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Discussion Starter · #1 ·
Last week I towed my '71 Charger to Pueblo Colorado with the old '86 Ram 150 4x4 (bought last December for $700.)

There was an all Mopar drag race last week, and after running some time trials with the Charger (12.18 @ 112 MPH), I decided to see what the old truck would do.

To my suprise the truck ran a mid 16 second 1/4 mile right off. I jetted the AFB, 1 jet size richer and droped 0.2 seconds off my second run. I should have tried richining the carb some more, but I didn't feel like disasembling the carb again.
I made a few more runs and got the 16.19 @ 89 MPH, going through the timming traps still in second gear!

The truck only has 3.21:1 gears and 31" tall BFG tires, and the 360 engine is the one I built a few years back for my '83 RamCharger that I found had a bent frame.

As for the 360, it dosen't like to run on low octane fuel (when towing). I had to run 91 octane. The compression ratio is about 9.5 to 9.6:1, and is running a small Hughes HE0914AL cam (208/214 duration @ 0.050"), and 0.489"/0.501" lift using 1.6:1 rockers.

If you plan to use this cam shoot for less compression ratio, or more gearing.
Anyhow this was the first time I got to mess with the tuning of the engine. I think riching the carb and re-curving the distribitor should help reduce the pinging problem, and also make the truck faster.


 

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what year is your motor?
i've got a 360 in mine that was pulled out of a '73 challenger, and it pings on low octane, too.(only while cruising on the highway)
I should probably try lead additive, right?
i have an Accel distributor and an edelbrock 600 i'm gonna put on, and it has a mild summit cam and a Weiand intake, what do you think i should do to this thing to make it run without pinging, and maybe if i'm lucky, have better mileage??
 

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Yeah I swapped in a '94 360 Magnum into my '85 RC and the power is a kick!
Only downside is it caused my 20 year old tranny to start showing it age. Time for a rebuild.
I'm running the same gear/tire combo. You are giving up your gearing running 31" tires. Imagine if you had the stocker 28" tires on! You would be low 15s easy!~
 

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RUSTCHARGER said:
i've got a 360 in mine that was pulled out of a '73 challenger, and it pings on low octane, too.(only while cruising on the highway)
what do you think i should do to this thing to make it run without pinging, and maybe if i'm lucky, have better mileage??
Too much vacuum advance. Only solutions are backing the timing off, or replacing the vacuum pod with one that has less advance.

-SM
 

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Discussion Starter · #5 ·
RustCharger, the 360 is just a 1976 from a Chrysler Cordoba, bored 0.040" over with Keith Black #232 Pistons. The block was zero decked and the heads milled for zero quench without the head gasket, so the quench should be about 0.040", but I'm not sure if the quench really helps?

If you engine pings while crusing, you have too much vacuum advance. usually you can put a hex wrench into the vacuum advance (through the vacuum nipple) and reduce the total amount of vacuum advance.

I noticed the pinging in my engine mostly when I was towing the car. The car is #4,000 plus the weight of the car trailer, probbably over #5,000 combined weight being towed behing the truck. Add to that the trucks large tires (31") and high gears (3.21:1), and the engine really gets loaded in first gear (heck, I can do 55 MPH in first gear!) Once the car/trailer are rolling and crusing down the road, I have no problems with the pinging.

I may try lowereing the air inlet temperature (block the EGR crossover, and run a 160 thermostat), and use colder spark plugs to see if that helps. If not that dosen't help, I could retard the cam timming, or even swap in a slightly larger cam, but then I would really need to change the gearing (which would also help reguce the load on the engine at low RPMs.)
 

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Well, my truck ran 9.88 in the 1/8 @ 69 mph, with a smaller cam (hughes 215/221 .473/.491), 9.2 - 1, stock convertor and effectively a 3.21 gear. Yeah, the same big beast in the pics.

The chart says that is 15.3 in the 1/4.

I had the carb still set for rock climbing, so she was lean on the top end, and I ran the cam up past the 5200 rpm limit they say it has. My deck is also .110" (sucks big time).

