RPM's

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I followed the recurving directions from the Mopar Muscle article and it seemed to work well. I need to put some new timing tape on the balancer and check it again to see exactly where It ended up but it definately runs and responds better now.

http://www.moparmusclemagazine.com/techarticles/engine/mopp_0301_mopar_electronic_ignition_system/

My place is right off hwy 52 (about a mile) in Inver Grove Heights. You will probably drive right by on your way to the Mopars In the Park show.
 
straightlinespeed said:
I'll take a read thru the thread you posted and try to find a place that will curve my dizzy for me locally and go from there. I agree with everyone that I have a lot left in my engine so I will look into this first!
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You can do it yourself in about 10 minutes, with a HEI re-curve kit from the local-yocal parts store. Use the light springs, should get you close.

Take the distributor out, take out the screws in the housing that hold the baseplate, take a thin nail or something and knock out the roll pin that holds the shaft at the bottom plastic retainer, wiggle the plate up, unscrew the vacuum advance, remove it, and then slide the whole assembly out so you can work on it comfortably.

I'd say 16-18 initial, 32-34 total by 2500RPM, then plug in vacuum advance to a ported source and total timing should be around 50-52 max for best economy .


It will feel wayyyyyyyy more responsive.
 
Put a vacuum guage on ths car and take it out for steady speed, level ground cruise at 60 and 70 MPH and record the vacuum readings. Then check where your power valve setting is; you may be in the power valve at cruise.


Just one thing about the lower gears and taller tires: you'll lower the RPM and then get more TC slippage. So, there is only so much you can gain from that tactic with the converter you have. IMO, you are kinda stuck in a certain corner of the 'operating envelope' there with that TC.


The ignition and the carb need a lot of work IMO before doing anything else. Time to not suck at carb tuning anymore!

BTW, you need to read your plugs by running at whatever running condtion you want to check (WOT, cruise, etc.) for as long as you can and then IMMEDIATELY shut of the ignition and simultaneously shift to neutral, and coast to a stop, pull sthe plugs and then read them. Anything else is a waste of time.
 
fishy68 said:
[/COLOR]

[/COLOR]Yeah you need it re-curved cause even 38* is quite a bit for a LA. Too bad you ain't close. I've done numerous distributors. Doesn't take long at all and really makes a big difference.
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That is a kind jesture, thank you!

krazykuda said:
Do you smell any gas when you nail it and see your gauge moving?

Could someone have drilled in the trunk and gone through the top of the gas tank? I've heard of that before.


Pull your plugs? Are you running rich? Are the plugs wet fouled or black?


My 68 340 Formula S with a 3.91 gear screams at 4000 k at 70 MPH with a 650 Double Pumper. MP .484/284 cam with Rhoades lifters, stock converter and I get better mileage than that. (not sure of the tire size, but taller than stock).


You'd better shut that thing off when you fill up with gas, you'll gain on the gas pump and never reach full.... LOL!


I would check for gas leaks to make sure that it's not leaking out. Second see if you're running too rich. Then chase "more efficient" components...


Could a neighbor be siphoning your gas when you're not looking???
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No, no smell of gas anywhere and the car stays parked in the garage.

I pretty sure everyone is onto something with a good tune!

Abodybomber said:
My 02 cents: 360 ported heads/2800 9.5 GER converter /3:55 TracLoc./" those 275/60/15's " actually measure under 27"...(750 4779 d/p) : Was getting 21-22 MPG@62 MPH,with vac advance hooked up & a vacuum gauge. Your can is smaller,pay attention to the small details.
Click to expand...


Thats a nice set up. I will look into those tires to start, thanks for the heads up on them.
 
MobileCustoms said:
I followed the recurving directions from the Mopar Muscle article and it seemed to work well. I need to put some new timing tape on the balancer and check it again to see exactly where It ended up but it definately runs and responds better now.

http://www.moparmusclemagazine.com/techarticles/engine/mopp_0301_mopar_electronic_ignition_system/

My place is right off hwy 52 (about a mile) in Inver Grove Heights. You will probably drive right by on your way to the Mopars In the Park show.
Click to expand...

Thanks for the link! I'll read thru it and attempt it.

PoisonDart74 said:
You can do it yourself in about 10 minutes, with a HEI re-curve kit from the local-yocal parts store. Use the light springs, should get you close.

