Thread: 366 to 427

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I have a question and sorry if it is a stupid one, i don't know much about this kinda stuff. I have a 366 big block engine, what would i need to do to make it a 427, I have heard several things, like put a 454 crank in it...
Please lemme know what i need to do..

The problem with putting a 454 crank in it is there won't be any off-the-shelf pistons for it. You could have custom pistons made for it, but the cost of custom pistons would probably be more than just buying a 454. I'm thinkin' that about the best you could hope for on the bore is about 0.125" over stock, so a bore and stroke of 4.060" and 4.000" would net you 414 cubic inches. The stock bore on a 454 was 4.250, so there were no smaller pistons for it, only larger. Your 366 block has a stock bore of 3.935" and a stroke of 3.766".

does it matter that it is a tall deck? because won't it be able to take larger pistons?

if you want a big block tall deck look for 427 tall deck this can go to 526 with no custom pistons. some pistons can be used off the shelf stuff this is a 4.500 crank and 0.60 on bore.the 366 is not worth much .it is good beet truck engine and not to good to build for hp

well... I'm asking because I already have a 366 it came out a School Bus, and I'm pretty sure it was pushin 350 hp, Im just really wondering what i should do to it to get quite a bit more horses, I think this motor stock has 400lbs torque..... So anything i can do to boost the hp? And one other questiong about a turbo, I have a 5.9 litre cummins diesel turbo, would it be able to go into my car.

the tall deck is not going to just fall in . i have put a tall deck10.200 donovan 66 gto 620+ and a 573 this is work for a low hp 366. the short deck 9.800 is the way to go 396 to454 with bowtie block or dart or world block you get 581 with the short deck to make it work you spend big$$$$ and not get much out of it look at some of the threads on tall deck427 this will help

Hi, man i already went down this road once...learn from my mistakes bud, the prob with a 366 is this: #1 the bores, the bores are very small and there isnt very much room to bore them until you hit the water jacket, now you can always sleeve them for the low price of 900-1100 dollars for all 8 cyl to be sleeved, by then you could have bought a merlin block thats already bored out to whatever you want and theres plenty of room to sleeve it if ever needed. Now, thats just one problem, Next problem: #2
The clearance needed for a crank thats worth a shit, if you put a crank in there with 4.250" stroke its gonna hit so your gonna need to clearance the block right? no problem right? wrong, its gonna hit the water jacket if you clearance it that far because the block was cast for a 3.075" stroke (or close to that) crank. Other wise if you want one i have one rotting here you can have the piece o' $hit. Other than that they make damn fine door stop Let me know if you can get one to work out because if you could that would be awesome because thats a heavy duty block that would make a massive motor instead of an eye sore in my car port....later,Joe

The 366 has a non-standard crankshaft flange placement, it won't work with car-type trannys. It's a dog, anyway, all the weight and bulk of a big-block with less cubic inch potential than a small-block. Leave it in your bus and trade it to a farmer for a real rat motor.

if you want this 366?? do this use a 396 piston and 250 long I beam rod scat. gm 454 crank and O deck the block this will get to 427 check to see if it will take that much bore ??? this could be the way to go you will have to use 454 damper and fly wheel dam i am good

Pat, do you think the block will take a 0.156" overbore without hitting water or runnin' so hot due to thin walls that you can't cool it???

By the way, the rods would have to be 0.160" longer, not 0.250".

why do people tell other people all the bad things. why they cant do with what they have. he probably already knows its hard to work with and im sure if he had the $ he'd of bought a bigger one so why dont we just help him with what he's got



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"i was bored so?"

if you want it its still here....come pick it up or send someone to pick it up ask me and i'll give you my address. one less thing i need to haul off when i move. theres nothing wrong with it. well except that its a 366.

Im not busting on the dude im just saying, instead of putting all the money into a block thats not practical he could build a 454 and have a whole lot more motor. A lot more bang for his buck really.

Thanks for all of your help, I guess i can get a 454 block and just go from there, i have several big block performance parts, Just wondering if you could actually beef up the 366 any, I'm a small block person, Havne't really done anything with big blocks...

Big blocks+big bucks= big power...

torque=wheelies i need a 427 got one?