Hello! Log in or Register   |  Help  |  Donate  |  Buy Shirts See all banner ads | Advertise on TheSamba.com  
TheSamba.com
 
TDC and ignition timing
Forum Index -> 411/412 Share: Facebook Twitter
Reply to topic
Print View
Quick sort: Show newest posts on top | Show oldest posts on top View previous topic :: View next topic  
Author Message
Shlomi32
Samba Member


Joined: April 05, 2013
Posts: 118
Location: Israel
Shlomi32 is offline 

PostPosted: Sun Jul 10, 2016 1:33 pm    Post subject: TDC and ignition timing Reply with quote

I just bought an automatic 71 411 and I can't figure out how to adjust the ignition timing and how to locate the TDC to adjust the valves.

I looked at many videos at YouTube but the type 4 engines at them are different. It's seemed like type 4 engine on the 70's buses are little bit different from the 411 type4 engine.

Am I right?
Back to top
View user's profile Send private message Gallery Classifieds Feedback
raygreenwood
Samba Member


Joined: November 24, 2008
Posts: 21475
Location: Oklahoma City
raygreenwood is offline 

PostPosted: Sun Jul 10, 2016 1:42 pm    Post subject: Re: TDC and ignition timing Reply with quote

Yes....just sent you a PM. Why eont you copy my reply to you here so everyone can read it please.

Also....is it still fuel injected? If not you need to tell us what distributor it has....and also if you know anything else about the engine. Ray
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
Shlomi32
Samba Member


Joined: April 05, 2013
Posts: 118
Location: Israel
Shlomi32 is offline 

PostPosted: Sun Jul 10, 2016 1:57 pm    Post subject: Re: TDC and ignition timing Reply with quote

Thanks! Its really helped!

I just got the Haynes book and it just bad.
Again.. Thank you



OK....first things first. You need to carefully adjust the ignition point gap to .016".

If you have a dwell meter.....it is good to use that. In reality the .016" gap is close but approximate. You need to set the gap....start the car......adjust the idle speed to normal. Disconnect the vacuum hose from the vacuum advance unit on the distributor.

If the dwell reading is within the correct range....you are done with that. If it is too far out of spec from the book reading...stop....readjust point gap smaller of larger as needed to get the dwell reading correct.
Typically this will be in the range of .015" to .017". When done...correctly set idle speed.

Now.....on the 411 and 412.....on the cooling manifold shroud will be a black plastic plug about 30mm in diameter. It is directly over the cooling fan. Remove that.

If you turn the engine over by hand.....use the fanbelt to do this......while looking down that hole with a light....you will see a "V" shaped notch in the side of the housing toward the front of the car....about 12:00 to where you are standing. That is where the timing marks appear.

There are several different fans woth different timing marks. If yours still has the normal 411/412 fan.....from 1968 to 1973.....there are generally two marks on the fan....a stamped "0" for TDC....and about four fins to the right of the "0" is a red or black mark that represents 27° before top dead center.

Once you know you have these marks....connect a timing light to #1 spark plug. You can carefully connect the positive clip from the timing light to the + side of the coil and the negative to a spot on the engine case. Make sure they are correct and secure.

Disconnect the vacuum line from the vacuum advance unit. Its nice to have a tachometer to connect to the coil.....start the car......rev it to 3500 rpm and hold it steady. The red mark should stay steady in the "V" shaped notch.
The timing spec is 27° BTDC at 3500 rpm. If its off.....loosen the distributor clamp and adjust.
It must be spot on. Its important because the distributor position also adjusts the fuel injection timing......so the advance and the engine speed needs to be within about 100 rpm of correct when you set ignition timing.

When that is done......with engine off...remove the distributor cap. Leave the rotor on. If the distributor drive is installed correctly......the vacuum advance unit should be at about 2-3 oclock position and there should be a line of punch mark on the rim of the distributor at about the 5 oclock position. That mark is for number cylinder.

So using the fan belt.....turn the engine around so that the rotor points to the #1 mark on the distributor......and look into the timing hole at the fan.....turn until the "0" is centered in the "V" notch.
With the 0 in the notch and the distributor rotor pointing at the line on the distributor body.....you are at TDC for #1 cylinder.
Verify this by taking off the valve cover and making sure that both valves in #1 are even and at the top of their arc. Unless the valves are really tight you whould be able to rattle both of them slightly. This is where you adjust them.

The easiest way to do these.....really....is before you start....turn the engine around by hand and .count the # of fan blades and support posts. There are four quadrants on the fan with an equal number of blades in each quadrant.

