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I would rather be driving
 
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Jonny, I typically use Techline Coatings DFL-1. Application is reasonably forgiving.

Yes, when you coat bearings they will get thicker. There are instructions to burnish down to the final dimension. I would not consider the film thickness increase as a long-term solution to closing up bearing clearance. The films scuff off over time to a given thickness. For example, long term use on piston skirts shows that the film has been removed in spots, though the film lubricity still remains.

I do not have any long term bearing data of my own. On the engines that I have coated parts for I have only torn down top ends for inspection.

There is a lot of descriptions about DFL coatings working in extreme conditions. Look at offroad and motorcycle racing for some good stories. I happen to think that the TX weather and air-cooled engine are an extreme condition.
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71 911T SWT - Sun and Fun Mobile
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Old 01-14-2019, 08:17 AM
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Do you mind sharing which pistons those are? Brand, diameter, compression ratio?
Dan

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Old 01-14-2019, 08:38 AM
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JE. 10.5:1 nominal compression. 95mm for 3.0. I am not building a 3.2SS (98mm), just using what was in my storage shed.

The pistons will be CC'd to measure exact CR. That will all be a yet to come post. Expecting my heads back from Machine shop later this week. (Thanks Craig!). Can complete the head side measurements once they arrive.

The pistons have had some work done to the crown. I radius the top side transition between the valve pockets to smooth flow from one side to the other. I also radius the outside edges of the valve pocket. I think they are too sharp. I just file the edges slightly.
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Jamie - I can explain it to you. But I can not understand it for you.
71 911T SWT - Sun and Fun Mobile
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Old 01-14-2019, 08:51 AM
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Thanks! Do you mind also sharing the valve relief depth(s)?

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Old 01-14-2019, 08:57 AM
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Quote:
Originally Posted by jpnovak View Post
Jonny, I typically use Techline Coatings DFL-1. Application is reasonably forgiving.

Yes, when you coat bearings they will get thicker. There are instructions to burnish down to the final dimension. I would not consider the film thickness increase as a long-term solution to closing up bearing clearance. The films scuff off over time to a given thickness. For example, long term use on piston skirts shows that the film has been removed in spots, though the film lubricity still remains.

I do not have any long term bearing data of my own. On the engines that I have coated parts for I have only torn down top ends for inspection.

There is a lot of descriptions about DFL coatings working in extreme conditions. Look at offroad and motorcycle racing for some good stories. I happen to think that the TX weather and air-cooled engine are an extreme condition.
Thanks!! Another thing to spend money and time on LOL. We have extreme weather too but at the opposite end of the spectrum.
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Old 01-14-2019, 09:34 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #425 (permalink)
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This week has been entirely focused on the engine build. Specifically getting the pistons ready for installation. Yeah, I know many just snap on some rings and slide them in the jugs. But I prefer to spend the extra time. This is one of the reasons a 911 build gets expensive. It just takes time to pull together the details.

Let's start with the CC process. In order to accurately know what your compression ratio is you have to measure piston dome volumes and cylinder head chamber volumes. These are JE aftermarket pistons. They were ordered with a nominal 10.5:1 Compression Ratio (CR). I bought them used/uninstalled a few years ago when a particular engine build changed direction.

To measure CR you have to determine the piston dome volume. The easiest way is to pour some liquid in the top. If you know the piston over volume - you can do a little math to determine the crown volume.

I setup a chemistry burette. I have a 100ml glass burette with 0.2ml graduations. This is accurate for my needs and will give you a calculated CR down to 0.01CC. Yeah. splitting hairs here. The process is not well defined on the board so here is my method.

First you have to install a piston into a cylinder. I will often install a single top ring to help keep it from sliding down. The cylinder is then turned upside down on a flat surface. The piston is pushed down until the crown stops at the same height as the ceiling surface. I used my kitchen countertop. (My wife was already asleep. Make sure to clean up before you go to bed). While the piston is in place, smear a small layer of grease around the perimeter to seal and prevent the measurement liquid from leaking out. I use normal grease and a cotton swab to distribute. This position means that any added liquid will only measure the volume above the piston. The piston is then covered with a clear plate with two holes - a fill hole, and a air escape hole.


Using the burette you deliver a measured quantity of liquid into the piston void space. The liquid goes into the fill hole. When the air bubbles are gone, you read the volume and use this to calculate the CR. If you don't know how to read a burette, go back to your HS chemistry class and refresh your memory.




In my case, I measured a few pistons coming up with an average of 50.1ml of over piston volume. Now, you also have to measure the piston depth. In this case, you measure the distance from the sealing surface to the top perimeter edge of the piston or the lowest spot on the valve pocket, This measurement allows you to calculate an effective piston crown "cylinder" so that you do some subtraction.

