Stihl 038 Magnum II - Slight Rebuild

[bulletpruf]

The holes by the wrist pin have casting flaws and are a choke point ..venturi shape the in and out. Practice on a old piston first. Weigh before and after. I'll do a old piston and show a picture. I didn't take any pictures of this saw's piston or any others for that matter...its a racing trick and some people get butt hurt sharing racing secrets. You probably should pm me. Don't want to rustle any feathers. I have a killer trick for a MS200T . I just finished one and O-boy, even I'm impressed and I've crewed for a 6000 hp car.

Ok, I'll send you a PM. Figured you were a car/engine guy; not many are familiar with gas porting pistons.

Can't say that I've worked/crewed on a 6000 hp car (Top Fuel? Top Alcohol?), but I've built numerous hot rod engines - BBF's, Pontiacs, AMC's, BBC's, etc. Current rides include a 71 Javelin road race project with 500'ish hp 401, 68 GTO convt with 500 hp 455, and a 66 Fairlane GT convt with a 428 that's close to 500 hp. All pump gas motors.

 

[Adam08ski]

Finally got me my full 038 mag rebuild done. Absolute beast with a light exhaust porting, base gasket delete and muffler mod. Just need to tidy the muffler mod up and I may buy a Hyway cylinder and get on to some serious porting on it while still having this in use.

I have a few from the start of the trashed project to the finish.

 

[Chashowlett]

Pamona with Jim Eppler, we were the first Top Fuel F/C to go 300 mph. Also won that day.
Also was on a crew that qualified for the Daytona 500 in 1989. Charlie Baker no. 92. I built the qualifying motor in a little shop in Wake Forrest NC.
Cost 35k back then. It was called Winston Cup. Good times

 

[Chashowlett]

Oh, and we had to wear white pants!

 

[bulletpruf]

Finally got me my full 038 mag rebuild done. Absolute beast with a light exhaust porting, base gasket delete and muffler mod. Just need to tidy the muffler mod up and I may buy a Hyway cylinder and get on to some serious porting on it while still having this in use.

I have a few from the start of the trashed project to the finish.

Ouch! That thing was roached! What's the story on the K&N Super Clean? Did you use OEM bits or aftermarket on the exterior? If aftermarket, is it good quality?

 

[Adam08ski]

OK, the K&N cleaner was just what I had for any of the plastics at the time. Seemed to work a treat getting stuff off. And it was toasted, totally, crank was seized and stuck to the casing etc.

Full OEM rebuild on all mechanical parts that weren't salvageable. Only thing Not OEM are as follows:

52mm Caber ring and meteor piston
Clutch cover (Hyway parts perfect fit and finish minus the Stihl logo)
Cylinder cover (Farmertec and slightly darker than Stihl OEM, but good quality)
Custom Bracket for the cylinder to cover bolt as the farmertec cover is I'm guessing a ms380 copy.
Air filter cover (Farmertec and slightly darker than Stihl OEM, but brighter than the cylinder cover?!)
Muffler (Farmertec, good quality, not as thick as OEM but looses heat better, baffles removed)
Fuel and oil caps (Hyway parts, good seal thickness and nice feel to open/close)

 

[Chashowlett]

Got mine ready to go cut today

 

[Matt B]

Enjoying the thread. My MS381 rebuild is ready to bolt up except the original cylinder could not be recovered. Hoping to find a used oem in good condition. Cheers, Matt.

 

[bulletpruf]

OK, the K&N cleaner was just what I had for any of the plastics at the time. Seemed to work a treat getting stuff off. And it was toasted, totally, crank was seized and stuck to the casing etc.

Full OEM rebuild on all mechanical parts that weren't salvageable. Only thing Not OEM are as follows:

52mm Caber ring and meteor piston
Clutch cover (Hyway parts perfect fit and finish minus the Stihl logo)
Cylinder cover (Farmertec and slightly darker than Stihl OEM, but good quality)
Custom Bracket for the cylinder to cover bolt as the farmertec cover is I'm guessing a ms380 copy.
Air filter cover (Farmertec and slightly darker than Stihl OEM, but brighter than the cylinder cover?!)
Muffler (Farmertec, good quality, not as thick as OEM but looses heat better, baffles removed)
Fuel and oil caps (Hyway parts, good seal thickness and nice feel to open/close)

Thanks for the details! My P&C are good, but I'll go back together with Caber rings. Meteor stuff has a good reputation, too, of course.

Gotcha on the K&N cleaner. I'm always looking for something better that what I'm using, but I don't know if it's out there. These days it's Simple Green and chlorinated brake cleaner along with scrub brushes, picks, and compressed air. Helps to have an adult beverage, too, cause it takes me a while to clean one.