Want to see what she will do with a decent short block and better cam (probably 488/510 roller)

Guess the hughes cams do work....lol

I was offered a set of slicks to try, but my wheel studs were too short. Everyone thought I had a big block init she ran so well.

It's fun to turn some decent times in a big truck.
 

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Discussion Starter · #7 ·
I don't have the "good" run time slip here at home, but on a slower run my 1/8 was 10.603 @ 69.16 MPH, the 1/4 was 16.285 @ 87.87 MPH. It soulds like your running a larger cam than me, my lift is a bit more because of the 1.6:1 rocker arms.
I have an old Carter 750 CFM AFB on the truck, and it's too lean, but the bog on launch helped with traction. On one run the tire broke loose, and wouldn't stop spinning untill I shifted into third gear. I think I smoked the tire 1/3 way down the track ;D

I guess I should swap the 8-1/4 open rear diff and CAD front axle out of the truck and put in the 9-1/4 sure-grip and Dana44 from the '83 RamCharger into the truck?

It would be fun to see what the truck would run at lower altitude, and with the carb tuned better. Pueblo is 4,500 ft altitude.

The performance was better than I expected. Long ago I had a 1968 W200 with a slightly milider 360, but 4.10:1 gears, and it only ran 17 seconds flat at about 85 MPH.

Anyhow, I got some thumbs up after smoking a few newer Ram trucks.


 

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he he, did I mention it has 39" tires and wieghs in at around 5400 lbs ???? Stock idle, 17" vac at idle, 15" in gear...not much of a cam.
 

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I just ha to do this....
-stew-
 

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451Mopar said:
usually you can put a hex wrench into the vacuum advance (through the vacuum nipple) and reduce the total amount of vacuum advance.
This adjustment adjusts where (I.E. how much vacuum) the vac advance begins to work, not the total amount of vac advance. The only way to reduce the amount of vacuum advance is to change advance pods.

-SM
 

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Discussion Starter · #11 ·
First it was a 16.19 @ 89 MPH, and I never claimed that was "fast", even though if corrected for altitude it would be petty close to a 15.0 flat 1/4 mile.
I was just mentioning how the truck ran with the mild 360 engine combination, and the problem I had with pinging.
It sounds like "TheRamChargerMan" has a really nice running 360. I did check the effective gear ratio on your setup. The 4.56:1 gears with 39" tires, is about the same as 4.10:1 gears with 31" tires, so you still have a pretty good gear ratio advantage over me, but I think my truck is lighter.
 

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well, I don't know how you did the check, but using the moroso speed calculator...it's more like 3.10

31/39=% change in tire height...or .79
4.56*.79=effective gear ratio based strictly on advertised tire size.....or 3.62

When you take into account that my tires are actually only 18.5" from the ground to the center of the axle, it's even worse (37")...and comes out to like 3.43......when you assume trans slippage.....it lowers it even more...to almost 3.10 (the moroso calculator accounts for trans slippage).

Yours is still pretty quick for what it is....a heavy brick on wheels....just like mine.

I'm waiting to try it again when i have my 5.13's and d60's under it, and a better short block.
 

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Discussion Starter · #13 ·
Humm, Maybe my math is messed up. Here is what I did:
I first found my MPH @ 3,000 RPM with 31" tires = 86.226 MPH, then to find the equivlent gear ratio, I used the 3,000 RPM and 86.226 MPH, with 39" tires, which gave me a an equivlent gear ratio of 4.038:1?

But using the percent difference in tire of 39"/31" * 3.21 = 4.038:1 also?

Formulas:
MPH = (RPM * Tire Diameter) / (Gear Ratio * 336)

Gear Ratio = (RPM * Tire Diameter) / (MPH * 336)
 

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you are trying to find out the ratio, but doing it backwards.

31"/39" = .79%

.79 x 4.56 = 3.62

The way you did it, it won't work because 39/31=1.26 is not a percentage....since it is greater than 1.00

Simply put, my trucks effective gear ratio is the same as a stock truck with at best 3.55 gears....and that is assuming no slippage.

When I was doing the calculations, I used the stock tire size, which wAs shorter than 31".
 
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