The Bench Racers Journal

[Terry Bentley]

Chapter 128

This week is flying by too fast and Thursday is coming around a lot sooner than I would have liked. But so far, I was sort of ahead of schedule. The engines are very close to being assembled. Well Chris and Steves engines are almost finished. OK mostly in my head so far as what work is still needing to be done. I was still holding out for some speed secrets to try out on mine.

Made no sense to me doing all of this work and deciding against trying out some of the things that have been bouncing around in my head. I am sure most of the modifications should make a difference. Just dont know which things might actually help enough for the time and effort. Not to mention being reliable or not. If I left my engine alone and then tried some of the ideas on the modified engine might not ever get a chance to run it in a race.

The current plan is keep the modified engine as our spare. To use if one of ours takes a dump. Not to rely on as a main engine. My thoughts on this is having the fastest engine ready only as an emergency backup would make sense.

I could try some of the ideas out on this engine and since it would not be run except in an emergency more or less, should last for at least that one race. This is what I kept thinking. But I still wanted to find out if these trick mods did work and just as important if they would hold up. Cant find that out if an engine just sits in a box as a backup.

OK for my engine I have decided to use an E-65 piston for higher compression, but leave off the two lower rings. I will try out the epoxy mixed with that aluminum powder. There is only one way to find out if this works or not.

If it does not work, I will swap out to the backup engine. If Chris and Steves engines stay fairly mild, there should not be any problems or chance with one of them cratering during the race.

Since the Cates kart engine is already set up for the chopped down flywheel, I will go back with the lighter version of it this time. Not the one Mr Cates paid for and did not realize was even heavier than the one he sent out to get modified.

That engine from the Cates kart ran so well after swapping out intake manifold and bigger carburetor, so all three of our engines will eventually be set up similar to the same way. One thing I had not thought about until a long time after lightening up those first flywheels, is removing more cooling fins.

I could set up and remove every other or every third cooling fin. Just depends on how many there are on the flywheel. I dont know for sure to guess how many to cut off. I wonder if algebra could be put to use here? But I would still need to know how many fins are there either way. It not worth the trouble right now to walk out to the garage and count them. Since I should already be asleep.

Maybe I could throw this on Frank and see what a smart engineers brain can do. I bet he would go into some stupid spill about how the stock flywheel has been designed for a particular amount of airflow and should not mess with what has already been calculated in to the original design. Some help that would be.

My argument would be just the same. But Frank, since the flywheel is not being used as originally designed, then modifications can be made for its current use. This would probably cause a blank stare from him. To put a kink into his engineering brain waves is fun to do.

For now I need to cut back the shrouds to make up for the shorter finned flywheels. Eventually all of the four engines will be alike. One less problem when swapping them around. Not that there should be much reason for that or issue there.

Another option is swapping out to the aluminum flywheels. I have not cut the fins down on these yet, but they are less than half what the lightened cast iron flywheels weigh in at. This is another one of those things I wanted to find out on a practice day, but never happened.

Chris and Steves engines will be set to the stock timing at 35 degrees before top dead center. Mainly setting the point gap to the factory specifications. I want to try the timing bumped up a little bit more on my engine just to find out if this helps. I dont know how much yet, but not more than a degree or two advanced.

The carburetor bodies have already been cut, but still waiting to be assembled. I wonder if Chris would be able to put these together after I show him the way my first carburetor is set up? That will be a big help if something he can learn how to do and hopefully be good at. Steve doesnt want anything to do with the insides of these. Too many small parts to loose. He said I build it, he will bolt it.

Everything is mostly finished on the one engine for Chris and just about ready to finally bolt all the pieces together. His engine will keep the stock piston for now. His intake and exhaust ports are opened up a lot more, compared to what they were, so should make some difference there.

For now I decided to keep the ports round instead of squaring them off like on the Cates engine. I tried to measure and calculate the differences between them. The Cates engine has ports squared, but not so much enlarged. Our three engines have all of ports opened up from 7/16 to 1/2 inch.

It looked like I could still enlarge the ports more on the Cates engine by running the 1/2 inch endmill thru. But those ribs will end up thinner than I am comfortable with. It might be better idea to only widen the outer ports. This would just increase the overall width without decreasing the rib size anymore than already has been done. Dont know what to do for now. Should just leave it alone I guess.

For the exhaust, I wish there had been enough time to try out that tuned port muffler thing. Right now, I am running the tubing that came on the Cates engine. Steve is running what used to be that big box muffler.

We ended up chopping off everything from the stock box muffler. It is basically an open exhaust, but is directed straight down to the ground. Instead of blasting out the side like most everyone elses is. But we could remove the steel cover plate and have a very noisy straight path out.

Chris has what used to be a stock muffler from a chainsaw. That is what he told me. It is nothing but an extension of the exhaust port opening coming straight out about 3 inches. Originally it only had a small slit cut in on each side. Now there are three additional 1/2 inch holes drilled thru the end. It is very loud. When out on the track then you know when he is getting ready to make a pass.

So there are a lot of minor differences between the engines. I am keeping the engine for Chris just reliable as possible for now. Maybe a little bit down on power, but I would rather he finish every race instead of being a missile then watching the end of the race from sidelines because his engine fails.

Steve has been consistent no matter what. So his engine isnt going to be anything radical. Same thing as Chris. I want him finishing his race instead of watching it. He will have the E-65 piston, but with all three rings. Since my engine ran so well just from swapping out carburetor and intake manifold, his will be very close to that set up.

My engine can have all of the experiments done. I am not so worried about finishing the race. Right now I am mainly interested in finding out what works out to make the engines faster. Then figure out what will be reliable. A ba1ance will have to be found between very fast or long lasting.

The pictures of engines and everything going on right now will have to wait until they get developed. Unfortunately that may be another week or even longer. Just have to finish out the film rolls and drop off at the drug store. There should be a lot of pictures if I stay focused on things for the journal.

Pictures sure make up for a poor description. Makes for even better understanding of specific details. So will add them soon as possible. But may be after we make another race. Wow just thinking about that sounds so awesome. Finally getting back to the track and actually racing again.

So much work has been done for what little time we have spent racing. It has been a lot of fun doing the work. But without finding out what helps the most sure can be draining. I need some track time. Then my second race. I can not wait!