AFter the piston over dome volume is measured you have to determine deck height. I install a piston (no rings) and slide a wrist pin in place. Then drop a cylinder on top with no base gasket. You measure the height of the piston edge to cylinder sealing surface. This allows you to calculate the thickness of your base gasket to achieve the desired deck height. In my case, I will use a stock 0.25mm gasket to acheive a deck height of 1.19mm (average). I target just over 1mm for performance builds.

Here are my pistons that are marked with the weight group, the cylinder number to be installed and a directional arrow indicating position in the engine. The two heavier ones are at the flywheel end. The two lighter ones are at the crank pulley end. Done.





I will show the same results on the cylinder heads once they arrive back from the machine shop next week. They are currently on a truck between here and there. The chamber volume is the remaining number to calculate CR accurately.

Next, I weigh pistons and adjust the groupings for position. My scale measures to 1g. That is close enough. After a short period of time there will some carbon buildup and the 100mg tolerance is quickly awash. So, weigh pistons and wrist pins individually. Make a table of their weights. Mix and match until you are close in weight. These JE were close. Pistons were +/-1g and wrist pins were 2 g tolerance. I put a heavier pin with a lighter piston and end up with a group of pistons and pins that are 1g deviation across the group. I am totally fine with reaching the tolerance limit of my scale. Here are the pistons and pins grouped together.



Oh, I forgot to mention. The wrist pins are also coated. I use a different product here. Basically, Tungsten disulfide powder. I make a slurry and wipe it on. Noticeable reduction in friction. This coating only works well on highly polished surfaces like the new piston pins. There. Secret spilled.


Next up, you have to size and gap the rings. Due to combustion heat the rings will heat up and expand. If the gap is too tight, the ends of the rings will meet and then bind against the cylinder wall. This causes excess friction and wear and yes, more heat. Its a downward spiral to wearing out your engine.

So, Again I install a piston in the cylinder. I use a small spacer block underneath to raise the piston so that the ring is seated about 20mm below the surface. Then insert a ring and push it down so that it seats against the top of the piston crown. This is just using a piston as a locator.




when you remove the cylinder the ring is now parallel to the sealing surface and the ring gap is easily measured.




I use two feeler gauges to measure ring gap. You can calculate the ring gap based on manufacturer specifications. In this case, JE specifies a formula that is cylinder diameter (measured) x a tolerance factor. The result is a target gap. The gap is different for top and middle rings. Make sure you measure both and keep track of them. I take them out of the package, measure and write the gap value on each package. I also keep a table on my notes.

The feeler gauges are setup like a go/no go. One is at the gap I want. The other is one size larger. Here you can see that the as-delivered new ring is a no-go.




The ring comes out and ready for adjustment. I use a very small, fine, flat file. Its wide and easy to hold.


The new ring has a coated surface on the edge. This is the dark coating.




AFter a few passes with the file the edge is gone meaning I took off a few 0.0001".




You keep fitting and filing until the ring gap is set to your liking. Here is my ring gap set. In this case, the specified value was 0.018".




The rings were then installed on the pistons and rotated such that the ring gaps are properly oriented. oil ring gap goes up, and compression rings are lateral and opposite. A few drops of oil on the rings make sure they rotate freely and with no binding. I will be installing them in the cylinders this weekend.
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Jamie - I can explain it to you. But I can not understand it for you.
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Last edited by jpnovak; 01-18-2019 at 07:18 AM..
Old 01-18-2019, 07:08 AM
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Yup. This is pretty much how I would do it too.
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Last edited by nameisbauer; 01-18-2019 at 09:37 AM..
Old 01-18-2019, 07:21 AM
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helluva thread my friend. ...I want a ride this Spring. (possibly on some really nice hill country roads)
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Old 01-18-2019, 09:05 AM
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Jay, I am sure that can be arranged.
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Old 01-18-2019, 03:23 PM
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As always, great documentation!

One question about cc'ing - what liquid do you use? If using water do you add anything to it to lower the surface tension to make the burette reading more accurate?

Another question - are Goetze rings standard with the JE pistons or was that an individual choice you've made? I have JE pistons (98mm) from my motor, they are in good condition but plan to file/fit new rings. Haven't even started down that rabbit hole yet - never had to chose a ring for nikasil but presume they need to be a chrome faced ring?
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Last edited by Jonny042; 01-19-2019 at 06:51 AM..
Old 01-19-2019, 05:35 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #430 (permalink)
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Jonny, I use a mixture of water and 30-40% isopropyl (rubbing) alcohol. Yes, the alcohol is to cut the surface tension.

The Goetze rings were spec'd by the PO when the pistons were ordered. I think JE uses rings that are very similar to Total Seal. I have used Total seal before with good results. I could be wrong.

