Need Performance Advice. new owner 70 Dart Swinger.

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Chadderbox70

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Hi Everyone,
I just got a 1970 Dart Swinger.

It has a non original 360 , an unknown lumpy cam, headers, edelbrock carb, edelbrock intake, full MSD billet distributor with MSD 6A.

Revs up like a mean machine but the car is not rapid to accelerate. I believe it has hwy gearing.

It has a 904 Trans and Im told a 2500RPM torque converter.

What rear gear would be great for me? Id love to hit the 1/4 mile with this car. Dont really care about hwy mileage.

Thanks
Chad
 
If you don't care about highway mileage then put a 4.56 in it. Small blocks need gears.

A general way to tell what gears you have is to jack up the car, put it in neutral, spin the wheel around by hand and count the number of times the pinion turns for every one rotation of the wheel. If you have a sure grip, spin it twice.

But, gears are not the entire equation, you need to verify some stuff before you start throwing money at it. Have you tried any tuning yet?
 
rmchrgr said:
If you don't care about highway mileage then put a 4.56 in it. Small blocks need gears.

A general way to tell what gears you have is to jack up the car, put it in neutral, spin the wheel around by hand and count the number of times the pinion turns for every one rotation of the wheel. If you have a sure grip, spin it twice.

But, gears are not the entire equation, you need to verify some stuff before you start throwing money at it. Have you tried any tuning yet?
Click to expand...
rmchrgr said:
If you don't care about highway mileage then put a 4.56 in it. Small blocks need gears.

A general way to tell what gears you have is to jack up the car, put it in neutral, spin the wheel around by hand and count the number of times the pinion turns for every one rotation of the wheel. If you have a sure grip, spin it twice.

But, gears are not the entire equation, you need to verify some stuff before you start throwing money at it. Have you tried any tuning yet?
Click to expand...

I have only owned the car for one day. I will definately take your advice and tune it first. I need to check the base timing im sure, then the advance somehow? and learn about edelbrock carb tuning.
 
Chadderbox70 said:
I have only owned the car for one day.
Click to expand...

And you're on here asking how to make it go faster? Drive it around, figure it out, understand what it needs. Get an A/F meter, it will be a good tuning aid. Baseline everything then start from there.

Chadderbox70 said:
I will definately take your advice and tune it first. I need to check the base timing im sure, then the advance somehow? and learn about edelbrock carb tuning.
Click to expand...

Well, sounds like you are kind of new at this - it's OK, everyone has to start somewhere. I've been doing the car thing for like 20 years and I still only know enough to be dangerous... but I digress.

You are right, the first thing to do would be to start looking at the timing and make sure you have that mostly squared away before even looking at the carb. You can plot the advance with a timing light. Might also do stuff like verifying TDC on the balancer and just going over stuff to make sure it's all in good order like no burned plug wires or carboned up distributor cap...

But, before any tuning is done, you might consider doing things like checking the throttle cable operation to make sure it's opening up the carb correctly, making sure there are no vacuum leaks, etc. You could also consider a compression and/or leak down test just to make sure you are dealing with a relatively healthy patient. In lieu of that, put a vacuum gauge on it and drive it around to see if anything looks way out of whack. There are charts everywhere about what a vacuum gauge can tell you.
 
rmchrgr said:
And you're on here asking how to make it go faster? Drive it around, figure it out, understand what it needs. Get an A/F meter, it will be a good tuning aid. Baseline everything then start from there.



Well, sounds like you are kind of new at this - it's OK, everyone has to start somewhere. I've been doing the car thing for like 20 years and I still only know enough to be dangerous... but I digress.

You are right, the first thing to do would be to start looking at the timing and make sure you have that mostly squared away before even looking at the carb. You can plot the advance with a timing light. Might also do stuff like verifying TDC on the balancer and just going over stuff to make sure it's all in good order like no burned plug wires or carboned up distributor cap...

But, before any tuning is done, you might consider doing things like checking the throttle cable operation to make sure it's opening up the carb correctly, making sure there are no vacuum leaks, etc. You could also consider a compression and/or leak down test just to make sure you are dealing with a relatively healthy patient. In lieu of that, put a vacuum gauge on it and drive it around to see if anything looks way out of whack. There are charts everywhere about what a vacuum gauge can tell you.
Click to expand...

Great advice. I had an 89 corvette before. It was all computerized and a decent performer after I redid the exhaust, plug in a chip and away you go! I have only done bolt on mods and its my first actual carbureted vehicle. I will definitely get a vaccum gauge right away, and follow your recommendations. I have a compression tester to try too!
 
20160708_205505_HDR_zpsufauof9h.jpg



I cant seem to find online what the base timing should be for a 360 LA block.
 
lumpy cam? set the initial at 17* to 20* then get the total to 35* in by about 2200 rpm.. should be a good starting point.. and fine tune from there..
 
Last edited:
abodyjoe said:
lumpy cam? set the initial at 17* to 20* then get the total to 35* in by about 2200 rpm..
Click to expand...

There is no exact initial timing setting, especially with with a non-stock cam.
If it runs mostly OK, the timing is probably in the ballpark but that does not mean it's optimal. Joe is correct on where the initial should be set. Even a stock 318 could probably take 18 initial as long as you limit the mechanical advance to achieve 34-36 degrees total.

You can set initial timing with a vacuum gauge. Remember to disconnect the vacuum advance when setting your timing. Put the gauge on, loosen the distributor a little so you can move it and start the car. While it's idling (in gear), advance the timing to get the most vacuum. Once vacuum stops increasing, back the timing off 1 degree and lock it.

