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4mulaSvaliant

4mulaSvaliant

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Hey guys and gals. Well I am mainly working out bugs on drive train and engine issues before I hit the body work real hard this winter. So here is what I have, and I am trying to get to a good solid Base point to start tuning.

OK here are the specs.
74' 360
Old Edelbrock 318-360 intake (dual Plane)
Retro fitted Electronic ign. (74') into my 69
Mild cam "RV" dont remember the specs anymore.
Edelbrock 1406 Carb. (650) I think
7mm wires nothing special
Autolite plugs (never had an issue) so no bias opinions! LOL
904 trans
8 3/4 Sure Grip 373s
Manual brakes so there is no extra vacuum issues.
Only vacuum is for the dist. advance.

So here is where I sit right now, I adjusted a few things a while back in an attempt to "tune" it, but as I figured my skills are lacking in that department.
Since then it DOES ping when I get on it, and the other very noticable issue is that it smells very rich. Problem with the thought of it being rich is, when I choke it slightly when it IS warmed up the RPMs will raise.
If I am thinking correctly then that would mean it is lean and welcomes that extra fuel in the mixture-thus causing it to raise the RPMs.

So as for tools for helping me through this, I have managed to gather all the correct tools just havent used them enough to be sure Im using them to there fullest potential.
I have a Tach in the car
A tach and dwell meter
Adjustable timing light (good quality craftsman)
Vacuum gauge

So I am asking the guys that are truly good at this to attempt to lay it out on where I should start and also how to properly use my timing light to its potential. I do not have the directions for it or Id just read em' lol

Any info is very appreciated. I know my motor has more to offer, because it has ran better before. Thx guys Im listening!
 
pinging is straight foward.. too much timing for you engine. first, disconnect the vacuum advance temporarly and see if it still pings.
back off the initial timing 5 degrees, reconnect the vac.adv.(to a PORTED vac.source) and see if it still pings. if it does, you either have:

A. Still way to much initial advance (should be no more the 15 degrees) or
B. Too much mechanical advance coming in too soon.

to find how much mech.adv. you have, you'll need a dial back timing light, or timing tape on your dampner.
should be no more then 38degrees(vac. disconnected) total at anything under 3000rpm. But I assume that you still have the stock
springs in the dizzy, so my bet is way to much advance. plus a rich mixture is sometimes and indication of too much timing.

as for your engine reving up when you give it slight choke, its designed to do that.

finally (i have to ask) are you positive your hearing pinging, and not an exhaust leak?

try those things. keep us posted.
 
Are you allowed on here? LOL Just kidding thank you very much for the info.
So here are my thoughts. I agree I probably do have to much advance. Yes its def. PING. Im sure I have an exaust leak as well but the Ping as you know has its own sound.
I am thinking that my process should be this. Correct me if I am wrong.

1. Adjust timing
2. Adjust the carb using a tach, and also a vacuum gauge to attain the highest vacuum setting I can get.

Here are the problems with this that I see I will have.

1. Where to adjust the timing too? I can get in the "ball park" but what signs are going to be most noticable to let me know I have hit the ideal setting.

2. OK say I get the timing where I think it should be, now I move to adjusting the carb mixture screws with a vacuum guage and a tach, but as I adjust them they have in-turn made my RPMs raise or lower and then the TIMING is looking different again with the timing light.

3. Say I get the timing and the mixture screws adjusted, so that the timing looks good and the highest vacuum is attained and NOW with those set, it is idleing too high or too low? Once again if I adjust the idle srew it will make the timing look different with a timing light.

I know this is exactly what defines the "ART" of tuning, so maybe Im asking a bit much to be explained to me.
I am sure that I have some misconceptions as far as some of this process is concerned please feel free to set me straigt.
Thx guys
 
Here are the problems with this that I see I will have.

1. Where to adjust the timing too? I can get in the "ball park" but what signs are going to be most noticable to let me know I have hit the ideal setting.~ a good starting initial point would be 10degrees BTDC you want no more then 38degrees total.

2. OK say I get the timing where I think it should be, now I move to adjusting the carb mixture screws with a vacuum guage and a tach, but as I adjust them they have in-turn made my RPMs raise or lower and then the TIMING is looking different again with the timing light.~ timing is looking different becouse the idle speed is no longer the same. on eddie carbs, seat the mixture screws completely, then back em' off 1 1/2 turns. good starting point.

3. Say I get the timing and the mixture screws adjusted, so that the timing looks good and the highest vacuum is attained and NOW with those set, it is idleing too high or too low? Once again if I adjust the idle srew it will make the timing look different with a timing light.~ refer to the above answer

I know this is exactly what defines the "ART" of tuning, so maybe Im asking a bit much to be explained to me.~ no worries, we're all here to learn. the choke will still raise the idle speed when engaged.. even if the engine is hot.
I am sure that I have some misconceptions as far as some of this process is concerned please feel free to set me straigt.
Thx guys~ feel straight yet? lol.

now, as far as me being allowed to post here I don't see why not.. i took the BEST SmallBlock ever made and put it into the best Car Body ever produced. cheers.
 
