Briggs 8hp hard to crank over manually, ok electrically.

[Arkie]

Briggs 8HP Horiz shaft, 12v electric start, model 190407, type 0661-01, code 7101141

Donor engine. Do not know past history.

Very hard to crank over manually with recoil rope. Starts and runs good with 12v electric start and has stator winding for battery charging. Someone has installed the electronic ignition or magneto that requires no points/condenser.

Valve lash setting is within spec. I'm thinking this old model Briggs does not have compression release?
I do not need the electric start. Just need manual rope start.

Anyone got any idea how to reduce the compression or ?? so as to get a easier manual pull rope crank?

[bgsengine]

compression release would be ground into the camshaft lobe, I do not believe it is mechanical compression release on that engine. However it would be one of those square drive ratchet recoils - they have a damper spring (and cap) between the rope pulley and recoil housing , if that is missing the rope can be really hard to pull might be worth popping the recoil off and check how hard it is to pull without the engine in the way

[KE4AVB]

Another thing to try is old trick. Bring engine to the top of the compression stroke and then pull to start.

This similar to starting high compression chainsaws where you use the spinning flywheel to get pass the compression stroke TDC. This something I have to do with my M8 as I just can't get enough speed otherwise on my TB Horse.

Just a thought as some of these old 190000 were started just using manual wind rope; No recoil.

Also it wouldn't hurt to have the exhaust valve closer to .009 instead .011 which make the ACR bump more effective for manual starting.

[Arkie]

compression release would be ground into the camshaft lobe, I do not believe it is mechanical compression release on that engine. However it would be one of those square drive ratchet recoils - they have a damper spring (and cap) between the rope pulley and recoil housing , if that is missing the rope can be really hard to pull might be worth popping the recoil off and check how hard it is to pull without the engine in the way

No hanging or friction of the recoil mechanism. It did have the old rope wind up start and a late model auto rewind added and all is smooth. The plastic dogs of the auto recoil are not going to live very long with the effort involved to get a pull thru crank
When the piston is pulled up to the compression stroke it takes a real effort to get a pull thru.

I thought maybe their might be some type of manual compression release that could be added on similar to what is used on some chainsaws to some crank relief.

[bgsengine]

I would assume you checked to see how it cranks with spark plug out, right? just wondering if there might be something right at TDC (carbon? squished gasket? screw that went through intake and embedded in piston or head?)

[Arkie]

Another thing to try is old trick. Bring engine to the top of the compression stroke and then pull to start.

This similar to starting high compression chainsaws where you use the spinning flywheel to get pass the compression stroke TDC. This something I have to do with my M8 as I just can't get enough speed otherwise on my TB Horse.

Just a thought as some of these old 190000 were started just using manual wind rope; No recoil.

Also it wouldn't hurt to have the exhaust valve closer to .009 instead .011 which make the ACR bump more effective for manual starting.

That old trick (to keep from losing finger meat) of easing it up into the crank through won't make it go either.
A late model auto recoil has been added and the plastic dogs are not going to live.

I thought maybe some type of manual compression release could be added?

Not easy to reduce the valve clearance on a L-head, but a option to see if made any difference in the pull thru would be to reduce the clearance with feeler gauge just to check the pull thru.

Engine really starts and runs good with elec start.

Wondering if two stacked head gaskets would reduce compression enough without upsetting timing, etc?

[Arkie]

I would assume you checked to see how it cranks with spark plug out, right? just wondering if there might be something right at TDC (carbon? squished gasket? screw that went through intake and embedded in piston or head?)

Right, cranks thru good with manual crank with spark plug out.
Engine does not smoke and runs strong and idles good.

[bgsengine]

Hmmm hold on a sec you mention starter has plastic starter dogs - which would mean this engine was retrofitted with a modernized starter then? Original recoil starter would have been cast aluminum body that bolts on the blower housing, and used a square drive starter clutch (the old classic ball bearing clutch) I would wonder just how well the modernized recoil was installed, and whether it was the correct one for the application (diameter of the rope pulley can affect torque multiplication, so wrong size starter might be much harder to pull than the correctly sized one) just to mention a few other ideas that come to mind....) and I would wonder if the starter was mounted centered as well... if the electric start can crank it over easily with no trouble at all, should be able to pull engine over with recoil just as easily.. so I'd kind of be leaning at taking a closer look at what's been put on that thing if it isnt the original ball clutch starter clutch and square drive pulley rope starter...

[KE4AVB]

I think Brian is on the right track here.

But let me make sure you are saying what I think you said that it has an old wind up start on it too? If so is it allowing you to pull through okay using a rope? If so then I would think there is a binding issue with the replacement recoil.

As for the valve adjustment yes it harder than the OHV but no harder then increasing the clearance on a L-head, just need to lap the valve to close up if isn't too much. But I would check with the feeler gauge idea using only a couple thousandths to see if it does help first that way you don't need to pull the head. If doesn't I would too be looking closer at recoil setup.

As far double head gaskets I haven't tried using two except when I have drastically decrease the head normal clearance while removing warp-age; just didn't want too little clearance. Never really got a good field test on them as the two engines only lasted 3 months before they ran them without oil during the extreme heat [100+ day temps] we were having. But I still think it was okay as they using them 8+ hours per day at the nursery.

[Arkie]

The 190407 8HP had the old wind-up wrap around rope type starter and factory 12v electric start. The wind-up rope was a hard pull also. I installed a Briggs 693900 or 390391 recoil assembly from another engine and engine compression is just too high. No binding on the manual starter assembly.

The electric starter will start the engine but sometimes it has to be jogged/ bumped over the compression hump with the 12v starter, once the 12v electric starter gets a run at the compression bump it will keep cranking thru good electrically. Only takes about 2 revolutions when the engine is warm for a start. You can tell that the electric start system has to be in tip top shape to crank thru the compression on the first compression revolution stroke.
I checked the compression on the engine but do not remember the exact reading. I just remember it was not weak on compression.

I'll check the ex valve lash and if on the high end in clearance I'll try the feeler gauge method to reduce the ex valve clearance too see if it gets any compression relief on crank thru. I really doubt that it's carbon buildup on the top of the head and piston.

May have to just sit the engine back for use as electric start only.

(engine would be worthless if not for the electric start due to the hard manual crank effort)