Truck tall deck BBC GM block????
 

How much can you safely bore a truck tall deck? and How much HP will it handle? What would be the largest CI that one could safely throw at a GM truck tall deck block?

Back in my tractor pullin' days I had a 468 built with a truck block and .400" long rods. That thing lasted forever w/ a 10-71 on alky. Finally had to retire it when the deck was full of heli-coils, no water leaks 'cause it was filled to the top. I suppose you could go .100" or MAYBE .125" over, but better check for core shift and wall thickness to be sure. There is a reason the aftermarket blocks are so good..... 8) JB

I ended up with a supposed 540 bbc with Jesel Belt drive, jesel rockers, and Dart 345 heads. The engine ran a 8.25 in a 2500 lb chassised Beretta. The block is a tall deck, it has what looks like GM numbers, and says truck on the back. If its a 540 it should be a 4.50 bore.
I guess what I'm trying to decide is should I move everything into a Dart or Merlan block before I run the engine. Or is this truck block ok.

I've never heard of anyone boring a stock big blk short or tall more than 4.375 and still having any wall left. It could be a 4.375 with a 4.5 crank, but that would require lot's of grinding on the pan rails.

Zip.

4.375x4.500 is a 541 and doesn't take all that much grinding

This thread,

http://forums.racingjunk.com/viewtopic.php?t=8330

HeHe, it does with a dremel :lol:

Zip.

i've done 3 of them,i clearance blocks all the time,so i have a good grinder and carbide bits.With Eagle rods,the hard ones take about 2 hours, and some years of blocks have much more clearance to start with, and only take about an hour.

When these were all that was available,the books recommended .060" for the car & .125" for the truck.Of course there were some of us who went further.

The 10.2 truck block I have is .060 over with a Callies 4.5 in crank in it
The fellow I got it from had alum rods in it, I have .400 long Carrillos

Pulled the pan and the block is ground on extensively. The rod bolts on the outside of the rod are ground slightly to clear something, maybe the cam. I'm wanting to check the true displacement, can I do this by just pulling the pan. I believe the crank is at least a 4.375 and maybe a 4.5 stroke. What's the easiest way to check from here. Its also going to be a little hard to check bore size. Everything looks great, so I really don't want to tear the whole engine down if I don't have to. Its suppose to be new with just 7 passes and so far I can't see anything that would disprove that. I used a cheap set of plastic calipers and got 4.32 at the bottom of the piston skirt. The engine came out of a 2500lb chassised car that ran a 8.26. I haven't seen this combo before and I'm starting to wonder alittle about what kind of HP it will have.

It put 726 hp on the ground, at least that day it did.

I'm betting you have a 4.375 bore and 4.5 crank, if it's a true 540" motor. Take a piece of 1/8 welding/brazing rod and cut it to as close as you can to 4 3/8", then try and fit it into the bottom of the cylinder. If it's a 4.5 bore it will have plenty of room, if 4 3/8" it'll be tight. You can also measure the stroke from the bottom but it won't be as easy unless you have 1,2,3 blocks and a depth mike.

Zip.

Rip it apart
 

If you need answers, positive answers, rip it apart and do all the measuring yourself or have a good machine shop do it, then you will KNOW what you have exactly and not blow it up on your expense!!!!!!!
You will win in the long run doing it this way, and a little more spent now, save a lot more later :wink:

My 2 cents worth.

Elkyman

you need to measure the diameter of bore,my understanding is you got 4.320" well that would be a 4.250 stock bore size that was bored open .070".if you find a way to measure piston travel up and down that will be your stroke naturally,but without poping head off or dropping pan,dont know how to check for stroke any other way