280000 briggs l-head compression release

[38racing]

I'm in discussion of this on another forum. I've had many of these apart but none right now. I am almost 100% positive that there is no compression release mechanism on the cam but that release is built into the cam lobe and I believe it is the intake. I had one of these engines with the symptoms of the OHV not cranking. I had excess intake valve clearance and a new valve at right spec fixed.
Poster is insisting it has mechanical release and directs me to the service manual which in my opinion indicates that some L-heads have the mechanism but not all. Thought I'd get a second opinion here before stating my case elsewhere.

[KE4AVB]

Really need the complete engine numbers but if it is using the 697668 camshaft then it has ACR ground on the cam lobe. Now camshaft has been redesign to a skeletonize cam gear from the solid gear for weight reduction but all the images I found for the 697668, none shows a separate ACR. Even those skeleton gear don't a separate ACR.

[Walt 2002]

I agree, never have seen a cam for 28 series flat head different than post above with "Easy Spin" cam grind and have never seen a Service Manual showing anything different.

Did see something interesting while checking about a similar post. Some 11 series engines had both ""Easy Spin" cam and a mechanical compression release on the exhaust!

Walt Conner

[38racing]

I agree, never have seen a cam for 28 series flat head different than post above with "Easy Spin" cam grind and have never seen a Service Manual showing anything different.

Did see something interesting while checking about a similar post. Some 11 series engines had both ""Easy Spin" cam and a mechanical compression release on the exhaust!

Walt Conner

I saw it in the manual and it was in a section for the 11 series. Wikipedia has info on problems Briggs had with the grind when flywheel brakes were added on pushmowers.

[KE4AVB]

I agree, never have seen a cam for 28 series flat head different than post above with "Easy Spin" cam grind and have never seen a Service Manual showing anything different.

Did see something interesting while checking about a similar post. Some 11 series engines had both ""Easy Spin" cam and a mechanical compression release on the exhaust!

Walt Conner

I saw it in the manual and it was in a section for the 11 series. Wikipedia has info on problems Briggs had with the grind when flywheel brakes were added on pushmowers.

But I haven't seen push mowers with 12Hp engines that I am aware of. The biggest I have seen here has been a 8 hp Yazoo SP 24" mower.

Maybe someone has put in a cam from an OHV in it. But as I said the numbers would help to find what going on with the engine.

[38racing]

I agree, never have seen a cam for 28 series flat head different than post above with "Easy Spin" cam grind and have never seen a Service Manual showing anything different.

Did see something interesting while checking about a similar post. Some 11 series engines had both ""Easy Spin" cam and a mechanical compression release on the exhaust!

Walt Conner

I saw it in the manual and it was in a section for the 11 series. Wikipedia has info on problems Briggs had with the grind when flywheel brakes were added on pushmowers.

But I haven't seen push mowers with 12Hp engines that I am aware of. The biggest I have seen here has been a 8 hp Yazoo SP 24" mower.

Maybe someone has put in a cam from an OHV in it. But as I said the numbers would help to find what going on with the engine.

No, the OP has a 281707 with hard cranking and his intake valve clearance is above spec. I'm suggesting a new valve as I had exactly same problem on same engine. Another poster insists that I need to look at the service manual because he claims it has the mechanical release on it.

[KE4AVB]

No, the OP has a 281707 with hard cranking and his intake valve clearance is above spec. I'm suggesting a new valve as I had exactly same problem on same engine. Another poster insists that I need to look at the service manual because he claims it has the mechanical release on it.

Ahhh, Now the rest story is there.

I looked up the 281707 series which had the 212897 cam that is superseded to the 697668. You're right no mechanical release other than the cam lobe bump. Suggest to the other poster to look up the engine's camshaft and view the online images. Clearly no other ACR device in use. Don't personally know if it is on the IN or EX lobe but larger than normal clearance will cause problems of hard starting. Must have ground/file the valve stem too much or the cam lobe is worn down. This I have seen where lobes are badly worn. May be able lap the valve and seat back into normal clearance if it was a filing error; otherwise, I would check the overall lift by inserting a feeler gauge to remove the clearance temporary for checking the amount of lift. It may even that just the bump is worn down. This something you can do while checking the lift by looking for the bump.

Some posters are hard headed at times especially they think know what they are talking about but haven't check their facts.