Friday, October 24, 2008

Installing a BSP Restrictor Plate

Take everything off to this point.

Put on a gasket.

Put on the restrictor plate.

Put on a second gasket.

Install the carb

Install the air filter adapter.

WRONG! The air filter adapter is installed upside-down.
Notice the blocked air orifice.

Friday, September 26, 2008

Splined Post for Jr. Dragster Torque-Converters

For several years, ARC has been making billet crankshafts with splined PTO shafts to provide the added strength some of today's larger, more powerful cars require, but the availability of posts for various clutch assemblies has been limited. So we decided to make our own.

The main post is made of 7075 T6 Billet Aluminum. The replaceable collar is made of steel and is assembled to the post via piloted LEFT-HAND threads so the direction of resistence from the engine to the belt keeps the collar tight. Posts and collars will be available soon for ALL the major Torque-Converters used today.

Friday, September 19, 2008

ARC "Ported" Clone Air Filter Adapter

Installed Correctly (click on picture for larger view)
Installed Upside-Down (click on picture for larger view)

For maximum performance, ARC's air filter adapter is ported to the low speed (left) and high speed (right) orifice jets. This is necessary because the funneled velocity stack design would otherwise cover these jets. Improper installation of the air filter adapter will partially cover, and impede flow to the orifice jets because they are not in the same position. The engine will spit and sputter and lack both bottom, and top end power if these orifice jets are blocked.

Tuesday, July 15, 2008

New and improved GX 340/390 flywheels

The GX 340/390 engine has grown in popularity to the point that we were able to produce a more specific flywheel body to this engine. One major change is that these flywheels are designed to use the stock coil, and don't require any coil bracket. Both flywheels are SFI certified and have integral billet cooling fins.

We have two new models and they will replace our previous models.

First, the 6623. This flywheel is basically a billet replacement for the stock flywheel and plastic fins. The keyway is in the stock position and it is designed to use the stock pull starter. $195.00

The 6622 also has ARC's steel adjustable timing hub and a bolted-on ring gear made of super strong 7075 billet aluminum for the on-board electric start. Some adaptation is required if you also want to be able to use the pull starter. $250.00

Monday, June 30, 2008

Cutting EL Tires

More like grinding than cutting. I can take a new EL tire down to "low dots" in 8 minutes with this machine. I sell a new set of ground tires mounted on Douglas Q+ wheels for $380 plus shipping (and tax in GA). If you bring me your tires already mounted, I charge $20 per tire to grind them. Prepped tires CANNOT be ground. 800-521-3560

Thursday, June 26, 2008

BSP Valve Springs (when to change and why...or why not)

I have about 150 new springs in stock. I have checked about 50 of them in many ways. They are all so close to one another that I quit testing. I compressed a brand new spring to its solid height and it lost tension to the point that it was no longer better than a spring with 14 races on it. I stretched a spring, and it went up in tension, but after compressing it at full cam lift, it was right back to where an untouched spring was. All the fresh springs measured 10.8 lbs at .850”. My scale is only accurate to .2 lbs, but my measurements are accurate to .001”
So here’s the kicker. If you are running the stock air box and filter and the stock muffler, heavy springs are actually bad because the engine makes more power and is faster at about 5200 RPM, which is well below the 5800-5900 RPM valve float RPM. Added tension is just a waste of energy. With the little header and muffler along with an air filter adapter and bigger jet, the power band moves up slightly in the RPM range, but still not enough to turn the engine to the point of floating valves. So basically, if the intake and exhaust is left stock, worn out springs are better, and with an aftermarket intake and exhaust you will want to freshen your springs after a few races. Changing springs is very simple and can be done with your bare hands without removing the head from the engine. I'll do a picture story on that and post it here this weekend.

Wednesday, June 11, 2008

Parts for the 6.5 HP OHV Engines

ARC now has inventory of new parts for the Yellow OHV 6.5 Horsepower BSP engines and the Blue 6.5 HP engines.

We also carry high performance parts for these engines including stainless valves, HP springs, billet aluminum spring retainers, billet rods, billet flywheels, cams etc.

We are fully engaged in loading all these parts onto our webstore and expect to have all out clone related parts online before the end of February.

Monday, June 9, 2008

Pulsing the Fuel Pump from the Rocker Cover

I drilled a hole to insert a 1/8" pipe nipple into the rocker cover. The hole is below the baffle plate in the rocker cover so it is pulsing directly from the rocker chamber. The red vent tube is above the baffle plate. I have raced this a couple times now and it works very well.

Wednesday, April 2, 2008

New Cranks...Lower Cost

Our stock-stroke and +.200 stroker flathead cranks are now made of a less expensive, hardened chromolly steel. The stock stroke crank is also used as a stroker crank in the Animal.

The new stock-stroke crank is part number 6580-C and the +.200 in part number 6584-C

The new cranks are $299.

