Thanks, AEM has a german distributor and I ordered the kit couple of minutes ago. In regards to the bungs, it looks like that M18x1,5 is pretty much standard for the AFR-sensors.
Found some time to do compression and leak test today. Here are the results: and here is how the plugs look like after approx. 400 miles: It looks like to me, that cyl#6has an issue with oil (maybe valve shaft). That could explain the high compression pressure (reminds me about the old, but still illegal trick to inject some oil in the cylinders before doing the compression test ) Do not know why plug #2 is somewhat discoloured. Cyl#2 seems to be the weakest, however during the second test it almost reached 10bar, also. Overall the compression pressure seems borderline ok to me (overall level and difference in between the cylinders is less than 2 bar). The leak tester is calibrated, so that up to 40% the results are "green". All cylinders are below 40%, but again cyl#2 sticks out with 35%, whereas all others are 20-25%. To me the result gives no indication for the low level of performance. What do you guys with the vast Buick experience think?
Forgot to share what UPS dropped off today: Pretty fast turnaround, considering that I ordered it yesterday during lunchbreak. Now I need to find the time to weld the bung to the pipe.
40% leakage is far from ok. I could settle on 15-20% leakage on a motor with 150k How many miles on this build????? Could you hear where the air was escaping from......if intake valve bot sealing it will blow back up the intake... exhaust valve out the pipe, past the rings can be harder cause there is lots are area for the pressure to dissipate, but will hear it out the breathers. At the leakage rates posted, if test was done correctly .......that motor has some issue. A larger cam with more duration will cause a decrease in cranking compression and you will have to get the piston as close to tdc to do leak test as possible to verify valve are closed. In our motor it's just as easy to pull the rocker shafts and plug.......then all valve are close, it's easier to turn over because no spring pressure and any tdc will work
My race motor has less than 3% My gm 3400 in my 2000 van with 285k has less than 15 in all holes. Something isn't right here, either the test or the motor. But something isn't correct
Cheap Leakdown testers often give bad results. We used to have one at the shop and it was not reliable. Maybe you can borrow a tested leak down tester from an Audi shop. I am guessing you drive an Audi... Do not compare modern cars to your old one...my corporate car, a SEAT Leon Cupra was way faster than my buick before I tore it apart...and it "only" has 300hp. But 7 gears and AWD help a lot.... I can second Bens99gtp...pull the rocker shaft to be sure that all valves are closed when you do the test. And at 40% leak rate you should definitely hear the air escaping. I have been through the same stuff and now my car is torn apart waiting for a JW short block
Thanks for all the comments. The tests have been performed with the engine hot/warm. Here is a pic of the scale of the leak tester. I have to believe that the calibration is done such, that it fits to the color code. I agree with you guys, that a loss of 40% of the pressure would not be acceptable at all. But at that rate of leakage one would hear the air escaping thru intake, exhaust, or breather opening of the valve cover, depending on where the leakage occurs (like Ben described above). I did not hear any air escaping anywhere. So I still believe the engine to be ok in regards to leakage. What do you guys think about the compression numbers. Is 10.xx bar / 140-150 psi somewhere in the neighborhood. Would higher numbers be expected from a engine with stock compression. Even though the engine was rebuilt about 10 years ago, I believe that the car was driven very little (maybe 5000 miles) since.
wow! never seen one that low. Are you sure that gauge is accurate? It can't be, that gauge is not right, or that motor has problems.
I have never used a 1 gauge leak down tester. Mine has 2 gauges, one telling you the psi in and the other how much is left, simple explanation, the difference is leakdown. eg. set in at 80psi, second gauge reads 72 psi, thats 10% leakdown. Only time I've seen nearly 100% on second gauge is with total seal rings.
Unless you are running alchohol you have a fueling issue,...those plugs are cotton white. It needs some fuel imo
Modern ethanol hardly shows anything, but yeah you need much more of a tint to the plugs. They look bleached
I think that is a 2 gauge tester, looks like the air pressure gauge is "above" the pictured percentage gauge. We're getting into a bunch of guesses and possible issues. The one issue we know for sure: His advance curve is deadly slow. He NEEDS to fix whatever is wrong with his distributor and advance curve before he does anything else. It's easy, it's obviously screwed up, and it can cause the issues he's having. Fix what we know is wrong (the advance/distributor), see if that doesn't take care of it, then start screwing with other stuff like fuel mixture. You're not going to get a good reading on the plugs if the advance is extremely retarded such as it is, anyway. K.I.S.S. (keep it simple, stupid).
Yep, you are right. HORSES ARE BACK!! I am so happy that I share the reason, even though it is very very very embarrassing for me. Last night I went back to square one and decided to double check the wiring of the ignition cables. Simple mistake, I had missmatched the ignition cables of cylinders 2 and 6. Accordingly cyl2 was fired half way on his intake stroke and cyl6 was fired half way on his exhaust stroke. I fixed that and now the punch is really noticable. It is really amazing how well and smooth the engine still was running on 6-cylinders. No misfiring, super @ idle and still good throttle response. Just not enough power. I hope that the right cylinderhead was not damaged due to eneven heat. Now you are probably asking yourselves: How can that happen? Well, I do not know, my guess is, that during one of the nightshifts in desperation to get everything done my brain stopped working for some time :-( Sorry to you guys for the false alarm, even though I will still check the distributor, the timing and the AFR. Maybe I can even lure some additional horses . Thanks to all of you for all the great inputs, much appreciated!
I dont think I've ever heard of mixing 2 and 6 up. I have on more than one time swapped 5 and 7, but they are side by side
I installed a new cap and new cables along with my TH200 swap. So my mistake did not happen @ the plugs, but @ the distributor cap.
