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Why did this rebuilt engine fail? Was it the engine rebuilder’s fault?

Mr. Makesumwake, just an after-thought here......, check and see if your cylinder head castings end in 902!

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There is a Vortec cylinder head casting that ends in 062 that should be avoided for Marine use.

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10239906... 96-up...350.........."Vortec 5700", "L31", 64cc chamber, 1.94"/1.5" valves, 170cc intake port

12558062... 98......350..........L31 Vortec, truck, 64cc chambers, 1.94"/1.5" valves, 170cc intake port

Apparently, the 062 has head seat issues in a Marine application.
 
One other issue I have all though it may not be so big, is.

WHy the two barral carb? if you are going thru the rebiuld and the motor was/is .030" over bore and now a 355 cubic inch I would think a 4bbl would be apropriate to supply good fuel quantity. A 2 bbl may be a bit on the lean side for this motor...

I know some 350's use 2bbl carbs but this may not be good in this application at least not anymore......

Just sayin......
 
Just a quik note for you the older vortec heads are well knowen for cracking and let water into the cyl if you googel vortec cyl head cracking I think it was you can find the casting bach numbers that thay had the proble with you may have those heads even if thay were tested thay still could have cracked on assembly or soon after letting water in to the chambers I think you said you run it in saltwater and salt don't like to burn it will leave deposits in the chamber / pistons / valves that can feed detonashion ect even f the timeing is right on also its not just that to much water turning to steam in the cyl massively brings up com ratio and can easily brack stock pistons. Cast that is just something else for you to think about and I know I can't speel well good luck don't give up.
 
pay him 700 and let him run and tune it on a crate. Let him install everything and give it to you as a complete running motor.

So next time it implodes he can't say he didn't set the valves or the carb is to lean or whatever.

And you run the break in right.
 
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Rick, Thanks for the links, great info! (you CAN teach an old dog new tricks!)(me)

I gather from the article that Rick sent that it IS possible to run a High Compression

built engine, just that the timing would have to be retarded to prevent detonation.

And in doing so, performance would possibly suffer.......



My Donor Mercruiser 5.7 motor for which I plan to build up has #217 heads....

These heads are 64cc heads (high comp, same cc as Vortecs).

The pistons in the block are the Flat Tops with 4 valve relief cutouts.

(Previous owner stated it was a Mercruiser crate engine, If anyone has a way to verify/deny the Mercruiser motor

designation, I would like to hear. It is painted Black and has brass freeze plugs.....)

I wonder what pistons are stock in Vortec marine engine?

And what pistons are stock in a typical Vortec truck/van engine?

Onward with my quest,


John
 
duo_prop_dad said:
Rick, Thanks for the links, great info! (you CAN teach an old dog new tricks!)(me)

  1. I gather from the article that Rick sent that it IS possible to run a High Compression built engine,
  2. just that the timing would have to be retarded to prevent detonation.
  3. And in doing so, performance would possibly suffer.......
  4. My Donor Mercruiser 5.7 motor for which I plan to build up has #217 heads.... These heads are 64cc heads (high comp, same cc as Vortecs).
  5. The pistons in the block are the Flat Tops with 4 valve relief cutouts.
  6. (Previous owner stated it was a Mercruiser crate engine, If anyone has a way to verify/deny the Mercruiser motor designation, I would like to hear. It is painted Black and has brass freeze plugs.....)
  7. I wonder what pistons are stock in Vortec marine engine?
  8. And what pistons are stock in a typical Vortec truck/van engine?

John
Click to expand...
  1. Define "High Compression" for me. We don't typically want more than 9.4:1 in this engine.
  2. Not necessarily. Detonation is caused by more than just ignition advance alone. The full dished piston is a contributor to detonation.
  3. Via retarded timing...... yes!
  4. Not same as Vortec in many respects..... runner size being one! Higher compression is achieved via the piston selection as well.
  5. A good combination with the 5.7L and 76cc chambers only. Not good otherwise!
  6. To my knowledge, Merc has always offered a serial number on the block.
  7. These all come with the dreaded full dished pistons.
  8. Again, the stinking, aweful, terrible, silly, stupid, rediculous, dreaded full dished pistons that were created in the 70's as an emission control or smog piston.
My previous comments about the Flat Top pistons, were that the OP's engine builder made a bad choice in using this piston in several respects:
One...... they were used with the Vortec 64cc chamber heads.
Two..... they are double valve relief.
On a 5.7L w/ 76cc heads, they would have been a better choice in that both a more suitable C/R and a Quench Effect could have been achieved.
He clearly missed the mark on this!

.
 
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