Take the distributor out, take out the screws in the housing that hold the baseplate, take a thin nail or something and knock out the roll pin that holds the shaft at the bottom plastic retainer, wiggle the plate up, unscrew the vacuum advance, remove it, and then slide the whole assembly out so you can work on it comfortably.

I'd say 16-18 initial, 32-34 total by 2500RPM, then plug in vacuum advance to a ported source and total timing should be around 50-52 max for best economy .


It will feel wayyyyyyyy more responsive.
Click to expand...

Ive dissassembled the dizzy before, so this shouldnt be a issue. I'll read thru that article and go for it.

nm9stheham said:
Put a vacuum guage on ths car and take it out for steady speed, level ground cruise at 60 and 70 MPH and record the vacuum readings. Then check where your power valve setting is; you may be in the power valve at cruise.


Just one thing about the lower gears and taller tires: you'll lower the RPM and then get more TC slippage. So, there is only so much you can gain from that tactic with the converter you have. IMO, you are kinda stuck in a certain corner of the 'operating envelope' there with that TC.


The ignition and the carb need a lot of work IMO before doing anything else. Time to not suck at carb tuning anymore!

BTW, you need to read your plugs by running at whatever running condtion you want to check (WOT, cruise, etc.) for as long as you can and then IMMEDIATELY shut of the ignition and simultaneously shift to neutral, and coast to a stop, pull sthe plugs and then read them. Anything else is a waste of time.
Click to expand...

Checking the plugs that way would be very tough to do since I dont really want to cruise down the road for how ever long and then pull the plugs on the side of the road. I live in a suburb and there really is not any country roads around to do this type of check. City life is not ideal for this. I appreciate the idea but I dont think this is a option.
 
straightlinespeed said:
Checking the plugs that way would be very tough to do since I dont really want to cruise down the road for how ever long and then pull the plugs on the side of the road. I live in a suburb and there really is not any country roads around to do this type of check. City life is not ideal for this. I appreciate the idea but I dont think this is a option.
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You could coast into your driveway, or a parking lot, or into a public place. :D I live in the city too, where there's a will there's a way.
 
PoisonDart74 said:
You could coast into your driveway, or a parking lot, or into a public place. :D I live in the city too, where there's a will there's a way.
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I suppose your are correct. The more I thought about this, the more spots I thought of.

So when I do something like this, Im assuming I make sure the car is fully tuned to where I think it should be. When I pull the plugs what am I looking for exactly? Just making sure they are the correct color etc???
 
MobileCustoms said:
I followed the recurving directions from the Mopar Muscle article and it seemed to work well. I need to put some new timing tape on the balancer and check it again to see exactly where It ended up but it definately runs and responds better now.

http://www.moparmusclemagazine.com/techarticles/engine/mopp_0301_mopar_electronic_ignition_system/

My place is right off hwy 52 (about a mile) in Inver Grove Heights. You will probably drive right by on your way to the Mopars In the Park show.
Click to expand...


Now that Im home and had a chance to read this article. I did this with my old original dizzy, because I couldnt get the engine to sit at one set timing point. It hunted. So I welded up the slots to what they recommended in the article. I even had the exact same springs they said to use. After I got done with it, I installed it in the car and readjusted everything. I noticed that I limited my mechanical advance a ton. The car I had to have almost 26* initial timing (or close to that since it still hunted around) just to get to the 34* total. The car didnt like that. I brought the dizzy to a guy that had a sun machine. He ran it and couldnt get it to dial in correctly either.

So I picked up a MP dizzy from a close friend that had it in his drag car. He had both light springs in his. I do still have the original dizzy so that just saved me a bunch of time on welding up those slots. I can swap the parts over and give it a try in the car now. Oh and with the MP dizzy, when I set it at say 15* it stays at that...
 
Rice Nuker said:
There is a very well thought out and nicely explained timing tuning plan posted in this thread by jbc426 which entails using manifold vacuum which is supposed to enhance cruise mileage and part throttle torque. He explains that there is a symbiosis to initial, total, curve rate, vac can choice and settings which would likely require a lot of patience, bit of fab and a good level of skill. I am giving it a solid effort to duplicate his recommendations in the near future.

http://www.forabodiesonly.com/mopar/showthread.php?t=278252
Click to expand...


