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Thu May 15, 2008 4:02 pm

I have a unknown 40 hp with a big nut tranny in my 66'. I pulled it apart as it started to burn alot of oil (visible smoke screen when reved, but fine under constant load).... what I found was that on the #3 cyl piston the bottom of the piston ring groove had really tighten up on the compression ring... so I have filed down the ring groove carefully, re-ringed/ honed engine, bench tested it and now it doesnt burn a ton of oil... problem solved.... (as far as fixing the engine)

before I put it back in I want to see what people thought of this combo? (highway speed is only 55mph here and I really like the combo and got really excellent fuel mpg)

Im wondering if the big nut gearing is putting to much load on the engine and will just overheat this engine again?

Ive read of other people running this same set up (I think EV did at one point) and was wondering what there/your experience was? overheating issues?

Thu May 15, 2008 9:08 pm

IF you think its running warm, i would do a plug check, and see if your jetting at cruise is too lean. may want to step up a size. also check dwell and timing. make sure its all good. belt is tight, and crank that sucker up to about 70 mph. that should keep it cool. :D

i MAY try this combo in the future, but for now the earlier trans make me smile. knowing my 40 is singing back there. hehe.

Fri May 16, 2008 5:12 am

i have a 40 and a big nut and it is noticibly slow on hills and under acceleration. i would rather have a small nut back there.

Fri May 16, 2008 9:57 am

My '63 Standard had a 40hp with a big nut. It sucked on hills or with any headwind. It seemed like I was always putting it in 3rd gear on any long upgrade.

It was nice around town and on flat pavement though.

Sun Oct 26, 2008 7:51 pm

I have this setup and I'm trying to figure out if the power output of my engine is normal. On a flat road I can do 50 to 55 depending on head wind. As soon as I hit any hill I start to slow down when in 4th. So if I'm on a hill for longer than like 20 sec then I have to downshift to 3rd.

Does this sound like your experience? How fast can you guys go on flat terrain?

Sun Oct 26, 2008 7:59 pm

2Pack wrote: ...As soon as I hit any hill I start to slow down when in 4th. So if I'm on a hill for longer than like 20 sec then I have to downshift to 3rd.

Does this sound like your experience? How fast can you guys go on flat terrain?

Hehe, that sounds like my 1600SP early Bay too.

Oops, sorry to be off the topic here! :oops:

Mon Oct 27, 2008 9:45 am

aggri1 wrote: 2Pack wrote: ...As soon as I hit any hill I start to slow down when in 4th. So if I'm on a hill for longer than like 20 sec then I have to downshift to 3rd.

Does this sound like your experience? How fast can you guys go on flat terrain?

Hehe, that sounds like my 1600SP early Bay too.

Oops, sorry to be off the topic here! :oops:

Well, that's a useful data point. My only other bus driving experience was in a 71 with a stock 1600 DP. It was slow, but could go 60mph in 4th easily even on a mild uphill.

Let me clarify that in my 64 with 40hp and big nut tranny I lose speed in 4th gear on any hill. Sometimes I can't even tell I'm on a hill until I realize my speed is dropping. This bus is an early 64 model year with 15" wheels, which doesn't help either.

Basically I'm trying to figure out if I should continue troubleshooting or just accept it.

Mon Oct 27, 2008 11:00 am

40 hp 40 hp @ 3900 rpm
29hp @ 3000 rpm
34hp @ 3600 rpm for engines without govner

Mon Oct 27, 2008 11:39 am

I'd drop down to a small nut.

Mon Oct 27, 2008 1:17 pm

My German delivery '65 came with a 40 horse and big nut. After I rebuilt it it went another 200k on that block before I put a 1500 in it. My driving sounds exactly like your description except I have 14s and was able to get up to 60+ on flat stuff and more downhill. Even with my 1500 I don't like to go over 58ish but it will.

Mon Oct 27, 2008 2:59 pm

Thanks for the input guys.

It sounds like I might have a little to gain as far as top speed on flat terrain but not much.