Formula 500 Design/Build Help
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We at HRE have very high hopes for this new class. We hope
racers/builders will use this page as a resource for the construction
of their own F-500 or to simply get some FAQ answered.
racers/builders will use this page as a resource for the construction
of their own F-500 or to simply get some FAQ answered.
Suspension Helpers:
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.
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.
We've added a limiter strap here which
holds the rear suspension 3-3 1/2"
from bottoming out.
holds the rear suspension 3-3 1/2"
from bottoming out.
**Note we've moved the front rod back
4" to it's new home and secured our
front strap to it.**
4" to it's new home and secured our
front strap to it.**
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.
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.
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.
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.
Front End:
Our Radius/Tie Rod End & Bushing
kits fit like a glove. No drilling or extra
washers req'd to attach to stock strut.
kits fit like a glove. No drilling or extra
washers req'd to attach to stock strut.
| Side View. |
Ski & Carbide:
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".
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.
Most of the common rebuild parts are reasonable, Crank brgs. are only $15- $30 ea. and I
have found that D & D Crankshafts in Eagle River, Wi. 715-477-2030, will do a compete
rebuild for $125 plus parts {which you can supply}, He also will guarantee less than 1 week
turnaround. 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. Remember
you must use OEM stock gaskets & pistons but after-market crank brgs. and seals would be
fine. After-market intake manifolds should be alright (OEM ones are pricey),but MUST be
exactly the same diameter and length. The OEM stock head & base gaskets are a little pricey
but since a few thousandths can make a noticeable difference here, you will NOT be allowed to
use aftermarket.
We can sell main crank brgs. for $15 ea., crank seals $2 ea., piston rings for $8 ea., intake
manifolds $8 ea. This is far cheaper than OEM.
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.
Most of the common rebuild parts are reasonable, Crank brgs. are only $15- $30 ea. and I
have found that D & D Crankshafts in Eagle River, Wi. 715-477-2030, will do a compete
rebuild for $125 plus parts {which you can supply}, He also will guarantee less than 1 week
turnaround. 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. Remember
you must use OEM stock gaskets & pistons but after-market crank brgs. and seals would be
fine. After-market intake manifolds should be alright (OEM ones are pricey),but MUST be
exactly the same diameter and length. The OEM stock head & base gaskets are a little pricey
but since a few thousandths can make a noticeable difference here, you will NOT be allowed to
use aftermarket.
We can sell main crank brgs. for $15 ea., crank seals $2 ea., piston rings for $8 ea., intake
manifolds $8 ea. This is far cheaper than OEM.
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.
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.