18HP Vanguard need more power!!

[fulleraviation]

Ever wonder what the internals of the stock exhaust looked like. Gutted the exhaust to get alittle better flow.

[fulleraviation]

I seem to have come down with the H1N1 virus yesterday, and started and completed my engine mods.

I installed a precession cam, long billet rods, shaved the pistons, and installed new thin head gaskets.

It took the whole day. I only broke long enough to eat 2 ice cream sandwiches and drink 2 bud lights.

I deffinately have alot more power, and the 93 octane aint going to cut it. Went the the airport last night and bought some 100LL. Will drain the tank and see how the Avgas does.

Anyone have any recommendations for oil? I like Amsoil, but so far have run the 30 weight B&S oil.

Thanks,
Rut

[Meinfield]

Congrats on the build, that ought to wake that engine up! Just remember the factory briggs flywheels are only good to about 5500 rpm.
When you bump up the compression in these air cooled engines, it will raise the oil operating temperature so it is always good insurance to add an aftermarket oil cooler and fan. I like to run Mobile one synthetic 30W after the break in period.
Post some video!!

[lewis]

Sounds like that cat has some new claws!!!!!! Like to hear how she sounds so post up when your finished. Any plans for a clutch upgrade you should be turning a few more rpm's? Check Whippers exhaust system out it should let it flow better. More power.

Lewis

[fulleraviation]

Yeah, I'm not happy with the gutted exhaust and looking to custom fab something. Whippers exhaust looks awsome on his 50HP briggs Attex.

I have the ARGO high speed clutch, and very happy with it. Not looking to turn over 5,000 rpm, and will keep the clutch as it is for now. So the flywheel is good for 5,500rpm, what is the clutch good for?

I think that Micmac did a great job, and will probably do something similar. http://www.6x6world.com/forums/aatv-...-vanguard.html

What are you guys doing for oil coolers and fans?????

[Roger S]

For the small port 14-20 heads, 1" or 1.125 ID is big enough, 12 to 15 inches length. If you bring them into a collector, the rear pipe can be longer than the front. Collector design is an art of it's own, you might look around. Otherwise matched duals are fine, but two into one always gives a broader torque curve, starting at a lower rpm. Larger diameter tubes will kill low end. Whipper's heads have bigger ports than ours.

You can buy flanges from EC, but ask about tubing size, they may have more than one. The sleeve liners in the exhaust ports, leave them out. The problem with your muffler is the header pipes are too short. Flywheels, for the record, anything un governed is unsafe. A lot of the small mower engines have cheesy flywheels that can come apart. I was not told to get rid of the stock flywheel on the vanguard. Whipper's engine supplier said a stock wheel would be "ok" at the rpms he operates at A guy could build a scattershield..

The clutch, as I mentioned.. my 3 year old powerblock coughed up a lead slug at 6000. It was 3 years old and had two years of up to 6 grand operation. The phenolic "pucks" that hold the weights need to be inspected for cracks, or replaced yearly, that's my schedule. Not exceeding 5 grand often, lowers my anxiety level about a lot of things. 6 isn't that much faster anyway. No knowledge about the Max secondary clutch integrity..

I guess you used the offset key this time? I don't blip the throttle any more off a low idle, with high compression and 30 degrees fixed advance.. don't let it knock, it can break things. Richening it up will help also. Buy a .040" drill and use it on the main jet.


What cam did precission give you? and what lash did they recommend. This'll be at TDC, no more 1/4" past to worry about

Briggs makes a factory oil cooler, with a replacement oil filter adapter that is tapped for hoses. Richard Clark has them but don't know details or price. Otherwise something more substancial like Whipper or Meinfeld's coolers have to be better.

[fulleraviation]

George Herrin set me up with a 265 profile. At first John at EC wasn't going to recommend a cam, but I am glad that I did. Geroge spoke up while I was on the phone with John and immediately knew what I wanted and what the application was.

Here is some BIG NEWS: I have no problems using the pull starter!

Put 100LL in the tank and what a difference. This thing is sick!!! Can't wait to get it on the trail.

Also, I left the stock flywheel key in. I wanted the torque and not the revs. It will turn 5 grand easy, and that is plenty for me right now.

I can't wait to put a real exhaust on. Gutting the stock exhaust was a mistake! I did learn how to use my wire feed welder though!

Later guys,
Rut

[Roger S]

Glad it runs good.. I have no idea why the pull start works Mine is like pulling on a boat anchor, plug wires on or off.

I was hesitant to change the stock cam too, after hearing Matt's story about his Al Hodge vanguard.. but Herrin said the 265 grind would pull from 2200 on up. I had no loss of low end, had more power all the way up. Maybe the compression increase compensated for it. The 265 is not a wild cam anyway, sort of a healthy "street" cam. It's easy on the stock rocker arms, too.

It took the whole day. I only broke long enough to eat 2 ice cream sandwiches and drink 2 bud lights.

[coosaridgerider]

I just bought a 24hp honda motor from a guy that races mini pro mods,This motor has a two barrel carb on it.He said the 2 barrel made a big difference in the performance.This guy had a 18 vangaurd with the same carb on it.

[fulleraviation]

Made a new exhaust system today. Works great, but on the loud side. Sounds like a Harley with straight pipes. I used 1" Conduit and a couple of $4 lawnmower mufflers.

I am begining to think I have too much power now. I can spin the ASX Vamps without any problem now and drift arround corners. This thing is crazy!

BTW: With the thin head gasket and long rod, I was able to change sparkplug gap with the piston.

I installed new platnium plugs with 2 washers.

Rut