A tachometer in a P-30

[BULLETLS1]

Finally finished cutting the steel Stamping
That forms
The back of the instrument pannel, this is what looks like!

Comments!?

[Daveinet]

cncsparky wrote:

Daveinet wrote:
I think 2002 and later 2500. The 85 is rated for a higher load than the 4L80E.

Dave, do you have any info or a link to your swap? I'm looking into the same, but have not figured out how to handle the parking brake on the back of the tranny. Will the TH400 park brake bolt up to a 4L80/85E that had one from the factory?

Likely. My coach is front wheel drive, so there is a transfercase hanging off the back of the trans. When I had the trans built, I had them install a short shaft from a TH400 into the back of the 4L85e. The output shafts are interchangable. The bolt pattern on the back of both transmissions is identical. Where you need to get creative is the spacing. I machined a spacer between the trans and the transfercase because the back of the 4L85e is flat, where the TH400 is concave. This means the shaft sticks out farther on the 4L85e. Other than that, its pretty simple. So assuming the parking brake bolts on to the back of the trans (instead of a tail shaft housing) one should be able to just add a spacer and bolt on the brake.

[cncsparky]

Daveinet wrote:
I think 2002 and later 2500. The 85 is rated for a higher load than the 4L80E.

Dave, do you have any info or a link to your swap? I'm looking into the same, but have not figured out how to handle the parking brake on the back of the tranny. Will the TH400 park brake bolt up to a 4L80/85E that had one from the factory?

[Daveinet]

I think 2002 and later 2500. The 85 is rated for a higher load than the 4L80E.

[turbojimmy]

Daveinet wrote:

JimFromJersey wrote:
The vac gauge does let you know when the engine is performing 'efficiently', but it's somewhat disheartening to see the tach floating around 3000 rpm at 55-60 mph. I guess there's just not much we TH-400 owners can do...

Sure there is. 4L85E. It's not that bad of a swap. The underside of a motorhome has a lot of space, so its ends up being pretty easy to more a trans mount. Shortening the driveshaft is pretty cheap. Trans controller is 6 bills and easy to set up as well. It is actually kind of nice to be able to custom tune your trans for your specific driving style. I have mine programed to up shift late, but then not downshift until I really get into the throttle. It keeps the TC locked up most of the time, unless I really need it to downshift.

What did the 4L85E come in from the factory? New ones are spendy, but I have friends in the salvage business. Might be a good option for me.

[Daveinet]

JimFromJersey wrote:
The vac gauge does let you know when the engine is performing 'efficiently', but it's somewhat disheartening to see the tach floating around 3000 rpm at 55-60 mph. I guess there's just not much we TH-400 owners can do...

Sure there is. 4L85E. It's not that bad of a swap. The underside of a motorhome has a lot of space, so its ends up being pretty easy to more a trans mount. Shortening the driveshaft is pretty cheap. Trans controller is 6 bills and easy to set up as well. It is actually kind of nice to be able to custom tune your trans for your specific driving style. I have mine programed to up shift late, but then not downshift until I really get into the throttle. It keeps the TC locked up most of the time, unless I really need it to downshift.

[turbojimmy]

JimFromJersey wrote:
Doc & TurboJ, one of the POs of my Bounder installed a Vac gauge and a tach to the left side of the dash gauge cluster. It looks like a pretty simple job.

The vac gauge does let you know when the engine is performing 'efficiently', but it's somewhat disheartening to see the tach floating around 3000 rpm at 55-60 mph. I guess there's just not much we TH-400 owners can do...

I thought it might be taching that high at 55-60. I'm going on a trip at the end of the week and have plotted a non-interstate route.

[JimFromJersey]

Doc & TurboJ, one of the POs of my Bounder installed a Vac gauge and a tach to the left side of the dash gauge cluster. It looks like a pretty simple job.

The vac gauge does let you know when the engine is performing 'efficiently', but it's somewhat disheartening to see the tach floating around 3000 rpm at 55-60 mph. I guess there's just not much we TH-400 owners can do...