Like I mentioned previously, you might want to 'plot' the advance curve. Make a graph or chart where you note the amount of advance at a specific RPM from idle to about 2,500 rpm.

Is your balancer marked? If not, get a timing tape on it. (that's where verifying TDC on the balancer comes into play).

Distributor Setup - Quick Tech - Mopar Muscle Magazine

 
rmchrgr said:
There is no exact initial timing setting, especially with with a non-stock cam.
If it runs mostly OK, the timing is probably in the ballpark but that does not mean it's optimal. Joe is correct on where the initial should be set. Even a stock 318 could probably take 18 initial as long as you limit the mechanical advance to achieve 34-36 degrees total.

You can set initial timing with a vacuum gauge. Remember to disconnect the vacuum advance when setting your timing. Put the gauge on, loosen the distributor a little so you can move it and start the car. While it's idling (in gear), advance the timing to get the most vacuum. Once vacuum stops increasing, back the timing off 1 degree and lock it.

Like I mentioned previously, you might want to 'plot' the advance curve. Make a graph or chart where you note the amount of advance at a specific RPM from idle to about 2,500 rpm.

Is your balancer marked? If not, get a timing tape on it. (that's where verifying TDC on the balancer comes into play).

Distributor Setup - Quick Tech - Mopar Muscle Magazine

Yes my balancer is marked. I checked it today it is sitting at 20 degrees.
thats great info! thanks everyone! abodyjoe thats a great article thanks for sharing. thanks rmcharger!

Click to expand...
 
I set base timing to 25 degrees advanced. really woke it up.
I still have to look at the carb next. I havent pulled a plug yet either.
I have a 600CFM Edelbrock 1406 carb. Idle set properly thats it. Surely there is tuning potential in it. hopefully 600 cfm is not too small. I see online calculators say 535cfm is all that is needed and bloggers that say 700 is really good for a 360.
 
25 degrees is A LOT of initial. With that much you will need to limit the mechanical advance. Small blocks like 34-36 TOTAL advance so if you have 25 initial you should only have around 9-11 degrees in the distributor.

You have to check the total advance here. Rev the engine up to about 3K, hold it there for a second to stabilize the marks on the balancer and see where the timing is at, it's probably over 45 degrees at least. If it's at 34-36, you're good but I'd bet it's higher.

The MSD distributor will have stops/bushings to limit the mechanical advance. If your motor wants 25 initial, then shoot to limit the mechanical to 9-11 degrees like I said which will yield the 34-36 total.

Really though, you likely don't need that much initial timing. As an example, my 416 with a fairly large solid flat tappet cam has about 20 degrees initial timing and the total is set at 35 degrees. It's "all in" fairly quickly so it's at full advance before you really get into the sweet spot of the cam which is where it should be. I used the FBO limiter plate to keep the mechanical advance within reason.

It's probably OK to have that much initial to unless it makes the car hard to start but again, it's probably not necessary to have so much. You are bordering on 'lock out' territory. I'd back it down to somewhere around 18-20 degrees and see how that goes. You will still likely need to limit the mechanical advance but you will have more of it, like 15 degrees as opposed to 10 which will produce more of a curve.
 
ok. so far it runs much better. I am curious about my carb next. tomorow Ill pull a plug to inspect
 
Chadderbox70 said:
ok. so far it runs much better. I am curious about my carb next. tomorow Ill pull a plug to inspect
Click to expand...

Where did your timing wind up?

I would recommend not to touch the carb until your are 100% certain the timing is correct. 9 times out of 10 guys will start fiddling with the carb and get way out of whack with it when the problem was usually with the ignition timing.... (me included). Carb tuning is 100% dependent on having the correct timing.

Unless it's been messed with already and you don't know what's in it, IMO, the only thing the carb should be checked for at the moment is correct float level, adequate fuel pressure, reasonable idle speed and the idle mixture tuned with a vacuum gauge. Anything beyond that is for when you need to tinker with certain spots in the rpm range or you have a drivability issue directly related to carb settings. Most carbs will function OK without much tinkering unless their baseline is changed or it doesn't match the application.

I hate to open a can of worms but what carb are you working with here?
 
I hate to open a can of worms but what carb are you working with here?[/QUOTE]

600 CFM edelbrock 1406
 
My Friend had a good look at my carb. The Secondaries were not opening fully. adjustement made.

also the little tab on the throttle linkage side was only allowing the mains to open about 90% a little work with the die grinder and its now able to open fully.

This has made a quite difference.

Still though going to look at changing out the hwy gears for something that suits the 1/4 mile.
 
AJ/FormS said:
And you still have not told us that your power timing has been limited.So when your rod bearings end up in the oilpump, sorry.
Click to expand...

We can only do so much on the old interwebs, right? At least our OP here is trying...

What AJ is saying here is that your TOTAL timing (centrifugal + mechanical) NEEDS TO BE CHECKED AND VERIFIED.

Please do that and report back as to what it is. This is a BASIC task and should be verified on every engine. We are betting it's over the 'normal range' of 32-36 degrees. You may have gotten lucky but not likely. If it is more than 34-36 degrees (on the balancer) at 3,000 rpm, then you have TOO MUCH timing and need to LIMIT the mechanical advance as described previously.

Remember to disconnect and plug the vacuum advance (vac. can on distributor and port on the carb) when checking/setting your timing...
 
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