolds made(Dart) for the tall deck motors except if you want to maybe run dual dominators on tunnel ram use spacer plates--again very common-----use open chamber heads and with raised exhaust ports---------
This was what the combo was in the Monza in my avator pic----

i was told by some that these engines are useless and are just boat anchors and others tell me that with proper parts they can be made pretty snappy engines. do you think i will be able to make this a fun motor for a car or truck, what kind of hp and torque can i expect with the mods your telling me to do? is there a stroker kit made for these? and i actually am thinking about putting this in a Monza if i can find one for the right price. what kind of performance parts can i buy for this? i was also told if i brought it to a machine shop i could pay them to make this block accept performance heads.

Originally Posted by joede870

I'm going to get a working 427 tall deck from a friend, and i have been looking for performance parts like heads, pistons, intake manifolds, distributors , and i don't know where to look, i understand the tall deck is a truck motor heavy crank lots of torque. so this is why i want to make it a awesome hot rod motor. so if anyone can make suggestions to me or link me to performance pars that will fit this motor it would be very appreciated and any suggestions, comment, and opinions will also be appreciate.

its very common build just a 10.200 deck most all bbc parts can work like heads. intake cranks piston if you use a longer rod . some of the older tall decks did have big O ports and can be reworked. its not hard to get to 540 cid . intake spacers are not a big deal they make them in oval port and rect port and seal up just fine some companys make intakes for 10.200 tall decks .and MSD makes a slip collar dist or make one were you turn off the collar off old dist on a lathe.i done this many times to 9.800 deck distributors buy or make a collar.there many ways to go on crank and rods many big bbc are base off the 10.200 after market deck blocks were it not hard to get to 638 cid built many and some stock blocks to 526 to 540

Originally Posted by pat mccarthy

its very common build just a 10.200 deck most all bbc parts can work like heads. intake cranks piston if you use a longer rod . some of the older tall decks did have big O ports and can be reworked. its not hard to get to 540 cid . intake spacers are not a big deal they make them in oval port and rect port and seal up just fine some companys make intakes for 10.200 tall decks .and MSD makes a slip collar dist or make one were you turn off the collar off old dist on a lathe.i done this many times to 9.800 deck distributors buy or make a collar.there many ways to go on crank and rods many big bbc are base off the 10.200 after market deck blocks were it not hard to get to 638 cid built many and some stock blocks to 526 to 540

now im new to the whole bbc scene i have always worked on sleds and small to mid engine four strokes, but i know it will sound stupid but will any performance head for a bbc work on this motor as long as it is compatible to the pistons?

Yes------------------------






But of course you will need longer pushrods-------------------

what was the output that your monza had?

Ran 8.003/169.98 with 460 cubes, Lenco 4 speed, dual 1150 cnc dominators


Was a 4.280 bore, 4 stroke, venolia 4.280 gas ported pistons, Childs& Alberts alum rods, Howard cam, Chev C exhaust port heads------

Originally Posted by joede870

now im new to the whole bbc scene i have always worked on sleds and small to mid engine four strokes, but i know it will sound stupid but will any performance head for a bbc work on this motor as long as it is compatible to the pistons?

