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ichthos
08-02-2007, 10:39 AM
Hello,

Thanks to everyone's help, I adjusted my valves and my car is able to idle without my having to pull out the choke at stop signs (I still do not understand how the valves effected my idle speed so much.)I know I still need to bring the idle speed down and work on the timing. I set the points to .015", and used static timing (12 degrees BTDC) to adjust the timing. When I am driving down the freeway, my engine seems to miss occasionally. I am going to try and use a timing light to see if I can do any better. I am confused by the two books I have (Haynes and Bentley) and the current discussion concerning timing. I have a bunch of questions. It looks like the idle speed should be around 850 rpm. According to my Bentley manual, a vacuum line on the distributer is disconnected. Do I just pull off both vacuum lines from to the distributer? I am also confused by all the different settings for the timing - what is the correct setting for timing? My best guess would be 10 degress BTDC since it is closest to the static setting.(I don't know if this is just me, but do not understand why this is so difficult to find in my book.) If the idle speed is high, won't this throw off the timing? How would I compensate for the timing if my idle is too high? Any help would be appreciated. Thanks,
Kevin

TR3driver
08-02-2007, 12:40 PM
The procedure given in the books is incorrect for US-spec cars with the vacuum retard. There is supposed to be a plate under the hood with the correct information, but of course it's usually missing.

The 'proper' method is to disconnect only the advance line and time to the "dynamic" or "idle" value of 4 ATDC (assuming your vacuum retard works). The retarded timing plays a big part in idle rpm ... if you don't have 4 ATDC then you can expect the idle to be high.

High idle speed can definitely affect dynamic timing. Probably the best way to compensate (if you can't get the idle down) is to time the engine statically until you can fix the idle.

tomshobby
08-02-2007, 04:26 PM
This is from my '76 but is probably close.

https://smithtr6.com/images/forum_pics/timing.jpg

ichthos
08-03-2007, 10:17 AM
Thanks for the help. Yes, the sticker is missing. I can see where it was peeled off or fell off on the driver side of the bonnet. The sticker sure makes things a lot more clear.
The one thing I am not clear on is the vacuum retard. How do I know if it works?
Kevin

Tinster
08-03-2007, 10:28 AM
Not to be asking another stupid question but...

What does it mean the difference between

idle speed 800 rpm

and

fast idle speed (hot) 1600 rpm

A cold engine runs at 800 rpm and warmed up engine
runs at 1600 rpm?

I'm kinda confused on this one.

thanks,

d

RomanH
08-03-2007, 10:54 AM
What does it mean the difference between idle speed 800 rpm and fast idle speed (hot) 1600 rpm A cold engine runs at 800 rpm and warmed up engine
runs at 1600 rpm?
d

The spec for 1600 RPM (HOT) is for setting the high speed idle when the engine is hot. A warmed up engine should run at 800 RPM with the choke off and 1600 RPM with it on.

TR3driver
08-03-2007, 11:15 AM
The one thing I am not clear on is the vacuum retard. How do I know if it works?
Easy check is to disconnect it with the engine idling. If it was working, you will hear a large increase in idle rpm.
You can also double-check it's action with a timing light : with the retard disconnected, the timing should move to the "static" value of 10-12 BTDC (or a bit beyond due to the centrifugal advance coming into play at the higher rpm).

Tinster
08-03-2007, 11:43 AM
I am still a little confused.

My distributor has two "ears". Each of my carbs
has a skinny pipe going to a separate ear on the dizzy.

How can I know which pipe is for advance the spark and
which pipe is for retarding the spark?

I took both pipes off and set my timing light on 12.
I rotated the dizzy until the engine wheel marks lined up.
My plugs are gapped at .025"

The car seems to run OK after this procedure.

Do I have a mess for my timing or did I luck out
and it's OK?

thanks,

d

TR3driver
08-03-2007, 12:07 PM
That's fine, Dale.

I've got a nice diagram showing which pipe is which, but unfortunately not on this computer. If I remember (remind me ?) I'll post it on Monday.

At idle, the advance pipe does nothing; while connecting the retard will retard the timing and slow the idle considerably (like 400 rpm or more).

RonMacPherson
08-03-2007, 12:14 PM
Dale,

two pots(vacuum chambers) mean one is advance and one is retard. The vacuum advance should be hooked up to a port on the carburetor where vacuum is not present at idle, but does develop as the throttle is opened.

The vacuum retard is hooked up to a port where vacuum is present at idle, but dissipates when throttle opened.

The sure fire way to set timing, so that you have no detonation, preignition problems; maximum advance should be no more than 32-34 degrees at 3500 rpm. Checked with an advancing timing light, or marking your crank dampener pulley and lining the marks up.

Then your idle timing will result from this. Usually around 12 btd with out vacuum lines hooked up, which should drop to around 4 atdc with the vacuum retard line installed.

This is dependent on the mechanical vacuum advance weights, springs being clean, lubed and not worn out.

How to tell which is advance and retard? Pull of the distributor cap, see which way the distributor turns as it fires, then apply vacuum to either one of the chambers, the one that turns the backing plate in the direction of rotation is the retard chamber.

ichthos
08-03-2007, 08:15 PM
More questions. I static timed my engine to 12 degrees BTDC. I lowered the idle down to between 850 and 900 (I accidentally turned the idle trim screws - what do they do? How do I adust them? now that I have messed them up?) Now when I rev the engine, when it drops back down it drops very low - down to 500 or just dies. I decided to use a timing light just to see how close it was. Not even close (the 4 degree mark was off to the right side of the car.) It doesn't seem to make a difference if I pull the vacuum line from the advance vacuum (left side as I am facing distributer) or the retard vacuum (right side as I am facing the distributer.) Any ideas on what is wrong or what I am doing wrong? Any suggestions would greatly be appreciated.
Kevin

AltaKnight
08-03-2007, 10:39 PM
Dale.....
Use the advice above to make sure you have the correct distributor "ear" connected with the correct vacuum hose.
If you know who got that reversed it would sure screw up the way the car behaves.

AltaKnight
08-03-2007, 10:47 PM
Kevin.....
The vac advance won't make much/any difference at idle since it's vacuum is applied only as the throttles open.

The vac retard as you pull it off should affect the timing (as you view it on a strobe) and will change the idle speed a lot when at idle because it's vacuum is high at idle and drops off as the throttle opens.

If the retard makes no change then you've got a leak or a malfunction on the retard unit. You can live without the retard unit but the car will operate better with the advance working.

RonMacPherson
08-04-2007, 02:47 AM
Basic setting on the idle trim screws should be appx 1 1/2 turns from closed. Gently turn the screw in till it seats, but don't force it. Then back it out one and a half full revolutions. This will give you a starting point. These screws control the amount of gas admitted into the idle circuit of the carburetor.