Rebuilding a Wheel Horse underdog

[aHorseofCourse 261]

So I decided to upgrade my 308-8 and do an engine swap.  Main reason being the 8 horse Kohler struggles with the snowblower.  It's a great engine, just not quite enough hp.  Just about every machine I have has a Briggs in it and I've never had a problem with any of them.  So I thought why not drop an opposed twin in the big horse.  After searching for awhile, I found an 18 horse out of a workhorse on eBay.  Had the pto and engine mount I needed on it.  Turned out to be too far gone to rebuild, just flat wore out.  A few months later I got a nearly identical engine off a buddy for free, he was going to scrap it.  Long story short (too late!) I am making one engine out of 2.  The carb, tins, oil pan, and air cleaner housing are off the junk engine. The junk engine was a 1983, the rebuilt one is a 1984.  Parts are very hard to find for this engine anymore, lots of late nights searching eBay.  Model is 422437, splash lube ball bearing 12v electric start horizontal shaft.

 

The free engine I started with.  It sat outside for a few years.  After some tinkering and the carb and oil pan off the other engine, she fired right up!

 

Disassembly

 

The timing pin on both engines was worn, almost sheared off on the junk one.  Briggs only used this for a few years before going to an 1/8inch woodruff key after.  It is very apparent it was a weak point.  Had to drill out the old one.  

 

 

[aHorseofCourse 261]

Sent the block out to get punched .020 over and sandblasted.  I did some minor port and polishing and cleaned up the heads.

 

Some guys say to shave the lip off where the gasket goes to up the compression.  I've talked to some guys I trust and they say these L head opposed need more airflow than compression so that wouldn't gain anything.  Port/polish is the only easy gain I'm told.

 

[pfrederi 17,617]

Looks good...That should throw some snow!!

[ACman 7,608]

Grew up with these B&S I/C twins (vertical and horizontal shaft) and I got to say , they run smooth and last along time with normal maintenance . My 96 MTD probably has over 2000hrs and the one in the old Grazer probably had way more than 6000hrs (was a power lube w/ oilcooler and I maintained religiously) . Looks to me you know what you're doing....keep the  coming! 

Edited March 4, 2017 by ACman

[can whlvr 993]

we have a john deere zero with a twin briggs that has well over 6000 hours,never had any main engine work.

[woodchuckfarmer 333]

I have 2 tractors with these engines and they have given no problems .

[aHorseofCourse 261]

Thanks for all the success stories!  6k hours is very impressive and way more than I'll ever put on.  Wonder how many Onan's have that many hours on them? 

Next step pulling the exhaust valve guides.  They were still with in spec but I figured since I had it apart I'd replace them.  There's a plug gauge 19151 that either fits in (out of spec) or doesn't (still good).  Basically you just tap the old guide and pull it out with a bolt.  The service manual says to use a Briggs tool which is just a 9mmx1.25 tap and bolt setup.  Problem with that is 9mm bolts are about as rare as hens teeth.  I used a 3/8 NC which is about 1/64" larger.  Worked perfect.  Made a driver for the new ones out of an old valve stem I cut the ends off and welded a nut on.  Then came the paint.

 

[Sarge 3,463]

What brand is that tap driver handle ? Not sure I've ever seen one that style...?

Sarge

[richmondred01 2,237]

That's great. I think we all like seeing something that's been trashed brought back to life.

[aHorseofCourse 261]

9 hours ago, Sarge said:

What brand is that tap driver handle ? Not sure I've ever seen one that style...?

Sarge

It's a craftsman set maybe 5 years old.  What is different about it?

[Sarge 3,463]

The bit locks and handle are quite different in design to most - maybe not better or worse , just different . I prefer the sockets to fit the taps anyway - gives a lot more options and more control to keep the tap straight .

 

Sarge

[onanparts.com 181]

Sent the block out to get punched .020 over and sandblasted.

Looks good! :) What was the process used to remove all the abrasive grit, sandblasting media, glass bead etc. from all the nooks and crannies of the block? Internal and external. Just 1 or 2 small grains of sand/media left behind can cause a very bad day once the engine is up and running.  

[aHorseofCourse 261]

22 hours ago, onanparts.com said:

Sent the block out to get punched .020 over and sandblasted.

