I need engine tuning help.

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SirDan

SirDan

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I have a 73 318, unknown mileage, stock heads, LD4B intake, edelbrock performer 600 cfm carb, flowtech headers, 340 cam, 340 air cleaner assembly,323 gears, 275/60/15 tires, stock crap 904 with no converter.

Drives fine no hiccups,sputtering or stalling with normal driving. I did notice before if you have it in gear foot on the brake and blip it then let off it idles low or dies. The car pulls pretty good up top but I feel there is more to be had on the bottom end. It also gets about 10 miles to the gallon.

I have replaced the plugs/wires/cap/rotor very very recently so those are good to go. I also swapped the distributor with one that was in A LOT better shape.

My initial timing is probably around 15-20 btdc. Its hard to tell because the thing only goes to 10. I tried in a bunch of other places and where it is now it runs the best.

I have a kit with a ton of jets and stuff for the carb. I really don't have money to spend on any other parts. I could afford to buy new springs for the distributor if that would help but, not intakes or carburetors. What I have its what I'm using. I also don't want to get a converter as I have a full 4 speed setup I will be swapping in at some point.

Any help is appreciated.
 
When you dont have the cash for the user friendly stuff, you need to be smart instead. Soo... first, buy a timing tape, and install it after carefully cleaning and degreasing the balancer. Then you can look at the whole timing curve. My guess is, the distribuotr you have is not a performance model, and as such, it kills response, power, and economy. You should have no trouble breaking 15-18mpg in mixed driving once it's curved properly. Possibly more. But, you have to know where you're starting from and what you need to have.
 
The only problem I see with the timing tape is, I cant really see much further on the balancer as it goes behind the timing cover and water pump. Where it is at right now I can just barely see the mark.
 
Right... The tape is graduated so when the factory mark disappears, the other marks tell you where the timing is... Otherwise you need a timing light that has an advance function.. The tape's like $5...
 
oh I see what your saying I think. the tape will correspond to the 0 mark on the cover? which will tell me what its at? Sort of the reverse of how it is stock? sorry I have never used timing tape.
 
hillbilly timing tape

HillbillyTimingtape001.jpg


Search the site for that term and post by me and it will tell you how to do it. No special tools required and it doesn't fall off like a tape.
 
I'm really not that experienced. But my combo is not that far from yours and I got it running really good. I also senced there was more to be found in the bottom end. My initial timing is around 18-19*. But what really made the difference was finding a tiny vacum leak that I could not see or hear, only felt it with my hand. It was the drivers side Full-time vacuum port on the edelbrock that was plugged, but the plug was dried up and had the tinyest crack. So take a good look for vaucum leaks is my advice.
 
ok I cleaned my balancer and found out it already has marks on it up to 30. The car is at 18 btdc at idle and at about 40+ btdc when I hold the rpms up.
 
actualy scratch that. I just remembered I forgot disable the vacuum canister. I guess ill go out and check it once more.
 
I use an adjustable timing light, the only mark I need is TDC. Takes the guess work out of it.
 
Well i'm broke so I have to use the light I have.

anyway now timing it the the right way, I have 18 at idle and total timing about 36 at what sounded like 3k rpm.
 
18 btdc at idle and at about 40+ btdc when I hold the rpms up with it connected.

without it connected 18 at idle and total timing about 36 at what sounded like 3k rpm.
 
When you connect your vacuum advance your idle and timeing should advance at idle.

There should be significant vacuum where at idle for your vacuum advance.

so it sound like you have this hooked up wrong
 
Not to still a tread but I have no vacuum on my advance port on my carb till hit the gas. is this correct?
 
Typically not,

Does your car have a stumble when you accelerate from a dead stop ?
This may be why.
 
The vacuum applied to the advance can at idle should be next to or nothing. It is supposed to be attached to a ported vacuum outlet. In other words, very little or no vacuum at idle and more as you accelerate. It should have little to no advance at idle. If it has more than say 5* you probably have it hooked to the wrong place. A dial back timing light is something everyone should have in their assortment of tools. You can get a decent one for about 20 or so bucks. Save your money and get the right stuff. Also, that Mopar distributor has two advance springs in it. A big one and a small one. Removing the big one results in almost the same timing curve as the MP performance unit. Those weights are really held back at the factory. Maybe you could hook up with a forum member in your area who could help. I wish you were closer. I could hook you up on a Saturday afternoon.
 
The purpose for vacuum advance is to advance the timing when the fuel mixture is lean, since a lean burn time is greater. During acceleration the the air fuel mixture is rich, during idle and cruising the mixture is lean.

So you figure it out. If the vacuum advance was zero at idle then there would not be much need to disconnect and plug the vacuum line when you set the timing.

If you have it hooked up the other way, you may be having a stumbling problem when you first step on the gas.
 
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