2.0 help needed

POinNJ · 07-28-2008, 07:53 AM

First post in this forum, but I thought I get more help here than in the 912 area. I have 1976 912e 2.0 (same as 914) switched over from FI to dual Delorto Carbs. Performed the following after failing state emissions and for better driveability. Car would backfire through left carb on occasion and some exhaust backfiring while coasting.

Day 1) Adjusted all valves to .006 (which I later found out was wrong on exhaust side) Engine Cold

Day 2) Adjusted intake valves to .006 and exhaust to .008 engine cold. Changed Cap and Rotor, adjusted points so that Dwell was at 50 on 4cyl scale, changed ignition timing to 34 degrees BTC at 3200 RPM. Performed leakdown test on each cylinder 1- 6% 2-5% 3-6% 4-5% after engine was warm. Changed plugs to Bosch Platinum gap set at .028. Balance carbs with Uni Syn and adjusted idle however didn't adjust linkage as I though it still seemed balanced. Didn't adjust air imixture on carbs. Took the car for a ride for about 30+ miles and it ran the best I ever had it, nince sweet spot around 3000 RPM,then on return trip I got loss of power and hesitation.

Day 3) Double checked the Points and the Dwell was the same, double checked timing still the same and double checked the airflow balance from carb to carb, still the same. Pulled plug on cyclinder #1 everything appeared perfect. Decided to adjust air mixture (2 screws per carb) I turned them in till cylinder ran rough, backed it out till it smoothed out and then 1.5 turns out from there. Did that to all cylinders and went for a ride. Same hesitation and lack of power.

Day 4) Pulled valve covers for 3rd time on cold engine, checked all valves, found exhuast on cyclinder 4 too loose, so I adjusted it. While turning engine manually for valve adjustment I noticed that the new rotor was loose and not seated correcty on the distributor shaft. I still had the old rotor and sure enough it fit correctly ( the inside guide on the New Rotor was not correct). Cleaned old rotor put cap back on and took test drive. Very slight improvement. Checked air mixture again and made slight adjustment, advanced timing to approximately 36 degrees BTC. I noticed that as I pushed down on the middle of the throttle linkage that the carb for the #3 and #4 cylidinder was opening before the other side. I adjusted the linkage and now they open exactly the same. The stumble off idle is gone and the engine revs better than ever with no hesitation or carb backfiring, however there is a little exhaust backfiring. I take the car for another ride, big improvement, but not quite 100% and now there is exhaust backfiring during any coasting in any gear, pretty much whenever I'm not giving it gas. There is still a light stumble when using the accelerator pedal, but not manually push the throtte from the engine compartment.

Sorry for the long post, but I'm out of ideas except for a carb rebuild. I've only had the car for several months, and no knowledge of when the carbs were new or ever rebuilt. I'm begging for help, because I don't know where to go from here.

Ryan

racer · 07-28-2008, 01:49 PM

I'm not a "carb" man, but have you pulled the jets (idles and mains) to see if they are clogged?

Where is Riverdale NJ - maybe there are some local, still carb friendly shops in your area as well.

As for NJ state emmission, a carbed motor would be hard to pass since the FI was much cleaner. I can't recall as well if NJ is a visual inspection as well. Their computers should tell them the car came with FI and not carbs. With my 914 (carbed) of years and years ago, I had a local shop "pass" the car. I never asked how it passed, but always got a new sticker

Not sure how you intend to use the car, but why not go for QQ tags and skip inspection altogether?

Morrie · 08-03-2008, 11:39 AM

What's the latest? I posted a couple suggestions on the 912 forum but have not seen you comment in a bit...

MorriE

POinNJ · 08-03-2008, 01:11 PM

A few people suggested I post in the 912 area and 912registry which I did. Anyway, the carbs were synched side to side with the linkage when I manually pushed the throttle bar from the back, but when using the accelearator pedal it wasn't balanced. I readjusted the linkage and it is better. However, the exhaust popping is much worse, and it looks like I have exhaust leaks on both sides at the flanges that connect the heat exchanger and the exhaust manifold pipes.

I'll have to wait till next weekend for that project, but I'll post once complete.

Ryan

Morrie · 08-03-2008, 03:09 PM

Hi Ryan,

When manipulating the throttle linkage back in the engine compartment for balance, make sure you actuate the throttles by pulling at the cable attach point. If you just push on one of the throttle arms at a carb, the linkage system gets biased differently creating balance problems.

What sort of throttle linkage do you have? There are a multitude ofdifferent kinds and some are better than others at maintaining balance.

Also, have you checked to make sure the carb base mounting nuts are tight? DO NOT crank on them, but make sure they are snug.

Finally, make sure the engine itself is okay. If nothing else, pull the plugs and have a look to make sure they aren't burnt or oil soaked.

These are really fun little cars that are cheap to operate and are easy on gas.

MorriE