Another 3.6->3.8 Rebuild Thread...

[CBRacerX]

After some conversations with Charles and the comments from Henry, I have downgraded the apparent "damage" on some of these cylinders to be not so terrible. So now I will measure them and see if the Piston to Cylinder clearance is acceptable.

Charles provided this procedure that I plan to follow (thanks!!, posted with permission):

Assuming you know the diameter of the pistons and they are all the same since they are new, here's the way I like to measure cylinders.

You will need a table to collect measurements. I like using a digital precision dial bore gauge; I have one that reads in .0001" increments for this. You will want to orient the cylinder such that it is sitting how it would go on the engine. Picture 0 degrees as the top of the cylinder that points towards the heavens. Then also imagine a point 90 degrees clockwise from this point. You will be taking diameter measurements across the bore at 0 and 180, 90 and 270. To be even more thorough you can measure across at 45 and 225 degrees too.
I then measure at .800" down from the top (top being the surface that mates with the head), 1/2 way down the bore (not including the skirt of the cylinder- head to deck length of the cylinder only), and at the start of the skirt (right around the point where the ledge that rests against the case is). You will want to take each measurement such that it is repeatable within .0001". No more than .001" of taper from top to bottom is allowed, as long as the bore remains in spec with regards to total piston to cylinder clearance. No more than .0005" of ovality at any given point within reason, although I do like them to have little or no ovality towards the top (that's why I measure at .800") where the rings will be doing most of their work.
This is hard to nail down because it highly depends on who is doing the honing, the condition of the diamond stones, how many stones are used, honing pressure, etc. There is no such thing as a perfect bore. I have had customers searching for that perfect cylinder who go through the trouble of CMM'ing cylinders and it is possible, but it takes lots of time and $$$.

Another good measure of how square the cylinder was after being remachined (if top deck and cylinder bases are parallel) would be to measure the head to deck length of the cylinder at the four corners (45, 135, 225, and 315 degrees). It's hard to say what is right or wrong other than we shoot for the no more .0002" difference between measurements, although I would guess that anything +/- .0005" is as good as new.

Another measure is the perpendicularity of the bore to the decks, but this is almost impossible to measure statically. We have a special mandrel that centers on the bore across the entire length of the cylinder which we then can freely rotate the cylinder and use a dial gauge traveling across the top deck to do this measurement. Again, we aim for no more than .0002" difference but anything +/- .0005" is as good as new.

All measurements should be taken at ambient 65 degrees give or take a degree or two and all measuring equipment should be at the same temperature. Measuring tools will change their readings as they get warmer, do be aware that if you hold your measuring tools too long it will change readings as much as .0005". The same can be said of the cylinder base that rests against the case, although this is harder to measure.

Before taking any measurements I am careful to clean all tools and the cylinders thoroughly, and I lubricate the bores with a quick wipe of non-detergent 30 wt oil, but any oil will do.

This takes me about an hour to do to a set of six cylinders, and I do it all the time. Be patient and i'm sure you'll be able to do it.

Charles L Navarro
LN Engineering
http://www.lnengineering.com
Aircooled Precision Performance

[cnavarro]

The other thing I neglected to mention is the whole clearance subject. It's the bore minus the piston diameter gives you the total piston to cylinder clearance, since the subject was brought up on another thread.

If you have a used set of pistons and you are trying to re-use them with replated cylinders, short of match honing each bore with a piston that has already had it's skirts collapse, I like to find the largest diameter and set up the bore size based on that, as long as there isn't much more than .0005" of variance between pistons- you don't want one single cylinder to have excessive clearance or slap. Nice thing to note since most platers will not plate and match hone a re-plated cylinder to a used piston, so this is the way to get around that.

[CBRacerX]

Just a little advance warning that this thread will start to heat up again

Camgrinder has delivered my reground cams (Super C2), and reconditioned rockers and shafts (thanks!).

I have the case, crank, rods and heads coming back from the machine shop this Friday. So I am now making the "big list" of everything else I need to purchase, from bearings to sealant to big hammers...

PET is a big help, as is Waynes book for organization. But I do have a few questions...

I know there is another engine gasket kit I can buy aside from OEM, and it has gotten good review here. But I cannot recall the manufacturer?
EDIT: OK, I found that it is Wrightwood Racing

I am using 3.8 (102mm) machine in Mahle cylinders. What should I be using for a sealing ring on top (Supertec Graphite or ???), and what is needed where the cylinder enters the case (larger o-ring or ???)?

On the <3.6 engines it was standard to replace the cam chain ramps. Mine are now 16 years old, and made of plastic - so I guess they get replaced. How about the roll pins used to locate them?

Is anyone using the optional rocker shaft seals?

OK, that is enough of a grab back for now. Thanks everyone!

[cnavarro]

There are many options for the sealing ring. You can first of all use the stock sealing ring on your cylinder (if it has one), or you can flame ring it. EBS Racing can supply sealing rings, as can Performance Developments, who can cut both the heads and cylinders for their interlocking sealing ring. Turbokraft (Chris Carroll) uses an interlocking ring that uses the stock diameter, but gets cut deeper into the cylinder and the heads. You might want to do a search on sealing rings to see what your options are.

As far as the case is concerned, you can o-ring the case. Charlie at Wrightwood Racing can supply the o-rings for when you groove the cylinder spigots in the case. Short of o-ringing the case, I'd just use a thin bead of Curil K-2 at the base of each cylinder. Actually now that I think about it, I would use the Curil either way.