[Doc_Eagle]

Turbojimmy,I had room between the speedometer and AC controls to drill a 2" hole for a small Sun Tach. I also installed a small, like 1-1/2" vacuum gauge to the right of the AC controls. Was going to mount under them which would have looked a bit better but had issues on where my fuse box was located. Good luck with your project.

[turbojimmy]

I'm hoping for 6-7 MPG out of my '84 454. It's a Q-Jet setup. With a TH-400 trans, it's screaming at 55 MPH. I ordered up a cheap Sunpro tach for the steering column. I like the idea of tweaking the dash, but I'm too lazy to do it 🙂

[Doc_Eagle]

Ok last leg of trip we managed to get 10.2 mpg. Was very happy with that, I have been looking at the headers to fit. I am planning complete tuneup before next trip. Spark plugs, wires, distributor cap and rotor, oil change, etc. Have a small exhaust leak but sealed it with Quik Steel Extreme, don't want to mess with that until I am ready for changing to headers. I looked at the spec plate again, looks like at just under 23' it is about 12,500 fully loaded. Next trip is a return to Kings Bay Georgia Naval Base, wife wants to tour the base, camp ground was nice.

[Joatha]

I had a 1990 Winnebago on a P30 chassis with a TBI 454. It was 31 feet long and weighed (purely an estimate) around 13-14K lbs.

I got 6.5-7 MPG if I ran on a cool day (ie temp below 70) or at night without the generator going. On a hot summer day (temp above 85) with the generator, I'd get closer to 6-6.5 MPG.

[Joatha]

Edited due to being a duplicate

[Gjac]

Daveinet wrote:
I'm almost 32 feet. Weight is 13580 fully loaded.

Gjac wrote:
I am surprised also that the newer 8.1's and V-10's don't do better than the older motors. Most seem to report 7-7.5 mpgs on on the newer MH's with 5 & 6 speed transmissions, while 8-8.5 mpg seems to be the norm for a 454 TBI with a 4 speed transmission for the same length MH. Maybe more HP uses more fuel? Weight of stuff inside more slide outs?

They are significantly more efficient, its just that they are installed in units that are much taller and about 8K lbs heavier. Most the old 454 are running in coaches that are 16K lbs on lower profile chassis. The 6 speed does not help mileage, but just optimizes engine speed for best use of available power. In high gear, the engine RPM is still nearly the same, regardless of if you have a 4 speed or a 6 speed. The difference is that when you ask for more power, it will shift sooner, so the engine is turning the optimum RPM for the needed power. You also have a lower first gear.

Interesting, mine is a 1995 33 ft 11 ft 6 in high and weighs about 15,000 fully loaded. I did not think the weight would be that much difference. 8000 lbs is a lot of weight increase, but I guess when you look at the whetted surface area increase of the newer, higher, wider mh's plus slides the weight adds up quickly and it is still HP to weight that affect performance and mpg's.

[Daveinet]

I'm almost 32 feet. Weight is 13580 fully loaded.

Gjac wrote:
I am surprised also that the newer 8.1's and V-10's don't do better than the older motors. Most seem to report 7-7.5 mpgs on on the newer MH's with 5 & 6 speed transmissions, while 8-8.5 mpg seems to be the norm for a 454 TBI with a 4 speed transmission for the same length MH. Maybe more HP uses more fuel? Weight of stuff inside more slide outs?

They are significantly more efficient, its just that they are installed in units that are much taller and about 8K lbs heavier. Most the old 454 are running in coaches that are 16K lbs on lower profile chassis. The 6 speed does not help mileage, but just optimizes engine speed for best use of available power. In high gear, the engine RPM is still nearly the same, regardless of if you have a 4 speed or a 6 speed. The difference is that when you ask for more power, it will shift sooner, so the engine is turning the optimum RPM for the needed power. You also have a lower first gear.