Goes full throttle at start

[Auto Doc's]

Hello D.

Have you ever seen how slow SAE 30 pours out when cold? The same thing is happening inside the engine and an additive like Lucas just makes it flow slower the colder it gets. I quit using straight SAE 30 years ago except for gearboxes and older 50's tractor hydraulics.

I also used to use STP oil treatment year-round until I learned more about fluid viscosity and the cold. Great stuff, but it hampers the oil flow.

Try at least a good SAE 10W-30 and no Lucas additive. The additive has permanently penetrated the pores of the metal by now and adding more is just a waste.

My old series 6 Snapper RER has an 8HP engine that is a similar design.

I'm fairly certain that switching the oil will help resolve this issue.

Of course, check your throttle shaft on the carburetor for excess side play on the throttle shaft. I had to replace my carburetor because it wore the housing out at the throttle shaft and would not idle properly, but yours could be hanging slightly and not allowing the throttle plate to initially close like it should.

These old engines are great, but they have their quirks with age.

I think your governor is working, but sluggish. If it did not work the RPM would not come down at all.

 

[Dwayne Oxford]

Thanx, yep I know well the pain of pouring 30 wt. in the cold. As I said the Lucas helps in the summer, picking up grass, not in winter picking up leaves which this old tired unit is dedicated to.
I don't like running detergent oil in these with no oil filter. It keeps dirt in suspension. Tried 10W-30, had to add oil WAAY too often & these are PIAs to add oil to.
I reach behind and pull choke linkage to start, gonna have to push throttle linkage back at start till flys sling out.

 

[slomo]

I don't like running detergent oil in these with no oil filter. It keeps dirt in suspension.

So with non-detergent oil, is your oil perfectly clean? All the trash/carbon/unburnt fuel and such falls to the bottom of the oil sump? So are the internals clean as new parts all the time? I've never ran non-detergent oil.

Briggs and the others recommend detergent oils.

 

[Auto Doc's]

Thanx, yep I know well the pain of pouring 30 wt. in the cold. As I said the Lucas helps in the summer, picking up grass, not in winter picking up leaves which this old tired unit is dedicated to.
I don't like running detergent oil in these with no oil filter. It keeps dirt in suspension. Tried 10W-30, had to add oil WAAY too often & these are PIAs to add oil to.
I reach behind and pull choke linkage to start, gonna have to push throttle linkage back at start till flys sling out.

The engine code shows it is a '78-year model engine so it has seen better days. I started in a small engine shop part- time while in high school back in 1979. Things have changed a lot since then.

 

[Dwayne Oxford]

So with non-detergent oil, is your oil perfectly clean? All the trash/carbon/unburnt fuel and such falls to the bottom of the oil sump? So are the internals clean as new parts all the time? I've never ran non-detergent oil.

Briggs and the others recommend detergent oils.

They didn't recommend it when these were new and detergent was available. I'll run ND in these old unfiltered units.

 

[Dwayne Oxford]

The engine code shows it is a '78-year model engine so it has seen better days. I started in a small engine shop part- time while in high school back in 1979. Things have changed a lot since then.

Yup, kept it alive awhile now, hope to awhile longer. I'm 73, saw better days too.

 

[Auto Doc's]

They didn't recommend it when these were new and detergent was available. I'll run ND in these old unfiltered units.

Hello D.,

The oil sump on this thing has also likely collected large amounts of micro-particles of sludge buildup in the sump at this age. There are several cavities in the sump where this stuff will just lay in there from the day the engine began running.

 

[Dwayne Oxford]

Hello D.,

The oil sump on this thing has also likely collected large amounts of micro-particles of sludge buildup in the sump at this age. There are several cavities in the sump where this stuff will just lay in there from the day the engine began running.

Had to replace the sump gasket 7-8 yr. ago, was cleaned then, change oil every year.

 

[Auto Doc's]

As much as I hate to say this, it may be time for a full overhaul with a rebore, new piston, rings, gaskets and governor/ oil slinger. The trouble is that at this age the parts will be practically non-existent. Along with that, practically no machine shop would even consider the rebore without it costing a fortune.

Another option would be to check around any small engine shops and salvage to see what can be had. eBay is an option, but people have gotten so they think they own gold when it comes to older small engines.

Next option would be to repower with a newer engine, but most just do not hold up like the old ones. Most are Chinese Clone throwaway at best anyway.