Tuesday, February 5, 2008

ARC flathead billet flywheel for PVL

ARC now has a billet flywheel for the flathead that will allow you to use the new PVL ignition from B&S. We have seen substantial gains with this coil and flywheel over the standard (old) coil and ignition.

The new flywheel (#6617) weighs 3.85lbs. It has adjustable timing and is SFI certified.

Although this new flywheel has a larger diameter than a 3hp flywheel, the rim weight of the new flywheel is considerably lighter than the 3hp models. This means that acceleration with the new flywheel would be about the same as a 3hp model. BUT, the PVL ignition used by the new flywheel will give you gains beyond what you could ever get with the 3hp models with standard coils.

The reason this flywheel must have a larger diameter than a 3hp flywheel is because the PVL coil is designed for a specific diameter and appears to be sensitive to any deviation from that diameter.

Tecumseh OH Billet rod from ARC

ARC now has a stock replacement billet rod for the Tecumseh OHH 5-6HP engine.

Part #6282 3.484" (stock length). $59.95 MSRP

It does not use bearing inserts.

PVL Ignition on a 305

Hey guys, just wanted to pass along that Randy is working on coil brackets that will allow the use of the PVL coil and one of our new billet flywheels for the PVL on a 305. One of the brackets will be for a stock crank setup and the other will be for a stroker setup.

We have not tested this on the 305 yet, however, we found significant gains on 330' Outlaw Jr Dragster engines and on Animal engines over what we were able to produce with our original billet flywheels and standard coils. In order to get the greatest improvement, we had to richen up the fuel/air mixture and reduce timing from the settings normally used with the standard setup. On the Drag engine, we ended up with a longer header pipe and actually needed to put on a bigger carb because the engine wanted more fuel than the smaller carb could deliver. This testing was done at Roy Whaley's shop on one of his highest horsepower engines. The HP increase was anywhere from 1/2 to 2 HP and the fall off on top end was not as steep as with the standard coil.

ARC rod for the stock 305 crank.

P/N 6231 - 4.335" Uses the stock crank and an JE "EXF4500" piston with a .490 wrist pin.

This rod will give you the same compression height as our P/N 6235 stroker rod for the same piston does with our P/N 6585 stroker crank.

1.2 ratio rockers for GX200 and Clone

These are the stock rockers for the Yamaha YF200 engine and they work fine in the GX200 or Clone.  You will have to either make a new pushrod guide plate, or adapt the one you have.

part# F21-408-00

.032 Copper Head Gaskets for GX200

I have had these for a while and never have done a good job getting the word out.

P/N FG9591 Flatout .032" rubber coated copper $12.46ea.

GX120 ARC Billet Rod

We have a new stock length billet rod for the Honda GX120. P/N 6273
It does not use bearing inserts and weighs 28 grams less than the stock rod.

You must remove the low oil sensor unit and it is probably a good idea to check your crank and have it polished prior to racing. The crank we had was a little rough.

A new big valve option for the GX200 or Clone

I just got in the new Burris Gen III valve kit for the Yamaha and it works wonderfully in the GX200. We need to substitute a few of the parts with some others.

Here is what you need for this setup:
2 F21-408-00 rocker arms $9 ea
2 F21-405-11 intake springs $7.50 ea - yields approx 19lbs at the seat with plenty of room for shims
2 F21-417-00 lash caps $4 ea
2 F21-406-20 spring retainers $7 ea
2 F21-407-20 retainer lock set $7 ea
1 F21-402-25 stainless intake valve $31
1 F21-403-20 stainless exhaust valve $31

We carry .015" .030" and .060" shims @ $1.50 ea

I recommend the push rods from the clone engine, however, I do not have them yet.

The intake valve is 1.070" (.072" larger than stock) and you will want to either install or have installed a new large inside diameter intake seat, (p/n 6148Y $8) or have a 60° cut on the existing seat to open it up to take advantage of the larger valve.

You will have to open up the slots in the push rod guide plate on the GX200 if you go with the clone pushrods. If you are hopping up a clone, you may need to fabricate a new push rod guide plate.

This setup gives you a large intake valve, approx 30% more valve lift, and as much spring pressure potential as you could possibly need. You need to use a billet flywheel and a billet rod with this as well. I think the long rod and a JE EXF4500-120 piston would be the best setup there. I also think the PVL ignition, along with the matching ARC flywheel will be the hot ticket if you are going with methanol. I personally suggest calling EC Distributing for your carb and billet intake. I have a few intakes and some gas carbs. But when I need a rockin carb for methanol, I call Carroll Ford at EC.

With this setup, you will be taxing the limits of strength on both the crank and the block. Where the line will be will depend on a lot of things, but if you can't stomach blowing up a motor, you might want to let some of us who live for that sort of thing find the weaknesses and come up with solutions.

