Pat McPherson

A friend of mine has an opportunity to buy a running 427 truck engine.
Would this be a good block to build a stroker engine.
If so, what would be a good bore and stroke combo?
Is this the block that is used for 496 cube tall deck engines?

Gary Anderson

Mercs tall deck engines include 500hp, 540 cid bulldog; 900SC, 540, and the old 800 and 100hp 572 cid motors. Bore and stroke combinations can easily be 4.5" X 4.5" with these blocks.
However, I believe the old truck motors are not as strong as the bowtie, merlin, or other aftermarket hi perf blocks used in boat motors. I'm also not sure if all the truck motors have siamesed cylinders for large bores.
Gary

robyw1

There was never a 427 siamesed block produced. Unless I'm sadly mistaken. Right now I'm not sad so I must not be mistaken.


Roby

PatriYacht

Nope it's not a siamesed bore. With a .060 overbore and a 4.25 stroke, it will be a 496. These blocks do not have the relief for big stroker cranks. You have to grind that in without striking oil.

paradigm shift

Not sure what 496 motors your are referring to. You can make a 496 from a std deck height block also.

If the price is right they can work well depending on how much HP you plan on running. They are not siamesed but you can half fill the block with filler if you want. I don't think that is a real problem unless you bore them to big. They are NOT a BOWTIE or MERLIN or DART as for strength so make no mistake. 4.25 is not much of a problem and 4.5 can be done for stroke length with a little grinding. As for bore just make sure you sonic test the block first as always. Just my.02
Oh if the price is right and your friend does not want it I know someone that might. All they would want is the block actually.

PatriYacht

Simply saying what the size would be with those dimensions. Merc. uses 4.375 stk. for their Bulldog. 4.5 might require more than a little grinding.

Pat McPherson

I know of someone with a 496 tall deck Hawk Marine engine. It's about 10 years old. Maybe it's a stoker 454, not a tall deck.

PatriYacht

427 and 454 have the same bore 4.25. 454 has a longer stroke 4.00 vs 3.76. Tall deck blocks are the same for both except 454's had notches at bottom of bores for more rod and crank clearence. Newer 427 blocks may have the notches. Tall decks allow you to use longer rods and pistons and longer strokes. 4.5 stroke is possible but I would have a skilled machine shop do the clearence notches. Because they're not siamesed bores, they generally cannot be bored larger than 4.310 although I did bore one 4.350 after sonic check. Not recommended. Until the 502 block came out, a lot of people were building stroker motors out of these.

New 496's are an oddball bore and stroke different from all of these. I'm sure someone here knows what it is.

Pat McPherson

Thanks for the info!
We'll have to look into a kit including 4.25 stroke crank, rods, and pistons.
Does anyone have a good sorce for these components?
Also, We will need to compare the cost vs. a 502 short block.
I think the goal is to build an engine with 500+HP and 600lbs torque...

jspeeddemon

That block can be used successfully for 4.25 stroke and 4.375 stroke, most people do half fill them for swinging such a crank. I personally know many of these motors built with bores of .100 to .125 over the stock 4.25 bore. However I would prefer to use a 502 block over this combo, free cubes with that bore. I have seen Atlantic speed sell brand new blocks of this type for 500.00, and a new bare 502 is around 950.00. I think the extra money would be well spent. I have to laugh, coincidentally there is some guy on ebay wanting $1125 for these blocks right now, hell for another $500 you would be in a bowtie, or 502 for a couple hundred less. He thinks he has a rare find I guess.