Need some advice on engine rebuild

[leftynridge]

I recently purchased a 7m with forged internals. He was asking 1500 for the engine and I offered him 1200 for it and I would come and pick it up. JE pistons, eagle rods, clevite 77 race bearings, arp components, claimed to of had new crank, new head (port and polished), new cams, metal head gasket, etc.... I drove 71/2 hours to pick it up. When I got there I did a compression test and it was as follows 1-55psi,2-60psi,3-65psi,4-60psi,5-150psi,6-15psi. Needless to say I was pretty pissed off. Once I discovered what the compression was, I damn sure was not giving him 1200 for it. But I took a gamble and offered him 600 for it and he said yes.

So I just took it apart and there was carbon build up on top of the pistons and the rings were shot. However, the cylinder walls were nice and smooth. Everything else looked fine. Now I'm not an engine guy by any stretch of the imagination.

My question is what are some things that you must do to properly rebuild this engine or parts that you guys might recommend going with? Things that I can reuse and things not to reuse etc.....

Any advice or help would be appreciated. Thanks

 

[leftynridge]

So no one can give me some helpful advice.

 

[thedave925]

How do you know the rings are shot?
Why did the guy sell the engine in the first place?
Pics of said pistons and cylinder walls
Was there indeed a metal head gasket? If so, what's the condition of it?
Did you pull the pan at all?

For all i know the walls weren't appropriately cross hatched during the rebuild for the those rings and they didn't seat.
Or maybe the valve seats didn't get lapped and they didn't seat.

There's a lot to guess without a bit more info to go off of.
Pics are worth a 1000 words, get some up

 

[airhead04]

You should always replace the rings when rebuilding. Its just for good measure. Pull the pan and check the bearings, if you see any groves or anything foreign on them, then get rid of them. Me personally, I would just replace the rings and bearings just for good measure anyways. If the headgasket is a metal hg, then you can reuse it, provided it is still good. As for the block, cylinder walls being "smooth" doesnt do much. It needs to be checked by a machine shop.

Its extremely odd that he went from 1500 to 600. He dropped over half the price, which if the guy thought it was such a good engine, he wouldnt have done. So Id say rebuild it. Just to be safe.

 

[IJ.]

Could have 10 bent valves with those compression numbers depending on how big the "new cams" are.....

 

[I6Boost]

Agreed with airhead...

Also was the block bored at all or do you know?

Was there a MHG?

In my own opinion, i dont trust anyone else's work but mine.
So if i were you i would just go ahead and replace all the bottem bearings
with clevite 77's and get new piston rings, you never know what that guy did or
if he even knew what he was doing when he installed that stuff...

Just think of it this way, would you rather do all this work dropping in that motor
and right before you start it you got all these things going through your head like
"Well i hope that guy installed this right, well i hope he installed those right, i hope this
thing doesn't just blow up" etc etc.

And if your not totally sure about everything when you take it apart and everything i would
be more than happy to come and look over everything as i've built a few of these and im dropping
in one as we speak, im also in the dayton area so just let me know.

 

[leftynridge]

How do you know the rings are shot? Not 100% positive. I'm having a friend take a look at them.

Why did the guy sell the engine in the first place? Guy was doing a 2j swap and needed funds.

Pics of said pistons and cylinder walls? Will work on pics having problems uploading them.

Was there indeed a metal head gasket? If so, what's the condition of it? There was a metal head gasket but not 100% sure if it can be reused.

Did you pull the pan at all? Yes I pulled the oil pan when I purchased it to confirm parts that was listed as well as checking the bearings. They were nice and smooth.

For all i know the walls weren't appropriately cross hatched during the rebuild for the those rings and they didn't seat.
Or maybe the valve seats didn't get lapped and they didn't seat.

There's a lot to guess without a bit more info to go off of.
Pics are worth a 1000 words, get some up[/QUOTE]

 

[leftynridge]

Airhead I totally agree with you. I knew that something wasn't right when he came done to $600. Granted I knew something wasn't right when I saw those compression numbers. I knew by buying this engine that it could possibly be a parts engine. But I thought that the parts were worth a least $600. I did take off the oil pan and valve covers before purchase to confirm parts and check bearings etc.... The bearings looked and felt smooth.

The pistons are .40. I was told if the pistons and cylinder walls make out ok I should be able to reuse them again. This would be determined by what the piston to cylinder wall clearance is.

 

[whitemike]

I personally think it was a good buy for $600 as long as the pistons/rods are re-usable that's worth your money right there. I'd rebuild, get the head checked out, get the block machined for new rings/mhg and the crank checked. New bearings, new rings, new oil pump/shimmed. That's the direction I'd take although I've only done a couple of engines. Definitely take IJ's advice as well any other known engine building expert. The mods are definitely good people and here to help!

At any rate, good luck
-Mike

 

[leftynridge]

Sounds like a plan. This will take a while because funds are tight right now but if you want it done right you have to spend the money. Thanks for the advice guys.

---------- Post added at 02:49 PM ---------- Previous post was at 02:43 PM ----------

IJ this might seem like a dum question but I was trying to check out the valves to see if the were bent but could not really tell cause there still in the head. Is there a special tool that you have to use to get them out? Once I get them out what do I look for? Thanks

 

[IJ.]

Sounds like a plan. This will take a while because funds are tight right now but if you want it done right you have to spend the money. Thanks for the advice guys.

---------- Post added at 02:49 PM ---------- Previous post was at 02:43 PM ----------

IJ this might seem like a dum question but I was trying to check out the valves to see if the were bent but could not really tell cause there still in the head. Is there a special tool that you have to use to get them out? Once I get them out what do I look for? Thanks

A leakdown test will give you an idea of what's damaged in the engine, #5 being ok rings the alarm bells as if it were a ring issue why isn't it dead as well?

 

[leftynridge]

Ok thanks I will see what I can find.

 

[leftynridge]

IJ I have discovered That 1,2,4,6 on the exhaust side are leaking and 6 was leaking bad. More of a flow then a leak. But on the intake side there were no leaks at all.

 

[IJ.]

What's the valve lash on that side Lefty?

 

[leftynridge]

That is a good question. I'm a noobie when it comes to engines. So unsure of what you mean. But I guess that's why I'm on the forum to learn.