Torque Converter Question

[bullseye670]

Ok. So, I've got the 390 squished into the back of this Yellow Jacket. Fits pretty good. Tight, but good.
Question is the drive belt. 40 series. The best I can get on the belt distance is about 7 1/8". That's being generous. Comet say's 7 1/2". What's going to happen? Never fully get up to speed. Bad Slippage? Worst case scenario, I could grind off the tube for the driven and place it back a little further. Real pain in the ***, though. Can't move the engine forward. Even if I remove the starter.
I'm in the process of welding a new motor mount plate on top of what's there. Trying to get everything where it needs to be.

Thanks, all.

 

[panchothedog]

A half an inch doesn't sound like much, but for belt tension it's a lot. I think you're looking at " worst case scenario ". You said you need to weld in a new motor plate. Can you raise it enough to get the 7&1/2" of separation that you need? It's that, or move the mount for the driven back. Leaving it like it is your driver won't start to engage until the belt is way up on the sheaves as the clutch closes.

 

[bullseye670]

I hear you.
I was just hoping one of the experts would say, 3/8" isn't too bad.( I'm going with 3/8" short not 1/2") I'm going to have to back up a few steps and get this right.
Looks like moving the driven tube back is my only hope. I can't move the engine up any due to the restrictions. Mainly the head would hit the frame, and the exhaust and intake are going under the frame. They would hit the frame.
It just wouldn't work that way. I'm just glad I have an option. I really didn't want to cut the factory tube off. It's soo nice the way it is. After all, it was designed for a smaller engine with a 30 series.

 

[ezcome-ezgo]

Shorter belt?

 

[bullseye670]

I'd love to get a shorter belt. On the comet chart, taken from a belt, 7 1/2" center to center is the shortest they have.

 

[ezcome-ezgo]

Calling Dr Denny. Dr Denny you are needed for a consult.

 

[JimD]

My Comet book on the series 40 says the Center Distance between the two shafts is 7 1/4" on the Comet belt # 203783A. Manco had the belts made outside more than likely using the same people that Comet used which is the same thing we did.

 

[Denny]

I would try it before I went cutting things apart. Worst that could happen belt would ride a little higher in the secondary?

 

[bullseye670]

Wow. That's very interesting. I got the shaft and center bolt on the driver lined up pretty good. Gives me a pretty accurate measurement that way. At least 7 1/8". Wish I could hold the tape and take a picture at the same time.
I think I might give it a try. Thank you very much for that bit of information on the spacing. That's just what I was looking for.
Hey, one other thing. If my engine is touching the seat frame, do you think I'm going to get a crazy amount of vibration? I'm thinking yes.

Here's a good shot of that driven tube that I'd hate to cut out. It's so nice having it built into the frame. I'd put it back, but it's the whole idea.

 

[bullseye670]

I guess this ones going to be a pull start. I took the starter off the engine. That helped. I'm really close to 7 1/4" now.

 

[panchothedog]

Certainly looks like it's worth giving it a go. If your engine fires easily, it won't be that bad pull starting it.

 

[bullseye670]

Yes, I'm going forward with it as a pull start. My shoulders aren't what they used to be, but these things start pretty easily.
I'm ok unless the thing won't start and I wear myself out.
Everything is going to fit better this way.
It just so happens that I bought this plate by accident a long time ago, thinking I was getting a switch hole cover. Now I have a use for it.
Starter delete.