Looks good! What was the process used to remove all the abrasive grit, sandblasting media, glass bead etc. from all the nooks and crannies of the block? Internal and external. Just 1 or 2 small grains of sand/media left behind can cause a very bad day once the engine is up and running.  

I'm not sure how they cleaned it to be honest but it was spotless.  I think they used a glass beader to get everything off.  I sprayed it with simple green and pressure washed it after I was done lapping the valves and installing the valve guides.

[Sarge 3,463]

Most shops use 80 grit glass bead to clean engine parts - anything much finer can get packed into places you don't want and come out later to do damage . I spent a lot of afternoons in front of a buddy's blast cabinet squinting at cylinder heads and blocks to swap my time for his on my engine builds - worked out good for both of us . Once they are blasted , the parts go back into the hot washer to get completely cleaned in a solvent bath at around 140*F . Two rounds of that wash machine and the glass bead blasting leaves those parts about as virgin clean as it can get . The only trick with engine blocks is to get them air dried fast enough to prevent flash rust , and wiping those cylinders down with a clean oil rag , lots of passes since one missed spot can ruin the bore quickly on a humid day . We used to attack the V8's and larger engines with several guys , all using new lint-free cloths and atomized machine oil , going round and round the engine until each cylinder had at least 4 passes . Spent a lot of years and summer afternoons after work helping with engine blocks , blasting and sorting parts - not to mention countless hours watching him grind crankshafts , the guy was a nutty perfectionist at grinding them ...mirror finished to machined perfection . He was the one that built my 9,000 rpm Samurai engine , what an animal for something so small .

 

Sarge

[aHorseofCourse 261]

On 3/8/2017 at 9:36 AM, Sarge said:

Most shops use 80 grit glass bead to clean engine parts - anything much finer can get packed into places you don't want and come out later to do damage . I spent a lot of afternoons in front of a buddy's blast cabinet squinting at cylinder heads and blocks to swap my time for his on my engine builds - worked out good for both of us . Once they are blasted , the parts go back into the hot washer to get completely cleaned in a solvent bath at around 140*F . Two rounds of that wash machine and the glass bead blasting leaves those parts about as virgin clean as it can get . The only trick with engine blocks is to get them air dried fast enough to prevent flash rust , and wiping those cylinders down with a clean oil rag , lots of passes since one missed spot can ruin the bore quickly on a humid day . We used to attack the V8's and larger engines with several guys , all using new lint-free cloths and atomized machine oil , going round and round the engine until each cylinder had at least 4 passes . Spent a lot of years and summer afternoons after work helping with engine blocks , blasting and sorting parts - not to mention countless hours watching him grind crankshafts , the guy was a nutty perfectionist at grinding them ...mirror finished to machined perfection . He was the one that built my 9,000 rpm Samurai engine , what an animal for something so small .

 

Sarge

I dried it with compressed air then smeared some 30 weight on the cylinders right away.  The rest of the block is aluminum so I dont have to worry about most of it.  The more time and attention to detail you put into an engine, the better it runs.

[Sarge 3,463]

One thing learned with aluminum blocks - they love to migrate moisture into the steel or iron cylinder liners when they are open to the elements - we always dried them down completely with a high powered hair dryer - around 2,000 watts I think....

 

Details are everything with an engine - can't stress that enough . Learned the hard way dealing with a metric Japanese engine , everything has to be absolutely to spec , especially ring end gap and such or they will never hit stock compression levels - only seen 2 rebuilt that came out to factory spec , all the rest I've dealt with ended up at wearout limits . Small power equipment engines are the same way - if you want it to last you'd better be paying close attention , it's not a sloppy SBC...no offense intended .

 

Sarge

[aHorseofCourse 261]

11 minutes ago, Sarge said:

One thing learned with aluminum blocks - they love to migrate moisture into the steel or iron cylinder liners when they are open to the elements - we always dried them down completely with a high powered hair dryer - around 2,000 watts I think....

 

Details are everything with an engine - can't stress that enough . Learned the hard way dealing with a metric Japanese engine , everything has to be absolutely to spec , especially ring end gap and such or they will never hit stock compression levels - only seen 2 rebuilt that came out to factory spec , all the rest I've dealt with ended up at wearout limits . Small power equipment engines are the same way - if you want it to last you'd better be paying close attention , it's not a sloppy SBC...no offense intended .

