Detailed Rebuild How-to: Briggs 3hp Cousins

[Dr. Shop Teacher]

Starting a thread on these two kissing cousins. One is a 64 (???) 3hp and the other is a 74 3hp. Both are points engines, and have decent cylinder bores. I was able to source two 4 bolt PTO side covers. I also picked up two 2 quart tanks/carbs.

These will be my physical therapy once I'm off pain meds following surgery Tuesday, 29 November. Will also be mental therapy for my other half once I've driven her off the edge!:laugh:

So, until then....

 

[KMC3420]

Will be watching this one. Here's to a speedy recovery.

 

[jackeo21]

Hey Doc,

Hope the surgery went well!

Looking forward to seeing these engines undergo their restorations - I'm certain they'll come out awesome just like your other work! :thumbsup:

 

[Dr. Shop Teacher]

Hey Doc,

Hope the surgery went well!

Looking forward to seeing these engines undergo their restorations - I'm certain they'll come out awesome just like your other work! :thumbsup:

Hey, Jack! Unfortunately surgery was canceled today due to a major computer system failure. These two little guys get their refurb a little sooner than I expected. Hope all are recovering from the quake in NZ.

 

[Dr. Shop Teacher]

Cleaning and Disaassembly

While waiting for a new surgery date (and the weather was in the 70s), I power washed the two engines yesterday. I started disassembly on the 64 model.

The 64 was sprayed silver over the white original, so out came the aircraft stripper to get the silver paint off. Took a good 2 hours to get it all off and then it was degreased with mineral spirits and washed in the laundry sink.

Discovered Aircraft Stripper does wonders with carbon build up...brush on, let sit for a minute and then wipe away with steel wool.

 

[Dr. Shop Teacher]

Cracking the 64 Open

I was pleasantly surprised at the condition of the 64. Minimal gunk in the sump and the crank is in beautiful condition. Valves were in pretty good shape for their age and should clean up well. There is still good crosshatch in the cylinder

 

[Dr. Shop Teacher]

The 74 looks great, too

The first photo shows the twin PTO side cover. I'm swapping cams and covers but look closely at the crank PTO. It's actually sleeved from 5/8" to 3/4" and held in place with a C-clip. The 64 has a 5/8" crank PTO.

Here the block with the sump cover off. Same thing, very little gunk in the case:

The 64 was caked in grease and oil...the cover bolts were just barely tight. The gasket peeled off nearly in one piece, as a result. Both engines are in terrific condition...more photos to come.:thumbsup:

 

[Not so mini bike]

What is your plan? To have 2 useable engines? Or are they gonna be worked over a little? I would love to see a step by step on one of these 3hp Briggs as far as what people are doing to get a little more out of them. I know [MENTION=25918]Carp[/MENTION]lay had one on a streaker I beleive that had some work done but don't remember a thread on it. I would like to do one but don't know much about the little Briggs. Keep us updated Doc.

 

[jackeo21]

Looks like you've made a great start! I've never seen a 3HP with the double PTO shafts, I thought that was a feature only seen on the 4 and 5HP models.

Do you plan to make them both identical engines? That would be pretty neat to see!

I'm inspired to restart work on my little 2HP Briggs!

 

[Not so mini bike]

Looks like you've made a great start! I've never seen a 3HP with the double PTO shafts, I thought that was a feature only seen on the 4 and 5HP models.

Do you plan to make them both identical engines? That would be pretty neat to see!

I'm inspired to restart work on my little 2HP Briggs!

Yeah what happened? You were posting some awesome build threads on engines. Get back in the garage and get to work. Those engines aren't gonna build themselves. Lol

 

[jackeo21]

Yeah what happened? You were posting some awesome build threads on engines. Get back in the garage and get to work. Those engines aren't gonna build themselves. Lol

I've been caught up with restoring garden machinery and selling lawnmowers to fund the little engines :thumbsup: I'd like to get the 2HP done fairly soon as it's been too long since I've heard it! I've also got the Tecumseh H25 in a billion pieces.

