Biggest Bang For the Buck

[robert m fukumoto]

As a newbie who has yet to use his 76 Palm Beach, I wanted opinions on =
what was the most cost efficient upgrades to improve the towing =
performance of the GMCs. Sometime in the next few years, I want to tow =
my 3100 pound Chevy Malibu (all four wheels down). My drivetrain is =
stock with the engine being replaced in the last several years by the =
prior owner. I have heard that a new final drive would yield the most =
improvement for the $. But I have also heard that a larger exhaust =
system would be more cost effective.

What do you all think?

Bob Fukumoto

 

[russ bethel]

I have a stock 1976 Glenbrook. I installed Doug Thorley ceramic coated
headers, free flow mufflers, and 3 inch tail pipe. I still have the 3.07
final drive. I tow a 16 foot double axle trailer with a Jeep Grand Cherokee
on it. I also have a tool box and 12 gallons of gas (for emergency use) on
the trailer. I estimate that I am pulling about 4,000 lbs. I do not have
any problems on interstate highways. If I were going to be in mountains I
may think of changing to the 3.50 conversion using the different ratio
between the torque converter and transmission..

I think the first thing to do is the exhaust system with headers. That will
get rid of the exhaust manifold problems plus improve the performance. Then
install a good transmission cooler and larger lines from the transmission to
radiator. After that I would evaluate the situation to see what kind of
dollars I would spend vs improvement gain expected.

Russ Bethel
rbethel

 

[patrick flowers]

>
> As a newbie who has yet to use his 76 Palm Beach, I wanted opinions
> on what was the most cost efficient upgrades to improve the towing
> performance of the GMCs. Sometime in the next few years, I want to
> tow my 3100 pound Chevy Malibu (all four wheels down). My drivetrain
> is stock with the engine being replaced in the last several years by
> the prior owner. I have heard that a new final drive would yield the
> most improvement for the $. But I have also heard that a larger
> exhaust system would be

Bob,

One thing I would emphasize is that you're very comfortable with the
condition of your coaches running works. I *was*, but since I wasn't
sure when the last time some of the critical services(drive shafts,
bearings, etc.) had been done on mine, I decided to pull the front end
down and service these parts. I was scared by some of the things I
found. The right side axle nut was finger tight allowing approx. 1/8
inch of play and the outer race on the outer wheel bearing had separated
from the bearing. The inner bearing stayed in the knuckle along with
the broken race. The brake pads were coming apart. I'm still planning
some upgrades, but my priorities have shifted now.

My advice is, make certain of the condition of the following:

- - Brakes, including friction material, steel lines and flexible hoses
- - CV joints
- - Wheel bearings, front and rear
- - Oil lines(from filter adapter to radiator)
- - Fuel line from fuel pump to carburetor. If it's been cut and
flexible hose installed, replace it.
- - Radiator

If you're gonna' do the final drive, that would be an excellent time to
get most of the above done. Even if you don't work on your GMC
yourself, buy a good jack, some jackstands and a creeper. Spend some
time under your coach looking at the critical systems. I wish I'd done
it sooner.

Patrick
- --
Patrick Flowers
Mailtoatri63

The GMC Motorhome Page
http://www.gmcmotorhome.com

 

[hdavis]

>
> My advice is, make certain of the condition of the following:
>
> - Brakes, including friction material, steel lines and flexible hoses
> - CV joints
> - Wheel bearings, front and rear
> - Oil lines(from filter adapter to radiator)
> - Fuel line from fuel pump to carburetor. If it's been cut and
> flexible hose installed, replace it.
> - Radiator

After looking at fuel hoses from the tanks forward on a number of coaches,
I'd add checking the hoses as well. The reformulated gas used in some states
does a number on the old hose. Don't forget the hose to the gen set too!

Henry

Henry Davis Consulting, Inc / new product consulting
PO Box 1270 / product readiness reviews
Soquel, Ca 95073 / IP reviews
ph: (408) 462-5199 / full service marketing
fax: (408) 462-5198
http://www.henry-davis.com

 

[jim bounds1]

Bob,
A very good question with probobly as many answers as you can imagine.

