78 3.0 engine rebuild 2/11 - Page 2

TibetanT · TibetanT's Garage

Tom, thanks for posting the link to this video!!

If I understand the thought process correctly, this would suggest that all the connecting rods have their respective (stamped) numbers facing one way, correct?

I also took notice that they did not use Red Loctite on the rod bolts to secure the nuts.

tom1394racing · 02-26-2011, 01:07 AM

Do a You Tube search on "Nick Fulljames". There are about a dozen short clips describing the disassembly and rebuild of a '68 Mg case engine.

Flieger · Flieger's Garage

So, is it just so that you see which rod is which? Is there a reason the numbers have to be up?

TibetanT · TibetanT's Garage

Okay, I was able to get out into the garage today and check my 3.0L crankshaft. Here is what I have found:

All numbers stamped on the connecting rods are facing one way. I double checked the Bentley and it states that "all marked numbers should face exhaust side of engine."

Makes perfect sense when you think about the physics involved with the crankshaft moving in a clockwise rotation.

Hope this helps.

Flieger · Flieger's Garage

But if the rod is symmetrical, why does it matter?

tom1394racing · 02:30 PM

The rod is actually not completely symmetrical. The non-symmetry comes in because of the bearing notches in the big end. The trick is to orient the rods so the the notches are on the end opposite the side load.

Flieger · Flieger's Garage

Thanks, I will accept that. I did not know they were asymmetrical.

Incidentally, I saw an Aluminum connecting rod cap from an engine AJ Foyt used at Indy. It was cracked in half and the crack clearly began at the stamped number "3" where there was a sharp edge on the top (straight line) of the 3. It was pretty shallow but stamped on the thinnest part of the cap, right on the bottom middle. You could see the fracture pattern pointing to the initial crack. Premature fatigue due to a stress concentration.

tom1394racing · 02-26-2011, 06:44 PM

I think with the Porsche rods it is the bearing notches that are the stress risers. Orienting them on the non loaded side of the rod journal reduces the risk of rod failure.

boyt911sc · boyt911sc's Garage

Quote:

Originally Posted by tom1394racing

The rod is actually not completely symmetrical. The non-symmetry comes in because of the bearing notches in the big end. The trick is to orient the rods so the the notches are on the end opposite the side load.

Tom,

Would you be kind enough to illustrate or demonstrate this with some show & tell (pictures)? I'm still a little bit lost in your explanation because of my unfamiliarity with 'bearing notches' and 'end opposite the side load'. Really appreciate your posts. Thanks.

Tony

Flat6pac · 02-28-2011, 05:03 PM

Tony, I ll be at the shop tomorrow and get a couple pictures of the rods to answer your problem.
A few days ago PP wouldnt upload the pictures and now I found the patch cord to get the pictures loaded. The sealant seems excess but it requires application to both sides..but then I ve not had problems with center sealing.
Bruce

boyt911sc · boyt911sc's Garage

Quote:

Originally Posted by Flat6pac

Tony, I ll be at the shop tomorrow and get a couple pictures of the rods to answer your problem.
A few days ago PP wouldnt upload the pictures and now I found the patch cord to get the pictures loaded. The sealant seems excess but it requires application to both sides..but then I ve not had problems with center sealing.
Bruce

Bruce,

Is this the Y- bond (???) you mentioned to me one time? How many type of sealants do you use for your assembly? What happens to the excess sealant inside the crankcase? Could it peel off and get mixed with the internal oil? Just curious to know and learn from your engine rebuild successes (hundreds and counting). Thanks.

Tony

Flat6pac · 03-01-2011, 12:54 PM

The Y-bond doesnt break off, its actually hard to peal off the outside..
I use three different sealants for the engine, aircraft permatex for the heads to cam carriers. 574 for the lower parts of the chain case and cam gaskets.

Now the rods
The chat was the numbers are embossed on the side with the bearing notches.
The pictures are 2.4/2.7 rods just randomly pulled out of a box, it appears the number stamp can be on either side of the rod, no correlation with the notches for the bearing.

Bruce

Flat6pac · 03-03-2011, 05:33 PM

The shroud came back from a weekend at the spa on Monday, looking good, thanks Gary. Thats not paint, thats clean,
Bruce

carslutt · carslutt's Garage

awesome!...... i just took my 78' sc for its last drive before i start its motor over haul. thanks for the info

Flat6pac · 03-04-2011, 02:18 PM

The engine is a 78 euro. I installed the .25 base gaskets so it will have the 8.7 CR that the engine calls for.
Put a couple hours on it, P/Cs installed and the cylinder tin, all the circlips accounted for...
Bruce

boyt911sc · boyt911sc's Garage

Bruce,

How do you clean the your crank case? I've been cleaning and brushing my crank case for many hours and it is not cleaned and bright as yours. Any particular method or cleaning solution you used? The parts are all here now and ready for assembly but my crank case needs some TLC. Thanks.

Tony

Flat6pac · 03-04-2011, 05:02 PM

I have a Safty Kleen large sink and clean fluid, bunch of different brushes, AND the cases always look better in the pictures.
Bruce

Flat6pac · 04-04-2011, 04:24 PM

I ve been walking and working around the engine for a while and the 4 cam carriers full of heads as I m doing another 4.0 at the same time. Its time to give the heads to the machinist
Mike, you were righ about the broken spring on #1 intake, here is a picture of the spring as I just pulled the head from the cam carrier. There was nt a substantial sealant between the heads and the carrier as noted in the picture.
The heads in the shop first thing in the morning.
Bruce

ninesixfour · 04-05-2011, 06:02 AM

Two questions for you Bruce:

1. How many miles were on these motors, specifically, the one that had never had the case opened that looked so good?
2. How did you get the engine shroud so clean?

Flat6pac · 04-05-2011, 06:23 AM

Both of the engines I m doing right now have about 100K miles. I open the cases basically to reseal because I have rebuilt 100K engines, 3.0 and 3.2 and if the owner was standing next to me questioning why the old bearings look like the ones going in, there is no wear on the old bearings. I have seen 300K on the bottom and the bearings look great.
A friend said he would clean the shrouds and they came out near mint. I dont have the desire to stand and polish.

Bruce