How Can I "turn Up" My 237?

[cfw3]

Hello,

I have a 1970 Mack DM685 with a good ol reliable 237 backed by a siz speed tranny. It is a tandem dump and I just love driving the old girl, however most other drivers don't care for me too much when they are following me up any type of hill with a load on. The motor runs great and really doesn't smoke too much when she is at wot..no matter what rpm. This leads me to believe that she could stand to be turned up a bit? I see some Macks rolling thick black smoke at every shift but not mine.

Can anyone give me some more pointers on how to get some more power out of my motor with out sacrificing reliability? I just bought a 20 ton trailer to pull behind her so I really need all the power I can get. Thanks for any advice, Chuck

[David]

An aftercooler will give you about 50 hp.

[StorminNorman]

I own a truck like that also!Any more suggestions,besides an engine swap?

[Mack Doctor Jr.]

Hey guys does your trucks have tip fans on them? If not i would start there . If they do find out if u have a 237 fuel pump or the 300 hp pump the difference is the 237 pumps have a sloped cover on the back where the gov, is located. Keep in mind adding these things may require some timing changes a injector changing. I can tell u how to turn up the fuel , but would feel better if u emailed me personally. I dont think its to wise to have that type of info laying out there for everyone to see.

Thanks

Joe

[terry]

Hey guys does your trucks have tip fans on them? If not i would start there . If they do find out if u have a 237 fuel pump or the 300 hp pump the difference is the 237 pumps have a sloped cover on the back where the gov, is located. Keep in mind adding these things may require some timing changes a injector changing. I can tell u how to turn up the fuel , but would feel better if u emailed me personally. I dont think its to wise to have that type of info laying out there for everyone to see.

Thanks

Joe

Why what would be wrong with everbody seeing info? Terry

[rsmartyn]

Hello,

I have a 1970 Mack DM685 with a good ol reliable 237 backed by a siz speed tranny. It is a tandem dump and I just love driving the old girl, however most other drivers don't care for me too much when they are following me up any type of hill with a load on. The motor runs great and really doesn't smoke too much when she is at wot..no matter what rpm. This leads me to believe that she could stand to be turned up a bit? I see some Macks rolling thick black smoke at every shift but not mine.

Can anyone give me some more pointers on how to get some more power out of my motor with out sacrificing reliability? I just bought a 20 ton trailer to pull behind her so I really need all the power I can get. Thanks for any advice, Chuck

Hey Chuck, Screw them other cowboys, you could be going 85 uphill and it's still not fast enough for most of them. That old 237 is still running strong because it's not pushed to the max and I'll bet you don't use near the amount of fuel them hot dogs use. If you want black smoke then disconnect the puff limiter but the smoke cops don't like that too much and if they catch you , it'll cost you. If you're happy with your truck and it's making you money, that's all that matters. And most of these jerks are driving somebody else's truck anyway so screw 'em. If I sound like I'm ranting it's because I am. Just today I had one of those morons behind me in my '79 DM686 tandem. Driving somebody else's triaxle (probably overloaded) he's right up my butt while I'm doing 55 in a 50MPH area. Then as I slow down to 15MPH for a sharp turn that's posted 10 MPH I hear on the radio "Can you make it?" from this Ahole driving somebody else's truck. This is a famliy show so I'll stop retelling the conversation here but the jerk refused my request to pull over. This kind of stuff happens all the time so my advice to you is to enjoy driving your rig and when you finally get that new 800HP truck those same jerks will be up your butt whining "can't you go any faster".

[cfw3]

Darn straight, Rsmartyn! I think I may just leave her set the way she is because she has been darn good to me, and I don't need to be setting any speed records. Hell, the truck is 36 years old and it has never left me setting along side the road for many, many years now, so I don't have anything to complain about! I try to run the backroads as much as I can and that seems to work well for me. And your right, she sure does sip the fuel compared to the new trucks. So I think I'll leave her where she is set rather than risk melting some pistons down..

[ThaddeusW]

Darn straight, Rsmartyn! I think I may just leave her set the way she is because she has been darn good to me, and I don't need to be setting any speed records. Hell, the truck is 36 years old and it has never left me setting along side the road for many, many years now, so I don't have anything to complain about! I try to run the backroads as much as I can and that seems to work well for me. And your right, she sure does sip the fuel compared to the new trucks. So I think I'll leave her where she is set rather than risk melting some pistons down..

