So... Ive an interesting 1968 142 problem.

Preexisting problems: the car dieseled a bit when I would turn it off... Had been since I "rebuilt" the carbs, but not very badly, and I was planning on having a shop rebuild the SUs at some point...

Anyway... The car was running wonderfully and one day I decided to adjust the valves and change the distributor... My distributor is old and fairly worn, and doesnt stay very on time when idling... (but the engine DID idle and didnt turn off, etc). Additionally, both distributors Im going to talk about/mention have been fitted with Protronics, Petronics, whatever, replacement ignition, so there is no gap/ dwell/ condenser considerations... I adjusted the valves, engine warm, to 16-18 and put my replacement distributor in (the "correct" or orig distributor is an 0231 153 009 IFR-4 and the replacement that I got from my local Volvo parts buddy, is an 023 178 007 IF4 distributor). Perhaps naively thinking that the distributor would be the same, since its relatively unworn, fits, looks the same, etc. The car started right up and timed perfectly! It didnt vary or run up and down, etc. BUT when I did a short test drive, i.e., warmed the car up, it faltered like it had no power, and I could barely get around the block without giving it some throttle to keep it running. I got back to my driveway and it stalled. Huh, and I started it again, checked the timing again, etc, but it wouldnt run unless it was "cold". So I took that distributor out, put the old one back in, and rechecked the valves (under the premise that if I returned the engine to the old condition itd be fine, but even with the old distributor in, it ran the same. I read books, asked knowledgeable friends, read online, and decided to re adjust the valves using a technique I found on the web (see below) and to get a vacuum gauge to monitor if I had somehow screwed something up. I thought it could be the coil (orig coil, broken down, and dying under load and heat?) to no avail.

So the car has the orig distrib in it... readjusted valves at 20-22 cold, no vacuum leaks, with a vacuum of about 15-20 cold, and 12-15 cycling warm. I eventually got it running though it cycles up and down between 1100 and 1400 rpm, by increasing the #1 carb idle screw.

So... anyideas? (Again, it was running fine, like a "real" car, until I did the valves and distributor... I always change 2 things at once, Im not sure why...)

Thx, Ralph

PS here is the valve adjustment technique I used last....

The Haynes manual method for setting valves -- setting #1 when #8 is fully depressed, #2 with #7 down, etc. -- has worked pretty well for us until recently. Here's a method I find I like better, though, that works with any cam profile -- courtesy of David Hueppchen, who got it from Waddell Wilson years ago:



Bring the motor up to full operating temperature (this means, of course, that you want to adjust the valves to the "warm" spec found in your manual or supplied by an aftermarket cam's manufacturer).
Remove the spark plugs so the motor's easier to turn (I turn it with an adjustable wrench on the crankshaft pulley. Also -- needless to say, I hope -- make absolutely sure you know which plug wire goes back on where).
Turn the motor in the direction it normally runs -- clockwise, looking at it from the front of the car -- until an exhaust valve just starts to open. Look at the manifolds to see which are exhaust and which are intake valves. OK, I'll make it easy: counting from front to back, valves 1, 4, 5 and 8 are exhaust valves.
At this point, adjust the intake valve on that cylinder. In other words, when the rocker arm on exhaust valve #4 just starts to tip downwards, adjust intake valve #3.
Keep turning the motor through two complete rotations and adjust all the intake valves in a similar way.
Go around two more times, adjusting each exhaust valve just as the intake on the same cylinder begins to close. In other words, when the rocker arm on intake valve #3 just starts to come back up from being fully depressed, adjust exhaust valve #4.
Once the valve adjustment is correct -- and only then -- you're ready to set ignition timing and tune carburetors.

I like David's method a lot better than the way I've been doing it all these years -- and I'm sure you will, too.