55* total timing? WTH?

-
4mulaSvaliant

4mulaSvaliant

Well-Known Member
Joined
Oct 26, 2006
Messages
1,554
Reaction score
44
Location
Virginia Beach Va.
Morning guys.
So here are the specs:

360
318 heads ( I kow, I know... #-o )
Cam: I dont know specs anymore but it wasnt stock, and wasnt crazy. Id refer to it as an RV cam or "mild"
Stock Chrysler electronic ignition, scavenged from a 73 dart
"Chrome" ECU
Stock small block distributor

Plugs look great
Carb just rebuilt
Cap, rotor and wires in good shape

So here goes.
I got the idle set at 750 in park.

Initial timing: 15* BTDC (seems VERY high)
Vacuum Advance: 16*
Mechanical Advance: 24*
Total Advance being: 55*

Mopar performance suggests no more than 35* total timing.

At this point I have a few options.
But first its noteworthy to mention I am not so sure I believe my vibration dampener hasn't slipped and the timing mark is off... I say that only because it doesn't seem likely to run well or at least start very easily and it has been with no issues that you might expect with that much advance.

Now, the way it seems..... I need to reduce the degrees of timing by 20* total. My obvious options to get the timing down would be retard the initial to around 6*BTDC, reducing it by 9*, then the other easy option would be to reduce the vacuum advance the other 11* for a total of 20*

This, to me sounds a bit drastic! I don't care to tear into the distributor to change the mechanical advance, primarily because it is a stock unit and has probably never been toyed with, so I have no reason to believe its far off from where it should be.

My question is.... What does this tell you veteran engine guys?

I am doing all of this in order to tune this thing in, and just optimize everything.

Its worth noting that I DID, retard the timing to 6* initial timing and test drove it. It didnt seem to make much difference. Starting or otherwise... #-o

Any input is appreciated.
Thanks FABO! You guys rock!
 
Purple Haze said:
I would first start by checking the timing marks at TDC.
Click to expand...

Xs 2! That is the only logical way to go about figuring this thing out. You must always start at the beginning and that is to assure the accuracy of your measuring device(s). In this case, that would be the timing mark on the harmonic balancer.
 
IF..... this harmonic balancer has shifted. Is it still usable with timing tape or does it affect balance and need to be replaced?
 
Like PH says, check the TDC mark 1st.

55° total with the vacuum connected is not all that crazy. 15° initial sounds good to me too. However, don't worry about either one of those right now. Disconnect the vacuum, and set your total (mechanical) advance to around 35° at whatever RPM it stops advancing, probably around 3000 max. if its a stock distributor. Reconnect the vacuum and see how it runs. Should be O.K. This is over simplified, I know, but it'll get you close.
 
If it slipped once, it will probably slip again. I wouldn't trust it, but I would use it until I had time to buy and install a new one.
 
is it pinging or running bad or has gas mileage dropped /down on power? I run my 75 duster 318 at 50* 10 at crank/30 in dist./10 vacuum. when I go full throttle I lose the vac. and have 40 *I found it to get better fuel mileage with the 50*,with the leaner fuel curve when cruising it can use more time to fire the leaner mixture .
 
First verify timing mark is correct. If you really have 24* mechanical advance, set initial to 10* and verify total at 34*. If that's good hookup the vacuum advance to full manifold port and check total around 50*.
Take the car for a cruise and vary the engine load to check for pinging and performance.
If your vacuum advance canister has a hex looking end you can adjust vacuum advance by inserting a 3/32 allen wrench in the nipple. CCW retards, CW increases. Go one turn at a time and check with a timing light.
 
As above have stated chk tdc with piston stop. Then go from there. My.stock 360 in my 84 D150 and it likes 20* initial
 
Thanks everyone.
I plan to start from scratch again this evening. Starting with checking TDC against the balancer.

I was able to put an allen wrench in my vac advance diaphram, but it was siezed and Im pretty sure rounded out the hole. :/

In general though... NO. no pinging or major signs of timing being off. Though I do remember it seeming to have more torque.... I am just trying to get the car back in good running order after it has sat for some time.
 
My brother had almost the exact same numbers in his Dart 383. I argued that they were too high, but he argued they weren't, and the car ran well. Hard to argue with the results. That is why I don't like vacuum advance.
 
