Hey all, took my '75 2.0 to a dynojet dyno last week to establish a baseline of sorts. Based on receipts from previous owners, I think it has Euro-spec Mahle p's and c's, a web-cam of unknown grind, to go with the dual webers she sports. Here were the results:


I paid for two runs, but the guy running the dyno said I was so lean he wasn't comfortable doing a second pull. The sheet shows it being right around 14-17:1 most of the pull, and richening up after 5k rpm. Is that not where I should be with this car? Also, the resistance of the dyno wheel exposed the ignition irregularities you see on the power graph, any suggestions on what that could be? I'm running a svda dizzy out of a 1.8 car, with pertronix, and the total advance set at about 28 @3500 RPM (I THINK, I can't remember exactly, it's been too long since I did it, lol).
Thanks, as always!
Chris

Way too lean. So lean that it was breaking up and detonating, thats what those peaks and valleys are in the power plots.

Flat line it at 13:1 and the engine will be happy for AFR

Thanks Jake! Guess I'll be finding a good carb-tuner to get these re-jetted/adjusted. Is it likely that I've done damage running the car like this? (not too hard, just normal-ish driving)

Nice! Who's chassis Dyno?

Hey Rich! Marysville Speed and Custom in Smokey Pt, they had a 2 pulls for $50 deal last weekend.

If you just pulled it a couple of times you'll be ok.
I'd go up 2-3 main jet sizes to start, BUT check fuel pressure and float levels first, else jetting may not help.

That was the only pull, but I've probably put 3k on it in the past year set up that way, THATS what I'm worried about!

The street will take much longer to kill it than the dyno. It you were driving it around at WOT all the time I'd be worried, but you can't do that on the street.

Do you have ANY exhaust leaks?

I backdated the 75's exhaust with pipes from a 73-74, and they were a bit out of alignment, requiring a lot of massaging by the guys at triad to quiet down a leak once they were bolted up... Not noisey anymore, but could still be a small leak there...

Then thats where part of the lean condition may come from.. It may not really be that lean..

But the power was breaking up… Or the plugs are firing late.

was Cam running the dyno?

they're good guys up there.

Ok, any other way to check for exhaust leaks besides feeling for air?
I believe the lean reading honestly, the person I bought it from had some major issues getting it to pass emissions in his area, finally leading him to sell the car. I'm sure he had it set up to run lean trying to get it to pass...
Not sure the name of the guy running the dyno, seemed knowledgable enough to keep me from ruining my car, lol.

Cover the tailpipe (s) with a piece of wood while it's running.
Any leaks get louder and easier to find.

+1 ....... right where that dashed line is where the fuel should be under load ...... right around 13:1 .....