Broken part pics from E motor

[Cajun Kid]

Charles,
Any idea of the cylinder wall thickness on your new Dart block?

Don

Don the cylinder wall thickness is .230 at a bore of 4.165  so with my bore of 3.765 is should be .630  man that seems thick ??  It is a 4.00 bore block casting,,, they are using a smaller bore casting plug so the wall should be thicker by the amount of under bore plus the .230

Charles

[Peter Jack]

It won't be the lightest motor on the block!

Pete

[Cajun Kid]

It won't be the lightest motor on the block!

Pete

Agree but it sure should be stronger ?  I wonder how those thicker walls will handle and disperse the heat ?

Charles

[Peter Jack]

For the distances travelled, even at Bonneville, I don't think it should be a problem and the heat distribution should be pretty even. May take a little longer to cool down.

Pete

[salt27]

Don the cylinder wall thickness is .230 at a bore of 4.165  so with my bore of 3.765 is should be .630  man that seems thick ??  It is a 4.00 bore block casting,,, they are using a smaller bore casting plug so the wall should be thicker by the amount of under bore plus the .230

Charles

I think the thick walls will be a good thing.
What do you use for head gaskets with that high compression and small bore?

Don

[wobblywalrus]

Do you have a picture showing the crack patterns on the cylinder wall?

[maguromic]

Without seeing the block my guess is that your cylinders were going out of round from the cylinder pressures and started to crank from the fatigue.  Our XO/GMC has the same issues and I will be posting the block to help keep the cylinders from going out of round.  Tony

[Cajun Kid]

Don the cylinder wall thickness is .230 at a bore of 4.165  so with my bore of 3.765 is should be .630  man that seems thick ??  It is a 4.00 bore block casting,,, they are using a smaller bore casting plug so the wall should be thicker by the amount of under bore plus the .230

Charles

I think the thick walls will be a good thing.
What do you use for head gaskets with that high compression and small bore?

Don

Don we use Cometic MLS head gaskets for all our high compression engines, never had a one blow out.

Charles

[Cajun Kid]

Wobbly, I will get pics when I get back to the motor shop...it was depressing seeing the damage knowing we would miss the May event at Maxton with an "E" motor... there are so many one off parts and tons of machine work in doing an E motor, no time to get it done.

Tony, you are correct fatigue on the stock GM 305 block had to be the culprit.

This new Dart Block will solve that issue and also help strengthen the bottom end as well.

Charles

[wobblywalrus]

Years ago I built an engine with iron or steel cylinder liners in an aluminum block.  One of the liners cracked and the lower part slid down into the crankcase.  Like you, I shut the engine off and was able to save most of it.  I was eighteen or nineteen years old and I did not have a clue as to what happened.  I brought the pieces down to an expert and he looked them over.

The conclusion was uncontrolled combustion.  A controlled burn would start at the plug electrode and fan out across the piston and the combustion would produce a large but smooth power pulse.  My engine had too much compression when considering the combustion chamber shape and the octane of the gas I was using.  Too much of the burn was happening at the same time and it was producing concussive pressure spikes that fatigued the liner until it broke.  This was a long time ago and I do not remember exactly what the fellow saw among the wreckage that told tell him what happened.

It might be a good idea to check for this.  A new and stronger block will fix the problem if a weak block is the cause.  The stronger block might be only treating the symptoms if the combustion is not right and the problem will eventually recur, possibly with a broken piston or something else.  Just a thought.  I am no expert on carz.

[WOODY@DDLLC]

Probably some or all of the above Charles!  Hot rodding 101: Race, break, rebuild, repeat as required! 

Your dyno guy got something like this: www dot tfxengine dot com 

[MIKE MATY]

Charles you need ti valves. No valve spring can control that kind of weight. I guarantee those valves were bouncing off the seats at 8500 rpm. My guess would be a valve to piston. Dave and I learned this the hard way 2 seasons ago and we only turned 8000 rpm. We only turn 6600rpm now b/c we can't afford the valves we need. Also even the best load dyno can't produce the prolonged load of lsr. Dave has a piston bowl to prove it.

[Cajun Kid]

Mike, I agree on the need for Ti valves,, however we have used SS valves up to 8500 rpms for years,,, This is my first broke valve ever on a SBC...The broke valve does not explain the crack in 3 cylinders , the one with the broke valve and the two next to it have the valves perfectly intact and not even a scratch on top of the piston. ??

I sure wish we knew what happened and in what order,, all I know is we should have started with a new block, Now I know that and hope Dart does us a great job on the new block.

Since the bore is small the valve size is also not one you find in off the shelf Ti.... CV products/Excyldyne  will make me a custom set,,,, but I have no extra $$ for them,,,,, I am going to try to find some used ones from a Cup Team and turn them down... this may be affordable... The Springs, Ti Locks and Retainers on the heads only have  3 Loring runs on them and 5 Maxton runs on them,, they are in new shape...

Probably going to see if Luke or sombody can help me drop another motor in this week before I go on Vacation so it wil be ready for Maxton with a substitute motor while we wait on the new block ...


Charles

[MIKE MATY]

I was just talking to my engine builder about factory blocks. He said they can't take the high rpm bc the webbing on the main is very thin and causes the block to twist an crack. Kind of like yours. That's another reason we don't turn our motors anymore. We Still use a stock block. The dart block is where it's at. You should not have any problems with it. The webbing around the mains is hugeand will help keep that crank in line. Remember what you use to do in drag racing does not apply in lsr. It's a way different ball game. It's 4 times the distance, or more.

[Bootleggerjim]

Mike, I agree on the need for Ti valves,, however we have used SS valves up to 8500 rpms for years,,, This is my first broke valve ever on a SBC...The broke valve does not explain the crack in 3 cylinders , the one with the broke valve and the two next to it have the valves perfectly intact and not even a scratch on top of the piston. ??

I sure wish we knew what happened and in what order,, all I know is we should have started with a new block, Now I know that and hope Dart does us a great job on the new block.

Since the bore is small the valve size is also not one you find in off the shelf Ti.... CV products/Excyldyne  will make me a custom set,,,, but I have no extra $$ for them,,,,, I am going to try to find some used ones from a Cup Team and turn them down... this may be affordable... The Springs, Ti Locks and Retainers on the heads only have  3 Loring runs on them and 5 Maxton runs on them,, they are in new shape...

Probably going to see if Luke or sombody can help me drop another motor in this week before I go on Vacation so it wil be ready for Maxton with a substitute motor while we wait on the new block ...
Charles, did you check the valve spring on the broke valve....Jim

Charles