What are the trickiest parts about rebuilding one of these engines? Thanks |
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What are the trickiest parts about rebuilding one of these engines? Thanks |
Tdskip |
May 1 2019, 08:43 PM
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#1
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Advanced Member Group: Members Posts: 3,686 Joined: 1-December 17 From: soCal Member No.: 21,666 Region Association: None |
Or, in other words, where is a first time engine builder most likely to go wrong?
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Mblizzard |
May 2 2019, 06:59 AM
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#2
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Advanced Member Group: Members Posts: 3,033 Joined: 28-January 13 From: Knoxville Tn Member No.: 15,438 Region Association: South East States |
Incorrect alignment of cam and crank timing marks.
Breaking the eyelet off oil pickup when installing the bolt through the case. Not checking deck height and confirming compression ratio. Not lapping the cylinders to the heads. Not using correct sealant for case. Improper installation of oil cooler seals = leak Incorrect setting of the crank end play. Not surfacing pressure plate mounting surface the same amount as the clutch surface. Not that I have ever done any of those things. (IMG:style_emoticons/default/shades.gif) |
bbrock |
May 2 2019, 07:35 AM
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#3
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914 Guru Group: Members Posts: 5,269 Joined: 17-February 17 From: Montana Member No.: 20,845 Region Association: Rocky Mountains |
Not surfacing pressure plate mounting surface the same amount as the clutch surface. Is grinding the ridges off the flywheel bolts a suitable work around for this? When I had my flywheel resurfaced decades ago, I asked them to surface the mounting hub to match but I don't think they did it. I decided to grind the bolts to be sure I have clearance but haven't run the engine yet. Is that going to bite me in the butt? Also, it's been a long time, but it seemed like installing the distributor gear was a little tricky. |
Mblizzard |
May 2 2019, 08:00 AM
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#4
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Advanced Member Group: Members Posts: 3,033 Joined: 28-January 13 From: Knoxville Tn Member No.: 15,438 Region Association: South East States |
Not surfacing pressure plate mounting surface the same amount as the clutch surface. Is grinding the ridges off the flywheel bolts a suitable work around for this? When I had my flywheel resurfaced decades ago, I asked them to surface the mounting hub to match but I don't think they did it. I decided to grind the bolts to be sure I have clearance but haven't run the engine yet. Is that going to bite me in the butt? Also, it's been a long time, but it seemed like installing the distributor gear was a little tricky. I have seen that done but I think that is due to the removal of too much material from the surface and the bolts extend above the flywheel surface. If you fail to machine both surfaces clutch slippage will be a problem. If so much material was removed that you had to grind the bolts you might want to look at it again. I grade on a good bad scale. Anytime you have to modify bolts to fit stock parts it is likely bad! |
bbrock |
May 2 2019, 08:21 AM
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#5
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914 Guru Group: Members Posts: 5,269 Joined: 17-February 17 From: Montana Member No.: 20,845 Region Association: Rocky Mountains |
Not surfacing pressure plate mounting surface the same amount as the clutch surface. Is grinding the ridges off the flywheel bolts a suitable work around for this? When I had my flywheel resurfaced decades ago, I asked them to surface the mounting hub to match but I don't think they did it. I decided to grind the bolts to be sure I have clearance but haven't run the engine yet. Is that going to bite me in the butt? Also, it's been a long time, but it seemed like installing the distributor gear was a little tricky. I have seen that done but I think that is due to the removal of too much material from the surface and the bolts extend above the flywheel surface. If you fail to machine both surfaces clutch slippage will be a problem. If so much material was removed that you had to grind the bolts you might want to look at it again. I grade on a good bad scale. Anytime you have to modify bolts to fit stock parts it is likely bad! Whoops! Looks like a misread what you were saying. Yes, when my flywheel was surfaced, they took .027 off the friction surface and a matching amount off the outer ring where the pressure plate mounts. I mistakenly thought you were talking about the center hub where the flywheel bolts to the crank. That's what may not have been surfaced so I ground the ridges on the bolts just to make sure they don't hit the friction disc. Disregard my question. Carry on. (IMG:style_emoticons/default/smile.gif) |
jcd914 |
May 2 2019, 10:12 AM
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#6
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Advanced Member Group: Members Posts: 2,081 Joined: 7-February 08 From: Sacramento, CA Member No.: 8,684 Region Association: Northern California |
I mistakenly thought you were talking about the center hub where the flywheel bolts to the crank. This is not something that should be machined down when the flywheel is surfaced. It is a structural part of the flywheel and should be left alone. If enough material has been removed from the clutch surface of the flywheel the clutch disc can contact the flywheel bolts. Really that means the flywheel is past its wear limit and should be replaced but I have seem many the have had the ridges on the flywheel bold ground down to add clearance. I have not seen a failure related to the specific modification. There is a diagram with the machining specs for the 914/6 flywheel that seems to be the accepted standard for the 4cly flywheel as well. I don't think the bolts need to be ground if the flywheel is kept within the limits in the diagram. I don't have a copy of the diagram handy or I would post it here. Jim |
Mblizzard |
May 2 2019, 11:28 AM
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#7
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Advanced Member Group: Members Posts: 3,033 Joined: 28-January 13 From: Knoxville Tn Member No.: 15,438 Region Association: South East States |
I mistakenly thought you were talking about the center hub where the flywheel bolts to the crank. This is not something that should be machined down when the flywheel is surfaced. It is a structural part of the flywheel and should be left alone. If enough material has been removed from the clutch surface of the flywheel the clutch disc can contact the flywheel bolts. Really that means the flywheel is past its wear limit and should be replaced but I have seem many the have had the ridges on the flywheel bold ground down to add clearance. I have not seen a failure related to the specific modification. There is a diagram with the machining specs for the 914/6 flywheel that seems to be the accepted standard for the 4cly flywheel as well. I don't think the bolts need to be ground if the flywheel is kept within the limits in the diagram. I don't have a copy of the diagram handy or I would post it here. Jim |
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