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> Engine Rebuild, 2.5L Six
jfort
post Oct 4 2017, 09:18 AM
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I doubt that there will be anything earth shattering or even beyond common knowledge, but if only to document this project, here goes:

This is a big, first time project for me, an attorney and mechanic wannabe. My factory six with a 2.5L engine was missing. Turns out there was only 75% compression in #1 and it was leaking through the inlet valve. Auto Assets in Powell OH diagnosed and my friend and mechanic, Jay Kjoller confirmed. Thankfully, Jay, an experienced air cooled engine builder and racer who lives nearby agreed to take on the project and to let me help. I got the engine out and delivered it to Jay last week.

Attached Image

We started the disassembly yesterday.

Attached Image

Learned some things about the engine. It has an early aluminum case with Mahle 90mm pistons and Nikasil cylinders. Pretty sure they are 2.7L. It has a later 3-ribbed oil pump, which Jay says is sufficient for what I do.

Attached Image

The pistons have been lightened, which Jay said was unusual.

Attached Image

We expected to see something that would explain the problem with #1. Other than some carbon accumulation on the head where the valve closes there was nothing. But, having gone this far, we decided to go from top end rebuild to a full rebuild and we split the case.

Considerations. I think the engine was built into a 2.5 in the early 70's given SCCA classes at the time, but it is just a guess. My prior owner was Jim Chambers in Oregon. He bought the car in 2001 from Werks 2 in in Burbank CA, which was started a long ago by Harry Bieker (Bieker Engineering) and continued by his son, Galen Bieker. I exchanged emails with Galen but he couldn't remember any details that would help us decide how far to go on the rebuild. But Jay said whoever built it did a good job and he can recognize the approximate build date from the materials used, e.g., paper gaskets and 3 thin copper seals at the bottom of the cylinders. What I would call the wear points, (bearings, cam lobes, valve tappets, etc.) looked to be in good shape. But I wanted to be sure.

Jays says he has had good experience with something other than the existing E cam, a Solex cam? that is a little more aggressive. So, we are going to either source that or investigate grinding the E cam.

Attached Image

Friday, I will wash all the oily parts. Heads, valves, piston rods go to the machine shop, which is nearby. What can go into a hot bath tank will go there. What can be powder coated will go there. The air shroud, which is green, needs something. Not sure what to do about that.
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mepstein
post Oct 4 2017, 09:28 AM
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Early aluminum case - score!
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Optimusglen
post Oct 4 2017, 09:30 AM
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Are you running MFI or carbs?

I ask because I'm rebuilding a 2.2T carb motor right now and was considering trying to source a set of E cams for mine. If you're going to be regrinding anyway, would you consider a cam swap with some cash on my end? My T cams are in perfect shape.
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jfort
post Oct 4 2017, 09:38 AM
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The engine has Weber carbs. Let me see what the plan for the carbs is. Either way at my end, perhaps we can work a deal.
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krazykonrad
post Oct 4 2017, 10:01 AM
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(IMG:style_emoticons/default/popcorn[1].gif)

Looks like an interesting project. Good luck with it.

Konrad (fellow attorney and mechanic wannabe)
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Perry Kiehl
post Oct 4 2017, 11:52 AM
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There's a lot more cam options today, than there was in the early 70's.

You'll have a good time putting this together!
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Edward Blume
post Oct 4 2017, 12:23 PM
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Some additional HP sounds like its in your future. (IMG:style_emoticons/default/shades.gif)
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GeorgeRud
post Oct 4 2017, 01:21 PM
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Lot's of folks used the 2.7 CIS pistons and cylinders with the 66mm crank to get 2.5 liters. Unless the pistons were changed, this combination had a very low compression ratio (7.5/1). Hopefully yours has some higher compression pistons, but might be worth checking while it's apart.
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davehg
post Oct 4 2017, 01:37 PM
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Another attorney and wanna-be mechanic also rebuilding, this time a 2.7l. My engine guru says to use a solex cam for what will be a street car, not an auto crosser.
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Rob-O
post Oct 4 2017, 04:04 PM
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Knew Jay way back in the late 80's. He built my engine. I bought it from a fella named Yalman Balta. I'll bet Jay would remember him.
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burton73
post Oct 4 2017, 04:33 PM
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QUOTE(jfort @ Oct 4 2017, 08:18 AM) *

I doubt that there will be anything earth shattering or even beyond common knowledge, but if only to document this project, here goes:

This is a big, first time project for me, an attorney and mechanic wannabe. My factory six with a 2.5L engine was missing. Turns out there was only 75% compression in #1 and it was leaking through the inlet valve. Auto Assets in Powell OH diagnosed and my friend and mechanic, Jay Kjoller confirmed. Thankfully, Jay, an experienced air cooled engine builder and racer who lives nearby agreed to take on the project and to let me help. I got the engine out and delivered it to Jay last week.

Attached Image

We started the disassembly yesterday.