These JE are also spec'd with radius wrist pin clips rather than their usual spiral lock. Thank Goodness!
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Old 01-19-2019, 09:26 AM
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In the last installment I was working on the engine.

My heads came back from the machine shop. Craig Garrett (G2 Racing - Cgarr on the board) does an amazing job at a reasonable price. The usual stuff was done. Valve guides, seats, resurface, twin plug, etc. I also had the CIS ports welded up and the intake drilled for MFI ports.



The heads were then ported to clean up the casting around the valve guide and to remove casting flaws through the intake and exhaust tracts. They were opened up slightly to match the cam spec, peak HP rpm and overall gas flow rate (velocity). I have my favorite target numbers. Let's just say I usually favor smaller ports even if it slightly limits peak HP. The area under the curve is where its at.

Eventually the longblock was finished. Cams are timed. Just waiting on a few ancillaries to button it all up.




Since the longblock was finished I have to move quickly to start dressing the engine. I have opened up the throttle body and stack diameters to match my heads. They are tapered from top to bottom to help optimize flow and feed the Horsepower beast.

Along the way I have been test fitting the intake, fan and shroud. So far, so good.



And yes... Its a totally stock 72T engine. That's my story and I am sticking to it...



Under the car I have finalized my brake setup. 930 brakes front and rear. All new brake lines from the MC to calipers have been installed. Can't have enough brakes.





I also spent some time and refinished my cookie cutter wheels. This is a media blasted finish with satin clear coating. I thought this was well matched to the car.




However, in case anyone want to know... Cookie cutters will not clear 930 brakes unless you use at least 12mm of spacers. The internal support rib on the backside of the spokes hits the caliper. And it doesn't hit the fins. It hits the caliper half bolt. No shaving possible here. So... I had to get some different wheels. A local friend gave me a great price on some 15x7 Fuchs. The forged wheels have a flat backside of the spoke and clear with no issues. I knew this but didn't want to spring for new wheels at this time. Oh well. The paint is mostly stripped for the first step in the refinish process.



On the body I Have been working on panel installation. The front and rear bumpers are installed. I think they came out great. The oil cooler ducts and rear venting on license panel are well proportioned to the car. So far, its a winner to me.






I also installed the passenger door. I was waiting for some new hinge pins. One of mine was slightly bent and I didn't want to install it and not be able to get it out.

Here is the car on Fuchs with almost all the panels installed. So far, so good.



I am into a 6 week window to make HCR19 in March. Its going to be tight. I wish I Had more time so that I could finalize a few details of the build. But, I would also rather be driving it.

Next up is to finish dressing the engine, mate it to the transmission and get it in the car. Then I can wire the EFI and finalize my oil cooling system.

All these projects are converging at a rapid rate. I just have to remember to take pictures and document along the way.
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71 911T SWT - Sun and Fun Mobile
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Old 02-06-2019, 07:57 AM
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I've been looking forward to an update..... and am very impressed with the progress! Keep up the great work and thanks for the inspiration to get to the shop and get to work!

As always, thanks for sharing.
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Old 02-06-2019, 08:31 AM
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Thanks. The Day Job has been taking a lot of time and some travel. Stuff has got to get done but missing even a few hours of garage time has me guessing if I will make it or not.

Only one way to find out. Keep pushing forward.

Funny thing is that I have a mental list of the absolute minimum things needed to drive the car to the event.
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Old 02-06-2019, 09:59 AM
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You probably don't need to be told this, but just in case - don't let a self-imposed deadline ruin your enjoyment of the process.

Personally I don't enjoy myself as much when I have to worry about time, I build cars to escape that sort of pressure!
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Old 02-06-2019, 10:02 AM
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Exactly. I am enjoying the journey. I love all the working pieces of this giant puzzle that have been floating around the garage for a few years finally dropping into place. The fact that sub-systems of the car are getting completed and that there is visual representation of completion really makes it easier. I can see that stuff is getting done and that really helps.

I do have another car that is perfectly capable of making the event. But I would love to take the new one. Even if that means taking the big tool bag and sorting some issues along the way.
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71 911T SWT - Sun and Fun Mobile
72 911T project car. "Minne" - A tangy version of tangerine
classicautowerks.com - EFI conversion parts
Old 02-06-2019, 10:09 AM
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YES keep pushing forward can't wait to see it at HCR
Old 02-06-2019, 02:47 PM
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Looks hot!
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Old 02-14-2019, 04:18 AM
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Nice write up Jamie! Looking forward to trying to keep up with you in this car at HCR. For those that haven't followed or ridden with Jamie he is an efficient driver=fast.
Old 02-14-2019, 05:02 AM
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