Jump to content

Machinist Woes


Tim_C.
 Share

Recommended Posts

I took my shaved rods with melted hyper-u pistons in to the machinist to get my new Wiseco forged pressed on. This machinist is new to me, but my friends have all had lots of work done there and always good. This guy threw out about 15 G54B blocks over a year ago too. Great machinist, but I wish he would have kept them. He would have sold them for cheap too.

 

So, anyway he said he went to press the pins out, and one of them he barely pushed and it came right out practically on its own. He looked in the rod and saw where my previous machinist had to clean it up in there. the pin was so loose, it was about to come out on its own and cause bad damage to the cylinder wall. blocks usually don't survive that. So I guess it was a good thing my piston melted and I had to take it apart. Otherwise, the short block could have been trashed if the pin came loose.

 

I had 2 options if I wanted to keep the shaved rods. He said he does a racer clip the piston pin into the honed rod end with no bushing ($20 per), or bush it properly ($40 per) and it will last a very long time. I was like of course, bush it!

Link to comment
Share on other sites

Yep, it was a stupid thing by me, but they melted pretty quick. I boosted up a short hill, racing a 240 SX in my '85 non-intercooled automatic car. It was pulling hard at 9 PSI until I felt the slightest hesitation and let off. That was all it needed. We got to our destination, knowing something was wrong, so I pulled the plugs and #3 had a small piece of the electrode missing. I replaced it right there, and it ran fine after that for a while. Then it started dropping the cylinder without firing it every time. Checked compression and it was down to 90. Drove it like that for a few months LoL! and then it kept dropping more, so I parked it.

Everyone says the non-IC cars are 7 PSI stock boost, but that must be at low altitude, because all of mine are 4.5 with them set correctly. I'm at 5800 feet.

 

Oh, and yes, that 240 SX was eating my tailights from the start! I put a 10+ car spread on him in just a few seconds and then let off when I felt the very slight hesitation.

Link to comment
Share on other sites

I guess its a matter of vernaculer, when you say melt I'm thinking like a 2-stroke that goes lean and burns a hole through the piston. If that were the case it would be the first time I've heard of a melted hypereutictic, they typically shatter as they are more brittle. Most people don't run enough ring end gap and the piston alloy pushes more heat into the top ring until the ends touch and shears the top ring land off. I've seen recommendations of an extra 0.001" of ring gap for every 1" piston diameter for the hypers.
Link to comment
Share on other sites

Ring lands were perfect. The top outer edge was literally melted. Hyper-U's melt quicker on a boosted engine. Supercharger, turbo, etc.. they really aren't a good choice. I'll never run them again. Sure, I had fuel delivery problems that couldn't keep up with the demand, along with an intake charge that was simply too hot. But a set of forged would not have been hurt at all. They're worth every penny.

 

My old machinist was good. I believe it was winter time and he probably took measurements when the rods were sitting in his cold shop. He probably had no measureable problems when he did the job, but it was just a touch loose.

Link to comment
Share on other sites

Darn Machinists! I've got 5 years and over 12k miles on my hypers. Guess maybe I better start another build?

 

Dad

Link to comment
Share on other sites

  • 2 weeks later...

I took my shaved rods with melted hyper-u pistons in to the machinist to get my new Wiseco forged pressed on. This machinist is new to me, but my friends have all had lots of work done there and always good. This guy threw out about 15 G54B blocks over a year ago too. Great machinist, but I wish he would have kept them. He would have sold them for cheap too.

 

So, anyway he said he went to press the pins out, and one of them he barely pushed and it came right out practically on its own. He looked in the rod and saw where my previous machinist had to clean it up in there. the pin was so loose, it was about to come out on its own and cause bad damage to the cylinder wall. blocks usually don't survive that. So I guess it was a good thing my piston melted and I had to take it apart. Otherwise, the short block could have been trashed if the pin came loose.

 

I had 2 options if I wanted to keep the shaved rods. He said he does a racer clip the piston pin into the honed rod end with no bushing ($20 per), or bush it properly ($40 per) and it will last a very long time. I was like of course, bush it!

 

Hi Tim,

 

What machinist are currently using for thus build? I might just have to tear down and get it done the right way after all the hooplah I have put myself through. I am in Lakewood so hopefully this machinist is not too far from me.

 

Thanks in advance!

Link to comment
Share on other sites

Your machinist should have brought them up to room temp. not done them cold sounds like he just slapped them together to get you on your way.

Yeah, that's just my guess too. He isn't doing auto machining any more, so I can't take it back to show him in a professional way. I see him around town still, but I would never mention it unless he could do something about it. No need to make him feel bad over it.

Link to comment
Share on other sites

Darn Machinists! I've got 5 years and over 12k miles on my hypers. Guess maybe I better start another build?

 

Dad

 

LoL! Yes, mine melted due to a very short operator error, and clogged fuel filter most likely. I like the added protection forged gives. They wouldn't have been hurt much at all except for some scuffing. The cylinder wall is fine and nothing that a little hone won't clean up, so I know it wasn't that severe of detonation. Although the new forged need a slightly bigger hole, so I am honing it a bit hard for that.

Link to comment
Share on other sites

 

Hi Tim,

 

What machinist are currently using for thus build? I might just have to tear down and get it done the right way after all the hooplah I have put myself through. I am in Lakewood so hopefully this machinist is not too far from me.

 

Thanks in advance!

 

No, he is in Grand Junction, about 5 hours from you. There are a lot of good machine shops over there, but its been several years since I've lived over that way, so I really don't know the good ones now. It used to be Paul's was the best, but not cheap. You get what you pay for too.

Link to comment
Share on other sites

Maybe pick up a wide band 02 gauge, they are only $200.

LoL! Yes, you got that right! Except I only need 5 of them for the cars I drive. You're right, no excuse for melting anything since I should have monitors to tell me the state of the combustion chamber BEFORE I ever think about boosting. Even stock boost levels will melt pistons if there is a fuel problem. Let alone turning the non-intercooled boost up a little. I was asking for it. I just think it is quite interesting that the loose pin problem was caught before damage was done. Without the piston melting, I would never have taken it apart to find that.

 

I could just put bungs on all of my exhausts, and at least go around and check them closer with the WB02 I do have. This particular car was completely stock as far as fuel system and no monitoring. I at least have a DVOM on all of my others for the most accuracy that a narrow band can supply. Didn't even have that on this one. Pitiful, I know. At least I'm not whining about melting the piston other than I HATE hyper-u's with a passion! A hack like me needs a cushion!

  • Like 1
Link to comment
Share on other sites

Tim, couple questions:

 

-Are you using a krankvent system? ( I know, blasphemy for asking)

-Is your machinist using Spirolox as his "racer clips?" If so, double up on them if the piston will accept it.

 

-Dave

Link to comment
Share on other sites

No KV's on this set-up, but I do have one on my heavily modified engine. I still don't run very high boost since I don't have the fuel mods installed yet. They work very well with no crankcase pressure under boost.

There are pin locks, but I forgot what type they are. They're at the machine shop. I just bought the wiseco set from Dad a couple of months ago.

I didn't mean the clips are race, but the machinist offered a cheaper pin set-up for racers who don't expect their build to last very long. They basically just enlargen the rod pin hole big enough for the pin to rotate in it, with no bushing. LoL! Thus why I went with the normal bushed set-up for my street driven engine.

Link to comment
Share on other sites

 Share

×
×
  • Create New...