318 Idle Questions

Just joined and really happy to see that there is a wealth of info here.

My '68 Satellite 318 (no upgrades) has been giving me a crappy idle, but it's great at speed.

I hooked up my tach and have been trying to dial in the idle to 600 and then optimize the mixture. The mixture adjustments I have made haven't had consistent results. I figure this is because of the vacuum advance was still connected as I fiddled.

So I disconnected the vac advance hose. The RPMS drop to 250. No amount of idle adjustment will bring the RPMs back to 600. I have to pull the throttle 1/4 to 1/2 inch to get it up to 400.

I'm thinking I need to adjust timing before I am able to dial in the carb accurately. What do you think?

With the vac advance disconnected, I only have a limited amount of time before the car stalls and I can't start it again until it sits for a few hours.

(There are a lot of problems here, I'm sure, but I want to take it one step at a time)

Thanks for the advice.

check for vacume leaks.

Yes. Definately sure up initial & total timing then tune the carb. If you have a high duration cam its gonna want more initial. Start at 10* and keep advancing if the RPM's keep picking up. I'm guessing with a stock cam you'd be at about 12-14* initial.

Awesome, thanks everyone. I'm pretty sure there is going to be some sort of vacuum leak somewhere, probably in the carb gaskets. The idle screws twist out pretty far while still giving some benefit to idle. But I think that will be phase two of this process.

It's good to hear that the RPM should potentially be able to reach 1200 with the vacuum disconnected and using just the idle screw. I was concerned, for a moment, that I was trying to adjust to something that wasn't even possible.

As far as my timing, the spec sheet I found says 2.5 ATC. I think, though, that I'm going to advance the timing to the point of pinging and then back it off. Or would 2.5 ATC be better? I found the info here: http://www.tpocr.com/dodge1.html

Like he said "12-14 initial. (Not 2.5)

Try that and a 900rpm idle.

Great, will report back tomorrow.

OK, so this is a question that is going to be painfully obvious once answered. On a 318 distributor, which screw loosens it so I can adjust the timing? I tried 4 different screws all along the circumference just below where the cap sits. None of them seemed to loosen up the action to allow me to adjust.

What am I missing?

wow , don't loosen anything on the distributor itself, those screws retain the pick-up plate. you need to loosen the distributor hold down that is bolted to the engine block just below the distributor, its a 1/2 inch bolt

Disconnect the Vac Advance before you mess with the timing and always in this order.

1) Timing First
2) Then the carb.

That would explain the problem. I didn't hurt anything by loosening and then tightening those plate screws did I? I did all that with the engine off.

I do feel like an idiot, but I'm really determined to fix this thing myself finally. As always, I appreciate the feedback. I'll report back again tomorrow.

I also located my intake manifold vacuum leak. Will discuss that more when this timing is dialed in properly.

Keep in mind that the timing is supposed to be BTDC, not ATDC as you mentioned.....

68 no upgrades would have mechanical points. Loosening screws inside may have changed the point gap.
Some of the original tuning specs were quite strange ( like 0 +/- 10 ). Anyway.. none of those really apply with todays lower octane fuels.
The vacuum advance should have been attached at venturi or timed port so shouldn't make a huge difference whether it hooked up or not a very low idle. That is unless the advance plate is simply worn out , in which case the advance could close the point gap completely when the vacuum hose is disconnected.
I suspect everything about an original 68 points distributer is worn out.

videoword said:

Awesome, thanks everyone. I'm pretty sure there is going to be some sort of vacuum leak somewhere, probably in the carb gaskets. The idle screws twist out pretty far while still giving some benefit to idle. But I think that will be phase two of this process.

It's good to hear that the RPM should potentially be able to reach 1200 with the vacuum disconnected and using just the idle screw. I was concerned, for a moment, that I was trying to adjust to something that wasn't even possible.

As far as my timing, the spec sheet I found says 2.5 ATC. I think, though, that I'm going to advance the timing to the point of pinging and then back it off. Or would 2.5 ATC be better? I found the info here: http://www.tpocr.com/dodge1.html

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No you don't want to do that. Also as mentioned in the post above, You want the timing set BTDC--- Before Top Dead Center..... Not ATDC.

I would start in the 15* Range and go from there. You want to check your Mechanical all in too and see what that is. So after you get the initial set. Revv up the engine with your free hand and see where it stops advancing on the timing light at the balancer. You may need to adjust how far the mechanical advances too.

15*....................You have to be careful here. Some of the smog era stuff INDEED was spec'd at ATC instead of BTC

THE PROBLEM with simply twisting the dist. around to a great big initial figure is that these smog era distributors typically have a very loooooooonnnngggg and sllllllooooowwwww advance curve, and you could very well end up being OVER advanced "at the top end."

The only REAL solution is to either replace the dist. with a performance aftermarket one or to recurve the one you have.

You can cheat "some" but be careful.

True that on the long advance curve.
Wherever you end up setting it at you want to know the total all in number without the VAC Advance hooked up........ Like stated earlier you may need to re curve the distributor after you find out what the motor likes.

OK, so I started messing with the timing today. I found the faint timing marker and brightened it up a bit. I as able to see it at high idle with the vac advance attached coming in around 10-15*B. After disconnecting the vac advance the timing line disappears completely. I've got no idea where it is or what the timing might be.

I started turning the distributor, first clockwise - which seemed to retard the timing - then counter - to try and get the mark into view. I turned the dizzy until the engine started to struggle going each direction, and never saw the mark come back into range.

I don't know what that means.

At higher idle with the vac connected I was able to see the line, but it wasn't totally consistent. Like I said earlier, it woud range between 10-15 jumping around here and there. The timing light, also, would miss occasional flashes (this happened more at idle, but happened occasionally at higher rpm). I take it that means there is some issue with the signal going to plug 1.

