Topic: Oil Pan Difference 77-78

[sinnergsx]

After some searching, I didn't find a lot of information on the differences in oil pans from 70-76 and the 77-78s.

I had a cracked pan from a previous owner on my 78. Took a shot at an early model pan from a 70 and did a bunch of measurements.

From all appearances the pans appear to be the same minus extra cooling fins on the 77-78. Gasket pattern is the same, depth of pan is the same (although the 77-78 had more fins and material all around.

My conclusion is that the earlier pans are functionally the same and can be swapped. You will have more clearance for things like aftermarket exhausts if you use the earlier pans, but at the cost of less cooling on the lower part of the engine case. The oil drain plug does move to a slightly different location as well.

Just wanted to post this so others could find it in the future.
Pictures of the two pans attached.

-Cameron

[Tracksnblades1]

Good to know Kemosahbee….

11 fins a piece, just omitted over the sump…🤔 on the old one..

Either drain plug location will drain it right on top of a Yoshimura 4/1…😩

[BenelliSEI]

I didn’t know that. Thanks!

[sinnergsx]

Good to know Kemosahbee….

11 fins a piece, just omitted over the sump…🤔 on the old one..

Either drain plug location will drain it right on top of a Yoshimura 4/1…😩

OH to add to that- when I mean more fins I mean more fin height. The fins are all taller by a good inch, hence the added clearance on the earlier years. It actually made me think the pan was deeper on the inside. But alas it is not.

[HondaMan]

Yep, Honda's new engineers who made the K7/8 thought the engine needed more cooling than the earlier ones.

[willbird]

Yep, Honda's new engineers who made the K7/8 thought the engine needed more cooling than the earlier ones.

They had everything to run engines on dyno we would presume and the fact that they bothered doing it suggests that it had positive results. Some have mentioned used a CB350F housing and bolts which was longer in some years ? Adds a bit of oil volume and may cool a tiny bit better maybe ??

Unclear from a quick image search if all years are longer or just some.