9.8 or 10.2

I am building my first bbc blown alcohol motor am going to purchase a dart big m block should i use a tall or standard deck height and why? Thanks for any input

 

on a bbc deal i'd recommend the 10.2 and put the longest rod you can in it

 

What size stroke you plan on running? I have run a 9.8 for years with no problems. Just make sure you run good rods and heavy pins. I prefer GRP or MGP and at least a .200 wall pin thickness for a .990 pin. Hemi pins are better if you are buying all new stuff. The 10.2 is better for rod angle but its a heavier piece.

 

I have a 540 4.5bore 4.25 stroke in a 9.8 with a 14/71 wedge heads

wish I had a 10.2 would have made the rods/pistons easier, and manifold/port nossel clearance.

I probably would have went with the same pistons but longer rods or meet in the middle

 

i plan on running a 4.25 stroke with 4.50 bore i haven't orderd the rotating assembly yet but i was leaning to a standard deck height and maybe even less stroke 4-4.25?

 

If you don't have any parts yet, get the tall deck. I've had both and there is nothing wrong with the short deck but the tall deck gives you options. I had a 548 short deck that worked good. 4.250" stroke and 4.530 bore with +.400 rods. Compression height on the pistons is at 1.120", pretty easy combination as far as parts finding go. Good luck.

 

10.2 block

Run the 10.2 block you will never look back. You will love the long rod motor. The only minor problem is that the ports are wider apart. the shorter the deck the straighter the runners. But who cares with a supercharger motor. Don

 

weight

Short deck will weigh less, just something to consider as well

 

rods & intake also weigh less

If your 4.25 stroke or less it will fit in a short deck.

Overall engine height is shorter.