Doc, that cylinder head looks like new! I'd love to get my hands on some of that Aircraft Stripper but I haven't seen any at the local hardware stores :hammer:

 

[neo71665]

I've had good luck using oven cleaner (ez off is the brand over here) but you better not leave it on aluminum long as it will eat it up. It does eat paint, stickers, grease, oil, gunk, or anything else in the way.

 

[Dr. Shop Teacher]

What is your plan? To have 2 useable engines? Or are they gonna be worked over a little? I would love to see a step by step on one of these 3hp Briggs as far as what people are doing to get a little more out of them. I know @Carplay had one on a streaker I beleive that had some work done but don't remember a thread on it. I would like to do one but don't know much about the little Briggs. Keep us updated Doc.

Karl-- The one that was on the Broncco is the 1964 engine. It's staying stock. I talked with Eric a bit today, and we'll see what we can come up with for the 1974. I can definitely tell you that some porting wouldn't hurt---the casting flash in the intake is terrible in both engines. Port matching the intake runner?? Maybe. I'm going to true the heads and the mating surface on both engines.

 

[Dr. Shop Teacher]

I've had good luck using oven cleaner (ez off is the brand over here) but you better not leave it on aluminum long as it will eat it up. It does eat paint, stickers, grease, oil, gunk, or anything else in the way.

Yeah, I learned my lesson with Oven Cleaner.

 

[Dr. Shop Teacher]

Cleaning up the Blower Housings

I really want to be able to see the serial numbers on these engines once they are done. The 64 engine had been sanded previously with a flap disk before painting and the 74 was original paint. I came extremely close to saving the patina on the 74 housing, but in the end, I stripped it. The wire wheel on the angle grinder did a nice job cleaning up the swirl marks on the 64 shroud.

The 1964 Shroud:

The 1974 Shroud:

 

[Dr. Shop Teacher]

I've been caught up with restoring garden machinery and selling lawnmowers to fund the little engines :thumbsup: I'd like to get the 2HP done fairly soon as it's been too long since I've heard it! I've also got the Tecumseh H25 in a billion pieces.

Doc, that cylinder head looks like new! I'd love to get my hands on some of that Aircraft Stripper but I haven't seen any at the local hardware stores :hammer:

Jack--I was amazed. See the next pics.

 

[Dr. Shop Teacher]

Blocks and Heads

Here are the blocks and heads cleaned up. Lots of crosshatch in the cyl. No scoring at all. I took a wad of steel wool and some stripper and cleaned out the carbon from the runners and off the top of the block.
1974--

1964--

 

[Dr. Shop Teacher]

Pistons and 1964 Valves

You can tell how Briggs changed up parts over time. The 74, being a twin PTO engine, would be under a bit more stress and you'd think it would have more heavy duty internals--don't think so! The 1964 piston is on the left with the v-shaped dipper and the more conventional single dipper is on the 1974.

The valves for the 64 cleaned up quickly with a dab of stripper and the wire wheel mounted in the drill press. Look at the face of the valve--the lap marks are still clearly visible and really even.

Will finish cleaning up the pistons and other valves tomorrow. Gasket kits arrived and finished stripping one of the side covers today. Then outside to the gazillion leaves.... :doah:

 

[Dr. Shop Teacher]

Looks like you've made a great start! I've never seen a 3HP with the double PTO shafts, I thought that was a feature only seen on the 4 and 5HP models.

Do you plan to make them both identical engines? That would be pretty neat to see!

I'm inspired to restart work on my little 2HP Briggs!

Jack, a lot of lawn edgers had twin PTOs. This was a Montgomery Ward-branded engine (a store like Sears, now long out of business), and I bet it was from an edger.

 

[Dr. Shop Teacher]

A little teaching--

Young guys/gals and those who don't do engines on a daily basis probably don't know the correct names of valve surfaces. It's not as intuitive as one would think.

/gals