point n spark gap

[mixer911]

Hello ,does any know the proper gaps for a 1974 2.7 carrera
I keep getting conflicting gaps ..from different sources..
For points Ive read...012 and .016
for sparkplugs Ive read .022 and .028 to .032
Thankyou in advance..

[Bob Kontak]

It is pretty confusing. Depends on your distributor and the the plug you use. I will give you what I see in the US factory manual for Carerra 2.7 from 1973 model.

Distributor
Bosch 023 116 9011
Marelli 610 15 155

Point gap (mm) 0.35

Dwell angle
Bosch 38 +- 3 degrees
Marelli (same tolerance)

Spark plug gap in mm

Bosch W265 P 21 = 0.55mm
Bosch W260 T20 = 0.7mm
Beru 265/14/3P - 0.55mm
Beru 260/14/3 = 0.7mm

Use this to convert.

Length conversion - Online length converter - Distance & height converter - Length unit measurement -

Sorry - I don't know what this means for modern day plugs.

[mixer911]

I do have a metric gauge (gapper)
...I better check my distributor...

[Bob Kontak]

Just use the converter link and you can plug in the mm and english measurement will spit out.

[T77911S]

i have never used a gage on my points. eyeball it. make sure it closes and opens.

plugs, go for the wider setting unless they foul. i have opened mine to as much as 065 just to see what would happen, i think i settled for around 045.

[Bob Kontak]

Edit - I did not see that T77911S posted the above link. I thought it was mixer when I wrote this.

You should get a dwell meter to set the dwell angle. It's pretty easy and a dwell meter is $40.

You should also check the gap with feeler gauges and see that it is at the recommended setting when the dwell is correct - just to be sure you don't have some odd thing that is wrong (like the wrong points).

After the points are happy, re-set the car's timing.

Plenty of info on Google to read. I did see where dwell angle is not as critical on a 4 & 6 cyl engine as on an 8 cyl because there are less openings and closings across a given time but your car can easily spin 6k so I really would take the time to read and at the very least get the .35mm feeler gauge in there.

Here is that converter I forgot to post before:

Millimeters to Inches (mm to inches) conversion calculator

Some light reading

Point Gap and Dwell - 1968 Ford Mustang - Car Talk

[Hugh R]

I'm old school with British trash, if you have points you need a dwell meter, gaping them isn't enough. It takes in the dynamics of the points and the wobble of the shaft. Proper electrical coil saturation is a must.

[mixer911]

I eyeballed the gap on the points...just to get it running as T77911S suggested
Gapped the plugs @ .028...
It seems its only running on 3 or 4 cylinders..
I do have a dwell meter ,now just need to learn how to use it(havent played with points for years)

I picked up a compression tester today..Just to make sure the valves arent stuck open
Its been sitting for 11 or 12 years.

Anybody have a good link for testing compression on a 74 911 carrera
Should I unplug the fuel pump?(it runs all the time)
Should I pull all plugs first..or one at a time?

[Bob Kontak]

Originally Posted by Hugh R

I'm old school with British trash

My pal has a 78 Esprit and dwell is supposed to be maybe 50 and it reads 78. I cannot convince him to reset the dwell as the distributor is parallel to the earth and deep underneath the side draft Dellorto setup. I think you need to pull the distributor to do it correctly. It is a bear and he will not even let me do it with him, let alone solo. Anyhoo - I will show him your post - stand alone - and maybe that will convince him.

Mixer - focus on plug wire location to see if they are in correct order. You distributor turns clockwise, I am pretty sure, 1-6-2-4-3-5.

Here is a link to read that should help. Pelican Technical Article: Setting 911 Distributor Static Timing

Keep in mind, I do not know your level of experience so if I spoon feed to much it's in good faith.

I will look to see if your car has an air sensor switch and then you can check to see if it is in place. If it is disconnected (assuming you have one), your fuel pump will run when the key is in the on position.

Also will check for compression testing threads.

Edit - Give me six hours with that car and a buffer and the value will increase $5k. Thanks for posting pic.

[dipso]

Points are points. They either open or they don't. If you are having problems with certain cylinders it is not the points. Points don't discriminate.

[Hugh R]

Originally Posted by Bob Kontak

My pal has a 78 Esprit and dwell is supposed to be maybe 50 and it reads 78. I cannot convince him to reset the dwell as the distributor is parallel to the earth and deep underneath the side draft Dellorto setup. I think you need to pull the distributor to do it correctly. It is a bear and he will not even let me do it with him, let alone solo. Anyhoo - I will show him your post - stand alone - and maybe that will convince him.

You can pull the distro and put it in a vice and hook a rubber flex line to a drill motor and hook up the dwell meter and get an approximation if its that hard to get at. To lower the dwell, open the points.

IIRC, its a four cyl. hence 50 dwell, he can't time the engine worth a crap with the dwell off that much. You set dwell first, then time the engine.

