2.4 MFI Floppy Pistons

[Bobboloo]

I have a 2.4T rebuilt to E spec and I have noticed that the pistons are sounding floppy when the motor is cold. The motor was rebuilt by a previous owner. I didn't get a rebuild sheet cause he didn't have it anymore. Well repeated compression checks have shown diminishing numbers. Also the drain plug for the oil has a dark gray metallic paste. The case is tight and doesn't leak oil. The car runs fine but is loosing balls. So I decided to crack it open and inspect the pistons and cylinders.
A side note here: I found that you can pull off a whole bank of heads, with the heat exchangers, the chain housing and sprocket still connected to the camshaft,and cam housing all in one piece. The MFI stacks of course had to be taken off because of the engine shroud. I did this because (a) I didn't have the 8mm tool for the heat exchangers. (b) I didn't have the two expensive tools for removing the camshaft sprocket. and (c) I'm lazy and always looking for a short cut.
I also made sure that I heated up the 10mm head stud nuts with a propane torch before I loosened them as I didn't want to disturb the head studs because without a build sheet I didn't know if the case had been timeserted.
Well upon my inspection my suspicions were confirmed.Someone rebuilt the motor with worn out pistons and the rings were chewing themselves and every thing they touched. Here's the numbers in inches ...

Top Ring Groove Clearance
.007 max allowed is .004

Ring End Gap
.05 max allowed is .039

Piston to Cylinder clearance
.75mm
I guess you would divide that number by 2 so as to center the piston but still that's a lot.

The case appears to have timeserts and the cams and the valves look good. Also the motor was rebuilt with T (iron) cylinders so I think that has helped in the condition of the case as the cylinder and studs have the same thermal expansion rate.

I'm planning to sell the car but I didn't want to sell without disclosing the compression issue. Just cause I got stiffed doesn't make it right for me to do the same. So I plan to fix the problem before I sell.

Options:

(1) 2.2S P+C's 9.8:1? used in spec hard to find not cheap.

(2) 2.7S P+C's used in spec cheap, available, have to bore the spigots and cut the heads.

(3) 2.4*(85mm)J+E 9.6:1CR $1000 , and I have to bore my iron cylinders to 85mm. If they're not already past that!

Options #1 or #2 I can pull off for a little under $1000. However #2 would have 8.5:1CR. I would also have to put a set of Webers I have on it because my MFI is setup for 2.4. Option 3 costs the most but I don't have to open the case and have it machined. I also can leave the MFI setup on because it should be in the ballpark I would think. Also the iron cylinders should be easier on the case.

Which would you choose?
I'm kinda leaning toward #3 because it should be a blast to drive and the longevity factor might help me in resale over the 2.7.

Also does anyone know if 2.7S CIS pistons have a deep enough pocket for E cams?


*85mm should be a true 2.4 liters

Bobby
72TE' Coupe
72' Targa/Roadster Project awaiting 3.2 donor car.

[Early_S_Man]

Bobby,

Yes, #3 is the 'BEST' option, IMHO ... if you get that far into a rebuild. If you do decide to proceed, be sure to visit the JE website and look at the price list ... when I checked last year, the 911 pistons with valve relief cuts were only about $117 each. If you can order through a friendly local shop for a 10% special order fee ... that is a LOT less than $1K!

Before you decide not to open the case, please pull the rods and inspect the bearings ... that engine seems to have been suffering pretty badly, and lots of nasty stuff may have been circulating in the oil supply! That engine may be pretty-well wasted???

I fail to see how anyone with any integrity could call an engine 'rebuilt' to 'E' specs when it has worn-out 'T' cylinders and pistons still in it??? If he actually put 'E' cams in it, AND an 'E-spec' MFI pump in it, it still isn't 'E-spec' when you leave those cylinders in it, so I have to wonder if it even has 'E' cams, much less anything else done to it! I'll wager those are still the original 'T' cams ... with a bit of wear on them!

[Bobboloo]

Thanks Warren. I appreciate the advice. That's a good point about the bearings considering the particles that were in the oil. I know better but I think I'm still in denial. There was no brass color in the oil drain plug but all the same I'll pull a rod and inspect. If the rod bearings check out do you think that the main bearings and oil pump are safe without inspection.
I hope I don't need a total rebuild because that might make this a parts car and I really need the room so I can proceed on my project car.
The pistons are, or should I say were, E pistons. I'll pull the cams out and check the number on them.
I thought the JE pistons were cheaper last time I was on their website. I got that price from EBS. JE's website is under construction. I'm literally 5 min. from Pelican and 15 min. from Otto's. I'll check with those guys. JE is about 30 min. away but I don't know if they sell direct. It's bad business to under cut your dealers. Shasta sells their version and it's also $1000 for a set.

[Bobboloo]

Well Warren, you guessed right. The bearings are shot. Not sure what I'll do. I may just buy a used motor. Maybe I'll store this one and build a RS motor out of it later. The case seems real nice.
The bearing wear is unusual. I'm attaching two photos to show you. These came off the #2 rod. #2 had the worst compression. The clamp side of the bearing has virtually no wear. The rod side has exceessive wear on one of it's side. It seems particles in oil would have caused wear all over. Could this be caused by a contaminate when the motor was assembled?
I hope the photos work. I've never attached them before.

Bobby

[nick-moss]

Bobboloo

Try changing the file name of the image so that is doesn't have any spaces in it.

Bearing A.gif appears as Bearing%20A.gif

Try BearingA.gif or Bearing-A.gif

[Bobboloo]

Let Me Try Again

[Bobboloo]

Thanks Nick,
I was in the middle of switching them to jpegs when your message came so I took the space out. I use Macintosh which doesn't mind spaces I guess.

Bobby