Time to teardown. Another 3.0 rebuild

[jpnovak]

This thread begins last November with a valve adjustment. Yep, found the dreaded broken head stud on Exhaust #1. Dilivar rears its ugly head again. I have had too much going on to really begin a rebuild other than collecting parts. Last week I dropped the engine. Saturday I got it up on a stand and this afternoon my wife left me alone for a few hours to start teardown.

The build begins with a good pressure wash to rid much of the caked on crud, dust and dirt. The ST has seen some dirt road action and it was very dusty and gravely, especially on top of the exhaust.

First remove heat exchangers. I had no problems except for #2. At some point prior to my ownership an exhaust stud was broken. The replacement was drilled offcenter which made getting a socket challenging to say the least. I had to grind the head of a cheap wrench to fit between the nut and the cam-tower flange. Lovely. Finally they hit the ground after struggling for about 2.5 hours.



next, I removed the chain covers and then valve covers. After loosening the rocker adjusters, I pulled the chain tensioners. Next I plugged the 46mm socket into the impact wrench and quickly loosened the cam nuts. After pulling the sprockets, shim stack and backing plate it was time to loosen the heads. Out came the 10mm Long Hex head and away I went. I managed to find two more headstuds broken. Considering I had only driven the car 3 times in the past 8 months I think they spontaneously broke. these were #2 exhaust and #4 exhaust outer.

Once the head/camtower assembly was off it was time for a quick check. This is a 930/03 ROW 1978 3.0. In fact, it is number 92 off the line. It was delivered with mahle Nikasil cylinders. It was nice find these as I suspected. For the record they have 11 fins and no center rib.

The Pistons look good, nothing but carbon to see here.



Both banks of heads look good. A lot of carbon but really not bad considering how rich I ran my webers and now EFI. All the exhaust valve stems are nice and clean, no caked on crud. I never detected any oil usage, maybe half a quart between oil changes. It is so tempting to wipe them clean and reinstall on new studs. too bad I have "while your in there" syndrome.


Better one:


Better two:



AFter dinner I went out to clean my mess, organize parts and I could not help sliding the cylinders off the pistons and pulling the wrist pins. other than a few mangled cir-clips the effort was painless. No signs of any scuffing on all six. Rings are nice and tight in the lands.

It is now officially a short-block.




And so it begins. I know the next question everyone will ask is... What is your plan for this motor? Ok here goes.

3.2SS using:
98mm Mahle RSR P/Cs. Compression should come out approximately 9.9:1 based on the larger SC head. I will CC to verify.

DRC DC-40-108 grind. John ground these on a slightly wider lobe center to provide a better MAP pulse for my EFI.

Twin-plug heads from G2 Racing. Craig and Denny do incredible work. I had the heads camfered for the 98mm P/C set so I should be able to run an aggressive deck-height.

Nothing fancy in this build other than the thermal barrier coatings on the heads andpiston crowns. I will also DFL my entire valve train.

Should be a healthy ride and make my 2010# ST scoot. I am building for longevity not ultimate HP. I am predicting about 265 HP at the crank. There is evidence of more but I am being realistic on my numbers.

[trev0006]

don't forget to post after pix.

[jaybird840]

Keep posting progress pics, Jamie...That way I'll know when to ask if I can come over to watch before I butcher something on my own motor. Now if I can just figure out how to pace my own rebuild so I'm about a week behind you all the time.... Seriously, I'd love to watch a pro in action...

[jpnovak]

Jay, I am no Pro. This is my first engine build. I just pay attention to those who go before me. Wayne's book, this board and some great friends are what allow me to move forward and document my build.

Tonights activities are limited. I did not have much time in the garage. At least it was enough to pull some dilivar exhaust studs. Now that I had a chance to look the dilivars are quite shiny in comparison to the steel. They also have an alloy "ting" to them that the steel does not. Their resonance might be good for some wind chimes. Of course, they could also end up in the garbage like mine.

I started the night off by pulling out the M10 collet style stud puller. I thought I would try a few prior to heating. Much to my surprise I was able to pull 7 of them with no heat. Just gentle even pressure until they started to barely turn. The farther they came out, the easier they spun. I noticed a white gummy substance on the threads. I assume it is a thread prep/locking agent. It actually reminded me of Park "spoke prep" from my bicycle wheel building days after college.

The remaining 5 studs needed a little persuasion to come out. Rather than the BFH type of brute force I used a thermodynamic approach... The rosebud tip on my oxy-acetylene torch. I opened the valves and fired it up. I placed the heat on the outside of the case next to the base of the stud while placing a gentle pressure on the stud puller socket. It took about 20 seconds or so for the studs to free up and unscrew. This method took care of the two intact studs. now to deal with the three broken.

The only casualties from heating using the rosebud were a couple of rubber bands holding my rods in place (gotta remember to remove those next time) and some burned oil residue on the inside of the spigot bore. Both areas cleaned up nicely with some WD40 and a clean rag.

