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-   -   briggs 34cc head gasket (http://www.rcuniverse.com/forum/engine-conversions-92/11238912-briggs-34cc-head-gasket.html)

flyguyeddy 09-24-2012 06:01 AM

briggs 34cc head gasket
 
I may or may not have damaged my head gasket when I removed my cylinder head. Would a sheet of copper shim stock in the appropriate thickness work if I lapped the surfaces? I'm pretty sure they don't sell it seperate from Briggs.

All has anyone had luck Porting these little things for flow? The ports look TERRIBLE and I feel they could use a little work.

Also I can't manage to get the damn piston out, any tips?

flyguyeddy 09-24-2012 07:08 PM

RE: briggs 34cc head gasket
 
anyone?

av8tor1977 09-25-2012 08:50 AM

RE: briggs 34cc head gasket
 
No experience with that engine. Napa auto parts can usually get Briggs and Stratton parts for you if you can't find them on the internet.

I believe some Briggs engines are used in mini dragsters for kids. Might find some hop up info there... (again, internet search)

AV8TOR

flyguyeddy 09-25-2012 10:46 AM

RE: briggs 34cc head gasket
 
Well I dont want to run the stock head gasket if I don't have to. I'd prefer a nice copper gasket if I can figure out what the squish height needs to be.

I will probably remove the "eyebrows" around the valves tho.

Sport_Pilot 09-26-2012 11:39 AM

RE: briggs 34cc head gasket
 
Quote:

I believe some Briggs engines are used in mini dragsters for kids. Might find some hop up info there...
Those are much larger lawn mower engines. Not the little weed wacker four cycles.

erik58 09-26-2012 03:52 PM

RE: briggs 34cc head gasket
 
make one up. I've used them in briggs kart engine they work fine. :D

flyguyeddy 09-27-2012 06:14 AM

RE: briggs 34cc head gasket
 
Used what, copper?

w8ye 09-27-2012 07:02 AM

RE: briggs 34cc head gasket
 
I have a B&S 34cc four stroke weed whacker that someone gave me. It has a problem with the automatic compression release on the cam.

flyguyeddy 09-27-2012 07:20 AM

RE: briggs 34cc head gasket
 
Mine has no compression release. From the factory.

flyguyeddy 09-27-2012 07:30 AM

RE: briggs 34cc head gasket
 
But if you don't want I'll take it Off your hands

erik58 09-27-2012 12:59 PM

RE: briggs 34cc head gasket
 
yes copper I used differnt thicknesses depending on the fuel I used.

flyguyeddy 09-27-2012 03:22 PM

RE: briggs 34cc head gasket
 
What kind of piston squish should i use?

This thing has 3 rings! Just like the big boys

av8tor1977 09-27-2012 09:47 PM

RE: briggs 34cc head gasket
 
.020" is considered a safe minimum deck height, (piston to head clearance) on small engines. You might check your compression ration though, and set the deck height accordingly. I would shoot for around 10:1 compression if you can get it, and will be running premium gas and a good cooling system. An annealed copper head gasket should work, but I would coat it with Copper Coat sealer to be sure.

AV8TOR

flyguyeddy 09-28-2012 02:32 AM

RE: briggs 34cc head gasket
 
I'd like to run gas/glow on this one without the oil (heet and gasolinemix).

1QwkSport2.5r 09-28-2012 03:03 AM

RE: briggs 34cc head gasket
 

Quote:

ORIGINAL: flyguyeddy

I'd like to run gas/glow on this one without the oil (heet and gasolinemix).
Does that engine have an oiling system? If not, you will have to run oil in the fuel. I'm not familiar with that Briggs engine, I never knew that Briggs started making weed wacker engines... I guess you still can learn something new everyday.


flyguyeddy 09-28-2012 04:50 AM

RE: briggs 34cc head gasket
 
It is a wet sump 360 degree oiling setup. It even has an oil scraper ring on the piston along with two compression rings. Im goingto send the block and piston to frank bowman and have him make me a new top ring and delete the second one (or just make the second one too).

The head has already been sanded on a block of granite, ill do the same for the deck (to flatten it out). I thought of planing the head some. Any thoughts on that?

av8tor1977 09-28-2012 08:19 AM

RE: briggs 34cc head gasket
 
Once again, you need to measure everything and determine the present compression ratio before you start sanding things down and/or making thinner head gaskets. If you are going to run the Gas/Glow mix, the octane will be higher than gasoline, so you could probably get away with 11 or 12:1 compression.

AV8TOR

flyguyeddy 09-28-2012 10:32 AM

RE: briggs 34cc head gasket
 
There's non easy way to compute compression n this engine aside from cc'ing the head,and I don't have the equipment to do that (nor the block when I cut the eyebrows, which will lower compression

Nosedragger 09-30-2012 10:42 AM

RE: briggs 34cc head gasket
 
You are wasting your time with this. By time you get done modifiying and shipping back and forth on aftermarket parts you will have spent more than if you just bought a Honda and still not have as much power as a stock Honda.

Scota4570 09-30-2012 12:59 PM

RE: briggs 34cc head gasket
 
The deck height and squish can not be modified. The piston comes up even with the top of the jug. The gasket gives the clearance. The cavity in the head determines the compression ratio. A lot of the chat here is applicable to 2-strokes not 4-strokes. I have three of these engines. They have very poor power to weight. If it runs right you are ahead of the game the carb is a special 4-stroke type. It is not adjustable in any way. You will have to play with metering lever height and jet diameters. Porting and polishing has nothing to do with it. The cam is what it is and you can not change it. It limits the lift and duration. If you can rig it to get the engine running halfway properly you have done well.

flyguyeddy 09-30-2012 06:45 PM

RE: briggs 34cc head gasket
 
Nonsense the rotary barrel carbs with two needles hve been ised on these engines with success. And squish IS able to be set with a different thickness head gasket.

Scota4570 09-30-2012 07:55 PM

RE: briggs 34cc head gasket
 
The carb supplied for this engine has no needles in the conventional sense. There may be an idle needle in the barrel, if so it will be probably potted in place. It will be tiny, like an idle needle in a glow engine carb. Making it ajustable without destoying the carb requires luck. Top end will be adjusted with cut and try metering lever adjustments and/or drilling out the main jet. Other carbs, two stroke, types do not work properly. Squish bands refer to the ring shaped area around the peremeter of the piston in a hemispherical head. This engine is not made that way. I know these thing because I have spent many many hours fiddling with this exact engines. A thicker or thinner gasket will have no significant effect on the compression ratio in this case. The cavity in the head is too big.

Nosedragger 10-01-2012 02:29 AM

RE: briggs 34cc head gasket
 
Even if you could squeeze a full compression point out it, it would only give you a 3% increase in power.

flyguyeddy 10-01-2012 03:51 AM

RE: briggs 34cc head gasket
 
http://www.rcuniverse.com/forum/m_10...m.htm

This thread shows where to get rotary carbs with adjustable needles. Why wouldnt these work?

Also can you list the mods you have tried and results afterwards? What about planing the head down to reduce that combustion chamber pocket? I work at a machine shop so this would cOst me no money only time same as porting the eyebrows.

This engine would go on a fokker dvii where weight on the nose is required

Sport_Pilot 10-01-2012 04:21 AM

RE: briggs 34cc head gasket
 
Rotary carbs do not have low speed needles, instead a disk is used with a slot that widens as the throttle is opened. Perhaps you mean't a barrel throttle carb?


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