Using a Long Rod in an OHV Kart Engine

This Article is specific to the Honda GX200, but the same clearance principles apply to just about any engine.

Since wiseco is eliminating their kart piston production, we want to focus on the use of J&E pistons in our instructions in order to avoid confusion.

The long rod is 3.707" long (+.404"). With a 3.707" rod, ANY piston that will fit the bore of your engine that can be cut to a .520" compression height will give you the same overall length as the stock length rod (3.303") with the stock piston (.924" comp hgt).

We do not have undersized bearings for our Honda rods at this time. If you are running a babbited bearing, your crank wear will be almost nil. That Honda crank is very good.

Some of you guys are talking about decking your block and/or shaving the head. That all ties together with the required compression height of your piston.

Two rules:
1. The minimum distance between the bottom of the head and the top of the piston should be .030". (I'm not going to get into domed piston theory here because it is not applicable here.)
2. The minimum distance at the closest point between the valve head and the piston during operation .090"

Every block is a little different. Assume for a second that the piston and rod combinations are fixed at 4.227" (stock length). Let's say that your gasket is .010" thick. Your piston would need to be .020" in the hole based on the .030" rule. In order to maximize compression, after decking your block, you want to shave the head until the valve head is as close to .090" from the piston when they are closest using the cam you intend to run. That's the very best you can do without a domed piston with valve cutouts. All these things have to be measured by mocking up each engine.

OK, now throw in the fact that the aftermarket pistons will need to be cut down to get them to a .520" compression height to achieve the 4.227" stock length. There's nothing that says you must cut that much off the piston other than making certain that the .090" valve rule is respected.

Since a JE EXF4500-120 piston is only .004" larger than a stock bore piston, and it has a .610 compression height than can be cut down, lets use it.

note: FYI, the JE EXF4500-140 and wiseco 1982p140 pistons, which are .024" over stock bore, have a .620 comp hgt and can be cut down to .520" but the wiseco 1990p120 piston has a .565" comp hgt and may not be able to be cut down to .520". If you follow that, you will understand why the JE EXF4500-120 is the best first choice.

Back to our example above. We said the piston would have to be .020" in the hole. If you mock up your engine with a stock rod and a stock piston and the piston is actually .030" in the hole, then you have two options with the long rod and the EXF4500-120 piston. You could cut .090" off the top of the piston to take it from a .610" comp hgt down to a .520" comp hgt and also take .010" off the deck of the block, or you could just take .080" off the piston and leave the deck alone. In either case, you are moving the piston .010" up in the hole and .010" closer to the valves, so keep that in mind because of rule 2 above.

This long rod is designed to clear the underside of the JE piston without modification to the piston or the rod.

Hunter or I can help you with all this in order to cut the the piston for you. We will need to know how deep your piston is in the hole with the stock setup AFTER any decking you are going to do. We can only assume that you have checked your valve clearance.

Seriously, if you are building an engine, you need to grasp this stuff in order to build the most performance that won't grenade due to lack of proper attention to known constraints.

One last rule of thumb: The piston dome should not be less than .100" thick in the center.


New ECONOMY Flathead Billet Flywheel from ARC

We have a new SFI certified non-adjustable billet flywheel for the flathead. This flywheel is stock diameter, weighs 4.05lbs, and has the keyway set at 30°.

The only difference between this flywheel and our Limited Mod adjustable flywheel is that this one does not have the steel adjustable timing hub.

Part #6620 introductory racer price $125.00

We made the flywheel that best fits ARC's capabilities. It's the best piece we could make with focus on affordability and maintaining our SFI certification. That's the best we can do for the racer. The design allows you to start your engine with either an electric starter OR the Briggs BS555165 manual pull starter.

ARC billet rods for the Vanguard / Mitsubishi OHV 6HP

We have two new billet rods for the Briggs and Stratton Vanguard OHV 6HP

#6264 Stock Length 3.465", uses stock piston $83.95 MSRP

#6263 Long rod 3.850", uses JE piston #EXF4500-120 with approx. .090" cut off the top. It is .385" longer than stock. $83.95 MSRP

Both of these rods use the same bearing inserts as the Honda GX200 (and clone) engines. By increasing the number of rods that use this bearing, we hope to be able to justify undersized bearings.

Does ARC make Custom Rods?

Quoted from


How expensive is it to have a rod built to a custom length?


That depends on the length, and we have to make a minimum of 3 rods. A bore diameter change at either end is $750 (for each end) unless it matches up with a bore of one of our existing rods so we can borrow existing tooling. A length change could be as much as $2000, unless it is only a slight center to center change that will fit within an existing rod profile.  The same profile allows the use of existing jaws.
So, for the first 3 special rods, $600-$3500 (for all 3) depending on those factors. Additional rods made in the same run will be about $100 each depending on how many you get.  There are other factors that could make it more, or less expensive, such as material cost and availability.