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O.S. FS-91 Surpass lifter problem...

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Old 05-07-2018, 06:12 AM
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MFIGHT43
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Default O.S. FS-91 Surpass lifter problem...

Hello all,

I have torn down an OS FS91Surpass II that was gummed up and had the valves stuck open when I bought it. I removed the valve train, cleaned the valve seats/guides. Reassembled and they work better now. The lifters were nearly fully stuck, but I was able to remove them and clean the lifters and the lifter bores.

My issue is this, when I am reassembling them, they are very difficult to go back in and even get jammed in there. I am using oil to reassemble. Watching a video of this I see that they should just slide in easily. They act as if they are too big for the lifter bore.

Any thoughts? I have searched for new lifters but am unable to find any to purchase.



Lifter Bores are clean


These are the lifters...

Last edited by MFIGHT43; 05-07-2018 at 06:39 AM.
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Old 05-07-2018, 07:13 AM
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r ward
 
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it could be that the pushrod tubes have peened a small lip around the top of the lifter bore where the flange in the tube sits against the lifter body.. another thing to look at is that when tollerances are almost "0", as with a small diameter fitment like the lifters, any tiny misalignment as the lifter enters the bore, will feel like the lifter is too big to fit in the bore. wipe a tiny bit of grease on the end of the lifter and carefully rotate them as they enter the bore. also,... if there is room to insert the lifters from inside the crank case, do that.
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Old 05-09-2018, 11:47 AM
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the Wasp
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whats up with those Lifter Boars ?? is it corrosion or junk left over from the Lifers when they were stuck, ether way it looks ruff,

as for you not finding Lifters, you could check the part numbers on newer engines, they just may use the same Lifters ??? not sure ??/

if I was you I would ask David McIntire (click my link), he will know, you can find him here on RCU, , he may even have the Lifters and a Case that he will sell you that's in better shape than yours

https://www.youtube.com/channel/UCjm...m794jkGxutejcg

Good Luck !!

Jim
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Old 05-09-2018, 05:36 PM
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Solved! So what I thought was “ clean”, was not. I put the lifters in my “hot tank” and now they fit well! Apparently there was a very thin film of gunk that was impeding the lifters.

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