If it aint broke, dont fix it!

[rsmartyn]

Darn straight, Rsmartyn! I think I may just leave her set the way she is because she has been darn good to me, and I don't need to be setting any speed records. Hell, the truck is 36 years old and it has never left me setting along side the road for many, many years now, so I don't have anything to complain about! I try to run the backroads as much as I can and that seems to work well for me. And your right, she sure does sip the fuel compared to the new trucks. So I think I'll leave her where she is set rather than risk melting some pistons down..

Now you're talkin' Chuck! You've got a great truck that'll make you money so screw them jerks (who usually don't own their own trucks like you do) and enjoy the ride. And by the way, as you see in the photo, my old B is pulling a 20 ton tag trailer and does it just fine with it's original END673 putting out about 180HP. Bob

[Show Dog]

the jerk refused my request to pull over.

HAHAHA. But He's got a point. Disconnecting that Anti puff valve makes the throttle work a little quicker, but it's not enviornmentally safe. With that 6 speed you will put out A LOT of SMOKE if you disconnect it. Believe me, I know.

[Packer]

Hey Thad!

"If it ain't broke, fix it 'till it is"!!!

The first truck I drove had 205 horsepower. It made for a longer day but also a cheaper day!

Did you put a 'chip' in your pick-up? Neither did I!

Back in 'The good ol' days' (about three days after dirt) the more horse power, the lower the reliabilty. You got a good one now, and you own it. Pass them at the fuel pump and get your pay-backs then!

Packer

[mudslut28]

I dont think a 70 Model had an a-valve for pollution did they? My 76 doesnt my 88 does. As far as turning them up..in my experience a little to compensate for pump wear always worked well...but in my experience if you turn them up a LOT they pump doesnt seem to last nearly as long.

I can definitely relate when you talk about the smartazzes running someone elses truck make remarks about slow trucks. Both of mine have 300's...one a 6 speed and one a 7 speed. Hauling the average 35-45 tons they just didnt have the ooomph that the new non-Macks had. But the thing I always laughed at was the fact that the truckyards were full of JUNKED.....yes worn out junked Big I's and other assorted mid 90's and up various brands while my 30 year old "slow" truck hauls every day.

We may not get their first......but we will get there the MOST

[kevin mccune]

I dont think a 70 Model had an a-valve for pollution did they? My 76 doesnt my 88 does. As far as turning them up..in my experience a little to compensate for pump wear always worked well...but in my experience if you turn them up a LOT they pump doesnt seem to last nearly as long.

I can definitely relate when you talk about the smartazzes running someone elses truck make remarks about slow trucks. Both of mine have 300's...one a 6 speed and one a 7 speed. Hauling the average 35-45 tons they just didnt have the ooomph that the new non-Macks had. But the thing I always laughed at was the fact that the truckyards were full of JUNKED.....yes worn out junked Big I's and other assorted mid 90's and up various brands while my 30 year old "slow" truck hauls every day.

We may not get their first......but we will get there the MOST

Amen brother( used to bleed for others till I wised up -that one tale brings to mind when a couple of jerks got behind a stout superliner I was riding shotgun in-they had some lip- but they werent hauling near the load, besides didnt hold the AH's up 5 min-Kevin

[greg]

I have a 300 and I run with guys that have 400's and 500's . I may not pass them on hills but I get to the job site maybe a minute after they do , and that being generous with the time guess. I run everyday when they don't because of breakdowns and they are a higher hourly rate than I am, have to pay for all that fuel, sometimes I get a bit frustrated at being passed up hills all the time but at the end of the day when we are side by side at the pump , my bill is much cheaper, that's always a good reminder that bigger isn't always better.

greg

[bulldog man]

Amen yall give a ole 711, 673 ,237 ,300 or a 350 anyday i may not pass the fellas w/425&500 cats & cummins & detroits but will defently keep the pace within the load range & timewise & like a another poster said @ the pump side by side the fuel bill a lot cheaper ....

If anit broke dont fix it the ole 237 is a realiable motor & is as tough as wet leather we had several over the years in DM & R Models they are hard to beat .

yall have a goodone

bulldog