It seems that Dilivar is extremely hard. I had a really hard time getting a bite on the remainder of the studs. Thankfully they broke off nearly flush with the top of the cylinder. This leaves about 4 inches of material to grip. Clamping the stud did not work. So I had to grind a flat in the stud. I ground the flat using my angle grinder and a thin-cutoff wheel. I went in about 3/4" on two opposite sides. Make sure you cover and protect the chains and case spigots. I am only doing a top-end so cleanliness is important!





Next I clamped a pair of vice grips to the flats. Notice that I am parallel to the longitudinal axis of the stud. This was for clearance of the upper studs. I did not want to have to keep un- and reclamping the vicegrips.



Instead, I used my BFW to turn the vice-grip on the stud. this way, I had more leverage and clearance to keep from busting knuckles on the upper threads. It worked great.



The fruits of my labor. All 12 dilivar studs removed from the case. And to think this all took about 30 minutes. yep, that's right no hourly time commitments to deal with tonight.

[jpnovak]

Last night I disassembled the cam tower and head assemblies. Everything went smoothly except for a nearly stripped 5mm rocker arm bolt. I had to grind the end of the hex key square to get it to bite in the head.

I admit that separating the heads from the cam towers was an exercise in frustration. They did not want to separate. Once out I found that the center studs (under the rockers) were corroded to the cam towers. So far, all 6 heads have been this way. They clean up fine and the locating pins are clean. It just meant a few more blows with the wooden dowel to separate the heads.

Next step is washing parts and then put the heads into the bead blast cabinet. AFter they are clean I can begin the inspection.

[jpnovak]

The best plans have a way of going askew. The original plan was to build the 3.2SS. To make a long story short, the 98mm pistons I have must have had the ring lands recut at some point. After having called several shops the 2.0x1.75x4mm ring sizing is odd. Most were expecting 1.5 x 1.5 x3.5mm ring lands. This means that custom rings were in order and the time and price did not fit my budgets so I decided to go with the 3.0 JE's that were sitting in a box. A few days later a large box of parts arrives. Time to build, err no.

It seems that the heads I had done last winter were chamfered for the 98mm pistons. I did not want to use those so that I could save them for the 98mm PC set. so I sent my heads out for rebuild. Special thanks to Craig Garrett at G2 Racing. He goes by CGarr on the board. His work and turnaround time are excellent.

Now that the day job has slowed to a normal pace of urgency I decided to do a little measurement. Cylinders are in spec. On my dial bore gauge that measure at the top end of the limits but within the wear limits. No ovality to speak of. Cylinders in spec... Check.

Next up was compression ratio. I know many have spoken of CC'ing a head to measure its volume. Let's show how this is done. first you need a burette. I happen to be a chemist and we have many of these at work. I borrowed one and a stand for a few evenings. First you make a plastic cover that fits the diameter of the cylinder mating surface. Drill a hole (or two) for air to escape. Place head upside down on a level surface. Fill burette to known volume with fluid. I used isopropal alcohol (IPA, 2-propanol are all the same). write down the volume (it does not have to be zero). Open the stopcock and deliver the fluid. your setup will look something like this:



As you start to fill the head you will see a bubble form. Here is the bubble getting closer to the fill hole.



When the bubble goes away, note the total volume delivered. it took two fillings of the 50ml burette to fill the head. Total volume is 93.34ml. These heads are twin plugged and there is some loss of volume from the second plug hole.


next up was the piston dome volumes. I did mine slightly different from published methods. I reused the same cover as before. Why not!? The cylinders should be the same diameter as the heads, duh! A little grease smeared on the edge prevents leaks. Anyway... I placed the top two rings on the piston and pushed it into the cylinder. I put a ring of motor oil on the rings to seal them. IPA does not dissolve motor oil so there is little chance of a leak. Next, I pushed the piston until it just touched the plastic cover.



Now I measure the volume of air remaining in the cylinder. Use the same burette and deliver the volume. It is fun watching the bubble disappear. In this case the volume was 66.65 ml.



once finished, I carefully removed the cover and measured the "deck height" of the piston in this position. I get 14.65mm. The difference between the swept area and the measured volume equals the piston dome volume. Pretty simple. I calculated 36.59 ml dome volume.

now the bad news. After spending the bucks to twin-plug the head I end up with a compression ratio of 8.72:1. This is far from the nominal value of 9.5:1 that the pistons should be. This low CR is also far from the previous stories of JE delivering too high of a CR.

It all goes to show you ... To measure is to know.

Now I will continue with my twin plug plans. I guess its good that I did not go with more than a mod_S cam. I do not have enough static compression to support a cam. The good news is that I can run 89 octane all day and night without nary a worry.

[jpnovak]

I have been looking at the numbers. If I use a nominal 90 ml head volume I still only come out at 9.15:1. This means that the little volume loss due to the additional spark plug does not compensate for the small piston dome height.

Now to see if my budget will support some higher compression pistons. If not, I will just screw in the second plug as a place holder and run a single plug ignition.

