Topic: Opposed 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.

[Rooster]

1. Depends on the model of the 40 block, some of the newer ones were same block as the 42, while some of the older ones were quite a bit different. look at the heads off of the 40, if they are marked "42" then what you have is a 42 with a 40 crank and rods.

2.  42's

3.horizontal or vertical engine? Which one are you running?

4. False

5.They all run the same piston as the 28" singles

6.2 into 1 with equal length primaries.

As for your pulling class...I dunno, best advice there is talk to Flat Head Puller......HEY DENNIS!

[flatlanderfornow]

I'm building a horizontal for my 1606 Cub.  The vertical is in my Wheel Horse 750# tractor.
I'd like to find a 46 long stroke crank and try it, but the 42 will do for now

[amr5080]

It would be in your best interest to pick up an Opposed 101 dvd from G-team racing. He shows a lot of tips and tricks to make these things run and last.

[FlatheadPuller]

They will run with most anything class permitting. Use there torque and gear accordingly. I built a very strong one for my 126 cub a few years ago. Mine was not stock though. I had a billet flywheel made for it. Used a horizontal engine with a vertical intake and a kohler k series carb on an adapter. It would turn 5600-5400rpm and run with any S/A 14hp kohler in our club I pull with. I run the S/A 14hp and under class. We have to start with 14hp or less. Altered cams and must be stock apearing on the outside. I had Don grind my cam but Chuck vogel can as well. He makes a nice stock lift big duration cam for them. If you have to use stock parts use the pistons from a 28. There lighter and will drop in with no mods. Make sure both oil holes in the rod beams are toward the cam. Have the big end of the rod opened up for oil clearance. No less the .0025. You will burn it up otherwise. Use the big cast iron intake and carb from a 40cid. You will know it you see it. Pick up an old service manual for the engine off ebay. Has all the sizes in it for carbs and such. If you can use one just use a k series kohler carb on a horizontal intake for a vertical and on a vertical intake for a horizontal.

[flatlanderfornow]

I may have the intake already- my 16 horizontal has the 42 inch heads.  Carb looks the same as my 42 inch vertical engine.  I have to be careful with carbs as they check them pretty close.  I can
probably get away with a cam as long as it is stock lift and looks stock.  I'm competing against
OHV and big-cube Onans in this class, but the Onans are getting hard to come by and cost a
fortune to build.  Got any 42-cube horizontal cranks kicking around?  I'm from the no replacement
for displacement school.

[FlatheadPuller]

Todd most the carbs look the same on the outide. Its the venturi that is the different. The "big" carb is big compared to the rest. I do not remember the size but search the flathead forum on here and you will find it. I do not have my book anymore. Yup cubic inch is were its at. If you want you can put some arc rods and the 31 cid pistons in it with a 42 crank. yo uhave to have it sleaved but its a stock piston from briggs.

[THawley08]

Are you sure that I would ahve to be sleeved? From my measurements you can bore it to a 31 without sleeving.

[FlatheadPuller]

Tommy it depends on how thin you want the factory sleeve. Me personaly I would sleeve it. When a sleeve moves it does alot of damaged. This is just my own opinion.

[flatlanderfornow]

I got a carb kit that had 2 or 3 different size gaskets, and it took the biggest holed one.
We are allowed .060 overbore, any more than that will bring down the axe.  Next year
we are supposed to run purely stock engines, so will be interesting to see how that works out.
There are some gray areas in the rules, however.  From what I am learning about these engines,
it looks like you can get away with a bit.  I'm wondering if you could get a piston and rod
combo that would stick the piston a little above the deck and allow you to raise the
head without losing compression.  I bet that would rip.  I better get to bed, my imagination
is getting away from me.

[flatlanderfornow]

I was looking up parts for my 42 and noticed 2 different cam part #s- 212337 and 212415.
Anyone know the difference?

[birdman_express]

Splash lube and pressure lube take different cams.

[THawley08]

only difference is center drilled and a notch cut for oil pump drive.

[flatlanderfornow]

Thanks. 

[Rooster]

only difference is center drilled and a notch cut for oil pump drive.

You sure about that??