Budget 12A SP build

[NoDOHC]

Originally Posted by t_g_farrell

Your referring to the 2 oil control rings on each side of the rotors right?
I'll be getting a full soft seal kit so I expect that will include the o-rings for the
oil control seals. The A engine oil control seals look brand new, no shiny area
at all. The B ones definitely look older and worn and are shiny about half way
across, probably out of spec as well.

Turns out I may be able to use the lighter weight rotors from engine A which
already have brand new bearings in them. They look almost new. In fact
everything from engine A is looking better than the B engine. The B engine side
plates have noticable grooves in them from the corner seals. I may use the
A engine front rotor housing instead of the B engine rear rotor housing which
has the chunk chipped out of the exhaust port top opening.

I'm thinking of trying out the Goopy housing resurface service. Its certainly
priced right at $125.00 for a pair.

At $125 each, I have a few that I might send in myself. It makes even more sense to get 12A housings done as they are getting harder to find.

If there is no shiny place on your oil control rings, they are likely new. It sounds like engine A really was a recent rebuild when it ate the bolt.

Eating bolts is not that uncommon, I have a 90 4-port that ate a bolt (all seals were still ok, rotor and housing = junk).

[t_g_farrell]

Heres the A engine when I got it:



This is what all the oil control rings looked like.



The rotor bearings (like new, mostly silver with a touch of copper at the seams)



The damage the bolt did to the rear housing as it left the exhaust. I'm thinking
porting will take care of it. If not I'll use one of the other housings from engine B.



The right rotor shows a dent in the top edge of the combustion indent. None
of the apex seals got damaged and none of the apex seal slots looks
damaged. I think I can use the rotor? Opinions? Remember its a budget build.

[t_g_farrell]

I think I should explain the goals of this build. I call it a budget build because I
don't want to sink a lot of money into my 1st rebuild. This is a learning exercise
for me and if it works well when I'm done great. If it blows up in a year,
no biggie. Normally, if I was doing a full rebuild like this it would be with near
perfect parts and all new hard and soft seals and springs. My next rebuild
(see I know there will be another) will be of much higher quality.

The other thing going on with this is that the engine its replacing in my SA,
I will be keeping for another project. The current ignition, intake and exhaust
can all be reused with this rebuild. Just some small jetting changes for the
Dellorto. If the engines blows, I can just swap the stock port back in. I like
doing it like this because it will keep a lot of unknowns out of the equation while
I try to get my rebuild started and running the first time. Baby steps. Gotta
walk before you run.