 

Sarge

I'm prolly going on 4 months working on this engine for this very reason.   It's a ton of work to get everything in spec but I'm trying to get it perfect.  Latest problem is I can't get a timing pin anymore.  I dropped the crank off at the machine shop last week to get a woodruff key slot cut in instead of the stupid pin.  I don't know why the gear isn't a press fit on the crank.  I'm thinking of putting some red locktite on to snug it up.  Any thoughts on this?  The woodruff key will help anyway.  Briggs went to them a year or two after my year anyway but the gear still wasn't a press fit.

This little bugger has been the biggest PITA of the whole engine!

[Sarge 3,463]

If the pin diameter is a standard fraction - you can use part of a good quality hardened pin punch - I've done that in a pinch a few times and seems to work fine . They won't shear very easily since pin punches are designed to take a shock load so they aren't brittle . Just take your time cutting it , I use a thin cutting wheel in an angle grinder .

 

Sarge

[aHorseofCourse 261]

10 hours ago, Sarge said:

If the pin diameter is a standard fraction - you can use part of a good quality hardened pin punch - I've done that in a pinch a few times and seems to work fine . They won't shear very easily since pin punches are designed to take a shock load so they aren't brittle . Just take your time cutting it , I use a thin cutting wheel in an angle grinder .

 

Sarge

What are your thoughts on red loctite on the gear and crank to give it a kind of press fit?

[Sarge 3,463]

Red loctite isn't made to do that , although there is a version made specifically to do that job - https://www.permatex.com/products/thread-compounds/retaining-compounds/permatex-bearing-mount-for-relaxed-fits/

Pay very close attention to the directions ...

Sarge

[aHorseofCourse 261]

15 minutes ago, Sarge said:

Red loctite isn't made to do that , although there is a version made specifically to do that job - https://www.permatex.com/products/thread-compounds/retaining-compounds/permatex-bearing-mount-for-relaxed-fits/

Pay very close attention to the directions ...

Sarge

That's exactly what I need!  Thanks for your help!  

[aHorseofCourse 261]

Some long overdue progress.  Finally got the right timing pin after a 4 month back order and didn't have to go the machining route.  Used the Permatex bearing mount @Sarge recommended.  That gear isn't going anywhere now!  Can't thank you enough.  Got the heads polished up some more and my crank end play in check.  Assembled the pistons and rods today. I have heard about a thousand opinions on how to orient the ring gaps, any one have a tried and true method?  I know they shouldn't be lined up but I also heard not in line with the wrist pin or thrust face, which pretty much leaves no where.  I'm a little confused.

Heated the bearing in the oven at 225 then sat in on my hot plate while I put the bearing mount on.  Slid right on.

i needed the optional thrust washer (part 222951) to get my endplay down to spec.  I'm at .007

piston assembly

Box of goodies 

 

[diesel cowboy 263]

On the ring gaps, the not lining them up with the wrist pin and thrust face is a new one on me.  I've never heard about that before but in the approx. 2 dozen engines I've rebuilt in the last 20 or so years I do what my grandpa and dad (with my grandpa that info's coming from the way he did it back to the 50's) told me on the first few I rebuilt and that was to stagger them approx. 180 degrees from each other.  I go about 150-170 degrees just to keep the top and bottom ring gap from lining up and only had 1 failure where it started smoking again.  That was due to the fact that the customer refused to let us bore the block and it was so badly worn 2 bent quarters could be put down opposite sides of the piston and cylinder at the same time.                       Stewart

[6bg6ga 272]

I'll throw my two cents in for the heck of it. I've built a lot of engines over the last 50 years. One can get carried away and install the rings according to so many degrees apart but in the end the rings do move from their installed location a little over time and usage. The only important thing to remember is stagger them in my opinion. Never saw where it made any difference in operation and or compression or engine wear for that matter how they were lined up other than to stagger the gaps.

 

Just be glad the engine isn't supercharged or turbo in nature because that does result in higher break in periods and even to rings not seating at all. Been there done that.

[aHorseofCourse 261]

21 hours ago, diesel cowboy said:

On the ring gaps, the not lining them up with the wrist pin and thrust face is a new one on me.

Same here.  Maybe I just heard some gossip from a few arm chair mechanics.  I've always done the 180 stagger as well with no issues, just wanted to make sure I wasn't doing it wrong my whole life.

Thank you both for the input!