I wouls break down the towing performance question into 3 categories and
then list the upgrade posibilities in each.

1. suspension
2. drive train performance
3. hitch systems

1. SUSPENSION:
a. New and/of heavy duty shocks
b. Frontand rear sway bars
c. 4 air bag system
d. Upgrade of brake system

2.DRIVE TRAIN

a. Gear ratio change
b. RV cam
c. Header & 3" exhaust system
d. Transmission cooler & temp. guage
e. 90% rotation fan clutch

3. HITCH SYSTEMS

a. Class A hitch
b. trailer/ tow car brake system
c. Blue Ox or other foldable tow bar system

Now there are many other that probobly need to be included but you've
got to draw the line somewhere.

My personal opinion would be to pick an upgrade from each category that
you feel would help you the most, after all you will be the one behind
the wheel!

To me, the 4 air bag system would go the farthest in improving your
control. It is a bit expensive but it does work.

Engine performance for towing would be enhanced most by getting the
engine RPM up into the power band, the gear ratio change would do that.

I would be certain that the hitch you have is adequite fdor your load,
if it is, I would look into a braking system for the tow car. Actually,
it is the law and you can be assured to stop the train in an emergency.

Doing all of this will set you back a bit but after a day of white
knuckle driving, you would probobly spend even more if you had this
stuff.

I'm sure other have other opinions and I would suggest taking their
recomendations with as much interest as mine.

Call if I can help further.

Jim Bounds www.gmccoop.com

>
> As a newbie who has yet to use his 76 Palm Beach, I wanted opinions on what was the most cost efficient upgrades to improve the towing performance of the GMCs. Sometime in the next few years, I want to tow my 3100 pound Chevy Malibu (all four wheels down). My drivetrain is stock with the engine being replaced in the last several years by the prior owner. I have heard that a new final drive would yield the most improvement for the $. But I have also heard that a larger exhaust system would be
>
> What do you all think?
>
> Bob Fukumoto

 

[bartz paul]

Al:

Dick Crawford (616-649-1967) installed the Howell unit several years ago
on their 73 coach in an attempt to better poor gas mileage (i. e. around
5-6 mpg). Although he reports it starts easy cold, restarts when engine
is hot are reportedly difficult.

Dick has conversed with Howell several times and last fall upgraded to a
newer chip. Not a lot of improvement, I understand.

I'm not trying to influence your decision to switch, but wanted to let
you know that you may be in for a let down if Dick's experiences are any
indication.

Recommend you call Dick and learn about his experiences.

On the other hand, you probably previously read my e-mails earlier this
year about the great experiences I've had with my carb overhauled by A &
G in Oak Park IL in Aug 1996, all done over the phone and shipping via
UPS.

Paul Bartz

> From: ARChernoff [SMTP:ARChernoff]
> Sent: Saturday, June 27, 1998 11:55 PM
> Subject: Re: GMC: Biggest Bang For the Buck
>
> I just found out that my carb had gone south. It had been rebuilt
> three times and the last time it seems not to want to hold its
> settings. So in the interest of experimenting, I talked to Osborne
> who is one of the big guru's on the GMC. He suggested the Howell
> throttle body injection. I ordered one and it will be in next week.
> It is supposed to do all sorts of things and you can go to their web
> page and see. It if works as great as it sounds, it should solve the
> problem of vapor locking, altitude adjusting, and is supposed to
> provide max power at any altitude or driving... it uses all GM
> computer and parts/except for the holly throttle body. I have heard
> good things about how it boosts power and in talking to the chap who
> rebuilt my engine, it should be the best improvement I can make for
> the money.
> More when it's finished.

 

[heinz wittenbecher]

Another 2 cents worth:

I had been running the Howard for a few years and changed to the Ported EFI
from Rance.

I always had good starts, adequate power and reasonable fuel economy.

