Hey there fellas! Couple of 318 timing questions.

[8v-of-fury]

I am in the midst of finding the proper tune for this 850 TQ and electronic ignition swap to my old 88 5th Avenue.

It has been swapped a little over a year and maybe had about 2000kms put on it since.

The thing is, to time it to where it gets best and steady vacuum at idle it is up near 15* (or more) BTDC. With the vacuum unhooked and driving it, the minute you put load and throttle on she sounds like a diesel under the hood.

I feel like I hAve too much mechanical advance in the dizzy. ? Or is it ok to be static timed anywhere it makes more than 20 in.hg?

 

[Aspen500]

If it's a stock dizzy, running 15 initial will give you too much total mechanical advance. A rough way to estimate is subtract the stock timing spec (stock for the car the dizzy came from) from 15 and then take that amount out of the mechanical. For example, if the stock timing is 5 BTDC you need 10 less total, which actually translates to 5 degrees less in the distributor. One of slots needs to be shortened and right off hand I can't remember how much slot equals how much advance. I've got it written down somewhere here, if I find it I'll post it.
It can be trial and error to find the optimal total mechanical advance. Had my dizzy out and apart half a dozen times changing slot length and springs before I hit on the best performance and drivability but no detonation. Every engine is different and also depends on what car it's in (weight, gearing, cam, etc).

One other thing too, don't overlook carb calibration. Without a wide band A/F gauge it's a crap shoot (gauge HIGHLY recommended) but,,,,,,,,,if the carb is too lean (on TQ, jetting, metering rods, metering rod spring.........) you'll get detonation/ping. Ignition and fuel have to work together. Either one off and it's all screwed up. Wish there was a good way to know which! LOL Using the A/F gauge in my car I've probably got more hours than I care to remember doing carb and ignition calibration. Changing ignition calibration affects carb calibration and vice-versa. Once all that's dialed in, THEN hook up the vac advance and adjust it (if it's an adjustable one of course) to give the best economy without causing a surge at cruise. Put it this way, I started out with an average mpg of 7-8 and ended up with more power, WAY better drivability and an average of 12-14 mpg (depending on the weight of my right foot, lol)

 

[Cordoba1]

I was going to reply, but my answer would not have been nearly as complete as Aspen500's!

 

[Aspen500]

Well I did sort of go overboard just a tad, lol!

 

[gtsdude]

Here is one I found on the net, should get you close.

 

[Aspen500]

That's the chart I was looking for! Still no idea what happened to it......................................

If you don't have one, get a digital caliper. Even the $20 ones at Harbor Freight are accurate to within .001"
After taking the dizzy apart (and swearing many times with that tiny, frustrating little circlip that hold the plate to the shaft.....at least with my 50 year old eyes, lol) use a MIG welder and add just a hair of material. Then use a small, square file to clean it up and get to the size you need. If you knew all of that already, never mind!

 

[8v-of-fury]

So I got myself a fancy dancy digital timing light. It is pretty effin awesome. It is actually the shit. Built in Tachometer, and adjustable timing 90* either way of 0. $149 at Canadian Tire.

I found out, that with the base timing of 7-8* BTDC and the vacuum line plugged in... I was getting roughly 46* total by about 2500. TOO MUCH. So I unplugged the vacuum advance (as the mechanical comes on fast in this dizzy) and I have 30* total all in by 2750-3000. How do you feel about that? I think I will modify the dizzy next time I am home (3 weeks) so that I can run a higher base timing as the idle and startup was DAMN NICE with it timed to about 12-13*.

When do you want all in to happen? and how much total is safe on a stock 4bbl 318?

 

[8v-of-fury]

Dear sirs, any input?

 

[Joe12459]

I usually try to keep it around 35 or 36 degrees mechanical advance at around 2600 RPM. The vacuum advance should be set to bring it up to around 50 degrees. This is a good place to start, then tweak it for your setup.

 

[8v-of-fury]

I usually try to keep it around 35 or 36 degrees mechanical advance at around 2600 RPM. The vacuum advance should be set to bring it up to around 50 degrees. This is a good place to start, then tweak it for your setup.

