77 911s running issues
 

I have a 1977 911s with a 2.7ltr engine, CIS, Perma Tune CD, exhaust is original with reactors and EGR system (air pump installed).

I have set the points dwell to 38, replaced the distributor cap & repaired the coil wire (only two strands connected, so re-soldered the end). The timing is set at the Z1 mark, not sure if this is correct. Everything I buy for this car seems to be for the California car so should it be set to 15 ATDC? When warm it idles at 950.

It starts but dies, after a few starts it stays running but smells as though it is rich but acts as though it is lean (pops through intake & hesitates maybe a weak spark). Once it is warm I can drive it but when cruising in 5th gear @ 2400 rpm it is not smooth and judders until you drop a gear and increase the rpm. At full throttle it pulls very well all the way to red line. It also will quit without warning and backfire out the exhaust. The last time it quit it was at idle and I checked to see if it was fuel and the injectors squealed so it is electrical. Let it set for 10 minutes and it fired back up. I have removed the CD box & found a crack on the bottom and it also does not make any noise with the ignition on.

I'm going to test the resistance on the CD box, coil & groundings.

Any other suggestions.

Rocky

You might find this thread useful, it has some input from John Walker, read the whole thing.

http://forums.pelicanparts.com/porsche-911-technical-forum/184348-jwalker-35deg-3-5co-hp.html

I got rid of my points long ago and switched to the Pertronix magnetic pick-up system with no regrets.

I gap my spark plugs slightly larger than stock, helps to eliminate any crackles or bappling noises.

I and many other people recommend NGK solid copper spark plugs.
http://www.pelicanparts.com/catalog/shopcart/911M/POR_911M_BAStun_pg1.htm#item0

Loud backfires tell me your ignition timing is off, or you have a bad distributor cap with a hairline crack in it.

You just need to go though the whole car and eliminate one possible cause after another.

It's always the last thing you do which fixes it.;)

Kach22i,

Thanks for your info.

The distributor cap is new & it only backfires when it dies from whatever the fault is. It is running at approx 210 degrees.

I have noticed that there does not appear to be any vacuum at the distributor when at idle. Also I still do not know if the timing should be at TDC (USA) or 15 ATDC (California). It appears to have all the California emissions.

Rocky,
Try this test: open the engine compartment in a dark garage with the engine running and look for errant electricity. You may be amazed by the light show. if you see no arcs in a darkened garage (you may not be able to do this outside this time of year in England) then perhaps your ignition system is OK.

I just re-read some of that old thread, looks like JW said:
I don't know about California "smog control" but our cars seem to be similar.

210 is a little warm but within "normal".

180 F on cooler summer days, 210 F on hotter days, and 200 F I think is more the norm.

I know some guys run their car hard on the street and can see 230 F for short periods, but don't they have traffic camera's everywhere in the UK?

I have done the bench test on the Perma Tune Box & the outcome is I need a new one.

Mostly ground loop or over voltage damage. Now to source a new one along with a coil.

Does anyone have a working 3 pin Perma Tune CD Box for sale?

Check the Classified section.

check fuel pressures.

make sure you dont have ANY air leaks

check the thermo time valve (TTV). if you still have it. it is a small vac/electrical device locate on the left side of the engine. a vac line from the WUR goes to it. it is used to richen the mixture when the engien is cold.

it is always best to set things per factory until you get it running correctly. so for now, set the timing per spec, either 0TDC of 15ATDC, which ever your car requires.
after you get it running correctly. THEN modify timing anf other things.

check the CO level.

check the wiring fromt the dist and coil to the CD unit. it gets brittle and cracks and can short out.

if you suspect the permatune, you can go with MSD, cD and coil for not much money.

I have installed a replacement Perma-Tune CDI Box.

Now it will not even turn over, no click, nothing.
The battery is fully charged and the lights are good and do not dim when attempting to start.

Is there a fuse or a relay that I need to look at?

Start checking things, starting with the last thing you did and work backwards.

If you like, I can post the fuse section of my owner's manual if you do not have one.

Get out your test meter and start with the basics. Do you have power to the ignition system? If you pull a plug and ground it against the engine do you have spark? Are the plugs wet with fuel? You motor needs compression, fuel and spark. You will find the problem and it will be something simple when you finally spot it. As Kach22 says, work backwards from plugs to coil to CDI Box to the ignition switch. Follow the wires with your test meter in hand. Eventually you will a place where you should have 12 Volts but you don't.

Well the not turning over problem has now been resolved. The 18 pin connector was at fault, cleaned with electrical contact cleaner and it turns over and starts.

Still have the issue with the way it starts, but it starts.

I will now check the TTV as suggested by T77911S.
I know I have not vacuum to the distributor at idle.
What should I have as far as vacuum goes to this TTV unit?

i am pretty sure when the TTV fails it fails closed, IE, it makes the car run rich because it is blocking the vacuum to the WUR. pull the vacuum line at the WUR, there may be 2, the one on top should have vacuum on it,

I bought a California smog car

I removed thermo reactors and installed "tubes" as a replacement. I eventually installed SSI exhaust headers. The "tubes" [so called headers] suck for performance but can be bought used for less than $100us

I plugged stock Calif distributor vacuum hose permanently and set total timing to 35 deg. The distributor receives no vacuum retard

I removed EGR valve and its line to muffler

I set CIS fuel mix to 3.5


http://forums.pelicanparts.com/uploa...1340023904.jpg

RoninLB

I currently have the timing set to the Z1 mark which should be 0.
Is the next mark to the left of that 15 retarded (California Car)?
Are you running yours permanently 35 retarded?

When I bought this car someone had been working on it & I think there might be some vacuum lines connected in the wrong place. This care appears to have a vacuum limiter & I think the top vacuum line is suppose to go to the valve body but does not.

In the mean time I will check for vacuum at the WUR as T77911S suggested.

Switch to megajolt... Just sayin.

@ RoninLB, Not to hijack this thread but I am running a '74 CIS car converted to Zeniths and an MSD ignition. Not sure where to run the vacuum advance from the distributor? Right now I just have it plugged at the dist. Will this work? What would be the timing setting? You are the first person in a while that I have seen suggesting to just plug the vacuum advance. How are you set up?

Thanks, Andy.

I run my 1977 California Spec 911S the same way as RoninLB.

No vacuum retard, 35 degrees full advance, measured at 5000 rpm.

I had the W pipes (thermal reactor replacements) then went to early factory heat exchangers.

Ed

You might find this thread useful
http://www.lovelv.info/d.jpghttp://www.lovelv.info/h.jpg