Why did I switch? In part 'cause I'm a tinkerer, in part because I'd get
sudden fuel starvation once tanks were less than a quarter full. (A quick
switck of the tanks would fix).

Another problem was that we tried several chips and I even visited Howell's
and at best the proms (chips) ended up a compromise, due mainly (or in part)
to the RV Cam that was installed at last engine overhaul (or so I was told


I got tired of messing with it and finally left it be as it ran pretty good
and I found it better than the carb. Even went to a later model GM computer
and added speed and knock sensors.

I now have about 5000 miles on the Rance and found that plugs look a lot
better, power is good, no sudden fuel starvation and I'm able to improve
tuning as I learn more about it. In the meantime it's running well.

Using an aftermarket computer, etc. has not diminished my comfortlevel. It's
actually improved it as I can probably get a replacement at Autozone and
program it with same settings via any ol' laptop. (I did get the programming
cable and software as an optional add-on so that I would be selfcontained).
The other plus is that the Accell computer uses a little more current
technology, I believe. Could be wrong on that one though.

Example of pleasant surprise: Lost the throttle cable due to a worn clip
while zipping through New Mexico. As the rig slowed to a crawl it didn't
stall. The computer kept feeding suffient fuel to maintain RPM and that rpm
was enough to keep crawling along to a safe stopping place which turned up
to be a rest area up a slight hill. Kept us going up the incline until we
were tucked in safe in the rest area, made a temporary fix and off we went.
Not sure if the Howell would have handled it the same way.

This does not knock the Howell System. I liked it much better than the carb
and there is quite a cost difference so it's somewhat apples and oranges,
but as I said... just my 2 cents worth.

BTW, the sudden fuel starvation may have been an installation error rather
than the system itself. As the Rance was installed it was found that the
fuel return did not go into the filler pipe itself but rather it used the
vent line. (It now uses the filler pipe).

Heinz
www.bytedesigns.com/gmc

>
>Dick Crawford (616-649-1967) installed the Howell unit several years ago
>on their 73 coach in an attempt to better poor gas mileage (i. e. around
>5-6 mpg). Although he reports it starts easy cold, restarts when engine
>is hot are reportedly difficult.
>

 

[heinz wittenbecher]

It's been a mystery to me (and some mechanics/technicians over the years as
well).

The thoughts ranged from inlet being uncovered to a shrug of the shoulders.
Your too much pressure theory may be closest, but it doesn't seem feasable
enough pressure could build up to in effect block the return and thereby the
feed. Especially since it's only running at less than 15lbs of pressure.

It always manifested itself in a decellaration mode, i.e. coming off the
off-ramp, turn the corner, silence.

Pressure gauge provided no clues as pressure was always right up there.
Seems pressure is maintained between fuelpump and TBI even when tank is
empty. I assume a checkvalve doesn't allow pressure to bleed off.

I'm assuming other folks that have the Howell system are returning via the
filler pipe or indeed it's own return of sufficient size.

Just something to keep alert for.

Heinz

>>BTW, the sudden fuel starvation may have been an installation error
>>rather than the system itself. As the Rance was installed it was found
>>that the fuel return did not go into the filler pipe itself but rather
>>it used the vent line. (It now uses the filler pipe).
>
>I'm sure you'al gave that surprize finding some thought... Do you or
>anyone know what happens with the vent line at the quarter tank level?
>Does it all of a sudden get pressure or suction or something?
>
>--
>
>Regards,
>John Dolan
>
>jdolan
>

 

[john dolan]

>BTW, the sudden fuel starvation may have been an installation error
>rather than the system itself. As the Rance was installed it was found
>that the fuel return did not go into the filler pipe itself but rather
>it used the vent line. (It now uses the filler pipe).

I'm sure you'al gave that surprize finding some thought... Do you or
anyone know what happens with the vent line at the quarter tank level?
Does it all of a sudden get pressure or suction or something?

- --

Regards,
John Dolan

jdolan