Saving an old 2.7 case
 

What did I have to loose? So far so good, also added supports to mains: and took about 4 thou off the case halves: Reposted from GruppeB, you know, GruppeB those cheap Bas**rds


Well, Just got done center boring the case back to standard, This worked out so much better than I thought it ever would, I guess all that measuring and testing paid off. Here are some pics of the process. I then cleaned up the old bearings, set the crank and bolted it up to see if I was even close. This thing turns soooooo nice, I was surprised to tell you the truth. i dont know what the clearance is yet because I did not plastigauge it but the center main bores are within .0002 of standard. I guess all those nights setting up and resetting the reamer paid off.

Cutting the mains
http://i30.photobucket.com/albums/c3...1/casebore.jpg


Checking the finished bores
http://i30.photobucket.com/albums/c3.../casebore2.jpg


Setting the crank
http://i30.photobucket.com/albums/c3.../casebore3.jpg

Nice!

Oil bypass mod done!

http://i30.photobucket.com/albums/c3...r91/oilmod.jpg

Craig,

What's the history of this project, was this a line bore to standard following surfacing of the case, or to oversize with the case the way it was? On one hand, the bearing webs look like they have been surfaced, but on the other I see some red dye at the upper right and the right half has an M10 and two M8 studs installed, which makes it hard to surface :)

The plan was to bring the mains back to standard, the mains were oval shaped as many are in these cases, I took the case down as far as I dare, (all studs removed) the only area which is about a thou off is where the red dye is but that is not a critical area and it still bolts up well, next I used my jig to ream the main webs for the insert guides, then installed the necessary studs to bolt the case back together and bored the mains, next will be to cut the lay shaft bearings and the flywheel seal area. I didn't want to take off so much as to alter the chain boxes. I still have the casesavers to install but didn't want to do that until I knew I could bore it back to standard. Remember I really never thought this would work, it was a junk case and really only started as a personal challenge, I was running out of things to do! I'm almost 50 and been married for 20 years if you know what I mean!

Nicely done, Sir. :)

IMHO, this should SOP for ALL mag cases, nowadays.

After whipping out a home made cutter on the lathe I cut the rear main seal in the case.

http://i30.photobucket.com/albums/c3...r91/cutter.jpg

http://i30.photobucket.com/albums/c3...91/cutter2.jpg

thats a great jobs. I like to do a lot of stuff by my self because I consider it a challenge.
Craig, I think that you have do a lot of machine shop works, do you have a special procedures to remove the rusty cylinder heads exhaust studs? Mines are no broken yet, but in very very bad shape that I would like to replace all with a new ones.

If you really want more time in the shop, I have a few cases you can do.

Repaired the badly corroded oil relief tube with an aluminum sleeve, reamed to oversize and made a sleeve, only thing to do is re drill the ports.

http://i30.photobucket.com/albums/c3...mer91/tube.jpg
http://i30.photobucket.com/albums/c3...er91/tube2.jpg

That will be a good motor to test in the 74 when the body is completed

Craig, did you use an interference fit on the oil tube?

It was just a light press/slip in fit, and I bonded it in. The problem was I finished bored the center for the piston first and if I had to press it in then the bore would have been changed. If I was to do it again I would have pressed it in leaving the inside a tad smaller then reamed the bore to 15mm

Yea but its going to be a long time with only one sponsor so far, there is plenty of body panels for others!!!

man, if I lived near you I'd be camped outside your shop until you taught me what you know.

We actually have two shops......one for the clean work and the other for the rest

I'm about to build one (shop) for my stuff. Looking for a spare 2.4 or 2.7 to build. The 2.2 I built has over 1500 miles on it and is running better each time I drive it so I'm fairly confident she'll hold together. The 2.4 or whatever I get will take what I learned from that a couple of steps further. Nice looking machine work your doing there.

Sleeving the bore was a good idea, but did you consider using Bronze or Stainless for the sleeve?
I have R&O'd a bunch of piston-in-bore apps using Bronze, and I find the long term results are better with the harder material.
Also...when cutting the side openings in the newly sleeved tube, you might want to back cut the edges to prevent early galling of the piston.
Good job
Bob

Here is the other shop and the ENZYTE sponsored project:D


[IMG]http://i30.photobucket.com/albums/c3...er91/slant.jpg[/IMG]

Had to make a new plug since the reamer took out the original case threads. New threads are 3/4-20

http://i30.photobucket.com/albums/c3...mer91/plug.jpg
http://i30.photobucket.com/albums/c3...er91/plug2.jpg

Very clever replica of the old plug! "Modern" plugs have a hex head so you don't have to get out the P74!