15 35 and 55 are just about ideal.
..leave it right there if there are no detonation or driving issues
 
ir3333 said:
15 35 and 55 are just about ideal.
..leave it right there if there are no detonation or driving issues
Click to expand...

69mope said:
x2
Click to expand...

x3

BUT THAT IS NOT what he said

4mulaSvaliant said:
Initial timing: 15* BTDC (seems VERY high)
Vacuum Advance: 16*
Mechanical Advance: 24*
Total Advance being: 55*
Click to expand...

If he has 15 initial and 24 mechanical this is THIRTY NINE total under power. Way too much most of the time. If he backs the total (without vacuum) back to 35 or so, the initial AND the total with vacuum is going to go all to 'ell

What you want

Set the initial for "all it will take." This means tune for max idle RPM and vacuum, if necessary you can back this off a bit. "The test" is kicking back on the starter, and low speed ping.

Then you need to figure out what best / safe power is with no vacuum. This is your 35 or so, plus or minus. THE DIFFERENCE BETWEEN THESE TWO is what you need to curve the distributor mechanical for. IE 18--20 or whatever.

THEN you add the vacuum on the end, and this can be 'quite a bit' as the vacuum is only under cruise and light throttle. 55--approaching 60 is not uncommon on "fuel mileage" vehicles

AbodyJoe posted this years ago:

http://www.forabodiesonly.com/mopar/showthread.php?t=158842
 
I found this article to be very helpful in understanding timing (forgive me for the reference to Chevys).

[ame]http://www.camaros.org/pdf/timing101.pdf[/ame]
 
Good eye D273!
if there is no detonation or driving issues 39 could work at wot
if the compression is higher, back off initial 3 for 12 36 52
to get spot on he may need to recurve the distibutor
 
There's two methods of mapping a dizzy curve, one using ported vacuum and the other using manifold vacuum.
A ported vacuum setup could be mapped 18* initial, 16* mech, 16* vacuum, total 50*
A manifold vacuum setup could be mapped 6* initial mech + 16* vacuum, 28 mech, total 50*
When using the manifold vacuum port an adjustable canister let's you move the curve + or - to fine tune to what the car likes without pulling the dizzy.
Most open chamber heads like higher initial timing settings.
 
I know a few people touched on this, but I wanted to make sure the OP realized it.

Vacuum advance is not part of your WOT total timing.
Vac advance is only added in under light throttle/high vacuum when the engine can run more timing for light throttle fuel economy, so 50 with all three is about right on the nose.

As you were. :)
 
TrailBeast said:
I know a few people touched on this, but I wanted to make sure the OP realized it.

Vacuum advance is not part of your WOT total timing.
Vac advance is only added in under light throttle/high vacuum when the engine can run more timing for light throttle fuel economy, so 50 with all three is about right on the nose.

As you were. :)
Click to expand...

That's right, sounds like total with vacuum is fine. What is not fine, is WOT mechanical, which if he stated figures correctly is (likely) way over advanced
 
67Dart273 said:
That's right, sounds like total with vacuum is fine. What is not fine, is WOT mechanical, which if he stated figures correctly is (likely) way over advanced
Click to expand...

Exactly.
Gotta limit that puppy or settle for a less than optimum initial advance.
 
One thing bothers me.The OP states 318 heads onto 360 block. If i recall, 318s have smaller chambers than 360s. The c/r could be anywhere from 7.5 to 11ish depending on the combination of parts selected. This could throw a real curveball into the pot. The A/T might be the saving factor. Otherwise,in my experience,very good advice here. I have been running 13/34/58ish on my 360Eddy combo, for 14 years&125000 miles
 
AJ/FormS said:
One thing bothers me.The OP states 318 heads onto 360 block. If i recall, 318s have smaller chambers than 360s. The c/r could be anywhere from 7.5 to 11ish depending on the combination of parts selected. This could throw a real curveball into the pot. The A/T might be the saving factor. Otherwise,in my experience,very good advice here. I have been running 13/34/58ish on my 360Eddy combo, for 14 years&125000 miles
Click to expand...

I missed that for some reason about the heads.
A ratio to go on could matter quite a bit.
 
Not uncommon for it to be up around 60 including vacuum advance. Perfectly normal.
 
if it is running great and you are not detonating or "pinging" why mess with it. if it aint broke , don't try and fix it. you just might screw up a good thing.
 
You must log in or register to reply here.
-

Back
Top