I/c rototiller 5hp

[Thepartsguy]

Where to start a weird Briggs! But the best kind of weird! So they took a standard tiller coolbore crank at the factory and they just stuck a sleeve on the crank and pressed a bearing over the sleeve and stuffed it into a flywheel side I/c bearing block. Genius! They only did this on 80’s reduction I/c 5hp’s though. So that means now that I retrieved the sleeve off the reduction crank I can convert this reduction 5hp I/c to a standard 3/4 crank. Then I’ll hunt down a bearing sidecover to make a duel crank bearing I/c block. then comes the billet. A lot of billet.. Finally a worthy base

 

[Thepartsguy]

Sensible? Sensible been gone.. we‘re someplace else now.

 

[Thepartsguy]

just keep building just keep building

 

[Thepartsguy]

Keep busy now the tv isn’t going anywhere... I’ll go grab another can of paint before I let the tank not being painted stop me.

 

[Thepartsguy]

Whole engine is put together - the flywheel and starter clutch + oil/gas.. Gonna throw a stock flywheel on it and keep the rpm’s down till the 5hp flywheel shows up. I will get that arc sidecover. I’m happy with the paint. super weird the valves were three miles out of spec? Just wing it and no change here I suppose.

 

[Thepartsguy]

Off to get some oil and then I can hear it run.

 

[Hellion]

Ooooh me likey. Nice to keep it red but a brighter red. Guess you masked off and sanded/prepped around the old decals, aye?
I've done it too.

I "go crazy" and paint the inside of the blower housing too. Hate that they're bare metal and allowed to rust. I usually leave the recoil spring area bare metal after I polish it. Put a layer of grease in there usually so it should not be a problem.

What does 3 miles out of spec mean?

 

[Denny]

How long is a mile? Times that by 3 and you get you’re answer!

 

[Thepartsguy]

Ooooh me likey. Nice to keep it red but a brighter red. Guess you masked off and sanded/prepped around the old decals, aye?
I've done it too.

I "go crazy" and paint the inside of the blower housing too. Hate that they're bare metal and allowed to rust. I usually leave the recoil spring area bare metal after I polish it. Put a layer of grease in there usually so it should not be a problem.

What does 3 miles out of spec mean?

Yupp I ordered that top decal I ripped up with the pressure washer. And the valves has no clearance. valve spec on a 5hp is the piston 1/4 down in the bore past tdc compression stroke. If you set the valves at TDC it screws up the setting and the compression release won’t work correctly. both valves had ZERO gap. meaning the base circle was still holding the valves open. I had to file the bottom of the valve to gain 6int-9exh

 

[Hellion]

No, not weird. Zero gap happens on these engines as they wear. The valve seats just get hammered down and the gap between the valve stem and tappet closes up and the valves don't seat. The bores wear seem to wear very little, even on the Kool-Bore engines but the valve clearances go away, you lose compression and it fools you into thinking the engine is worn out.

The "compression release" is not operated from a centripetal lever on the camshaft that deactivates once it starts and the revs come up but it is always there, always operating. Doing away with that feature is a good idea as it will bump up the compression ratio on these pitifully low compression engines.

both valves had ZERO gap. meaning the base circle was still holding the valves open.

Never heard of a base circle but I figure a "parts guy" would know they are called... tappets?
Then again that's my wild guess and maybe the only one who understands you is your mother.

 

[Thepartsguy]

No, not weird. Zero gap happens on these engines as they wear. The valve seats just get hammered down and the gap between the valve stem and tappet closes up and the valves don't seat. The bores wear seem to wear very little, even on the Kool-Bore engines but the valve clearances go away, you lose compression and it fools you into thinking the engine is worn out.

The "compression release" is not operated from a centripetal lever on the camshaft that deactivates once it starts and the revs come up but it is always there, always operating. Doing away with that feature is a good idea as it will bump up the compression ratio on these pitifully low compression engines.



Never heard of a base circle but I figure a "parts guy" would know they are called... tappets?
Then again that's my wild guess and maybe the only one who understands you is your mother.

the compression release is a bump on the camshaft that’s must be ground off with a grinder to be removed.. I advise highly against removing that compression release bump. As I and many others have figured out that besides a smoother idle there is no gain. The only thing you do gain is a sore arm from SnapBack with no compression release. Briggs junkie forum members who have forgot more then I’ll ever learn have advised me to stop welding the cam lobes. Instead grind the back of the camshaft Called the base circle. that will let the lifter set lower on the base circle Making your valve gap spec 90thou we will say. well when you install your 100+ billet lifters you grind till you get stock cam specs of 6int/9exh and gain enough lift on the stock lobe cam to have to check the head/valve clearance. Edit: I was told not even to buy 100+ lifters but actually stick a weld dot on the stock valve stem then grind that weld to gain the lift that way instead of taller lifters.

 

[Thepartsguy]

Here’s a better picture then the one I just tried to post showing the base circle.

 

[Hellion]

Where to start a weird Briggs! But the best kind of weird! So they took a standard tiller coolbore crank at the factory and they just stuck a sleeve on the crank and pressed a bearing over the sleeve and stuffed it into a flywheel side I/c bearing block. Genius! They only did this on 80’s reduction I/c 5hp’s though. So that means now that I retrieved the sleeve off the reduction crank I can convert this reduction 5hp I/c to a standard 3/4 crank. Then I’ll hunt down a bearing sidecover to make a duel crank bearing I/c block. then comes the billet. A lot of billet.. Finally a worthy base View attachment 140552View attachment 140553View attachment 140554View attachment 140555

Was the new bearing a tight fit on the crankshaft? What's the specs on the bearing?

.....Instead grind the back of the camshaft Called the base circle. that will let the lifter set lower on the base circle Making your valve gap spec 90thou we will say. well when you install your 100+ billet lifters you grind till you get stock cam specs of 6int/9exh and gain enough lift on the stock lobe cam to have to check the head/valve clearance. Edit: I was told not even to buy 100+ lifters but actually stick a weld dot on the stock valve stem then grind that weld to gain the lift that way instead of taller lifters.

This sounded like Greek to me. Can you explain it like I'm a runny-nosed 4 year old?

 

[Denny]

This sounded like Greek to me. Can you explain it like I'm a runny-nosed 4 year old?

Blow and wipe your nose then!

 

[Whitetrashrocker]

Was the new bearing a tight fit on the crankshaft? What's the specs on the bearing?



This sounded like Greek to me. Can you explain it like I'm a runny-nosed 4 year old?

The cam i put in El Chingon. The one on the right is a bigger cam. The left one is stock.

Reference point is the center of the shaft.

From there, to the top, of the stock lobe is the same distance as on the modified cam.
The difference is on the base .
See how the distance from Reference to 6o'clock is greater on the stock vs the modified?
This means the lifter/follower travels a greater distance.
It starts lower.

The modified cam on the right also has a longer duration. The lobe is wider and not as pointy.

Does that make sense?

 

[Hellion]

Does that make sense?

Well of course it does when you explain it. But I was hoping to avoid that. You write well.