Kohler OHV on a Briggs flathead 5hp
- Thread starter Thepaetsguy
- Start date
Now timing this thing??? I need to shorten the pushrods as the rocker studs will not screw all the way into the head without the whole ratio being off wildly. Once the pushrods are shortened the rocker studs will screw in tight. Then set the piston to TDC 1/4 down in the bore and instead of setting the valve gap in the stock 5hp valve box like normal I’ll instead set it to about 3thou each valve with feeler gauges at the rockers? There will be no springs or anything anymore in the stock valve box.
I can picture things just not explain them.. See the threads under the rocker? They should not be there. So I’ll shorten the pushrod. BUT that will then mean that valve could open way to much. So THEN I have to start making the rockers the shape I want them so they open and close when I need them to and the right amount I need them to.
I had to make sure the valves were correct so I installed and gapped stock flathead valves. Then rolled the engine till the piston was 1/4 down in the bore past TDC compression stroke. And watched what valve opened next. The exhaust valve.
Then I redid those steps rolled the engine to 1/4 past TDC on the right stroke and left it there bolted on the OHV cylinder head and watched what valve moved next while rolling it over. Thankfully it was the exhaust valve. The OHV cylinder heads valves function just as the stock ones did. Now to get the correct pushrod length.
Then I redid those steps rolled the engine to 1/4 past TDC on the right stroke and left it there bolted on the OHV cylinder head and watched what valve moved next while rolling it over. Thankfully it was the exhaust valve. The OHV cylinder heads valves function just as the stock ones did. Now to get the correct pushrod length.
This thread is great @Thepaetsguy !
Not that I'd ever try it, but the knowledge it takes to mix and match stuff like you do, is amazing to me.
And you always seems to figure out how to keep the expense down. In my opinion that is half the challenge when attempting stuff like this.
Keep up the good work, and thank you for sharing with us.
Not that I'd ever try it, but the knowledge it takes to mix and match stuff like you do, is amazing to me.
And you always seems to figure out how to keep the expense down. In my opinion that is half the challenge when attempting stuff like this.
Keep up the good work, and thank you for sharing with us.
Some of the coolest things on this earth came about from adapto games. It really does take me back to 2017 when I knew nothing and was on the Briggs forum asking if an 8hp had points how to file them and if that engine could ever run again 
It’s tons of fun even the thought of something possibly working and then my brain gets going. And I use 1/4-20 inserts for Briggs intake/exhaust threads and they work very very well. I figure some bigger 3” ones threaded down into multiple cylinder fins could do the trick. I need to take one of the head bolts to the T@S and verify what thread It is so I know what size heli-coil to buy.
It’s tons of fun even the thought of something possibly working and then my brain gets going. And I use 1/4-20 inserts for Briggs intake/exhaust threads and they work very very well. I figure some bigger 3” ones threaded down into multiple cylinder fins could do the trick. I need to take one of the head bolts to the T@S and verify what thread It is so I know what size heli-coil to buy.
Compression was slipping past head bolts so I cut the heads off head bolts and ran’em in with lock tight. I’ll fill the tops in with JB and file it all smooth.
But even bolting the head down with the aluminum threads that are there now and turning the engine over makes a TON of compression. With a new headgasket and the tops filled with JB the cylinder should have no trouble sealing.
The valve guide area is gonna have block off plate for the stock flathead intake/exhaust port. But the rest of the valve guide area will be left alone and manually oiled by a pulse pump. As long as the cylinder seals all else is a given I can stand there and oil everything external with a can of motor oil like they did in the start of engines if I have to.
But even bolting the head down with the aluminum threads that are there now and turning the engine over makes a TON of compression. With a new headgasket and the tops filled with JB the cylinder should have no trouble sealing.
The valve guide area is gonna have block off plate for the stock flathead intake/exhaust port. But the rest of the valve guide area will be left alone and manually oiled by a pulse pump. As long as the cylinder seals all else is a given I can stand there and oil everything external with a can of motor oil like they did in the start of engines if I have to.
They have open pushrod setups etc… Take the valve cover off a predator and watch the whole system work while running and spitting oil all over the ground. So it’s just sealing a cylinder and making the valves work off the stock cam/tappets. Piston down in the bore 1/4 past tdc on the compression stroke. Gap the rockers to .003 each and its setup just like flathead valves. Zero difference. If someone got a few 5hp blocks and did some aluminum welding in the right places they could do a really really good job at this OHV swap.