Well then it is perfect, 'cause that is what is happening. However, I have the vacuum advance disabled right now (unplugged) as with it functional I do get up to 46-47 degrees which is fine in park.. sounds great, revs nice.

In gear she is a different beast however. Cruising no load, minimal throttle the initial throttle provides GREAT response. Stay in it and she starts pinging like a cummins under the hood. From what I read up there, perhaps I am WAY too lean on my idle circuit? maybe the primary rod/spring on the TQ needs to be richened. I guess the next mod is a wideband A/F meter I'm excited. lol

So it would seem though, my timing is damn near dialed in perfectly. It is all down to fueling at this point.

 

[Aspen500]

You should have no vacuum advance at idle. The advance hose hooks to ported vacuum, not manifold, so it only works at part throttle cruise using a vacuum signal from above the throttle plates.

Honestly, I wouldn't mess with the carb calibration too much until you can get a wideband gauge installed. Without it, it's all a crap shoot because changing the idle mixture will affect the part throttle/cruise mixture because at that point you are running off both the idle circuit and the part throttle circuit. That will of course, affect the WOT mixture. See where I'm going with this?

Think I mentioned this somewhere before but here goes again. I'd recommend an AEM brand gauge. It's one of the lower priced setups but also one of the best. Only downside is the installation instructions are written more for the experienced professional person but I'm sure you can figure it out.

This one: http://www.summitracing.com/parts/avm-30-4110/overview/

 

[8v-of-fury]

Sorry, I don't see where you got that from I do not have any vacuum advance at idle. It is from a ported source which is on the front drivers side of the carb. Just off idle there is full vacuum.

Yes, I agree I definitely need a wide-band for sure. How anyone ever tunes without one is ludicrous..

 

[kkritsilas]

Cars were tuned just fine prior to wide band AFMs. It was done all the time, in fact, most of the muscle car era didn't have wideband AFM meters, or AFM meters of any type. It was not only possible, but at one time, a very common occurance.

 

[8v-of-fury]

The ones that had the luxury of plucking their engines and sticking them on a dyno, or taking the car to a dyno several times.. yeah I'll agree with that! LOL

Everything else seems like it was just a game of roulette! LOL.

I'm not saying PRO TUNERS can't tune an engine by sound and feel.. but what would that be %5 of the tuner population? the rest people who don't know a damn like myself when it comes to a carb.

 

[kkritsilas]

The ones that had the luxury of plucking their engines and sticking them on a dyno, or taking the car to a dyno several times.. yeah I'll agree with that! LOL

Everything else seems like it was just a game of roulette! LOL.

I'm not saying PRO TUNERS can't tune an engine by sound and feel.. but what would that be %5 of the tuner population? the rest people who don't know a damn like myself when it comes to a carb.

There were no tuners back then, just mechanics. A lot more than 5% of then could get a car in decent tune. As time has gone on, and with the diicontinuation of carbs now going past 25 years, most of that has been lost, and with that loss, went the people who understood and could teach younger guys how to do this. They didn't pull engines out in order to tune them, nor did they strap them to dynos (as if there were a lot of dynos around back then). It was tune as best you could, and for muscle cars, a trip down the old 1/4 mile. On the other hand, there were a lot more local/mom&pop drag strips back then, too.

Most of the tune ups were with timing lights and sound/feel. And a lot of feel by the mechanics. Good ones would get stuff pretty much perfect, the lesser ones would just get a decent tune that was usable in day to day driving.

And, I am not criticizing; I don't know how to tune a carb'd car either. It's just that we. as a newer generation seem to think that there is only the current way of doing things. Our current day methods, as good as they are, may or may not be the best way. I had a similar discussion at work when talking with a co-worker about buying a new car. One other co-worker said that she needed all wheel drive, traction control, ABS, brake assist and stability control. I pointed out that cars had existed in the past without any of this stuff, and people seemed to be able to get around fine without all of that, even in the winter.