So count the exact number of blades and spaces to be able to make a Sharpie marker mark....exactly 180° from the "0".....in the "V" notch.

After doing this.....once you have adjusted the valves on #1 cylinder.....turn the engine with the fan belt by hand.....in reverse.....so the distributor rotor is turning counter clockwise.

Watch through the riming hole unfil the 180° mark is centered in the "V" notch.....then look at the distributor rotor and you will see it has rotated coujter clockwise by exactly 90°. This is TDC for cylinder #2. You can now adjust both valves on #2..

Then turning the engine in reverse again...until the "0" is centered in the "V" notch....you will see the rotor has now moved 180° from where it was in cylindef #1. This is TDC for #3.....and you can adjust both valves.

Turning in reverse one more time until the 180° sharpie mark is once again centered in the "V" notch.....and the rotor has moved counter clockwise a further 90°.....this is TDC for #4 and you can adjust both valves.
Ray
Back to top
View user's profile Send private message Gallery Classifieds Feedback
raygreenwood
Samba Member


Joined: November 24, 2008
Posts: 21475
Location: Oklahoma City
raygreenwood is offline 

PostPosted: Sun Jul 10, 2016 3:51 pm    Post subject: Re: TDC and ignition timing Reply with quote

What I also find that really helps is to take the time too mark your fan if its not already marked.

Image may have been reduced in size. Click image to view fullscreen.


This is a standard 411/ 412 D-jet injected 1.7L fan.

It has a "0" stamped in it from the factory...and a red mark to the right of teh "0" which is 27 BTDC.

The other marks I have on this fan are:

5* BTDC just to the right of "0"....which I use for static timing with a teet lamp if needed.

I will be adding a mark at 12* BTDC. This is where I find that highly tuned D-jet runs the best for idle timing.

The mark to the right of the red 27* BTDC mark is 30* BTDC. I use this as a reference. When i time with vacuum disconnected at 3500 rpm.....you will find that at high rpm and low throttle opening...like rounding a curve at 60 mph downshifted into third with the throttle at 1/4 open....you pick up some vacuum advance again.

Hitting about 30* BTDC at part throttle at 3500 rpm is what I consider normal.

You will notice that I have added red dash marks down the middle of the two fan support stanchions. These are approximately where another fan blade would be. So this essentially makes each 90* quadrant...12 blades each. Ten real blades and two equivalent spaces.
That makes each blade 7.5* .

Image may have been reduced in size. Click image to view fullscreen.


Aso....to GREATLY aid valve adjustment. I have made a mark at 180*....directly across the fan from the "0". This way when you are setting valves.....you set #1 on the "0"...#2 on the 180*...#3 on the "0"...and #4 on the 180*.
Ray
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
Shlomi32
Samba Member


Joined: April 05, 2013
Posts: 118
Location: Israel
Shlomi32 is offline 

PostPosted: Sun Jul 10, 2016 10:42 pm    Post subject: Re: TDC and ignition timing Reply with quote

My engine is 1.7 with 2 carburator and automatic transmition.
Are the marks the same?
Back to top
View user's profile Send private message Gallery Classifieds Feedback
raygreenwood
Samba Member


Joined: November 24, 2008
Posts: 21475
Location: Oklahoma City
raygreenwood is offline 

PostPosted: Mon Jul 11, 2016 12:00 am    Post subject: Re: TDC and ignition timing Reply with quote

Shlomi32 wrote:
My engine is 1.7 with 2 carburator and automatic transmition.
Are the marks the same?


What year....and is this a 411? If these are factory carbs, distributor and cam......yours should be set....with vacuum hose disconnected from the advance unit (if you have one).....at 32° BTDC at 3500 rpm.

The books I have state to time it to the red mark at 3500 rpm usijg a strobe.

What I do not know is if you have a different factory fan where your red mark is at 32° BTDC instead of 27°BTDC. But looking at my fan pictures. ...you can see where 27° is. If your res mark is 5° to the right then its at 32. Ray
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
Display posts from previous:   
Reply to topic    Forum Index -> 411/412 All times are Mountain Standard Time/Pacific Daylight Savings Time
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum

About | Help! | Advertise | Donate | Premium Membership | Privacy/Terms of Use | Contact Us | Site Map
Copyright © 1996-2023, Everett Barnes. All Rights Reserved.
Not affiliated with or sponsored by Volkswagen of America | Forum powered by phpBB
Links to eBay or other vendor sites may be affiliate links where the site receives compensation.