Formula 500 Build Help/Notes -

Prepping skis & carbides:
You need to make certain the flat back of the carbide is resting solidly against the ski.  Even
though the carbides only have 3/8" studs, we machine slots 1/2" wide and 5/8" long to allow
clearance for the weld holding the stud.
We have tried using smaller holes and grinding down the weld, but it weakens it and when someone is hurrying at the track one of the studs will break loose. We only grind the small amount of weld that usually hangs over the side of the bar to make sure it can easily fit down in the groove in the ski. Never use a setup where the carbide is not fully supported by a groove in the ski bottom, the studs will not keep the carbide in line.  You may also need to cut some off both ends of the bar, it only needs to extend approx. 1" beyond the last stud.  We cut both ends at a 45 degree angle so they don't hang up on anything.
Never guess on the angle when sharpening, make it fit the gauge exactly and I would grind
down the steel bar on both ends until the groove is gone to help these 6" carbides penetrate.  As we've stated many times before.  Sharpening your carbides is VERY important.  Be sure to get them "Perfect".

Engine:

We have been measuring stock Indy 500 cyls. and have got some dimensions that can be a
guideline for racers to verify that their cyl. has not been modified;
The following height dimensions are all measured from the top of the Cyl. ;            Exh. port= 1.165", Transfer ports= 1.885", Bottom of intake port= 3.860",                 Overall cyl. height=4.570"
Port widths are: Exh.= 1.810,                      Main transfers= 1.090,                      Secondary transfers= .860",   Intake= 1.960"

There is always a slight variation in port dimensions but if yours measures different than these
specs. by more than .020" YOU SHOULD HAVE A TECH. GUY CHECK IT BEFORE
ASSEMBLING.

  Stock Cyl. bore size should be 2.836- 2.838. The stock spec. is 2.835 but they will seize easy if you run a little lean or timing advanced to maximize power output. 

Dyno Testing Results

The pipe has the after-muffler cut off and the internal stinger removed, this leaves a 1 1/2"
hole in the tail end of the chamber for which we made a bushing to reduce it down to 1.160" {29.5 mm}, this was the size I found to be best. (make sure to taper the transition from 1.5" The engine was freshly rebuilt with .010" oversize pistons, all new crank bearings and seals. The squish clearance on the head is .130" and the engine only pumps about 115 p.s.i. cold. This engine will live on 93 octane (normally) but if you are going to push it to the limit on timing and jetting I would run 98-105 octane for safety. I used VP red fuel for my testing, it is a little over 100 octane. The weather conditions were: 45 deg. air temp., 1200 ft. elevation and aprox. 50% humidity.
All testing was done with no air box and 110 deg. water temp.

Best main jet was 250 {ALWAYS USE OEM MIKUNI JETS}, needle clip was in fourth position from top.  Ignition timing needed a lot of advance, I had to move the magneto plate counter clockwise almost all the way (approx. 2-3mm from maximum advance on screw slots). I checked the timing with a dial indicator and a light after I found the best setting it was .260" BTDC @ 2800 rpm.  To check your timing put a dial indicator in the mag. side plug hole, find TDC then turn the engine backward until the piston is down .260 inches, while holding in this position make a mark on the flywheel (thru the viewing window on the top-front of the flywheel housing), this should line up when checking with a timing light @ 2800 rpm. (the mark I made on the flywheel was aprox. 1/8" past the last factory mark). These timing specs. may be different on other year ignitions.

** UPDATE ** I just ran a complete 89 ign., the timing specs came out the same as the 1990.

This engine made 75.3 hp @ 75-7600 on long hot runs, it started at about 70 hp with all
factory settings.

Luber:

Drill 2 small holes in the rail to run straps
through.  Strap your hose to the rail.  About 1"
from the end of hose put a glob of silicone
(black glob you see), just so lube doesn't run
down the rail and be un-effective.

Suspension Help:

In order to keep the springs away from the track clips and use 4-5/8" OD Wheels we welded on offset 1-3/8" OD tubing as pictured.  If you don't offset the tubing you'll need to run 5-1/2" Wheels

We added an adjustable front strap
as shown (available from us as a kit)
for adjusting the rails.  We've taken
off all marginal snow wheels and
removed the front shock as well.  (Note - we've moved the front rod back about 4" to it's new location).

Tech Updates:

New for Predator 1100 & 1108 Triple - Gas Pressurized Piston w/ Rings!
We have found 3-6HP Gains by adding a series of .040 Holes around the circumference
of the piston dome to improve ring seal on these single ring pistons.  If your pistons are in
good condition we can modify them accordingly for $20ea.  
All New 1100 & 1108 Pistons now come with this update.


Predator 1035 - We have found that some of the 800 + 900 ignitions have less timing
than others and may require a larger offset key for best performance. If your 1035 will not
pull 76 gram arms to at least 7900 R.P.M. this may be the problem.

*To check (have your dealer do this) - Using a dial indicator, put a mark on the flywheel
when piston is .050 before T.D.C., then check with timing light at full throttle, this can be
done on a jack-stand with brief full throttle bursts. If timing is less than .045 at full throttle,
then a larger offset key should be installed. (each .007 of key offset = approx .010 more
timing advance, measured in piston travel)

**Example: If your engine has .030 timing (instead of .050) when checked and you have
a .020 offset key installed, then you need to install a .035key, which should give you
approx. .050 timing advance, measured in piston travel.



*Important - Whenever you change the flywheel key you MUST use your dial indicator
again and remark the flywheel.

Any Engine:  Please don't bother to ask us about your Exhaust Temperature Gauge.  
We have not found any use for using such an instrument in tuning for performance.  If the
engine is running and 1 pipe is iced over and 1 will cook hotdogs nicely... you've got a
problem.

**For all the latest rules and regulations for racing classes please refer to the latest publications produced by the actual sanctioning bodies of the sport.  This goes for Ice Oval and Drag Racing.  Be sure you have the latest set of rules so that you are sure to be building in such a way to pass technical inspection at the track!