Chief Cylinders 38-39

[sirhrmechanic]

I continue to do some research on cylinders. Hatfield's book has been very helpful!

Question for the Chief experts: Are the '38, '39 and the 40-43 cylinders all functionally the same? Ie... intake/exhaust ports, bolt holes, etc. identical?

I know there were some changes in fin shapes and external pattern. But I can't tell from the pictures in Hatfield whether the cylinders will interchange despite the external shapes. Also, will the fins on the later (reproduced) cylinders interfere with any other features of the earlier bikes if installed?

If the cylinders are the same functionally, I am wondering if I can take a pair of reproduction cylinders and mill/reprofile the fins to match the '38-39 pattern? With a rotary table and some templates... it should not be hard to do. But if things like the ports are in different places, the idea is a non-starter...

Has anyone tried this or heard of this?

BTW, I think I got my answer on Castleland (ebay seller of repro cylinders/pistons). Pretty sure they are the Indian ones referenced in another thread on this forum. In some more digging, I found that you guys have already well-covered the Indian (as in Bibbidy Bibbidy, tengu berry mud, not Springfield-made) parts, along with a list of modifications that need to be made just to make the parts from overseas work. Looking to me like Starklite is a better choice... but they don't make a 38-39. Thus my question about modifying.

Unless someone has a pair of '38-39 jugs they want to part with ;-)

Cheers,

Sirhr

[exeric]

The cylinders did not change in their dimensional core design. The challenge to make a pair of late cylinders look like pre '40 cylinders will be shaping the area between the base, and the first fin. Shaping the fins to match an early cylinder shouldn't be a problem.

[sirhrmechanic]

Thanks, Eric! That's what I wanted to know! If I take on the challenge, I'll post some 'how to do it' pix.

Cheers,

Sirhr

[bikerdds]

Dear Sirhr, the cylinders are identical except the casting numbers, which are unmistakeable. 38 is 85996 and 85998. Both 39 cylinders start 92xxx, but forgot the last three numbers for each at the moment. Indian may have had a subtle change in the valve guide, which I can't see in order to say the cylinder was different, but after having many in my hands, I can't see anything. The correct cylinders and casting numbers has a dramatic effect on bike value. They are hard as hens teeth to find today, and normally need a lot of work if you can find them. Reworking new cylinders is a lot of work and close at best. 35-37 is a different animal as well. They are 85612 and 85614, and they are different from 38 and 39, but still look better than later cylinders.

[sirhrmechanic]

Hi Bikerdds...

Thanks for the additional clarification. I have some inquires out for originals.

I am not trying to do a full AMCA restoration. But if I am going to build up the original cases, I at least want to *try* and make things look correct. And the '40-up cylinders are way off.

Right now, the bike has a '46 engine in it. So if I can get the original cases back in it with a good facsimilie of the original cylinders, that is a plus. I also have a ton of time to find original parts. But currently I am doing some planning, thinking and designing, which is what I generally do long before ever turning a wrench or cutting a chip. Thus my question.

Thanks again, though, for the input and advice. It's all valuable!!!

Cheers,

Sirhr

[ChiefTwoKicks]

this may be of interest... I have a '36 Chief Bobber that has later cylinders, valve covers and an alternator (mounted behind the center post). For me, the most important thing is the tranny lid. It is an early (shorter height) lid, and the shifter rod is also shorter. The reason is for clearance on the lower fins on the rear cylinder. The later (taller) lid won't fit without grinding clearance for the fit. I'd like to mount a Kabota 12V alternator in front of the post which is correct for a rigid frame application, if there is room for it. I may have to settle for mounting the Kabota alternator (looks like the correct Autolite gen.) behind the post. At least I will be able to get rid of the bulky Mitsubishi charging device.