tjsea
Full Access Member
The studs in the actual kit are a hair shorter than the bulk studs to keep them from contacting the rocker guides. Either can be used. Typ4 has been selling the bulk studs long before arp had an actual kit.
Machine shop aggrivations
- Thread starter IDIBRONCO
- Start date
tbrumm
Full Access Member
The stampings were just barely touching the tops of the studs on my engine, so it wasn't an issue, but it was close. I know the studs could not go any deeper into the block. Idiot had this happen on his "Project Asmith", and I believe he got the shorter 6.2/6.5 studs from Justin to solve the problem. While you will probably be okay, it is just one more thing to watch out for.
IDIBRONCO
IDIBRONCO
I'll keep an eye out for that and if there's an issue, I could probably get away with trimming a little bit off to clear the studs.
IDIBRONCO
IDIBRONCO
Well I didn't get to measure the Play Do yesterday I did it today instead. I spent most of the day yesterday trying to decide which way to go with this project. It's definitely overhaul time. I just ordered a set of Silvolite pistons that are -.015. Between that and the .010 thicker Fel pro head gaskets, that gives me .025 clearance already. Two of the valves were at .0045 on the Play Do, but I didn't have the pistons completely spotless and I sprayed WD-40 on the heads and piston tops so that the Play Do wouldn't stick. They was easily .001-.002 of extra "material" in with the Play Do so I should be at the .030 minimum clearance. There is minimal wear in the cylinders and no grooves or scratches either so I'm going to hone and install the new pistons. I didn't think that there should be much wear since there's maybe 130,000 miles on a rebuild that was done before I got the engine. There's still cross hatch in all of the cylinders too. At least that's one thing on this project that finally went my way.
Macrobb
Full Access Member
Why not just have the heads modified to recess the valves? Do not take anything off the valves, just recess the seats. It looks like the seats have a ton of material anyway, so .030 wouldn't be a big deal.
.030 might need a tiny shim under each rocker, but it should easily be taken up by the lifters, so...
.030 might need a tiny shim under each rocker, but it should easily be taken up by the lifters, so...
IDIBRONCO
IDIBRONCO
Maybe I forgot to mention, two of my pistons have marks on the tops where something was banging around on them. I assume it was broken off cheap glow plugs. A third one is starting to be eaten away along the top edge that's closest to the camshaft. This is very common with engines when someone doesn't know how to properly use their turbo. This one had a turbo that came with it. It had about 100,000 miles on a rebuild when I bought it. It would have been cheaper to find another pair of heads too, but I'd still have three bad pistons. That's what made me go this in this direction.
Macrobb
Full Access Member
I'm not entirely sure why this matters, especially the corner getting eaten away a little. The top ring is a good 1/2" down, so a few thou off the corner isn't going to affect it.
Same with the small dents - smooth them out so there's nothing to crack and call it good.
IDIBRONCO
IDIBRONCO
One pit is not so small. Without measuring, I'd say that it's getting close to being halfway through the top of the piston. I really don't want to put the engine together with these pistons just to have issues in a year or two. I'm trying to have this be as reliable as possible. I would worry about it until I had the pistons replaced. With a pit that deep and installing a turbo, I wouldn't trust it at all.
icanfixall
Official GMM hand model
Piston dome thickness is .560 to .58o thousands thick in the center. It gets MUCH thicker near the edges. Now how deep is the hole thats about 1/2 way thru the top???
IDIBRONCO
IDIBRONCO
I haven't measured. I'm just guessing that it's close. Maybe I'm wrong, but it's way too deep for me to feel comfortable with. The engine's sitting in my garage which is 15 miles from my house (long story). Looking at the piston with the "cam side" as the "top", it's just to the right of center, straight across from the right hand valve relief.
IDIBRONCO
IDIBRONCO
Ok. I apologize. I was in "panic mode" when I eyeball measured it. Using the same orientation of the piston, from top to bottom it measures .404" From side to side, it measures .359" My best measurement was only .040" deep. It's still a large pit to of in the top of the piston. The engine is down to just a block now. The new pistons are sitting in my garage. I'll pick the rings up tomorrow.
