Rebuilding an engine with used rotors/housings/irons
Thread Starter
Joined: Jul 2007
Posts: 1,370
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From: Trois-Rivieres (QC)
Rebuilding an engine with used rotors/housings/irons
Assuming they are within specs, I've been told it's a bad idea to rebuild an engine without resurfacing the irons/housings. What are your thoughts?
Joined: Mar 2001
Posts: 30,807
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From: FL-->NJ/NYC again!
Not true at all. Any time you alter internal engine components, be it by enlarging apex seal grooves to accept thicker seals, lapping iron surfaces down, or resurfacing the rotor housings--- you're introducing an element of human error. It's a roll of the dice, and while it's possible to have these things done right you'd better make damn sure you know what to check for. I've handled more botched 3mm rotors than I care to count, and have seen lapped irons that had too much material removed so they were paperweights--- the coolant seal grooves were too shallow.
As a builder I much prefer to use untouched hard parts, or the opposite of what you've been told.
A lot comes down to the condition of the parts you're dealing with.
As a builder I much prefer to use untouched hard parts, or the opposite of what you've been told.
A lot comes down to the condition of the parts you're dealing with.
Joined: Oct 2001
Posts: 6,279
Likes: 728
From: Florence, Alabama
there are certainly numerous people that do believe in lapping irons but i am not among them.
the heat treatment is quite shallow as to penetration so any lapping is going to remove most of it or be ineffectual. given that corner and sideseals are spring loaded a bit of wear is in my opinion not a major issue.
i totally agree w Rich re 3 mm apex seals. they are really heavy and it is quite a challenge not only to get the groove width correct but also to not skew the groove. done properly they are O K but i prefer Goopy's answer...
apex seal to groove clearance ideally should be around .002. most used motors show around 3 to 4 thou in the center and 6 at both ends. Goopy offers a .004 over stock seal that with a bit of filing delivers the .002. a way better solution.
i do buy into rotor housing re-honing. as in anything it must be done right. many used rotor housings can be made to seal as new.
all that said, there is nothing quite like new parts for max compression but often it makes $ense to refresh what you have.
good luck
Howard
the heat treatment is quite shallow as to penetration so any lapping is going to remove most of it or be ineffectual. given that corner and sideseals are spring loaded a bit of wear is in my opinion not a major issue.
i totally agree w Rich re 3 mm apex seals. they are really heavy and it is quite a challenge not only to get the groove width correct but also to not skew the groove. done properly they are O K but i prefer Goopy's answer...
apex seal to groove clearance ideally should be around .002. most used motors show around 3 to 4 thou in the center and 6 at both ends. Goopy offers a .004 over stock seal that with a bit of filing delivers the .002. a way better solution.
i do buy into rotor housing re-honing. as in anything it must be done right. many used rotor housings can be made to seal as new.
all that said, there is nothing quite like new parts for max compression but often it makes $ense to refresh what you have.
good luck
Howard
Not true at all. Any time you alter internal engine components, be it by enlarging apex seal grooves to accept thicker seals, lapping iron surfaces down, or resurfacing the rotor housings--- you're introducing an element of human error. It's a roll of the dice, and while it's possible to have these things done right you'd better make damn sure you know what to check for. I've handled more botched 3mm rotors than I care to count, and have seen lapped irons that had too much material removed so they were paperweights--- the coolant seal grooves were too shallow.
As a builder I much prefer to use untouched hard parts, or the opposite of what you've been told.
A lot comes down to the condition of the parts you're dealing with.
As a builder I much prefer to use untouched hard parts, or the opposite of what you've been told.
A lot comes down to the condition of the parts you're dealing with.