Attached Image

Learned some things about the engine. It has an early aluminum case with Mahle 90mm pistons and Nikasil cylinders. Pretty sure they are 2.7L. It has a later 3-ribbed oil pump, which Jay says is sufficient for what I do.

Attached Image

The pistons have been lightened, which Jay said was unusual.

Attached Image

We expected to see something that would explain the problem with #1. Other than some carbon accumulation on the head where the valve closes there was nothing. But, having gone this far, we decided to go from top end rebuild to a full rebuild and we split the case.

Considerations. I think the engine was built into a 2.5 in the early 70's given SCCA classes at the time, but it is just a guess. My prior owner was Jim Chambers in Oregon. He bought the car in 2001 from Werks 2 in in Burbank CA, which was started a long ago by Harry Bieker (Bieker Engineering) and continued by his son, Galen Bieker. I exchanged emails with Galen but he couldn't remember any details that would help us decide how far to go on the rebuild. But Jay said whoever built it did a good job and he can recognize the approximate build date from the materials used, e.g., paper gaskets and 3 thin copper seals at the bottom of the cylinders. What I would call the wear points, (bearings, cam lobes, valve tappets, etc.) looked to be in good shape. But I wanted to be sure.

Jays says he has had good experience with something other than the existing E cam, a Solex cam? that is a little more aggressive. So, we are going to either source that or investigate grinding the E cam.

Attached Image

Friday, I will wash all the oily parts. Heads, valves, piston rods go to the machine shop, which is nearby. What can go into a hot bath tank will go there. What can be powder coated will go there. The air shroud, which is green, needs something. Not sure what to do about that.

I am an old friend and customer of Harry Bieker from 1978 and having Harry do the machining and balancing of my S engine back in that time, the rods where ground to weigh the same as well as the big buck balancing job. Galen and I where buddy’s and I used to ski with him. He builds a great engine. Back then in 1978 a 911 was 30 hours of labor at $30. = $900 Labor. Plus all parts and machine work and that cost a lot.

Bob B
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mepstein
post Oct 4 2017, 04:37 PM
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I think today's number is 40 hours but that doesn't take into account the 100+ hours for disassembly, cleaning, powder coating, sourcing parts, sending parts to the machine shop, etc.
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Mark Henry
post Oct 4 2017, 06:46 PM
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QUOTE(mepstein @ Oct 4 2017, 06:37 PM) *

I think today's number is 40 hours but that doesn't take into account the 100+ hours for disassembly, cleaning, powder coating, sourcing parts, sending parts to the machine shop, etc.

(IMG:style_emoticons/default/agree.gif) Exactly, start adding up the total hours.
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Mark Henry
post Oct 4 2017, 07:01 PM
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I'd consider dumping the pistons, get the cylinders plated and put in a new set of JE 9.5CR pistons. Then match the cam to engine.

This would really wake the engine up.
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gereed75
post Oct 4 2017, 10:10 PM
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Highly recommend the mod Solex cam (DC30). Peak power around 6200 rpm, pulls hard to 7200 and makes very gratifying torque from 2500 up. Not sure if they can be ground on E cams or not. With those, S ported heads and 9.5 JE pistons you would probably be making 200 - 210 hp.

That is a favorite combo of Henry Schmidt at
Supertech Performance. Check his build threads on Pelican. Great motor in a six !!
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jfort
post Oct 5 2017, 06:37 PM
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Turns out I was wrong. It is a 70.4 mm crank with 2.7L pistons and cylinders. Not the short stroker I thought it was. Perhaps someone was making a 2.7RS - like engine with a milder E cam.
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Dr Evil
post Oct 6 2017, 09:28 AM
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Hey neighbor! Cool build. I didn't know people used CIS pistons for anything but CIS as someone stated. I like Mark's recommendations.
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Mark Henry
post Oct 6 2017, 09:49 AM
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QUOTE(jfort @ Oct 5 2017, 08:37 PM) *

Turns out I was wrong. It is a 70.4 mm crank with 2.7L pistons and cylinders. Not the short stroker I thought it was. Perhaps someone was making a 2.7RS - like engine with a milder E cam.


Trade the crank if you want a short stroke.
2.7 std/std magnifluxed crank is a easy sell on the bird.

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jfort
post Oct 7 2017, 05:45 PM
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Jay recommends staying with the German Mahle pistons and I’ll stay with the crank we started with. Will change to the Solex cams however.

Distributor needs rebuilt. It is too sloppy. The heads, piston rods, case halves and new valve guides delivered to the machine shop. Engine tin headed to body guy for blasting and black power coating. I’ll have him weld patches for holes in tin. Also going to have him make the shroud look as good as possible in red. Powder coating alternator strap and air filter covers black. Jay is ordering bearings, fasteners, etc. can’t wait to begin putting it all together.
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Cairo94507
post Oct 7 2017, 09:17 PM
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Excellent project. (IMG:style_emoticons/default/popcorn[1].gif)
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