Thread: 427 tall deck combo question

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i got a 427 tall deck. i got a 427 standard forged crank and i also have a BBC forged crank with a 4.250 stroke. what options do i have for each crank. length of rod for each and type of piston compression height for each crank. Bearing in mind of course that i don't have the funds especially custom pistons so i would like to either use 454 or 427 pistons with their stock compression heights. What are my combo options and choices?

i think Jerry C and i told you what to used some time ago posted 2-17-2009 427 Tall deck what to do

you did buddy and i appreciate it but now my knuckle head son got a hair up his butt and got a 4.250 stroke crank that he wants in there when i already had the parts for the 427 crank. so what can i do with that. I'm about to quite on it and let him handle it on his own. the whole project was suppose to be for a cruiser that's turning into a strip car that he probably would never take to the track.

I think your boy is on Hottrodders.com as Shoo Head. He was askin' about swappin' a 427T into an S10. Here's the thread....
http://www.hotrodders.com/forum/427t...-d-155557.html
I don't think he ever mentioned his Pop having any parts already.....

Originally Posted by LuckyBadAzzBoy

you did buddy and i appreciate it but now my knuckle head son got a hair up his butt and got a 4.250 stroke crank that he wants in there when i already had the parts for the 427 crank. so what can i do with that. I'm about to quite on it and let him handle it on his own. the whole project was suppose to be for a cruiser that's turning into a strip car that he probably would never take to the track.

if you used the 4.250 crank then your need to run a 400 long rod then you will have a CH of 1.520 piston same as a 9.800 block with a 4.250 crank with a stock rod 6.135 SRP number 258266 or some thing like that with a CH of a 1.520. or a 6.800 rod with a CH of 1.270 and SRP number 258243 they are domes i look up and a 060 over bore but the CH is what you need to look at and what size rod your going to use. you can build the 4.250 crank with stock rods in the 9.800 but not with the 10.200 block. get ready to spend money a stock 427 pistons will not work with the 4.250 crank or a 454 pistons the 427 pistons would need 075 off them with a 6.385 rod and you could not getway with cutting off that much off the top of the piston or a custom set of rods they start at $1800. then your 427 pistons would need to have S locks to hold your pins in and could hit the counter weights of the crank on The come around so it would be way better to buy a piston for the job at hand using a self rod like 6.535 or 6.800

Thanks for getting back to me. I looked up those pistons and they are a budget buster using that 4.250 crank. So please let me know if these options i got in mind are correct or not.

a- 454 standard crank with 6.535 rods 454 pistons with ch of 1.645 gives me a minus deck clearance more or less -0.02, instead of decking it below zero can i just get a slight dome on the piston to make up the difference and at the same time adjust the compression? that way i don't have to readjust everything else.

b- 454 standard crank with 6.385 rods 427 pistons same thing here i get a -0.05 deck clearance can i get a domed piston to make up the neg. deck difference and adjust the compression?

c- 427 standard crank with 6.535 rods 427 pistons. again here if i use 1.765 ch pistons i get a neg of -0.02 can i dome here also.

d- 427 standard crank with 6.535 rods 454 pistons with 1.645 ch pistons neg deck height again but a tad to much at -0.14. can i dome there or do i have to deck the block -0.10 and make up the difference with the dome and if i deck it at -0.10 how much do i really have to adjust everything else.

how far`below the deck can one go safely without creating a situation were the compression ratio is just way to low. or can like mentioned earlier used domed pistons to make up for the compression lost?

I have aluminum merlin heads i got from a friend who owned me cash for remodeling work i did for him. they have 119cc chambers, rectangle port runners large valves

you could use a speed pro hyper piston h552cp with the 6.535 rod with the 4.250 crank .you do not adjust the dome if your in the hole you deck it .... i like not to be in the hole much on any build . i would say fine if your deck is at 010 and if not get it cut so your not more then .010 in the hole or O you can cut the dome some to move the ch if you want to move the ch a bit but it better to buy a piston that works

hi pat this is what we did. we decided to use the 4.250 stroke crank and the h-beam 6.535 rods, we got some speed pro hyper pistons with a ch of 1.525 a dome of +.100. we decked the block to 10.195 which according to my poor math should put us at about -0.009 in the whole then we got a nice copper gasket that according to specs should give us a 0.032 compressed thickness which should give us a quench of about 0.041. My question is should i deck the block more to get a smaller quench or is the 0.041 okay. The math formulas are driving me nuts but it should give me a compression ratio of around the ball park of 9:3 with the 119cc aluminum heads. they have large intake and exhaust valves. Now the next headache is choosing the right cam were thinking hydraulic or solid roller cam between a 625-675 lift but have idea on the duration yet. i figure it has to be a longer duration because of the longer stroke? another thing is the pushrods for the rocker arms since i decked the block i probably need to resize those, don't i? and how about the distributor? this might be my first and last stroker lol.

Originally Posted by LuckyBadAzzBoy

hi pat this is what we did. we decided to use the 4.250 stroke crank and the h-beam 6.535 rods, we got some speed pro hyper pistons with a ch of 1.525 a dome of +.100. we decked the block to 10.195 which according to my poor math should put us at about -0.009 in the whole then we got a nice copper gasket that according to specs should give us a 0.032 compressed thickness which should give us a quench of about 0.041. My question is should i deck the block more to get a smaller quench or is the 0.041 okay. The math formulas are driving me nuts but it should give me a compression ratio of around the ball park of 9:3 with the 119cc aluminum heads. they have large intake and exhaust valves. Now the next headache is choosing the right cam were thinking hydraulic or solid roller cam between a 625-675 lift but have idea on the duration yet. i figure it has to be a longer duration because of the longer stroke? another thing is the pushrods for the rocker arms since i decked the block i probably need to resize those, don't i? and how about the distributor? this might be my first and last stroker lol.

throw the copper gaskets out and use a 1017 -1 felpro head gasket there 039 and 10.5 cc and deck to 005 in the hole and call it good .on your push rod they need to be 400 longer as well BUT you need to do a mid lift check for the right push rods with your alum heads they very well could have a hi port more then stock iron by 3/4 so you need to check this there are many things that can throw this off and every engine and with a roller cam like small base circle and decking milling the heads many other things so it needs to be checked. NO if ands or buts you dist can work if you need to know more you can call me my fingers are sore been a long day pat mccarthy 989-667-4071