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> Engine Rebuild, 2.5L Six
jfort
post Oct 4 2017, 09:18 AM
Post #1


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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.

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We started the disassembly yesterday.

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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.

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

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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.

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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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Posts in this topic
jfort   Engine Rebuild   Oct 4 2017, 09:18 AM
mepstein   Early aluminum case - score!   Oct 4 2017, 09:28 AM
Optimusglen   Are you running MFI or carbs? I ask because I...   Oct 4 2017, 09:30 AM
jfort   The engine has Weber carbs. Let me see what the pl...   Oct 4 2017, 09:38 AM
krazykonrad   :popcorn: Looks like an interesting project. Goo...   Oct 4 2017, 10:01 AM
Perry Kiehl   There's a lot more cam options today, than the...   Oct 4 2017, 11:52 AM
Edward Blume   Some additional HP sounds like its in your future....   Oct 4 2017, 12:23 PM
GeorgeRud   Lot's of folks used the 2.7 CIS pistons and cy...   Oct 4 2017, 01:21 PM
davehg   Another attorney and wanna-be mechanic also rebuil...   Oct 4 2017, 01:37 PM
Rob-O   Knew Jay way back in the late 80's. He built ...   Oct 4 2017, 04:04 PM
burton73   I doubt that there will be anything earth shatter...   Oct 4 2017, 04:33 PM
mepstein   I think today's number is 40 hours but that do...   Oct 4 2017, 04:37 PM
Mark Henry   I think today's number is 40 hours but that d...   Oct 4 2017, 06:46 PM
Mark Henry   I'd consider dumping the pistons, get the cyli...   Oct 4 2017, 07:01 PM
gereed75   Highly recommend the mod Solex cam (DC30). Peak po...   Oct 4 2017, 10:10 PM
jfort   Turns out I was wrong. It is a 70.4 mm crank with ...   Oct 5 2017, 06:37 PM
Mark Henry   Turns out I was wrong. It is a 70.4 mm crank with...   Oct 6 2017, 09:49 AM
Dr Evil   Hey neighbor! Cool build. I didn't know pe...   Oct 6 2017, 09:28 AM
jfort   Jay recommends staying with the German Mahle pisto...   Oct 7 2017, 05:45 PM
Cairo94507   Excellent project. :popcorn:   Oct 7 2017, 09:17 PM
jfort   update on the build got the engine tin and the en...   Dec 6 2017, 12:44 PM
Mark Henry   On the twin plug carbs with a trigger ignition her...   Dec 6 2017, 01:53 PM
jfort   thanks, Mark!   Dec 6 2017, 02:51 PM
jd74914   I believe you can also use Microsquirt now for 6 c...   Dec 6 2017, 04:13 PM
Mark Henry   I believe you can also use Microsquirt now for 6 ...   Dec 6 2017, 08:43 PM
jd74914   Yeh who wants to put that super old 90's EDIS...   Dec 7 2017, 03:40 AM
Larmo63   I have a 2.4 7R cased motor with Daugherty cams DC...   Dec 6 2017, 04:52 PM
Justinp71   :popcorn: My uncle has a 2.5L in his '70 911,...   Dec 6 2017, 06:29 PM
gereed75   Assuming mean the hole for twin plugs, I bet Craig...   Dec 6 2017, 06:46 PM
914forme   I have the SDS system here, and the extra coil pac...   Dec 6 2017, 07:41 PM
Mark Henry   Since the OP is running carbs the MS box is anothe...   Dec 7 2017, 06:09 AM
mepstein   Since the OP is running carbs the MS box is anoth...   Dec 7 2017, 06:25 AM
JmuRiz   Another in agreement with the two above....I'm...   Dec 7 2017, 09:27 AM
brant   I agree with the above. no need to go to twin plug...   Dec 7 2017, 09:38 AM
914Toy   Like Larmo, I have just installed single plug Clew...   Dec 7 2017, 09:53 AM
Mark Henry   Nice :wub: But I'll raise you by 3.0 :evil...   Dec 7 2017, 10:01 AM
jfort   beautiful! now we're talking. almost too b...   Dec 7 2017, 11:01 AM
Mark Henry   Brant and I are running TP dizzy's, Brant (lik...   Dec 7 2017, 11:35 AM
mepstein   Unlike a 911, you see mostly see the back of the e...   Dec 7 2017, 02:34 PM
pete-stevers   I won't be running twin plugs in any engine bu...   Dec 7 2017, 09:55 PM


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