Ok finally read this article also.

So he says to use the manifold vacuum instead of ported vacuum (thats usually recommended). I think I understand why he says this but does anyone care to elaborate more on it? Oh and WTH is gas knock?
 
Holler at him and see. I suspect that he is referring to ping caused by sudden increased in throttle resulting in faster burn conditions in the chamber which requires the reduction in timing to compensate.

The argument regarding ported vs. manifold is never ending. I got no comment on that because of lack of experience. I am going for no vac adv first then migrating to manifold after I recurve / limit my mech and start tuning my vac can. But my guess is that the difference would depend on factors of timing curve, total, initial, and engine build / load.

Considering how much trial and error is involved in setting up all those variables, maybe talking to this guy and a few others with years of experience about base line timing setups based on builds would be a good way to get you 75% closer to perfect timing.


I am dealing with a very mild 440 in a 4200# car, so timing is going to be challenging. I gotta get timing tape and a piston stop and set my balancer marks first. Then drill a hole in my cap and see if my rotor is phased decently. Then the next forty steps to this archaic timing curve operation. :) ahhh the fun of working with old iron. May as well be a timing the valves on a steam engine compared to this new stuff running down the street.

Good luck!

straightlinespeed said:
Ok finally read this article also.

So he says to use the manifold vacuum instead of ported vacuum (thats usually recommended). I think I understand why he says this but does anyone care to elaborate more on it? Oh and WTH is gas knock?
Click to expand...
 
straightlinespeed said:
Ok finally read this article also.

So he says to use the manifold vacuum instead of ported vacuum (thats usually recommended). I think I understand why he says this but does anyone care to elaborate more on it? Oh and WTH is gas knock?
Click to expand...

The reason he says to use manifold vacuum is it gives you more initial timing at idle. The more initial timing you can dial in and the car still run good without spark knocking (what he calls gas knock) under acceleration the better the fuel mileage usually is. The only problem is with a engine that has a much larger than stock cam (such as yours) it may or may not have enough manifold vacuum at idle to keep the vacuum advance pulled in so it'll idle erratic. With the cam you have I'd expect your car to pull 10-12" of vacuum at idle which is kind of right on the line. Wouldn't hurt to try. You can always swap it back if it doesn't work. If it works it might save you from having to pull the distributor apart to rework the advance slots

BTW: earlier you mentioned your other car and how the distributor caused it to "hunt". More than likely that's because the advance springs were too light. I ran into that problem back in the early 80's when I started tinkering with distributors. I've found using one light and one medium spring usually works better. Most street engines don't like full advance by 1200 rpm like 2 light springs will give you unless your running a real big cam that has low cylinder pressure.
 
If you are running a decent amoutn of initial I don't think you need it in really fast. My total is all in by 3500 and I have a 3500 convertor.

At cruise speed i'm a little under my max advance but over 30 degrees. The second I step on it I have full advance and with almost 20 initial it isn't soft off idle either.
 
straightlinespeed said:
I suppose your are correct. The more I thought about this, the more spots I thought of.

So when I do something like this, Im assuming I make sure the car is fully tuned to where I think it should be. When I pull the plugs what am I looking for exactly? Just making sure they are the correct color etc???
Click to expand...
Yes, plugs will change appearance pretty fast under changing operating conditions; if the mixture was rich at hard throttle and put carbon on the plugs, for example, backing off and running at light throttle for any distance at all would burn off the carbon from the plugs and you would never know the actual hard throttle burn conditions.

Of course, a wideband O2 sensor does some of what plug reading does; not everything, but it is the fast, automatic way to take some readings.

If you are in a bad part of the city, just turn your googly eyes in your avatar pix on them and they will back off!
 
I have tomorrow off and Im going to attempt to retune my set up. I will keep you all posted, unless your already bored with this post LOL
 
Tune the idle mixture adjustments as lean as you can get them and it still idle decent. That should help the around town mileage some. Let us know how it goes
 
Ok boys and girls. Here is what I did today..