 

[Aspen500]

I didn't mean to imply you can't tune a carb using "seat of the pants", you certainly can and it will be fine. However, with an A/F gauge you can tune it even closer to ideal and in a whole lot less time. I figure the fewer times you have to pull the carb off to change jets or idle air bleeds, etc.... the better. I had mine calibrated to where it felt good and seemed just fine. Once I put the gauge on, discovered it wasn't even close. If the technology is there, and priced so the average guy can afford it, why not use it? I'd love to have EFI on my car which takes all the tuning variables out and added bonus will change it's "tune" for the weather and altitude automatically which equates to better mpg's. With cars like a lot of ours, even gaining 1 mpg avg is nice! Why don't I have it? Price.

Guess I misread your post 8V. When you said with the vacuum advance hooked up you get 46-47 degrees which is fine in park.........I took that to mean idling in park, with the advance hooked up you had that much advance which now that I think about it, wouldn't even be possible! My bad.

On a side note: Even on an engine dyno you can't get the tune perfect. Well, it may be perfect on the dyno but stick it in a car and the cars weight, gearing, trans, underhood heat, etc changes everything. Basically you can get a good baseline tune on a dyno. The fine tuning can only be done in the car the engine is going to live with.

 

[compubert]

Well then it is perfect, 'cause that is what is happening. However, I have the vacuum advance disabled right now (unplugged) as with it functional I do get up to 46-47 degrees which is fine in park.. sounds great, revs nice.

In gear she is a different beast however. Cruising no load, minimal throttle the initial throttle provides GREAT response. Stay in it and she starts pinging like a cummins under the hood. From what I read up there, perhaps I am WAY too lean on my idle circuit? maybe the primary rod/spring on the TQ needs to be richened. I guess the next mod is a wideband A/F meter I'm excited. lol

So it would seem though, my timing is damn near dialed in perfectly. It is all down to fueling at this point.

Hey 8v, you didnt mention if you were running high octane fuel or regular. Friend got a beautiful 69 GTO and popped the crown on three pistons running regular... be careful..

 

[compubert]

There were no tuners back then, just mechanics. A lot more than 5% of then could get a car in decent tune. As time has gone on, and with the diicontinuation of carbs now going past 25 years, most of that has been lost, and with that loss, went the people who understood and could teach younger guys how to do this. They didn't pull engines out in order to tune them, nor did they strap them to dynos (as if there were a lot of dynos around back then). It was tune as best you could, and for muscle cars, a trip down the old 1/4 mile. On the other hand, there were a lot more local/mom&pop drag strips back then, too.

Most of the tune ups were with timing lights and sound/feel. And a lot of feel by the mechanics. Good ones would get stuff pretty much perfect, the lesser ones would just get a decent tune that was usable in day to day driving.

And, I am not criticizing; I don't know how to tune a carb'd car either. It's just that we. as a newer generation seem to think that there is only the current way of doing things. Our current day methods, as good as they are, may or may not be the best way. I had a similar discussion at work when talking with a co-worker about buying a new car. One other co-worker said that she needed all wheel drive, traction control, ABS, brake assist and stability control. I pointed out that cars had existed in the past without any of this stuff, and people seemed to be able to get around fine without all of that, even in the winter.

Try this for SAD, the Dodge/Ram place in DeLand, told me they didn't have any mechanics staffed that could adjust my valves for me. Apparently all the guys there only run the computer to "tune" an engine....

 

[Aspen500]

If all their tech's were born long after our cars were built, they never really had any reason to learn valve adjustment (or carbs, or distributor ignition, etc). By the time a dealer tech gets to a certain age, they get smart and GTFO of dealer service and go to an independent (like I did). We get lots of older vehicles in because the word is we have a shop staffed with "old guys" lol. Actually, the average age in the shop is 53 and still know how to adjust valves, build barbs, replace points, do drum brakes..........................

 

[80mirada]

I have been doing all of that "old guy stuff" since I was 16, oh poop, that was 24 years ago.............I will make sure my kids can do those things.