3.2 Short Stoke Twin Plug

[JackkTheMackk]

Posted this in the technical section but I might get more help over here. I spent the last week pulling the motor myself and splitting the case. I knew I had two broken head studs so I started the rebuild of my 3.0 finally. Plans for the build are

3.2 Short Stroke
98mm 10.5:1 JE Pistons, skirted.
Twin plug JB racing Dizzy
PMO 46
Elgin Mod S cams
Valve job and porting on the late SC heads. Will be matching Carrera head specs.
Race springs and TI retainers.
1 5/8" QSC V band headers
Scart sport muffler
RSR flywheel
964 oil pump.
Cross drill and groove crank.
GT3 main and rod bearings.
Standard cam chain tensioners with safety collars

Dropped everything off at EMS this morning. 3-4 month turn around time so it might be crickets here for a minute.. Took a look around back and was thoroughly impressed with what engines he had back there.

For the case they are cleaning it, checking the line bore, and removing the head studs.

For the rotating assembly they are cross drilling and grooving the crank, micro polish, and magnaflux. The rods are getting rebushed and magnafluxed. The entire rotating assembly is getting balanced with my RSR flywheel and Sachs pressure plate. I have a 15# Sachs pressure plate right now and considering buying a lighter one for this build. PM sells a 7# aluminum one.

The heads are getting surfaced and ported to 40I/38E to match Carrera head specs and twin plugged. Full valve job and new exhaust studs. Rocker arms are getting refurbed. The cam housings and boxes are getting blasted and all cleaned up also.
Open to suggestions from anyone if I'm missing some fun parts. I slipped down the slope and am tumbling now.

Thats the gist of it. If I'm going to split the case and do this, I want to tick every "while I'm in there" box because I'm young and have no real responsibilities at the moment.

Pulled the motor myself in the driveway. Here's happy me after I got the engine on the stand. Used a chain at the cross member side and a tow strap around the rear hook to meet the chain at the front. Really easy way to get it up. Harbor freight hoist for $140, cheap and does the job great.

I found one head stud while pulling the tin. Next up was pulling CIS off and exhaust to get down to a long block. The exhaust was RUSTY. Originally a Michigan car. All 6 Allen key nuts came off no issue, the 13mm nuts were a different story. I took a Dremel to all 6 to split them open and whacked them with a large flat head and hammer to pop them off. The studs will get replaced to didn't mind grinding into them.

After pulling the manifolds, cross over, and cat in one piece, I worked on the lower valve covers. Found 4 broken head studs in total, even though the car ran great before pulling it.

The CIS, dizzy, and miscellaneous parts will hit the classifieds soon if anyone is interested. I am really a parts hoarder, but to be honest I really don't see myself ever using CIS in the future so its time to make room.

Also, the RD350 I just finished restoring in the background is for sale

[JackkTheMackk]

Rod #3 closest to the trans had a score in the bearing. Other than that everything looked great but upgrading to gt3 main/rod bearings "while im in there" and a 964 oil pump.

[Helix8]

Talk to your builder about needing race springs and Ti retainers. Don’t over spring your valves and Ti wears. Otherwise, ARP or Raceware fastners maybe?

[JackkTheMackk]

Originally Posted by Helix8

Talk to your builder about needing race springs and Ti retainers. Don’t over spring your valves and Ti wears. Otherwise, ARP or Raceware fastners maybe?

Arp rod bolts and supertec headstuds is the plan. Reusing the case through bolts.

Every other similar build I've seen is running springs and retainers with DC40 cams. The specs of the springs I purchased is install @ 34mm = 80lbs on the seat, and at 13mm lift = 260-270lbs over the nose.

[MBruns]

Do a search for Toddu (Todd Uhl) I did one for him many years ago and he documented it well, he can give you a lot of feedback if you like. Have fun
Mike Bruns

[JackkTheMackk]

Originally Posted by MBruns

Do a search for Toddu (Todd Uhl) I did one for him many years ago and he documented it well, he can give you a lot of feedback if you like. Have fun
Mike Bruns

Hey Mike,

I saw his thread for the 3.2ss. Lots of the same parts and just about a clone of his.

Two questions, do you know if you used 1 5/8” or 1 3/4” headers? I saw they’re the william knight headers.

Was also curious if you did springs and retainers in the Carrera heads.

Todd was nice enough to share his experience with the motor so far. Sounds like he’s loving it.

[MBruns]

We used the 1-3/4” primary’s, have him check the slip fit at the collectors the last set was extremely sloppy, I ended up welding them to stop the air leaks and the effect it had on the O2 sensor reading, I don’t use Ti retainers for the most part especially on a street build due to the wear.
Mike Bruns

[MBruns]

BTW nice RD, I grew up working on all the early 2 stroke twins and triple’s, send me some pics of it.
Mike Bruns
Brunsmspts@aol.com

[FST14]

I have the same basic build in a 914 6 GT clone, but I went with GE60 cams and ARP studs.

What are your plans for induction? I am running 46 PMOs and a JB Racing distributor with MSD 6ALs. I would recommend EFI and coil packs. I would have go that way if I had today’s wisdom yesterday.

Best of luck!!! Looks like a great project!

[JackkTheMackk]

Originally Posted by FST14

I have the same basic build in a 914 6 GT clone, but I went with GE60 cams and ARP studs.

What are your plans for induction? I am running 46 PMOs and a JB Racing distributor with MSD 6ALs. I would recommend EFI and coil packs. I would have go that way if I had today’s wisdom yesterday.

Best of luck!!! Looks like a great project!

I will be running your exact set up. I went back and forth between EFI and carbs but opted for carbs.

Why would you have gone EFI?

[FST14]

Originally Posted by JackkTheMackk

I will be running your exact set up. I went back and forth between EFI and carbs but opted for carbs.

Why would you have gone EFI?

It was a long journey to get the carbs working well. I have a version of PMO 46s with 3 transition ports that caused me a couple years of tuning fits. They are much better now that I’ve added the fourth port after I discovered there was more than one configuration of transition ports over the years. I just think that efi would have been more accurate and adaptable to weather, altitude changes and today’s poor fuel. I not going to change now, it’s a great engine and I want to drive and enjoy it rather than start a new science experiment. The distributer has been fantastic. Just works.

[stownsen914]

I was going to comment on the bike as well. Caught my eye right away.

[JackkTheMackk]

Originally Posted by stownsen914

I was going to comment on the bike as well. Caught my eye right away.

Thanks, I just finished restoring it. I think I have a buyer for it lined up. That money is going straight from that corner of the garage to the other, where the motor is..

https://youtu.be/skrIu5p-NcA

[HaroldMHedge]

Nice RD350. Years ago, I used to ride an RD400.

[stownsen914]

The old 2 strokes are bringing good money these days. I picked up an old Hodaka Road Toad in rough shape a while back. I'll get to it one day, lol.

[JackkTheMackk]

Originally Posted by stownsen914

The old 2 strokes are bringing good money these days. I picked up an old Hodaka Road Toad in rough shape a while back. I'll get to it one day, lol.

Listed it for $6k and got my asking price yesterday. They have definitely rose in price, as all cult classics. New owner has it parked in his garage with a 993 and 997.