 

[bulletpruf]

Pamona with Jim Eppler, we were the first Top Fuel F/C to go 300 mph. Also won that day.
Also was on a crew that qualified for the Daytona 500 in 1989. Charlie Baker no. 92. I built the qualifying motor in a little shop in Wake Forrest NC.
Cost 35k back then. It was called Winston Cup. Good times

That is COOL! Kudos to you! What year was that when y'all hit 300 mph? Qualifying for Daytona is pretty darn impressive, too. The amount of hp that you could wring out of SBF or SBC is incredible. Wasn't/isn't it around 900 hp from 350/351 cubes? Something like 9000 rpm?

 

[Adam08ski]

Thanks for the details! My P&C are good, but I'll go back together with Caber rings. Meteor stuff has a good reputation, too, of course.

Gotcha on the K&N cleaner. I'm always looking for something better that what I'm using, but I don't know if it's out there. These days it's Simple Green and chlorinated brake cleaner along with scrub brushes, picks, and compressed air. Helps to have an adult beverage, too, cause it takes me a while to clean one.

I used an old dishwasher with solvent de-greaser and put a whole disassembled 254xp in. Saw came up a treat, dishwasher now no longer works....

Need to get me one of these parts washers.. It is a ball ache cleaning stuff. compressed air is by far the best for me, if you don't care about the area around you

 

[bulletpruf]

I used an old dishwasher with solvent de-greaser and put a whole disassembled 254xp in. Saw came up a treat, dishwasher now no longer works....

Need to get me one of these parts washers.. It is a ball ache cleaning stuff. compressed air is by far the best for me, if you don't care about the area around you

I've got one of the 40 gallon Harbor Freight parts washers. I get a lot of use out of it. Filled with diesel now, but I prefer mineral spirits.

Agree with you on the compressed air -- it makes a big mess. However, I start off with a brush, pick, etc, and get the big chunks knocked off. Then it's a brake cleaner blast. Then usually to Simple Green with a water rinse. Followed by brake cleaner again. And THEN the compressed air. If you start off with compressed air, you get big chunks of oily crud EVERYWHERE.

I've been using an ultrasonic cleaner for the smalls. Usually fill it up with 50/50 Simple Green and water. It's one of the units that heats the solution as well, which really helps. It's not magic, but it's pretty darn good for smaller stuff.

 

[Adam08ski]

I've got one of the 40 gallon Harbor Freight parts washers. I get a lot of use out of it. Filled with diesel now, but I prefer mineral spirits.

Agree with you on the compressed air -- it makes a big mess. However, I start off with a brush, pick, etc, and get the big chunks knocked off. Then it's a brake cleaner blast. Then usually to Simple Green with a water rinse. Followed by brake cleaner again. And THEN the compressed air. If you start off with compressed air, you get big chunks of oily crud EVERYWHERE.

I've been using an ultrasonic cleaner for the smalls. Usually fill it up with 50/50 Simple Green and water. It's one of the units that heats the solution as well, which really helps. It's not magic, but it's pretty darn good for smaller stuff.

Well I think I need to expand my set up.. haha

 

[rocketnorton]

Enjoying the thread. My MS381 rebuild is ready to bolt up except the original cylinder could not be recovered. Hoping to find a used oem in good condition. Cheers, Matt.
View attachment 565056

pm'd you back.

 

[Matt B]

Many thanks rocketnorton.

 

[Chashowlett]

464 with the restrictor plate about 750 with a 750 Holley. 93 in Pamona. That cylinder may clean up, that piston debri

 

[Chashowlett]

Debris will scrape off with a flat edge of a file. Just be careful not to scratch the chrome. And you'll be surprised at how good it Will run, even if the chrome has scratches, as long as they are below the intake port, it will run , there are other ways of cleaning the aluminum deposits too, like sulfuric acid but I would practice on a junk cylinder first.

 

[Chashowlett]

I use 3/4 Seafoam 1/4 VP gas for my carb cleaner. Does not hurt the gaskets and works awesome.

 

[Adam08ski]

So continuing on the 038 thread, where can I find a used magnum cylinder OEM. My 038 is working lovely with its slightly modded cylinder and no gasket,muffler mod etc. I want to do some transfer porting and a bit more but need this saw working while I have a play with the steel. So I don't want to tear it down to have it in bits while I take some time to port it properly.

 

[Mad Professor]

Check the trading post here. Also Craigs list and fleabay. Sometimes saws show up at tag sales or farm auctions.

Most people don't realize most "scored" cylinders can be cleaned up so parts saws are worth a look. Even if P/C is no good the "carcass" can still be a parts source.

I found a NOS/OEM P/C on fleabay a few years back that was cheaper in cost than an Italian Tecomec at the time.

If you can find an Italian NOS Tecomec P/C assy they were OEM quality. They have since moved production somewhere in the far east. I think Meteor is still all Italian but have not worked with their cylinders. There is a slew of Chi-Com manufacturers but I've not seen any that are as good as OEM casting, plating or finish.