Doesn't take much force to distort a 109
- Thread starter Mike T
- Start date
- Joined
- Jun 18, 2001
lol, they move around a ton and most people look at me like Im nuts when I tell them I actually BENT a Stage 2 on-center block. Cam bore was so distorted we had to beat the cam out of the block. Spun the cam to check it for straightness thinking it was bent and it was dead on, the block was bent. No cracks or issues with the block, and motor was just apart for a freshen. I hard blocked it after that and it is still running today.
BobbyBuick
Well-Known Member
- Joined
- May 24, 2001
i just unbolted mine after banging on it for 8 years had 4 broken pan rail bolts on the girdle
- Joined
- Jun 18, 2001
All the way down at the oil pan location? Where there's no support? It better move there. That's not a structurally significant part of the block, and if the iron wasn't ductile enough to flex in that location, then the block would just shatter anyway.
A more useful test would be to install the mains and heads, bolt it to a stand by the motor mounts, put a bellhousing on the thing, and then twist it by the bellhousing and check the cam and crank bores for misalignment and distortion.
A more useful test would be to install the mains and heads, bolt it to a stand by the motor mounts, put a bellhousing on the thing, and then twist it by the bellhousing and check the cam and crank bores for misalignment and distortion.
If the motor mount bolt bosses were at the very edge of the pan rail, it would flex a lot... At the bottom of the pan rail.
When you think about it, you really didn't flex them that much. 2 thin pieces of unsupported and unloaded iron moved .002". That's only a thou of deflection over a few inches length.
(for those that don't know, .002" is the thickness of forearm hair)
What's amazing is my personal 4.1 has ,0009" main bearing clearances. That's 9/10,000th over a foot in length. The block should deflect more than that just from heat.
But it still spins like butter.
When you think about it, you really didn't flex them that much. 2 thin pieces of unsupported and unloaded iron moved .002". That's only a thou of deflection over a few inches length.
(for those that don't know, .002" is the thickness of forearm hair)
What's amazing is my personal 4.1 has ,0009" main bearing clearances. That's 9/10,000th over a foot in length. The block should deflect more than that just from heat.
But it still spins like butter.
Mike T
Well-Known Member
- Joined
- May 3, 2013
I intentionally set up for the best visual perspective. I did it that way so that you don't have to be a "expert" to see that these blocks do move.
Yes I knowingly grabbed the weakest part of the block to demonstrate. Truth is though the rest of the block isn't really that much thicker and this area moved like nothing.
Yes I knowingly grabbed the weakest part of the block to demonstrate. Truth is though the rest of the block isn't really that much thicker and this area moved like nothing.
Mike T
Well-Known Member
- Joined
- May 3, 2013
Yes you have an excellent point. I actually started out squeezing the block together with my bare hands and could not determine if the dial movement was due to the block collapsing a bit or me shaking the entire setup.
The clamp gave good repeatable results.
- Joined
- Sep 24, 2010
must be a few supermen in here to flex a block with bare hands. Come onNow put 7/800 rwhp to it an yes there is flexing .
Me Mongo, flex blocks all day long, nothing else to do...........
must be a few supermen in here to flex a block with bare hands. Come on
Have you tried?
Nope. Really couldn't be bothered. To old for rethinking that
. Use a girdle or caps or both. We have pushed these cars since 1985 to now to. all sorts of power levels. (700+ RWHP).That's the point. It doesn't require "strongman" status.