In addition I weighed out my pistons. Each of the 95mm JE's weighed at 420.X g. The distribution was less than 1g. Each stock Mahle 8.5:1 CIS stock piston weighed 533g. Both were measured without rings or wrist pins. I was shocked at the difference in weight. I was not expecting that much of a difference. Each JE piston wrist pin weighed between 104 and 105g. I will use them as-is provided I do not go to a higher compression setup.

[jpnovak]

I just repeated my volume measurements. No changes in piston dome volume. I thought I might be leaking past the rings. No such luck. This might be the first set of low compression JE pistons. I really thought that wedge dome would have more volume. Of course, the valve pockets are HUGE and really remove a lot of material.

Just to verify I took out a 98mm RSR. These should be 10.3:1 used with an RSR head. The SC head is slightly larger in chamber volume. I measured the dome volume to be 43 ml to yield a compression ratio of 10.1:1. Now if I only had rings to go with them.

I guess I will be purchasing some new pistons tomorrow.

[cgarr]

Jamie, is the bottom end of this engine together? If so could you bolt up one cylinder, piston and head, set to TDC and check the volume filling thru the spark plug hole with the engine rotated on its side? This is what I did on my 3.4 I never had good luck trying to measure everything separate.

[jpnovak]

yes, the bottom end is together. I don't have head studs right now to bolt up a single head. I have thought of doing it this way. If I get studs by the weekend I will try it. Its time to take a motor break and put the car back together after its recent paint job.

[914obsession]

You ran this 3.0 liter with carbs? What cams did you use, I see you were using the stock CIS pistons. I'm building a 3.0 with stock CIS cams and pistons but using webers and wondered if this was a decent setup without getting too expensive. What was the carb setup if you don't mind me asking (the jetting and emulsion tubes)?

Thanks

[jpnovak]

I just bolted carbs on after removing CIS. No changes in cams or pistons. It ran better than CIS, much crisper throttle response. The motor went very flat above 5K. Typical of a stock cam when you are used to an early car. A 964 cam would help but you are leaving lots of power on the table with CIS pistons and cams when you switch to carbs.

btw, I Have a set of pistons that would work well for you.

The carb setup was straight out of Bruce Anderson's "911 Performance Handbook" I used weber 40IDA carbs. Then I switched to a TWM ITB setup using Megasquirt. The car ran much better with EFI than with carbs.

[kenikh]

Who did you have spec the custom rings? How much were they going to cost?

[jpnovak]

Kenik, I did not buy custom rings. EBS thought they could have some made but I don't recall the vendor. I spoke with Henry and he have me a few leads as well. I have not had a chance to follow up.

The rings were going to be quite expensive. This is the reason I was building the 3.0 using pistons I had bought a few years ago and not the 3.2SS. Now I am faced with expensive new rings that will take about 6 weeks (estimated) or buy new pistons. I am trying to see what my budget will support.

Jamie

[kenikh]

Thanks! I guess my question was: "which is cheaper, JEs or custom rings?" I know of numerous 2 liter 'S' Mahles that are in perfect spec except for the ring lands.

[cgarr]

Did you ever check with Hasting piston ring? They used to make me a lot of custom rings for our old outborad racing engines. They are not far from us here.

[jpnovak]

Well, there is an update... Work finally slowed long enough to send a few emails and make a few calls. I was looking for rings for my 98mm RSR pistons that we assume have had the ringlands recut to a larger size. Stock should be 1.5x1.5x3.5. Mine measure 2.0x1.5x4.0. Hastings does not have them. Two other ring manufacturers do not have them. Total Seal didn't have them but is making me a set. Total cost is ~$200. turn around time approximately 1 week. This is far different than the price and lead time I was quoted by EBS. That being said, Troy at EBS was most helpful in putting together a group of other parts for this motor. And yes, I have supported our host as well.

Kenik, Call Keith Jones at Total Seal 800-874-2753. He had lots of sizes that are not available to their suppliers. He keeps the inventory of non-stock sizes and knows what has been made in the past and if he has the material to reproduce a run. He was most helpful.

That being said, I am now back to building the 3.2SS. I have measured the compression of the pistons and I will end up at 10.1:1 perfect for twin plug and street gas.

As soon as I get the rings I will resume the engine build.

[jpnovak]

I realized that I had taken pictures of the DFL coated cams, wrist pins and rocker shafts. (OK only part of the rocker shafts made it into the picture)

[carslutt]

i know this is old but wow, that looks like a real pain to really CC the heads and pistons. ....

[sc_rufctr]

I did it on a Fiat 500 I rebuilt years ago.

That was a two cylinder air cooled engine of 500cc... Tiny motor but it ran super smooth when it was finished and it could keep up with modern traffic...lol

It's not hard to do but you have to be organised and extremely accurate with your fluid measurement and choice of equipment.

Is it worth doing on a 911 engine? Absolutely yes! Our engines are powerful but as with anything mass produced there is an element of imperfection when built by the manufacturer. Porsche probably take more care assembling their engines than most manufacturers but they have always needed to make a profit so some "tolerance" between components is allowed.

Why not give it a go? When/if my engine needs rebuilding I'll certainly being doing the same.