238cc Tillotson race motor build

[Flyinhillbilly]

So be it!!! I'm still waiting on a delivery truck myself...

That’s the hard part.

Well, that and paying for it all, lol.

 

[Flyinhillbilly]

The brown truck came today and brought me a hog, a hog of a camshaft
Custom ground billet tool steel unit with ramp angles so aggressive that it requires bigger diameter billet lifters to keep for breaking out the lifter bosses.
My head guy went on vacation, so I won’t have a new head for a couple of weeks since I decided to get a new laid back racing head built for it rather than reusing the one I have. It only has three races on it, but still I’d rather have a new one built and leave that one on the orange kart that’s became known as the orange crusher. Tomorrow night I’ll probably check clearances, tonight I’m fondling my new cam and watching street outlaws.

 

[BigWes]

Those aren't even lobes. They are square notches

 

[Flyinhillbilly]

Those aren't even lobes. They are square notches

Yeah, and they’re causing me fittment issues too. The lobes are so big that they hit the crank, and the block.
Back to clearancing......
For some reason I can’t get pics to upload. It’s saying they’re too big.

 

[BigWes]

I meant to say big square nobs but somehow autocorrect changed it for me...I was gonna fix it then the server went 'poof'...

Fitment issues suck. I didn't get a chance to work on mine today. My son and his wife stopped by so I didn't mess with it any.

So how do you think you can make it work? Or will it?

 

[Flyinhillbilly]

I was able to make it work by grinding the corner off of the lifter boss, and cutting a notch in the counterweight on the crank.
So now there’s a point where the intake lobe actually dips inside of the crankshaft.
The angle of that picture makes the cut look awful. It’s actually pretty nice, but that’s the only angle I could get a picture from.

 

[Flyinhillbilly]

Now that the pictures are working again, these were the issues I was having.

 

[BigWes]

Wow, so lemme ask you a dumb question. I know you are building this thing to turn some serious RPM. Are you going to have it balanced now since you had to cut away the crank like that? Even a few grams of weight will generate high frequency vibes enough to cause damage especially with the RPM I feel like you will be getting into. I'm guessing 10k with major torque loads with all that duration.

I wanna hear that thing turn dead dinosaurs into loud noise dude... really bad... I'll be waiting for that footage!

 

[Flyinhillbilly]

I didn’t remove any more metal than I had to, it looks like more than it was in the picture, and that crank is generally used with a 3” piston, and I’m using a 2.835, so I actually feel like I’ve improved the balance if anything. I’ll set it up on some steel plate edges with the piston hung and do a poboy balance on it. I know a lot of guys that do it that way with good results. I don’t really feel like you can accurately balance these engines anyway. You might get it just right in a narrow rom range, but the nature of a single cylinder engine is not very agreeable to the traditional idea of balancing.
Short version, I’m just gonna send it.

 

[BigWes]

Well then...there ya go

Looks like you'll be sending it!!!

 

[Flyinhillbilly]

Since I won’t have a head for this engine until late next week, or early the week after, I took a break from it to build a new engine for one of my buddies that had a professionally built engine grenade on him.
I didn’t take a lot of pictures because I had no real intention of posting about it, but decided to when I found the cam was polished from the rod touching it because it wasn’t properly clearanced. This one is a 70mm bore block I picked up from ARC wit a stick predator crank, 3.595 ARC long rod with a two ring Wiseco piston and 320 NR cam. Everything fits as it should after some time with a die grinder and shouldn’t be a problem moving forward. It’ll have a 32/28 fully ported head with 60lb dual springs, and 1.2 roller rockers and be fed by a 28mm flat slide mikuni.
I just thought I’d take a second to preach about the importance of clearances.

 

[BigWes]

Yeah... I'm glad I checked mine real good after the pic you took of yours where you had to clearance below the piston sleeve. I had to clearance both sides. The ARC rods have a much different profile...better check twice.

---------- Post added at 10:02 PM ---------- Previous post was at 10:01 PM ----------

That and I also installed a slightly longer rod... don't tell anyone about that

 

[bob58o]

I just thought I’d take a second to preach about the importance of clearances.

And the importance of having a good engine guy.

 

[Flyinhillbilly]

Yeah, I was a little disappointed in the quality of the pro built engine. I really feel like for what he charges it should’ve at least been built where it wouldn’t self destruct.
On a happier note, my pushrod kit and 1.2 rockers showed up from EC Tillotson today. With the lift my cam has, 1.2 rockers will give me .396 lift at the valve.
Now I’m just waiting on the head.

 

[Flyinhillbilly]

Well hot dog!!!
It looks like I can post pictures again.
That’s a good thing because I’m expecting a super nice head a little later this week.
Anyway, here’s a pic of the rocker arms and pushrods

Nothing super exciting today. The header came in. .960 inside diameter, and I bought this specific pipe on the advice of my cylinder head guy. He said with a few modifications this header shows 1/4 - 1/2 extra horsepower.
I can’t share or show the mods because I’m sworn to secrecy on this one.

 

[BigWes]

Those roller rockers are beautiful man.

But I just can't comprehend 14 1/2 EXTRA hp from a header... that's extra power... So just how much are you estimating that mill to be putting out anyway? 38-40hp?

You gonna name it Little Farley then try for a Melt Down!lol

Man I can't wait to hear that thing turn dead dinosaurs and corn liquor into glorious noise and sweet perfume...too bad I won't really be there to smell the burn! Oh well...you can tell me how good it is!!!

 

[Flyinhillbilly]

I had to edit that, it was meant to say 1/4 -1/2 extra hp. I really have no idea what it’ll make, I’m just hoping for “enough”.
I really believe it’ll leave the one on the orange kart in the dust though.
Just wait until you see the head. He sent me some pictures of it, and I can say without a doubt that it’s well beyond anything I’ve had in the past.
Hopefully I’ll be shaking it down this weekend. I plan on assembling the short block tomorrow night.

Got the ring filed and the short block assembled.

I’m honestly starting to get pretty excited about this.

 

[Flyinhillbilly]

The head came in this morning, and it is a nice piece. I happen to be off work today, so it looks like I can finish this motor up.
I may even have time to fire it up.

It’s done.
I got everything finalized and port matched, etc today.
I took it for a little test rip, and it’s nasty. Way faster than my orange kart.i can burn the tires at will, and when I say burn the tires, I don’t mean spin a little, I mean that I have to let off the gas for fear of over revving it.
I’m putting it on the track Saturday night and will update when I get some real world results out of it.
It seems promising.

 

[BigWes]

that thing is the best dude! and it sounded awesome! you gonna run it this weekend?

 

[Flyinhillbilly]

Yeah, going full send Saturday night