help my engines reversing

[cumminsbayou]

i just got a cam i think its 245 lift or something bigger then stock i know. i put it in my 5hp briggs lined the dots up and its sucking in air in the exhaust and pushing it out of the carb. whats causing this and how can i fix it the dots on the cam and crank are lined up perfectly

 

[bandit 40]

Did you install this cam WITH THE PISTON at TDC. Top dead center ?

 

[texasfabguy]

He said he lined up the dots. The crank is 1:1 the cam is 2:1.

 

[cumminsbayou]

well i did to start with but was told it wouldn't run that way

 

[cumminsbayou]

also i for got to say when i put my motor in top dead center it suck in the intake and blowed out the exhaust should i put it back that way?

 

[toomanytoys]

you have it 180 out.

The exhaust is opening on the intake stroke and the intake is opening on the exhaust stroke.

Put the piston at TDC, and reinstall cam.

 

[texasfabguy]

Better yet,pull the side cover with the dots lined up and take a picture for us. That will give us all something to look at and help with what you see.

 

[bandit 40]

you have it 180 out.

The exhaust is opening on the intake stroke and the intake is opening on the exhaust stroke.

Put the piston at TDC, and reinstall cam.

:thumbsup:

 

[jim210]

Like texasfabguy said.. it doesn't matter where the piston is as long as the dots are lined up. What lifters are you running? Did you set the valve lash?

 

[texasfabguy]

you have it 180 out.

The exhaust is opening on the intake stroke and the intake is opening on the exhaust stroke.

Put the piston at TDC, and reinstall cam.

If you turn the crank it would be a 180 out again,it's a 2:1 ratio on the cam so every stroke of the crank the cam moves 180 deg.

I think the problem he is having are the valves are to tight and need to be trimmed. It's because of the welded cam lobes are taller.

 

[bigrob]

I dont want to offend anyone but a little bit of reading on how a four stroke engine works would give you a little back ground information as to what is suposed to happen and when
It seems a lot of people think instaling a new cam is the same as screwing in a light bulb
Anyway show us some pictures good luck

 

[cumminsbayou]

how would i set my valves correctly? the dots are perficlilly lined up

 

[texasfabguy]

To long to type out but I'm sure you can find it in print by google,search for valve adjustment on your engine model.

 

[Txpowdercoater]

If you turn the crank it would be a 180 out again,it's a 2:1 ratio on the cam so every stroke of the crank the cam moves 180 deg.

I think the problem he is having are the valves are to tight and need to be trimmed. It's because of the welded cam lobes are taller.

winner

 

[Txpowdercoater]

how would i set my valves correctly? the dots are perficlilly lined up

dang, tearing into a motor with no clue and zero research....todays youth:doah:
real world, I'd bet a search in the forum section he is posting in would yield a very good "how to" on valve adjustment....also videos on you tube so he can watch the valves being adjusted. Just a smidgen of effort is required on the OP's part.
I mean, you searched and bought a cam, why not search and learn more about the motor while your at it.

 

[cumminsbayou]

dang, tearing into a motor with no clue and zero research....todays youth:doah:
real world, I'd bet a search in the forum section he is posting in would yield a very good "how to" on valve adjustment....also videos on you tube so he can watch the valves being adjusted. Just a smidgen of effort is required on the OP's part.
I mean, you searched and bought a cam, why not search and learn more about the motor while your at it.

lol yeah no hope for this new generation of kids is there :laugh: im pretty good with motors except moding and valves in a flat head

 

[Txpowdercoater]

here ya go ,briggs flathead valve adjustment remember, its hard to hurt those motors so give her hell and have fun.

 

[Neck]

Well if you set it up like this..

I have to ask, when you pull the rope, does the engine have any compression?
A big enough cam will have overlap and will suck in through the exhaust and blow back through the carb at slow crank speeds near 360 ATDC