Racingjunk Forums

Racingjunk Forums (https://www.racingjunk.com/forums/index.php)
-   Engine Tech (https://www.racingjunk.com/forums/forumdisplay.php?f=9)
-   -   Truck tall deck BBC GM block???? (https://www.racingjunk.com/forums/showthread.php?t=22675)

dparker 01-02-2009 10:05 AM

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?

sc4405 01-02-2009 05:49 PM

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

dparker 01-02-2009 06:00 PM

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.

zipper06 01-02-2009 07:51 PM

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.

outlawrcr426 01-02-2009 09:05 PM

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

zipper06 01-03-2009 06:47 AM


Originally Posted by outlawrcr426
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.

outlawrcr426 01-03-2009 08:04 AM

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.

desoto30 01-03-2009 09:15 AM

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.

henny 01-03-2009 07:04 PM

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

dparker 01-04-2009 12:10 PM

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.


All times are GMT -8. The time now is 05:14 AM.