im wondering the max.cruising speed with this combo?does it help to change out the fuel pin to get some extra power or is that wasted on the already close to being maxed out 4spd????????

I say the practical cruising limit is 65mph, based more on RPM's than horsepower. Changing throttle cam/ramp might get you there a wee bit faster.

The '94 28's went to the GM 6.5L TD; while I replaced the OEM engine, the original would do 85 mph, as Mogan suggested, because the shorter-stroke GM is yellowed at 3500 RPM.

thanks guys!! the fellow i bought it from told me its at 1600rpms@60mph,but i find that very hard to beleive with that 4spd.what do you think?

i bought it and didnt drive it yet!!i really liked how there made.i travel alot to BC and its more then hilly there,just wondering if i have enough power now to pull the big hills,or do i need to change out to a 6spd.what do you figure the rpms are at 65mph????

1600 RPM @60 MPH is about what mine does but has a 6 speed with double overdrive.

Do a search as this had been discussed many times onn this forum.

For sure 1600 RPM @ 60 would not be correct with the 4 speed.

If you are looking for more power for the hills, you would have to change out the rear end to a 4.1:1 and then go to a 6 speed for lower RPM at cruise. Not an easy or cheap thing to do.

The 5 speeds and 6 speeds have nearly the same ratio in first and second as the 4 speed does so just changing to the 5 or 6 speed will not help for low speed power or acceleration.

quote:

Originally posted by jamie j:
i bought it and didnt drive it yet!!i really liked how there made.i travel alot to BC and its more then hilly there,just wondering if i have enough power now to pull the big hills,or do i need to change out to a 6spd.what do you figure the rpms are at 65mph????

I had essentially the same configuration. With dirty fuel filters, coming home from Mesa, AZ, 60 was the best I could do. My recollection is that was 2000rpm. So, I'm trying to remember if I was getting 65 @ 2500 with clean filters.
With only 190hp, your 16000# (+/-) coach is going to slow waaaayy dooowwwn on hills. Towing a modern MINI Cooper, on a Featherlite trailer, I was down to 25mph full throttle trying to crest Vail Pass and Loveland Pass.

here is a link to a discussion of a few years ago about changing a 4 speed to a 6 speed. I believe it also discusses engine RPM.

6 speed conversion

quote:

With only 190hp, your 16000# (+/-) coach is going to slow waaaayy dooowwwn on hills.

And it's probably the standard 160HP...

quote:

Originally posted by Rusty:

quote:

With only 190hp, your 16000# (+/-) coach is going to slow waaaayy dooowwwn on hills.

And it's probably the standard 160HP...

Indeed, NA is more likely w the 28, Rusty

Mine turns 2550 @60mph. I am really jealous . I think I have a trans problem.
5.9 (220hp) Allison at542

What size tires are you running?

If you have 8R19.5 = 614 tire rpm
If you have standard re it's 3.73

This give 2477 engine rpm's at 65 mph. This assumes a lockup convertor which the 542 does not have. I used to turn about 2550 at 65mph.

Thank you, Gary. Then my memory still works (sometimes)