[mixer911]

Ill admit..I'm not great with ohm meters..or tact/dwell meters..I just haven't read up a lot yet (I own both)
Also Ive replace every tune up item but wires.but here where i lIve in Canada they want $450.00 for wires ..talked to our friends @ pelican..they will ship me a set of magnecor
for $200.00 but 7 days ground mail
To be honest I'm sure how much to put into the 911.. because I I'm not sure of Its value..I picked it up for $1000.00 and so far Ive spent another $400.00

Ive had a heart on for 911s ever since my parents were serving (Canadian air force) in Germany..Id watch them they owned the autobahn...police drove them (I was 10 in 74)

Thanks for the encouragement
please anyone chime in

[Bob Kontak]

Originally Posted by Hugh R

IIRC, its a four cyl. hence 50 dwell, he can't time the engine worth a crap with the dwell off that much. You set dwell first, then time the engine.

Oh sweet! This will convince him.

Timing is supposed to be 0 (at specified RPM) but best we can do is 10 BTC to make it run "normal". I did chat on Lotus forums and they said 10BTC sounds about right but that is not what the factory manual says.

Great info, Hugh R. Don't be angry if I leach off you in the future. :-)

[Eagledriver]

While dwell is important on cars with traditional non-CD ignition systems, it is unimportant in the car in question. All the points are doing in this car is sending a fire signal to the CD system. There is no effect on coil saturation since capacitors fire the coil. The points should be set close to the spec to ensure the points open an close reliably.

-Andy

[Bob Kontak]

Originally Posted by mixer911

(I was 10 in 74)

You ain't as young as you said. You are young middle aged.

I will buy that off you right now for $1,400. You got a long way to go before you are in trouble $$$ wise. Where at in Canada?

I did not know a thing about anything 15 years ago but I just started fiddling and searching the internet for solutions. Books are great but loading in a good search expression into Google is better for a quick solution.

For fun, if you have an ohm meter, draw a heavy lead pencil line on a piece of paper and measure the resistance from one end of the line to the other with the probes. That gives you an idea of the struggle it takes to for juice to get from one end to the other. Touch the probes together and you get no resistance - maybe some tiny bit of resistance that indicates your gauge is not calibrated perfectly. When you are testing circuits for proper ground, the reading needs to be the same as if you are touching the probes together. Essentially NO resistance should be indicated. Take the probes and touch one to something on the engine and then the other to the car body - say the bolts that hold the engine lid lock assy. No resistance should be indicated. Should be the same resistance as the two probes touching together.

[T77911S]

Originally Posted by dipso

Points are points. They either open or they don't. If you are having problems with certain cylinders it is not the points. Points don't discriminate.

+1

points dont keep you from running on all 6, and since these points are just a switch for ground, the gap is not critical. i do set it on the narrow side, so that they are not open too long.

here are some things that will make it run bad:
plug wires
clogged injectors
fouled plugs due to mixture or oil. even new plugs can get fouled. if you do haev a problem with plugs fouling, got to a hotter plug
bad compression, perhaps due to rings, valve adjustment(too tight), carbon lodged in valves keeping them from closing.

if only the left or right bank runs, its cam timing, if some from both sides run, its not cams.

start it cold, feel which exhaust ports are getting hot. that can tell you which cylinders are firing.

[mixer911]

I did the Compression test today


3@175 6@158
2@170 5@175
1@152 4@170

140 thousand miles on the engine

How bad are those numbers?(it was on a cold engine)

By the way Bob..Im on vancouver Island

[T77911S]

#1 does not look good, but it wont stop you from running on all 6.
when i get a low one like that, i usually run it several times to make sure i am not doing something wrong.
i would follow up with a leak down to try to find out if it is rings or valves. if you are lucky, it may just be carbon blocking the valve.



what about injectors?
while you wait on wires, i would pull all the injectors, put each of them in a jar, turn on the ignition, lift the sensor plate and check for flow and spray pattern out of all 6.
if you have some bad ones, i would first pull them off the lines and spray some carb clean in the input to try to clean them out a little. then i would check the flow out of the lines from the fuel distributor to make sure that is not the problem.

you can also have air leaks making it run on less than 6. injector sleeves, Orings, manifold gaskets, and intake runners are common places that could let in air to lean out a cylinder and make it not fire.

with a car that has beem sitting that long, your 2 biggest issues will be injectors and the fuel distributor.

you also need to verify the advance is working on the disttributor. this will rust and get stuck.

check the gas tank for rust and clogged screen.

this is just a starting point for a car that has been sitting for so long.
i would first look over the car rust and see how bad it is and what it will take to get it on the road. then i would get it running with as little money as possible to find out about the motor and tranny.

why has it been sitting?
i might also pull the valve covers and check the head bolts, just to make sure none are broken.

still, a good deal for $1000.

[mixer911]

Pulling injectors today...picked up new Orings
While picking up Orings talk to the VW/Porsche mechanic...he felt the compression was OK...
While sitting for years.. two valves will be left open and will rusted...but they should clean up nicely..
Thanks for all the advice