Ok so here is what I mustered up after a bit of messing with it. I have about 18 degrees total advance, and eneded up with about 18" of vacuum.
These results were obtained with the vacuum advance OFF and the carb port for the vac. adv. plugged. I left the pcv vacuum hooked up and put my vacuum gauge on the small vac. on the right side. (if you are looking at the carb from the front of the car)
It was completely warmed up and now idles around 800 rpms. with all theses items set.

Results are as follows.
Ping: has gotten much better, the "pinging" is not so noticalble but is still there under a load. (in gear, accelerating fairly hard)
Carb reaction: Before, it had some serious lag. If you stomped it, it would slightly stall and then pick up.
Now it has nearly NO stall prior to revving if you stomp it. (mainly refering to manualy moving the throttle by hand at the carb.
Smell: It does seem to smell much better. Not so rich smelling.

My opinion. I did this over the course of about 2 hours, thats running it around the neighborhood and all. So in my opinion I have just scratched the surface with getting it dialed in but I seem to be going forward anyhow.
I think at this point I may need to either retard the timing further or run premium gas. I guess the easiest way to solve that would be to try it, especially since the tank is nearly empty at the moment.
Still open to any advice, but thx for your input Z28.
 
TIMING 101

Timing seems simple enough ... pull out the book & the timing light & set the timing to the spec listed.
But is this really where the engine runs the best & makes the best power & or fuel mileage ??
First lets go over the pricipals for timing an engine. Fuel burns at a given speed & takes time to burn so we want to start the fire early so maximum pressure from combustion happens when the piston is at TDC.
If we start the fire too soon maximum pressure is reached too early & trys to stop the piston from reaching TDC. If we start the fire too late the piston is past TDC & the pressure in the cylinder is starting to drop as the area expands before the maximum pressure is reached. This wastes fuel & power.
Another factor is the fuel quality ... contrary to popular belief low octane fuels burn faster & more easily , while high octane fuels are harder to light & burn slower. Also heat is a factor, so actual compression as well as altitude , & cam profile all have an affect !!
Cam profile is rarely considered when timing an engine .. for example a short duration cam with low overlap will build a lot more compression at lower rpm increasing the heat in the cylinder, conversly a longer duration cam with more overlap traps less pressure at lower Rpm reducing heat in the cylinders , this effect reverses at high rpm as the exhaust leaving the cylinder will help draw in a lot of air/ fuel mix effectively supercharging the engine often well above 100% volumetric effeciency. Shorter duration cams tend to lose this effect & starve at higher rpm. So how can a book determine the fuel quality & dictate a correct timing position for your engine

Lets start with the base timing setting at idle
A book may state that you need 6* BTDC of timing at idle so the fuel now has ^8 to complete combustion & maximise pressure in the cyl to get the best use of the fuel
But is this what the engine really needs? The Easy way to test this is to advance the dist at idle [clockwise for Big blocks , counterclockwise for small blocks] & either listen to the engine or watch the tach to see if RPM increases , generally it will. Most engines like 14-18* initial timing [at idle ] or more , generally just making this change will increase fuel milage & throttle response dramatically. Now the fuel is more completely burned when the piston is at TDC & more pressure is created , with long duration cams advancing the timing is virtually a must just to get the engine to idle.
Now we have a problem you probably have a 32* curve built into the dist so with the idle set at 6* btdc you had a total of 38* advance ,But now total timing may be set at
48* this is where the advance curve in the dist needs to be altered to still work correctly . In reality the total timing is far more important then the timing at idle , first how much time is spent at idle & how much power is needed at idle ? Not much really, most of the time the engine is at 2500 Rpm or more & this is where the power IS needed. You can time any engine with a light by making a mark on the damper 2 3/8" clockwise on the damper from the TDC line , this will give you a mark at 36* & you can use the
scale on the timing cover to adjust from there , most engines like between 36-42* when set at around 3000 rpm.

Understanding the curve
The curve is present so the fuel has the correct amount of time to burn even as the time to burn becomes shorter as the rpm increases so the fire has to be started earlier to maximize pressure in the cylinder at TDC the same as at idle. There are 2 curves in the distributor. Mechanical using weights & springs & vacuum which rotates the pick up plate inside the distributor. The vacuum advance is designed to advance the timing as rpm increases to add time for the fuel to completely burn at TDC, a very common mistake is too hook the vacuum to the manifild vacuum source which is high at idle & decreases with RPM , this is incorrect as it give more advance at idle & & decreases it with more RPM which creates the burn way too late & will kill off power & mileage so make sure the vacuum is hooked to a Ported / Venturi vacuum source.

