Ruined Shortblock/unknown future
 

My son has been working on a redoing a 91 Mustang GT. Several months ago he purchased an assembled Bullitt 347 Stroker shortblock made with a Dart Block, Forged Steel crank, Scat rods, Ross blower pistons. All nice stuff. The short block has been covered and on an engine stand since December when I helped him dial in the cam. Today he was going to install the heads and begin the final assembly. He rotated the block upright and said he saw some small abrading beads (?) laying in the machined relief of one of the pistons. He says they came from the water jackets. While attempting to get them out, 1 or 2 or (?) rolled out of the relief and down between the piston and cylinder wall. At that point he attempted to flush it out with carb cleaner, cranked the piston upwards, flushed some more and then cranked the piston to the bottom. It was then that he saw a score created in the cylinder wall. He pulled the pan and removed the piston and rod assembly and the piston had a definate scribe in the upper portion of the above the top ring lands (no big deal) it will clean up with some carefull file work or wet or dry 400 grit sand paper, but the cylinder will definately have to have a hone put in it at this point. What I'm concerned about is that if the mark will not clean up without material removal then the clearances are compromised on that cylinder and it will neccesitate an overbore, new pistons and subsequent rebalance. Anyone ever run into a similar situation. This engine is set up for a supercharger with AFR 205 heads and Jessel shaft rockers. A lot of planning and to have this happen is heartbreaking to say the least.

PS: I had earlier associated Dart and Man-O-War. This is not correct. They are different products entirely.

Hey Rick
Is there any kind of warranty with the short block from the builder? Maybe talk to him first?
I was thinking that if you tried to do some work on it, the builder might not take it back for that reason alone.
Larry

Rick,
Could you not bore the block and sleeve it, hone it out to match original tolerance specs and use the already purchased parts, I would think that would be less expensive than the alternatives? Sleeves, one cylinder? all? (to keep things "balanced") and the machine work.
Of course this is all assuming the cylinder walls will not be compromised by this process....
Mark

Rick,
You have a PM.

Can you even feel the scratch with a fingernail? I'd be surprised if a scratch like that would cause any difference in compression or oil use. I'd be more concerned about getting all the rest of the glass beads out of the water jacket and wherever else they might turn up. There are a lot of much more knowledgeable people here than I, but unless someone who's really an expert told me to tear it apart, I'd be inclined to use it the way it is.

Just my $.02

Good luck.

Lowell

Yes there are 2 definate scratches in the bore, not just visual but small grooves. The beads were metal.

I would definitely talk to the builder before doing anything else. There should not be any foreign material in the water jackets or anywhere else by the time the short block is assembled.

Rick,

When I built my 302 I had the same thing happen but I was the engine builder. I had to hone it out at the top and never had any problems fortunatly the scratch only extended about a 1/4" down from the top of the cylinder.


Clois

Rick,
Any luck?

Engine builder said "Just hone it a little and run it". Block manufacturer pointed fingers at the engine builder. No resolution from either party. Took it to local shop for evaluation.

So much for the theory that every engine block MUST be 'torque plate' honed.

While thats certainly true when your building an all out hi performance motor it's just not always justified, like in this case.

In a situation like this try using a very fine grade 'Flex Hone'- The type with a lot of carbide balls on nylon bristle's.

This type of hone will not undo all the good work done with the torque plate and material removal will be minimal.

Jac Mac

Rick;
I bought a Dart 351 block when it first came out. After having the machine work done and, while washing down the block, I found chunks of what appeared to be black sand in the water jackets. Some of these chunks were too big to drop out and I spent hours with a hammer, screwdriver and a flashlight breaking them up so they'ed come out. There are still a couple of big pieces with wire in them that wouldn't break up so I'll be running a coolant filter for a while. According to Dart this is normal, but I have my doubts. In retrospect I should have had the machining done, ground off the casting marks and flashing on the inside and then I should have taken it and had it acid dipped to remove all the casting sand. If you go that way you'll have to redo the cam bearings but you'll sleep better.
Bill Stradtner