Revo Parts F.A.Q.
Frequently Asked Questions

Topics Covered:

*Weight increase?                *Roto-Start Engines
*Clutch Shoes that fit           *Pull-Start Engines, and why not.
*Engines that fit                   *Manifold Gaskets
*Rubber Elbow?                  *Shims

What do you mean by non-pull start engines?
Non-pull engines are classified as any engine with fixed/one-piece back plate.  These are engines that have to be started at the flywheel.  These are the engines the RBBC kits are designed to work with without suspension arm modification.  Any other starting system may not work with our kits.

Why not offer a kit for pull-start big block engines? What about Roto-Start engines?
There is no "good" way put a pull-start big block on with the stock chassis.  One method would be to substantially raise the engine.  This creates several problems.  First and foremost, the center of gravity is raised quite a bit.  If  you lean the engine any further than stock, the idle screw and mid range needle adjustments will be virtually impossible, rear suspension adjustments would be tougher, and reaching the glow plug with an SUV body on would be nearly impossible as well.  Quality is not only about materials and craftsmanship....it's design as well.  There are too many compromises to make a pull-start big block engine fit.  Most of the special aluminum rear suspension arms  made to clear the pull-start mechanism have a very very weak area and the clearance would only be enough for a small selection of pull-start engines.  HOWEVER, all hope is not lost. Removing only a minor amount of material from an RPM rear suspension arm (PN 80191, 80192, and 80195) will allow the fit of a STS .28 engine with shaft-start (mostly likely the STS 30 and 21 as well) to fit using our kit.  See pictures provided.  This may or may not work with other roto-start engines.  The OS 30VG ES looks very promising, but we have not tried it yet.  The key is a very short profile starter housing.

Which non-pull engines fit the Qoncepts RBBC kits?
Nearly all non-pull big block engines without boost bottle back plates .21-.32 should fit.  There has only been one reported engine that will not fit without replacing the carb.  Axial .28 and .32 seeming come with 2 carb choices.  One has a common configuration, the other has an uncommon high-speed needle orientation which points forward when put in most monster trucks.  With this carb, the needle will hit the spur gear on the Revo.  Make sure you get the one with common orientation.  Click here to download Axial's Instructions in PDF format and look at first photo on the first page. This is the carb you DO want.  Look at the diagram below the picture.  This is the carb you DON'T want.  It is possible the carbs are the same and can be adjusted.  We do not know.  You will have to contact Axial (949 600-8642 ext 200) to be sure.

Isn't my Revo going to weigh a ton with a big block and big clutch bell?
What do you think?  NOTE: Qoncepts, no longer uses the blue silicone component seen in these pictures.

Which clutch shoes fit the Qoncepts flywheels?
The pin placement is fairly standard and works with most common 1/8 scale clutch systems on the market.  HPI Savage systems range from $7.00 to $9.00 for a set of shoes and springs.  ONFA and XTM shoes work as well, but cost a bit more.  Kyosho's MP-5 clutch shoes should work.  Aluminum clutch shoes made for many 1/8 buggies also work.  Make sure that the shoes have a centered slot for the spring coil.  Shoes with non-centered slots may not allow some springs to line up with the clutch nut. Shoes that come with the Kanai 3, are such shoes.

Which exhaust manifold gasket should I use with the RBBC?
The fit diameter of our manifold (header) works with gaskets that fit the engines that are most popular in the .21-.28 category  for monster trucks today.   In most cases, the gasket that comes with your engine will work.  We know this is true with the popular Wasp .26 and all engines that share their case designs.  The Wasp .28 requires a different gasket.  The most  important thing is that the gasket is flanged.  The flange, along with the spring will seal the header to the engine.   Other gaskets that we know will fit are:
OFNA 10068 $5.95 Retail for a 2-pack  Fits the smaller external diameter exhaust ports like on the Wasp .26
HPI 87049 $3.00 Retail for a 2-pack   Though the Wasp .28 has a larger exhaust port, this gasket works with it and our manifold.
 

Why is there a rubber elbow on the RBBC manifold?
Freedom!  Freedom to change the orientation.  Freedom to change the length of the exhaust path.  Freedom to remove your engine without disturbing the pipe mounting.  It can take hits better than a rigid manifold without bending or breaking.

When would I need a shim kit with the RBBC kits?
The stock flywheel will not position properly on a big block engine.  Without the shims, the clutch nut can not be tightened against the flywheel.  Some big block engines may require shims with the Qoncepts flywheel in order to get the clutch bell in perfect alignment with the spur gear.  This is the case with the Wasp .28, which requires a 2mm shim when the Traxxas collet is used.  As every collet may vary by a minute amount, so does every part (bearing, shaft, shims, bells, etc.).  This creates a small tolerance stack-up.  For this reason, we recommend you purchase a shim kit regardless of your engine choice.  It's one of those things that is good to have around anyway.  Several companies sell shim kits;  OFNA comes to mind. Your local hobby shop should carry an assortment of shims.  RC411 has a good article for clutch setup and maintenance.

 

Why are most of your aluminum parts black?
Qoncepts is about function, not flash.  Black blends in and looks like the plastic parts on the truck.  Qoncepts is the last place you should look for bling bling R/C components.