Shortening the curve ... there is an allen screw inside Most Mopar dist so turning this screw adjusts the length of the curve , turning counter clock wise decreases the length of the curve by approx 1* per each full rotation of the screw, the vacuum pot allows 14 turns max & no damage is done if you turn too far you will hear a click at the end of the threads. But turning clockwise again re-engages the threads. Some times using no vacuum advance by either unscrewing the allen screw all the way or just diconnecting the vacuum hose yields the best results.
The other way to shorten the curve is to decrease the Mecahnical advance curve , this is more difficult to do as the distributor needs to be disassembled & the slotted advance plate needs the slots welded in [ the new Mopar performance Distributors come with an allen screw to adjust this as well ]
to set total timing I set by ear , you can hear the rpm rise, then it goes flat & quits rising & if you continue to advance it will start to pop into the exhaust basically you want the timing set just at the point where the RPM quits rising for best performance , you can also experiment with a light & or a tachometer. Adjust the setting higher until you feel no power or rpm increase.

The other consideration is the speed of the curve , there are 2 springs on the mechanical advance plate, by using a heavier or shorter spring you can slow the curve so the timing is advanced at a slower rate, conversly using a lighter spring speeds up the curve which generally increases power unless you encounter pinging which nessesitates slowing the curve.
When pinging is encountered [sounds like rocks in a metal tin being shaken ] it really is not a timing problem , it is a fuel problem. Pinging, really known as detonation is a condition where the fuel is burning from heat before the spark plug can start the fire, or the fuel is burning too fast, the real solution is too use better fuel , too bad 104 octane is not available. Other solutions are to use a colder spark plug, octane booster, or a bigger cam to decrease cylinder pressure. Detonation is generally only a problem at lower rpm so lenghtening or slowing the curve or decreasing initial timing can cure the problem while still maxinimzing power at higher rpm but this is really a band aid approach as the engine will make better power & mileage with the timing advanced
Another factor is oil consumption , oil burns at a lower temp than fuel so if you have an oil consumption problem , detonation is far more likely.

for CARB TUNING 101:
http://www.forabodiesonly.com/mopar/showthread.php?t=46728
scroll down and happy reading!
 
Break it down! LOL, no but seriously, thank you for investing the time into answering my thread. And thx for the lead on the link. Ill be sure to read that.
Being hoonest I have always been a "by ear or eye ball it" guy, so I have a feeling Ill be trying that next. It seems easier for me to pick up on whats happening with it by ear rather than looking at several gauges and not knowing exactly what Im after.
Chances are that you are correct about the dist advance. I have done nothing to it and it is a 74' model.
I am glad it has been spelled out actually, because I had'nt thought through to the point of how the timing is set at the "normal" rpm. Makes perfect sence and I think Ill run with that idea and see where it leads.
I do have the vacuum advance hooked up to a ported source. And actually as I think about it I wonder if there should have been more vacuum there than there is.
At an idle there seemed to be NO vacuum where I have the vac. adv. hooked to. Because I plugged it while adjusting the timing I have no idea if the vacuum is actually working when the rpms rise either. Ill be sure to check that tomorrow.
I hooked the vacuum gauge to the port that has contstant vacuum of decent proprtions even while idleing. (18") to be specific.
It is very possible that m,y Ping is coming from being to hot as well, but wasnt really thinking that way yet. My car has been running at 210* if it sits much more than 5 min at idle. I have known this is a bit high, but hadnt tied the pinging issue to it.
Thats a whole other issue I have yet to solve. However it will drop down to 180/190 while cruising around. I have a 180 Tstat currently.

Well we shall see what tomorrow brings unfortunately I have limited time to give to it so who knows what will happen.
Again thanx for the education!
 
I know this is exactly what defines the "ART" of tuning, so maybe Im asking a bit much to be explained to me.~ no worries, we're all here to learn. the choke will still raise the idle speed when engaged.. even if the engine is hot.

I may be wrong here, but if you start closing the choke at idle or higher and the engine speed raises would mean your running lean. Think your fighting two problems, get your timing straighten out. And adjust your carb. If your lean on the high speed you'll need to change the metering rods and or jets. Edelbrock has a kit you can buy that comes with rods/jets/springs.

Had the same problem on my 360
 
yah he said "open a little" not enough to choke it off, but just enuff to open the throttle and raise the idle.
BUT..
you are very possibly correct.
cheers.
 
Sorry, never seen where closing the choke would open the throttle,unless you opened the throttle by hand.Something to do with those notches.
Z28, Nice job on the timing 101. And Welcome to the forums. Now if we can just get that engine into A Body. :toothy10:
 
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