A1Viper

Hey, is the gasket between the backplate and the crankcase really critical? I melted mine, and none of my local hobby shops have it in stock. My fav. LHS ordered it for me, but it's going to be awhile before I get it and I really want to run my truck!

Thanks

djlyon

Make one, out of heavy paper if necessary, but I wouldn't run without it. Air leaks are baaaaaaaaaaad.

Calhob

Yes, Viper, the gaskets in both sides are critical alright. But they are sooo easy to make. Get a piece of heavy brown paper as from a large envelope. Press the crankcase on to a stamp pad and then on to the brown paper. That should give you an exact impression of the gasket. Very carefully cut out the centre circle with an Xacto knife and the outline with a small pair of nail scissors. The screw holes are best cut with a punch such as is used for leatherwork, or you can use a pice of wire heated up; they must, of course, be in exactly the right places. Lightly oil your gasket and install it. It will be just as good as the bought ones. Easy!

jetpack

My Feedback: (1)

Gaskets sometimes also double as shims. I've seen some backplates that were too close to run without the factory designed gasket thickness. Just be sure your Crankshaft Pin isn't in threat of rubbing it, otherwise it will give your piston a nice bath of alumimum. All mine are OK of that because I've checked them and sanded them down when necessary to give clearance.

On engines that have a front bearing case, a gasket can also adjust the position of the connecting rod end to the crankpin. I would say if your motor was broke in using a bearing housing gasket, keep using them or it will have to reseat and wear a new spot which will sometimes can add an unexpected amount of slop. A good idea to have is if your not a big fan of using gaskets, before putting a new motor into service, take all the gaskets out first and start checking if its going to disturb anything.

When everything is go, I use CRC Disc Brake Quiet for sealant. Squeezing it out of a fine tip glue bottle I can trace the finest bead of it, and dries in a jiffy. Before you decide what part gets the goop, be sure you determine it is the part that is the most easy to work with peeling it off when it comes time for that. Then before you stick it and finish bolting, give its mating surface a quick wipe with WD-40 so it keeps itself stuck ONLY what you traced the bead of sealant on - you dont want to be gluing your model airplane motor together with it. A fine bead and a wipe of WD40 will keep you happy, and it will seal just fine until its time to come apart.

If you make a mistake, its water based...just go soap it off and try over. Much better than solvent on the hands like you would have to with RTV. When it is dry, taking it off is easier than rubber cement, it just peels or rubs off with an eraser or rag. Practice making narrow beads on some paper first with the bottle, but its easy you'll see. It works for me.

I've built my motors to be mechanic friendly about this issue, and polished up both sides of the seal area on all my motors. This helps with sealing and removing the sealant. Work well around the corners when polishing to allow for any squeeze-out that has to be cleaned when assembling.

A1Viper

Wow, okay, lol. So I'm not sure what you mean by large envelope, will construction paper work? And I could just use WD-40 for the oil?

Thanks

w8ye

My Feedback: (16)

Use the cover page from a magazine like Model Aviation.

A1Viper

Yeah, I don't exactly have any magazines laying around, and I sure as heck ain't going to tear up my 4Wheeler.

How about a cereal box?

jetpack

My Feedback: (1)

Pick what you think is compacted the most, or has the chance of swelling up like popcorn the most when you wet it with oil. Thats what comes to my mind as to the grade to look for. That tan or brown office envelope material seems like a good one like you say.

A1Viper

okay guys, I tried making a gasket out of the envelope paper (great to use), but I just can not get the middle hole cut out. Any ideas? I've used exacto knife, etc. and can't get it cut out right.

jetpack

My Feedback: (1)

If you dont have a compass with a blade, then try spinning the paper under the blade to make a circle.

Take a couple small tears of masking tape one on top the other for thickness and poke a pin through it for an axle to turn the paper under the knife.

After you poke it into a soft base like my desk/workbench/dining table, take it out and then mark half the diamter of what your trying to cut. Thats where you jab the knife and spin the paper against the knife.

Then your left with cutting the outside profile by hand with the scissors or nips.

Jim Thomerson

Once you manage a center hole, put the protogasket on the backplate and assemble the engine. Mark the screw holes and make screw holes in the gasket. Bolt the backplate and gasket on, then trim the gasket down around the outside with your Exacto.

A1Viper

I successfully made a gasket! I used one of them large envelopes to make it out of, then I sprayed it with the jet turbine oil stuff my dad uses. Worked great! Thanks for the help guys.

-Andrew