Reply With QuoteOriginally Posted by Jeff N.
Grand Master
Baconator - gimme a call tonight when yer done with dinner...
Spoke with Rowe today. Oi. I have a gut feeling here.....
Bellevue WA
90 535iM - not much stock remains. 3.7 liters, ported head, cammed, 3.73 diffy, M5 brakes, MAFed, yadda yadda yadda
86 Porsche 951 - Track Toy
Super Moderator
Hmmm. what might that be...?
Grand Master
...my cam is waaaay off. I'm betting it's several degree's retarded even with the current "+4" gear setting. Sounds like Jim times in his cams on every engine he builds - can't assume the "+" bolt pattern get's you to the right cam timing with his setup.
Lessee...low mileage, low intake vaccuum, peaky output suure sounds like a retarded cam setup. That or it's too hot. Gonna get to the bottom of this soooon.
Talking to him is a bit like talking to forgetful professor...
Bellevue WA
90 535iM - not much stock remains. 3.7 liters, ported head, cammed, 3.73 diffy, M5 brakes, MAFed, yadda yadda yadda
86 Porsche 951 - Track Toy
Grand Master
ok...we're goin' in. One 1 tooth adjustment comin' up. Report to follow...
Bellevue WA
90 535iM - not much stock remains. 3.7 liters, ported head, cammed, 3.73 diffy, M5 brakes, MAFed, yadda yadda yadda
86 Porsche 951 - Track Toy
Grand Master
Better now.
Checked the cam timing relative to indicted TDC on the dampner using a dial gauge to measure rocker arm lift. Looked pretty close actually to what Jim R. said it should be.
Decided to roll 4 more degrees advance into the cam. (+1 tooth less 2 degrees retard via the cam gear). Appear to be running about 8 degrees total cam advance now.
Much better. Less peaky for sure. More mid-range jump. Interestingly, car now has a strong knock at 5k RPM under load. Either going lean or too much ignition advance. Theory suggests with the cam adjustment it should want more advance offcam and less advance on cam. Might have to tinker with some different chips laying around - running the JC at the moment. Need to try Marks - his is better than Jim's. Also running mid range gas in it at the moment - 89. Have to try it with a tank of 92.
The baconator did a great job! I'm sorta hamped with toasted right thumb and was left to beer duty. Thanks Martin!
All in all - promising!
G'night.
Bellevue WA
90 535iM - not much stock remains. 3.7 liters, ported head, cammed, 3.73 diffy, M5 brakes, MAFed, yadda yadda yadda
86 Porsche 951 - Track Toy
Super Moderator
Did you already back the fuel pressure down? if so it may be time to raise it again-
if the knock is that strong you may want to pull the plugs right away and check for signs of preignition damage...
Grand Master
FP is @ 3.0 bar with a stock FPR. Will pull the plugs tonight to check. Also am going to try the stock chip, others less aggressive like the RD, etc.
We may toss in the spare fuel pump from the crash car just to try something different...
No problems with normal driving.
Bellevue WA
90 535iM - not much stock remains. 3.7 liters, ported head, cammed, 3.73 diffy, M5 brakes, MAFed, yadda yadda yadda
86 Porsche 951 - Track Toy
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