[CBRacerX]

I finally got the parts back from the machine shop today (Atlantic Enterprises EDIT: http://www.precisionheads.com ), and I am happy with the work done.

Crankshaft Polished
Rods Reconditioned
Heads Machined for sealing ring 102mm cylinders
Valve Job with new exhaust valves and Camgrinder valve springs installed
Case Machined for 102mm cylinders

I now just have to do the final case checks (squirters) and cleaning, then start assembly. It is time to start making things happen!

















H'mm - did I forget anything? ...

[herman maire]

Great tread

I cant wait to see it all go back together.

How much $$ did the machine shop work run you? I am looking for a good shop in the east and dont trust any around my area.

[mppickett]

Originally posted by CBRacerX
H'mm - did I forget anything? ...

Nope, looks really good and I see you included the case of Corona.

[CBRacerX]

The machine shop (http://www.precisionheads.com in Pitman, NJ) was $1700, and that included pulling two plugs in the oil cooler area, so I could install an oil filter housing in that location. Includes the new TRW Exhaust Valves.

Tell 'em Chris Brown referred you, I get a bag of candy for each new customer

[CBRacerX]

Sending Dist to Mark Cohen for a belt replacement (preventitive maintenance move)

Mark.A.Cohen@delta.com

The history on this is unknown. It does have the belt vent kit, but this the perfect time to get it current. I am replacing the alternator brushes for the same reason.

[ChrisBennet]

Originally posted by CBRacerX
The machine shop (http://www.precisionheads.com in Pitman, NJ) was $1700, and that included pulling two plugs in the oil cooler area, so I could install an oil filter housing in that location. Includes the new TRW Exhaust Valves.

Tell 'em Chris Brown referred you, I get a bag of candy for each new customer

Note: "Precisionheads" is the web address for "Atlantic Enterprises" The machinist/owner Bob is the greatest.
-Chris

[CBRacerX]

Today the wife and kids went swimming - without me.

I got the case clean - really clean. It took a while, with razor blade, copper brush, heavy duty "paint prep" scotchbrite pad, dremel wire brush and lots and lots of brakekleen (bought the one gallon size). I also cleaned the oil pump up, it was dirty enough that after a partial cleaning it would no longer complete a 360 degree revolution since gunk was in the gears. That took a laquer thinner bath and movement of the pump, then a Brakekleen bath. Also cleaned up the intermediate shaft, and Wayne's book was right on, lots of gunk in the shaft after removing the plug. Cleaning the case sealing surfaces was time consuming, the machine shop had done a great first pass (in fact they cleaned the case twice), but it was not enough. I also confirmed the operation of the piston squirters, and cleaned the thru bolt passages. Cleaned the crankshaft as well, confirmed the oil passages are clear. Also cleaned up the cam towers and new chains.

Then I assembled something! Got the bearings in the case and installed the Oil pump, chains and intermediate shaft. Checked the backlash. Wayne's book has this going in after the crank, but I checked the crank fit installing afterward and all is well.

In the category of "while I was there", I replaced the alternator brushes and voltage regulator.

Next: Crankshaft assembly awaits the new scale from UPS...

[ANTONIO]

I don't see the machined grove on the cyls. spigots, for oil sealing O ring, it will leak some if you don't do it., cheers, Ant.

[kirkf]

I was under the impression that with the green viton O-rings and a little threebond 1211, a leak at the cylinder base was unlikely.
More of a race motor option.

Kirk

[CBRacerX]

I am only going to use the Threebond 1211 on the cylinders, prior experience tell me this will not leak.

EDIT: No Base o-rings are planned to be used, and I may use Curil K-2 on the bases.

[ANTONIO]

As soon as you tight the cylinders down, the seals will split, they are to big for that small grove on the base of the cylinder, 1211 will do its job, but it will be a bandaid fix, if you have everything apart, why don't do it?, this happened to me once, on a 3.8 993TT, I did exactly what you are going to do, in a few months I was spliting the case, to do the RS seals., cheers, Ant.

[CBRacerX]

Thanks for the details, I am not planning on using the o-rings at all. I agree with you that putting them on without the machining is a mistake.
Cheers,

[911teo]

Chris
fantastic thread. I am looking fwd to the updates.

[CBRacerX]

(Re-written in abrreviated fashion after failure to post - arrghh!)

After getting my scale in house, I took a few hours today to weigh the rods, wrist pins, pistons, rod bearings and rod bolts. I didn't consider the wrist pin clips - so sue me

I was lucky that I had just the right combinations of heavy piston and light rod and light piston/heavy rod to get everything to exactly the same weight without doing any machining of the parts (whew!).


Weighing piston w/o pin (417 grams)


Weights and matching components (I got lucky!)


Rods with old bolts removed and surgical cleaning!


Last check of wrist pin fit


All parts ready for assembly

[CBRacerX]

Get unstretched measurement of each ARP rod bolt


Bolts now in place and sizes/locations recorded on build chart


Torquing rods bolts, this was the first time I used the stretch method, these were all set to 0.0120" inches of stretch per ARP specifications:
Before with indicator installed and zeroed


After with stretch indicated


Completed Crankshaft - whoo hoo!

[CBRacerX]

But could not seal up the case tonight because I somehow lost the dowel pin for #8 bearing. Had everything laid out and ready and was about to apply the sealant trio...

Crapzola.

Anyone got one they can spare?

Thanks,