any head that would work on a 396 to502 with std bore spacing block could fit on the 366 and427 tall deck same as the heads on the tall decks will fit on older engines 9.800 decks from 1965 to 1989 or so. if the pistons have dome.s then of coures you must use a piston that will matchs head chamber and valve spark plug location and valve angle some after market heads may move one or all i listed but stock Gm heads you would be ok with just checking for dome to head chamber fitment if stock size valves are used but still need to check piston to valve with big cam . there is many heads to look at . same with pistons what head you use for the CR you want the block 427 tall deck is just that a tall 10.200 deck block with a 4.250 bore four ring piston rods crank heads timming set oil pump . oil pump drive head gasket are much the same as a low HP 427 9.800 deck car /boat engine. heads there AFR . RHS. DART . WORLD .BRODIX .EDELBROCK ,PROFILER, CANFELDS. old pro stock 861 and OLDS PRO GRAM #39// BIG CHIEFS .some other i used as well they all can if the std bore space bbc you have many pistons to used a very long list i used many and have many custom s made as well for the tall deck builds to get what we wanted to fit the job at hand. for rods GM only ever made one size rod that is 6.135 long in this rod there are about 5 forging shapes of this rod some better then others the rods you have could very well be called thumb rods or truck rods having more steel in the fork end/big end. if you use the 6.135 rod the most you could go would be 427 with the 3.765 stockcrank with stock pistons . but if you go with a 400 long rod 6.535 long then you can go to a bigger crank or a 9.800 3 ring pistons many to pick from. to work out what piston you need look to the CDor CH this is the wrist pin to top of the pistons this is called COMPRSSION HEIGHT OR COMPRSSION /DISTANCE . every piston company has this listing this will let you know what pistons you need for the rod and crank you going to use in you build .here one i just did. i wanted a piston for a tall deck so 10.200 and hand a 4.500 stroke so half of the crank stroke is 2.250 rod i used was 6.700 long so add that and sumb the deck and the Cd or Ch would be piston would be a Ch of 1.250 now if the engine was decked or want to deck some build the piston to around .025 less so a piston Ch would be 1.225.0 then you need to see what bore size you can go to stock GM block is about 4.350 max over bore .the longer rod works better allround i like a 400 longer 6.535.or better 6.700 is un common. building a 598cid will use a 4.500 stroke crank and a 6.800 long rod were my piston Cd/Ch is 1.120 so my deck of my block needs to be around 10.170 if i want the piston at O deck or if .010 in the hole then i deck block to 10.180 . some piston Ch for the tall deck numbers areCH 1.645 rod6.535 crank stroke4.000 1.270 for a rod 6.800 crank stroke4.250 ..1.395CH rod 6.535 crank stroke 4.500 ...1.120 CH rod 6700 crank stroke 4.750 ..CH 1.245 rod 6.700crank stroke 4.500 . should fined pistons in small bore size. the 4.750 crank could be done but would be a custom for the small bore for low compression street fuel if this is not a big deal then the part number wiseco part number k241a6 4.310 bore or 4350 bore k241a100 is some of the few builds a shelf stocking piston for the 10.200 deck block . i would stay under 4.500 crank as there is some triming in the bottom of the block .if you think you want a 4.500 crank what ever rod you used make sure the crank counter weigths are cut to clear the rod your going to used there much more a could write a book i done just about all of them

last one i built was a 4.375x4.500 540 street engine pump gas small cam over 650hp at the back wheels. custom pistons CD 1.230 for a 6700 rod . small soild roller cam

Originally Posted by pat mccarthy

last one i built was a 4.375x4.500 540 street engine pump gas small cam over 650hp at the back wheels. custom pistons CD 1.230 for a 6700 rod . small soild roller cam

Thanks for the great info I think rebuilding this engine is going to be my summer project, I'm going to get it ready to drop right into a car or truck, I Think I may bore it out if I can get the work done for a decent price. I want to make this a 550 hp motor at the least and I am wondering what the price would be to bore it to 460-502 and how hard would it be to find internals and heads for that, and would the power gain be worth the price and I want to keep it carborated would two Holley 4 barrels be any good? And what would you recommend for a trany, I can drive standard but I have heard with 500+ hp cars it's a better idea to go with like a 3 or 4 speed auto what would you recommend for decent reliably with good street potential and when I start this project may I pm you for references or opinions?

As you can probably see, both Pat and I have a lot of respect for the 427 truck block with 10.2 deck ----and to this day, I will haul any I find home with me----
Back in the "day" before any decent long steel rods were available, we had to use aluminum rods and the bottom ends were so big and took so much clearancing of the bottom end, we didn't do a lot of long stroker stuff(1970s) but these days with all the steel rods and longer stroke cranks out there----just pick a number!!!!!!!


guess we were both typing same time----------You will be using a stroker crank for most of your gain in cubes, as you probably should stay at 060 or so oversize--


an 4.375 bore (+125) will give you 481 but the walls are getting thin and it would be more sensible to stay at 060 or 100 over to allow some rebuild freshening up room

Your question about the Monza---never had it on dyno---------


After GM did the bow tie blocks----with a 4 9/16 bore and stock 4.0 crank and 7 inch rod---car ran 7.60s at near 180

Originally Posted by jerry clayton

As you can probably see, both Pat and I have a lot of respect for the 427 truck block with 10.2 deck ----and to this day, I will haul any I find home with me----
Back in the "day" before any decent long steel rods were available, we had to use aluminum rods and the bottom ends were so big and took so much clearancing of the bottom end, we didn't do a lot of long stroker stuff(1970s) but these days with all the steel rods and longer stroke cranks out there----just pick a number!!!!!!!


guess we were both typing same time----------You will be using a stroker crank for most of your gain in cubes, as you probably should stay at 060 or so oversize--


an 4.375 bore (+125) will give you 481 but the walls are getting thin and it would be more sensible to stay at 060 or 100 over to allow some rebuild freshening up room

So should I only bore it out to 460 like you did and what would a machine shop on average charge to do this, would I be able to get the 550-600 hp without boring easily, or would you bore it? And may I pm you for advice and referances during this project?