First off I changed back to factory jets in the 670. I reinstalled the 65's, the carb guy gave me 69's.:prayer: I also pulled my dizzy and went to do the curving thing to it. Well my MP dizzy was a different style. I didnt have to weld up any slots, I had two set screws that allowed you to adjust a plate to limit the amount of mechanical advance. Hell ya, that was awesome. I then ran to the parts store and picked up the Mr. Gasket kit that had the springs in it. I installed the 2 black springs which seemed a little stronger than the pink springs that were originally in the dizzy. Reinstalled the dizzy into the car and proceeded to tune it.

So with the tuning, I did as in the one article that was posted. I used a vacuum gauge and found the best vacuum where the needle didnt bounce around. Took me some time because as I would turn the dizzy, the rpms would go up as would the vacuum, decided to check it and I was at about 45*:eek:ops:

So backed it back down to about 10* and reset everything. I only had my idle at about 800 and it was rough, engine shaking and all that. So I bumped the idle up to 1000, then proceeded to twist the dizzy to find the highest vacuum. Whats that??? WOW the needle isnt bouncing any longer and I have about 15hg's of vacuum! :blob:I've never had vacuum this high at idle!:cheers: I grab the timing light and I was at about 22* initial. I decided to rotate a bit further to see if I could get it any higher. The vacuum gauge started to flutter so I reversed rotation and got it to smooth out. Yep 22* is the highest smoothest vacuum I could pull.

So I went to check total timing. I reved it up and I have 35* total. So 22* initial + 13* mechanical. Only thing I cant tell you is when its all in by. But it does come in slower than those pink springs. I didnt have anyone in the car to tell me what the rpms where.

I then moved on to the carb adjustment. Screwed the idle screws all the way in and it wants to run rough, yep thats what its suppose to do. Started backing them out at first a half turn, little by little I get the highest vacuum reading I could. Which was just over 15hg, (like a needle width over). Both screws are just shy of 1 full turn out.

Car is running smooth, so I decide to go take it for a drive. Mind you it was 90* today. I roll the windows down, and take off down the road. Watching the temp and all that. at first it held at 190*. Then I had a stop light. Crept to 200* Pulled into the gas station and filler it up. Heck with it, Im already 6 miles from home, might as well take the scenic route home. Highest the temp crept up to at a light was 210*. Now I dont have a shroud on this car but I will be looking for one at Mopars in the Park this weekend. Car seemed to run very good and very smooth. I kicked it down a few times to see what it would do. Only thing I noticed is that I have a delay/hesitation before the secondaries kick in (I have another post on that). Total distance driven was 18 miles today. Kicked it down about 4 times for a quarter mile or so and the gauge stayed put. It was still on full as I pulled in the garage... :blob:

So with that said. What do you guys think about what I have done? Think I nailed it?

Now
 
As far as the curve is concerned, that's up to you on the spring selection, if it 'feels' better then go with it, if not swap back. It's one of those things you gotta play with to get right.

In fact, the whole timing curve and carb tune is one of those things you've got to 'feel' what it likes, you keep going till it doesn't like what your giving it, then back it off.

Make sure to check your vacuum advance setting as this is damn important to get good mileage! 48-52 total by the time it quits pulling. Ported vacuum works best on my setup, manifold feels spongy. You can adjust the canister with a 3/32? allen wrench inserted into the vacuum port on the canister, 1 turn is 1HG, clockwise add, counter-clockwise subtract.

Your on the right track with the carb, I still think you should check the plugs; hell pull em' after it cools down and look at the base ring, if it has 1 full turn of color your good. I know you can get real anal about reading spark plugs, but you can get close by just scoping them out at your leisure.


What carb are you running?
 
Sounds like you've found it to me , fill it up drive it for an hour then refill and do the math on your mileage . I would do it twice once around town and once down the highway , try not jumping on it during the highway run just find an on ramp gas station and go 1/2 hour from full there to an exit then loop back to the same spot refill and do the math , I bet you get at least 12 mpg .
 
Sounds like you made some good progress and got real lucky with the dist. It's one of the MP distributors that has the Mallory type advance which sure makes it nice. Only thing is I would have expected it to like lighter springs than what you used but if it's running good leave it be. Check your mileage like Cannucky said. That's the only accurate way to tell what it's really doing. What the fuel gauge says isn't accurate usually. The one in my Cuda will go about 150 miles before it drops to 1/2 tank then it drops from 1/2 tank to empty in about 80 miles. Fuel gauges on our old stuff generally isn't linear so that's why the only accurate test is like Steve said
 
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