I took the distributor cap off to take a look at what is going on in there. Everything looks OK as far as I can tell except the top metal piece on the rotor looks slightly bent. It isn't flat, it hits at a slant. If that is abnormal let me know.

I have an brand new electronic ignition waiting to be installed. Do you think this would help alleviate some of the headache to put that in now? I was telling myself that I would get things dialed in properly the way they are and then put the electronic one in, but perhaps the replacement could be part of a solution.

Thanks again. I anticipate bad news.

That really sounds like it jumped time because of a sloppy timing chain.
It is also possible that the balancer ring has moved, but usually when the timing mark jumps around it's the timing chain.

You can get it close if the balancer has moved by getting the number one cylinder to TDC and making a new zero mark, then set the timing again using the new marks.
If I remember right, every quarter inch on the balancer is 5 degrees.

Search hillbilly timing tape and mark your balancer at 15 and 30* BTDC. That should give you marks to see wherever you end up on initial and total.

I'd turn the idle up a bit.

TrailBeast said:

That really sounds like it jumped time because of a sloppy timing chain.
It is also possible that the balancer ring has moved, but usually when the timing mark jumps around it's the timing chain.

You can get it close if the balancer has moved by getting the number one cylinder to TDC and making a new zero mark, then set the timing again using the new marks.
If I remember right, every quarter inch on the balancer is 5 degrees.

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I think this is what I'm going to have to do for now. It's weird because when it is at 1600 and idling with the vac advance, the mark is visible around 10-15. If I rev it, it does get to what looks to be 30ish. Which seems accurate? Or with the vac advance should it be significantly more?

Is there an easy way to find TDC without turning the actual crank with a socket? Can it be done by turning the engine by key?

videoword said:

I think this is what I'm going to have to do for now. It's weird because when it is at 1600 and idling with the vac advance, the mark is visible around 10-15. If I rev it, it does get to what looks to be 30ish. Which seems accurate? Or with the vac advance should it be significantly more?

Is there an easy way to find TDC without turning the actual crank with a socket? Can it be done by turning the engine by key?

Click to expand...

If you have a standard fan you can usually turn the engine with it by pressing on the belt at the same time to get it to grab the pully better.
Other than that, you can bump it a little at a time by jumping the relay while you have a finger on the plug hole (or do what I do and stick a peice of rag in the hole.)
When it pops the rag out you are getting close to TDC.

So far what you are seeing on the timing light sounds pretty normal.
Are you sure this carb is ok, and that there is no intake leaks?

If you have a standard fan you can usually turn the engine with it by pressing on the belt at the same time to get it to grab the pully better.

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Nice! I'll give that a try.

There is a vacuum leak that I've located on the manifold.

So far what you are seeing on the timing light sounds pretty normal.

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There are some things that are concerning me about what I'm seeing with the timing light, one of which being that the light "misses" occasionally.

****This is identical to the conclusion of my other post - but I wanted to post it here as well in case some poor sap like me comes along looking for how the story ends*****

Thank you all for your help. I fixed it this morning.

I want to post this as a conclusion in case anyone else finds this thread in the future they will know how it wrapped up.

So after verifying TDC and making sure wire 1 corresponded closely with the direction the rotor was pointed, there was still no change in my ability to tune the car.

Adjusting the timing further advanced didn't seem to do anything meaningful either.

The more I tried to tune things, the worse the signal to my timing light would get and I noticed a lot of skipping in the flashes. I was trying to use the light as a diagnostic to see that each of the plugs was receiving signal, but the light was coming through so sporadically I couldn't tell where the problem was.

So I decided to do all new (and nicer) plugs and wires - to improve the signal before replacing the points with electric ones.

After doing this, the car ran slightly better - but idle was still rough and none of the major issues were resolved. The worn old plugs and crappy old wires were no longer a problem though.

I replaced the points with electric Pertronix ones, but then the car wouldn't start at all. I thought maybe the ballast resistor might be the problem, so I tried bypassing that with a hot-wire from the battery with still no response. I ordered the hotter coil also by Pertronix to match the new points. To my surprise the car started.

There was a mean knocking. I took a look at the signal coming from the timing light - it was steady as a drumbeat with no misses. I took a look at the timing mark even though the vac advance was still attached and the car was still not to temperature. It looked a bit too far advanced, even with those two elements still being in place, so I retarded it just a bit until it seemed to be in a reasonable range.

I let the car come to temperature. The idle did not drop to 250 when the choke let out. It stayed at about 1200. I dialed it down to 800. It was a significant distance to get it down to 800 actually. The idle setting before was definitely a crazy overcompensation for a bigger issue. After getting down to 800 rpm, I disconnected the vac advance and plugged the port. This time there was no change in engine performance - there was no longer any vacuum - the rpms did not drop to 250. I checked the timing - it was too far advanced after all the tinkering from the past week. I dialed it in to 12*B (I might tale it to 15-20 soon, it seemed to like it better a bit earlier, but I didn't want to push it at this point).

Then I dialed the rpms down to 700 and started to mess with the mixture. I got a steady reading from the tach while playing with my idle screws. I maximized the performance and dialed the idle back again.

I turned her off, turned her on. And had to literally pause and ask my girlfriend, "Is it on?" It wasn't shaking, wasn't making a bunch of noise. she runs like a charm.

Next up I'd like need to try to bypass the ballast resistor for some extra voltage - I tried building a bypass wire with 2 1/4" flat male leads (I don't remember what they were called) - crimped with a 10 gauge wire. I don't think the 1/4' were the right size. So I'm still running with the ballast.

Thanks again for all the help. I learned a ton. If any of you ever has a question about Avid or Final Cut (something I know a lot about), just send me a message!