McTurff
Well-Known Member
No
Just the two gaskets under carb that sandwich the riser off manifold
I knew i would need new gaskets having taken carb iff so many times!
Easy fix
Then move on to tuning!
Briggs 422707 opposed twin carb
- Thread starter McTurff
- Start date
Just the two gaskets under carb that sandwich the riser off manifold
I knew i would need new gaskets having taken carb iff so many times!
Easy fix
Then move on to tuning!
Some general info about the Briggs twins: (from experience)
Keep a heads up on the 3 screws that hold the air filter base.
If one vibrates loose it has a direct shot into the intake and into the engine. I've found some engines with a screw imbedded into the top of the piston or hung under the intake valve.
You mentioned a air leak at the carb riser on the opposed twin carb. Some of them plastic spacers are up/down directional. If turned upside down they won't seal. (due to a locating molded tit on one side)
You mentioned sealing the twin Inteks intake to head. I started making flat gaskets like is supplied in some gasket kits that I install instead of relying on ONLY the O rings to seal. Some gasket kits do not included the intake square sided o rings. Over torqueing the plastic intakes will also result in warping of the flat surface and leaks
Also on the opposed twins: make sure the breather hose is connected to the bottom of the air cleaner base BEFORE it leaves the shop.
If it's inadvertently left off unfiltered air has a direct shot into the carb throat,
I've found some of those engines with bad rings due to leaving the hose off and the opening is bypassing the air filter.
I really prefer the Briggs opposed twins to the new twin Inteks.
They are really good engines and last long time with just little bit of proper care. (keep the cooling fins cleaned especially under the tin on the heads)
Keep a heads up on the 3 screws that hold the air filter base.
If one vibrates loose it has a direct shot into the intake and into the engine. I've found some engines with a screw imbedded into the top of the piston or hung under the intake valve.
You mentioned a air leak at the carb riser on the opposed twin carb. Some of them plastic spacers are up/down directional. If turned upside down they won't seal. (due to a locating molded tit on one side)
You mentioned sealing the twin Inteks intake to head. I started making flat gaskets like is supplied in some gasket kits that I install instead of relying on ONLY the O rings to seal. Some gasket kits do not included the intake square sided o rings. Over torqueing the plastic intakes will also result in warping of the flat surface and leaks
Also on the opposed twins: make sure the breather hose is connected to the bottom of the air cleaner base BEFORE it leaves the shop.
If it's inadvertently left off unfiltered air has a direct shot into the carb throat,
I've found some of those engines with bad rings due to leaving the hose off and the opening is bypassing the air filter.
I really prefer the Briggs opposed twins to the new twin Inteks.
They are really good engines and last long time with just little bit of proper care. (keep the cooling fins cleaned especially under the tin on the heads)
Last edited:
ILENGINE
Lawn Royalty
And will leak even worse with the flat paper style gaskets if the intake warps
McTurff
Well-Known Member
Yes make my own gaskets alot
Only time I can get them to seal is using the rubberized cork or rubberized paper gasket materials that are gas and oil resistant !
I don't mess with the inteks!
But those OHV plastic intakes to carb are hard to seal like you said with the o rings and like the rubberized materials for them!
Thanks
Auto Doc's
Lawn Addict
Famous last words: Trust me I'll pull out.... LOL
McTurff
Well-Known Member
Lastest update
Found my air leak wasn't the riser gaskets ended up being i guess would be throttle valve shaft where it goes through carb body!
I don't know if it is supposed to have some type of seal but mine did not so found a perfect sized o- ring that sealed it!
I looked at my other new 3 screw carb im working on and it had some kind of foam gasket ??
Anyway put an o- ring on that one also!
Engine running even better now not perfectly dialed but im at 1500 low and 2700 high rpms sounds pretty good in that range probably mess with it a bit more
Couple pics
Found my air leak wasn't the riser gaskets ended up being i guess would be throttle valve shaft where it goes through carb body!
I don't know if it is supposed to have some type of seal but mine did not so found a perfect sized o- ring that sealed it!
I looked at my other new 3 screw carb im working on and it had some kind of foam gasket ??
Anyway put an o- ring on that one also!
Engine running even better now not perfectly dialed but im at 1500 low and 2700 high rpms sounds pretty good in that range probably mess with it a bit more
Couple pics
Attachments
Auto Doc's
Lawn Addict
Many carburetors had a fiber material type of seal that would keep dust away from the shaft. Excess dust would gradually cause wear and excess play which would draw in excess air. The O-ring is a good substitute as long has it does not cause drag and delay the throttle operation.
McTurff
Well-Known Member
You nailed it!
The o-ring caused some drag but seals well so I cut the little o-ring in half not easy!! with a hot exacto knife!
And that worked!
Broke out my bass fishing o-rings for skirt material!
Haha
I just noticed that in Post #1 the air filter metal base has a screen.
In post #8 no screen.
I've never seen a screen at the base. Good idea to capture a base screw if one gets loose. I've found a base screws under intake valve and also imbedded in top of piston.
Have to do a double gasket or ??? to get a good dust seal though
In post #8 no screen.
I've never seen a screen at the base. Good idea to capture a base screw if one gets loose. I've found a base screws under intake valve and also imbedded in top of piston.
Have to do a double gasket or ??? to get a good dust seal though