While waiting for my shell reamer to cut the lay shaft bearings I made a jig to cut oil grooves in the main and rod bearings. This is just an old test set. Yes I'm bored..

http://i30.photobucket.com/albums/c3...91/bearing.jpg
http://i30.photobucket.com/albums/c3...1/bearing2.jpg

Nice work!

I have a similar jig we made to cut the bearings.

http://www.rudtnersracing.com/engine/one.jpg

http://www.rudtnersracing.com/engine/finished.jpg

Dont think there is a need to modify the rod bearings though, you want them to be as robust as possible. We have more than a few engines running with the crank crossdrilled and the main bearing modified, not the rods.

On a 9000 rpm engine we built we reground the rod journals, had the radii modified, etc. and used Clevite Nascar rod bearings ;)

You can get Clevite bearings already cut if you ask.
Also...Clevite has a special type of cut they do to make the oil groove area look sort of like a leaf (veins) to allow the oil to migrate to the outer edges.
I have used these in high HP race engines and find they do reduce the oil pressure slightly, but the longevity is amazing.
Also...Clevites have embedability (?) properties that will save the crank instead of galling it.
Bob

this is the first time I heard that. Do you have pictures of how that bearings looks? Also what is the purpose of that modification in the engines, better lubrication at high speeds?

No pix I'm afraid, but the overall look of the grooves are like those in a leaf of a tree.
The main groove goes along the bearing and the shallower diagonal grooves lead off of that main groove.
Let me stress the importance of the smaller veins going in the correct direction....with the rotation of the crank...and they are very shallow...almost like lines drawn on the bearing.
I haven't used them in some years, so I cannot state that they still carry them.
The idea was to allow full width hydraulic lift on the bearing.
You know that in operation, the bearing does not touch the crank, only the oil "wedge" supports the crank.
If evrything is correct, the worst thing you can do is "start" the engine, because every time you do, the oil has to build up pressure to "lift" the crank.
The best possibility is to never shut the beast off.
This is why big diesel rigs last so long, they rarely ever get shut off.
Bob

thanks, I understand now.

Got the layshaft case bore cut, 26.5mm and 27.5mm on the money, piston oilers are out, next is the case savers, then a good cleaning.

http://i30.photobucket.com/albums/c3...1/layshaft.jpg

Wanted to check the crank in the case before I go any further. I got .002 on the mains, .0015 on the flywheel and .001 on the layshaft.

http://i30.photobucket.com/albums/c3.../checkcase.jpg
http://i30.photobucket.com/albums/c3...checkcase2.jpg
http://i30.photobucket.com/albums/c3...checkcase3.jpg

Craig, great job so far. I'm enjoying watching this progress. How did you get your case looking like an Aluminum case? Man, that thing looks clean for a one-time basket case.
Dion

A speical G2 formula that is in testing stages right now

So, are the tests done, and can I get some? :)

Dion

Are you not using a dial bore gauge to measure the bearing clearances and ovality of your case? I am concerned the accuracy of plastigauge is not accurate enough for this. It won't show an egg shape in your main bearing bores (although I doubt there is any).

Did you use a fly cutter or a face mill for your case surfacing? Also how do you account for the taper in the bed/ways of your mill?

The case was surfaced on a surface plate not a mill. The bearing bores were cut with a shell reamer then checked with a bore gauge. The plastigauge was only used to check crank bearing clearances not to check bearing bores.

Craig

do you do this for a living or a hobby.

I have a couple of 2.7 cases that need saving.

Michael

Right now its just a personal challenge, but if you have a case that is headed for the trash anyhow, then we have nothing to loose. I would like to get 2 or 3 more done before I will call it just luck on this first one..

Has anyone tried machining the case halves and using an automotive line hone instead of boring? I can't picture that a few thousands would be enough to require the main seal to be re-bored. I have a mill to machine the halves and access to a line hone........Don't know how to do the intermediate shaft bore. Got the daughter project engine to do.

Very difficult to hone a hole into round.
Boring to make it round...then honing to size (slightly) is preferred.
The hone is a spring loaded tool and as such will "bounce" in and out as it hits harder spots in the parent metal.
This will end up making an out of round hole.
And dont forget...after machining the case halves....the seal hole will be oblong to start with.
Bob

Bob, the Sunnen automotive line hones are rigid and not spring loaded. They are about 4 feet long. On V-8's you cut the main caps, bolt it together and line hone all the mains at the same time. It does a great job. I can't see any reason why this wouldn't work for a split case after machining the case halves. The problem is going to be the intermediate shaft. Anyone tried it?

I have a 2.7 engine coming apart and I'm sure it's gonna need a repair.

Craig,

I now have 2 cases to work on(as projects to learn and practice on) and wanted to know how you checked the case half mating surfaces to arrive at the .001 off?

I was planning on mounting the case level, and using a dial indicator on an arm go over the surfaces. Any suggestions?

D