Topic: Briggs Opposed twins questions

[flatlanderfornow]

1.  40 to 42- just change crank and rods?
2.  best head to use, our rules don't allow any mods to head, so it will have to be stock
3.  add spacer to carb or not-doesn't have one on my horizontal but my vertical does, and
     both are original
4.  I heard the ignition timing retards as RPM goes up, true or false, and if true any way to
     prevent this. Can't run advanced timing key.
5.  best stock pistons to use, I've seen a couple different part #s
6.  best exhaust system design- I'm going to run a stock lift reground cam, but I believe
    a straight pipe is not the best choice unless the valve timing events are setup specifically
    for it   
Tractor will be used for pulling, ungoverned.  Guys are telling me these engines won't be
competetive in the class I'm pulling this in.  I'm just stupid enough to pick up that gauntlet.
I put this in the Flathead section as it had more recent activity, but pulling ain't racing.

[mr.smitty_78]

I dont know that much about the briggs opposed or any of the twins really but in the yahoo groups theres a group called GardenTractorPulling and another Called BeltDrivePullingTractors I know there are plenty of guys on there that will do more than answer your questions some may even let you come check out there setups and show you some tips and tricks. If I knew more I would help but as Ive found out allthough there are some similarities a race engine and pulling engine are two very different things. But these racing guys have tried about everything with these and Im not saying dont listen Im just saying get input from both sides and then compille it togetther and find the common things and go from there. If that makes sence. I hope this helps you Thanks Josh

[flatlanderfornow]

Thanks.

[Rooster]

1. Depends on the engine, some of the newer 40's were the same as a 42 with the shorter stroke...in that case then yes.
    The older 40's had smaller valves and some camshaft differences. The best way to tell is look at the heads, the big-valve 40's run a 42 head as well.

2.If you cannot modify the head it will have to match the block, an unmodified smal chamber 40 head will not clear the valves on a 42.

3. Depends on application.

4. False, there is no advance in the ignition system.

5.Pistons are all the same with the exception of the big bore 46's...if you have one of those...we need to have a meeting with me, you & my wallet!

6.I run a 2 into 1 equal length header, but I am racing....I would think pullers might do something different.


Lastly, the man you need to talk to most is Dennis, AKA Flathead Puller.....HEY DENNIS!!

[FlatheadPuller]

What class you pulling in Flatlander. I was told they would run as well but built one. blew it up. built another and blew it up. Third one was a bullet and won me a points championship in a stock altered class 14hp and under. They will run. In pulling they like 5500rpm. Dont need anymore, might not even rev that high, but they make a ton of torque and that is what you must gear for.

This is the one I built.

[flatlanderfornow]

2 classes- 750# 8"rear wheels, Briggs twins only, supposed to be stock, not all are. 
              1000# 12" rear wheels, 18 hp or less twins, supposed to be stock, not all are.
we have to run turf tires, but can cut them.  I'm going to pull with another club closer to
home as well, rules are a little looser.  I blew one up as well, seemed to be lack of oil to crankpins.
We run about 5000 out of the hole, but engines don't stay there, probably in the 4000- 4500 range.