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Join Date: Oct 2006
Location: MYR S.C.
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TIMING concerns

as you know, i have been battling this annoying miss. sounds like it on the rev limiter.

anyway, i have been looking at the timing and AFR's and their relationship.
both vacuum ports work. i can see the timing advance/retard with pressure or vacuum. the mechanical advance works.
first off, at idle and the retard not connected, my timing mark is just ppast half way between Z1 and 26 degrees, i figure around 15 degrees.

note, i have removed the retard because i do not have any solenoids to block boost going to the retard pot preventing the boost side from retarding the advance. on that note, with it being connected and the PO running 1bar, shouldnt that have killed the motor? i am runng it at .8 now
on that same note, i have forgotten to reconnect the advance/boost retard line several times now and have gone on boost. that has not killed it. (?) also, with it not connected, i cant really tell any difference in the way it drives. (?)

the other day i was reading 14.4 at 2500rpm. i removed the vac advance and it got leaner(???) to 14.9. with the tests i ran on my 77 with timing, it should have gotten richer.

my vac pot has been shimed for some reason. anyone ever seen this before?

with the vac advance connected and when i check timing, the timing looks like it around 30 degrees. so i know it is advancing. with the vac removed it is at 26 degrees.

i am thinking about removing the intake to check for a cracked intake block, but i just dont feel like that is it because all the plugs look the same.



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86 930 42kmiles [__] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD
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Old 05-29-2013, 07:17 AM
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no help with the timing?
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86 930 42kmiles [__] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD
88 BMW 325is 200K+ SOLD
05 BMW 330CI 130K:: [__] RUNNING: [__] NOT RUNNING:
08 VOLVO V70 190K:: [__] RUNNING: [__] NOT RUNNING:
90 B2200[__] RUNNING:[] NOT RUNNING:__2000 MER E320 WAGON [] WRECKED:[]RUNNING:
Old 05-31-2013, 06:52 AM
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actually it might be more than half way, more like 20 degrees.

i retarded the timing a few degrees and my AFR's at 2500 got richer, and as expected at idle they got leaner, about one point. from 12.1 to 13. so i brought it down to 12.5. now my 2500 rpm AFR is 13.8. i am still at 3bar WCP and could raise it up to get the AFR to 14.4, but it seems to run better here. so i will leave it for a while.

now my idle timing is around 10-12 degrees and full advance is abput 3 degrees before the mark.

as for the timing mark. i am not sure if 1mm equals 1degree on the pulley, but it looks like my timing marks is 29mm past Z1. since i have the euro FD head, and i think the euro cars are set to 29 degrees, are the pulleys different and would they have swapped pulleys???

i still have the shims under the vac pot. now that things are a ilttle better, i can re-test some things and hopefully get correct results.

man there was a LOT of heat coming up from the engine that made it hard to adjust the timing. time for new thread.
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86 930 42kmiles [__] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD
88 BMW 325is 200K+ SOLD
05 BMW 330CI 130K:: [__] RUNNING: [__] NOT RUNNING:
08 VOLVO V70 190K:: [__] RUNNING: [__] NOT RUNNING:
90 B2200[__] RUNNING:[] NOT RUNNING:__2000 MER E320 WAGON [] WRECKED:[]RUNNING:
Old 06-13-2013, 04:10 AM
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These engines work on wide range of timing and afr. When it cuts what is the afr? It might be too rich to ignite when on boost ramp and lower rpms!

I run 10 to 15 btdc on idle and from 13.5 to 14 afr on idle. The only misfire or revlimit like experience I have seen is from too rich and thats close to 10 afr with msd6a. Now that I have removed msd it might hit earlier/leaner?
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Old 06-13-2013, 11:21 AM
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thanks. thats what i waas wanting to know, idle timing.
when i set my full advance to the 26(29) degree mark, my idle timing is past half way between Z1 and the 26 degree mark. if it is a 26 degree mark, then i would say idle is at 15 to 17 degrees.
idle afr is 12.5

i think i am too rich on boost, plus i have retarded my timing some so i cant adjust the fuel until i bring my timing back up. i am down to 10, maybe even lower at times.


i think i may have finally fixed my air leaks.
usually when i drive about 65, the boost gauge is pegged at -.5bar. when it has run good, it has been just above that. well this morning at a steady 65, it was about -.4 or -.45bar.
even when we went on a trip, at 80-90 it was still pegged at -.5bar.
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86 930 42kmiles [__] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD
88 BMW 325is 200K+ SOLD
05 BMW 330CI 130K:: [__] RUNNING: [__] NOT RUNNING:
08 VOLVO V70 190K:: [__] RUNNING: [__] NOT RUNNING:
90 B2200[__] RUNNING:[] NOT RUNNING:__2000 MER E320 WAGON [] WRECKED:[]RUNNING:
Old 06-14-2013, 02:57 AM
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today i set my timing dead on the mark for full advance, no vacuum lines attached. then at idle i pulled a vac on the vac advance at it went to the full advance mark. is this the same for anyone else out there?
i still have my vac retard disconnected

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86 930 42kmiles [__] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD
88 BMW 325is 200K+ SOLD
05 BMW 330CI 130K:: [__] RUNNING: [__] NOT RUNNING:
08 VOLVO V70 190K:: [__] RUNNING: [__] NOT RUNNING:
90 B2200[__] RUNNING:[] NOT RUNNING:__2000 MER E320 WAGON [] WRECKED:[]RUNNING:
Old 06-22-2013, 05:34 PM
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