1. What do these wires connect to? (comes out of frame and then splits to red plug and red wire - can't remember if I cut it or it dead ended in the wire loom) [not used for cruze control]
2. Where can I buy a replacement linkage? (it was seized and it broke when I tried to adjust it shorter...looks like something from a hobby shop) no they are throttle hem joints may have 2 left here
Working on carb tuning, fixed a small fuel leak on the return line. I have vacuum at the PCV valve now pulling evenly from the 8 ports - if I measure and adjust it, any ideas how much vacuum the pcv needs at idle? [12 to 18 inches] Also I started balancing idle airflow on the 8 barrels using the unisync guage. 7 of 8 are close and just need balancing between barrels per carb, but cylinder #8 the airflow is high and bouncing up and down. [check the air bleed may be pluged with paint ] Cylinder 7 is steady and a little low so I can't fix it with the idle speed screw for 7 and 8. Also they are outside the adjustment range of the air bypass balancing screws on 7 and 8.[check srew by removing it and make sure the bleed hole is not pluged] Going to check the fuel pressure as I suspect it's at 4psi and that is the first carb after the regulator. Dellorto book says it should be 3 psi and anything over 3-1/2 will cause spillover - hopefully it's that easy. If not that, I'll be checking for partially plugged idle jet circuit, vacuum leaks, spark plug condition etc. Once the idle speed is done, I'll be adjusting mixture on each barrel to find the sweet spot between lean snaps and rich smoke. I already adjusted from 3 turns out for initial startup to 1-1/2 turns out (leaner).
For dialing in the initial timing and 3000-8000rpm not sure how I'm going to baseline tune that without a dyno. Book suggests 12 inital and 24 degrees progressive as baseline settings for a SBC while I was running 0-4 initial and 18-22 previously on the Northstar.10 and 28 for nstar max power total 38 degrees at 7 thou Obviously I don't want hard starting or detonation, but enough advance to get the best horsepower - any suggestions will be helpful.
Mostly I'm thinking out loud here and more reading and tinkering will help keep things going in the right direction. I realize that most Fiero owner don't have to tune 8 cylinders individually but hey if you were at the 25th, you can vouch that the exhaust note is uniquely worth it
Fiero2m8
APR 28, 11:47 AM
More questions, inquiring minds want to know...
Plug and red wire goes to alternator - other two go to A/C compressor?
Coolant fans and guage are working currently - does polarity of these wires matter?
Is this plug also cruise control related or is it for something else (i.e. lighting) or not used?
doublec4
APR 28, 03:46 PM
quote
Originally posted by Fiero2m8:
Is this plug also cruise control related or is it for something else (i.e. lighting) or not used?
I could be wrong... but I think that plug was for the original electric trunk popper, and the trunk light. Don't think it was for anything else, unless thats a different plug?
bubbajoexxx
APR 28, 05:46 PM
quote
Originally posted by Fiero2m8:
More questions, inquiring minds want to know...
Plug and red wire goes to alternator - other two go to A/C compressor? [ac]
Coolant fans and guage are working currently - does polarity of these wires matter?[yes ] one is light other is gauge
Is this plug also cruise control related or is it for something else (i.e. lighting) or not used? [cruze ]
Fiero2m8
APR 30, 12:21 AM
Here's a video of the carb idle air balance issue on cylinder #8:
Since the problem couldn't be corrected with the air balance bypass screws, I removed the carb to bench reset the butterfly valves. I removed, cleaned and the swapped their bores:
Then I used the 0.003" feeler guage to set the gap on the tighter barrel, then slowly bent the throttle shaft until both sides fit the guage like a glove. Now I should be almost perfectly balanced and any final adjustment can be done with the air bypass balance screws:
Erik
APR 30, 04:43 PM
quote
Originally posted by bubbajoexxx:
offset is moved out 1/8 of an inch for the corvette rotors and calipers but you can remove 1/8 from the bearing stop to retian stock offset
Is the hub circle size the same as the stock 88? The reason I am asking is I would like to use my current wheels which have the 57.1 mm hub centering circle and the 5x100 bolt pattern Could a 5x100 bolt pattern be drilled on the caddy hub flange? I am desperate to do this mod if possible as my stock hub is getting noisy
[This message has been edited by Erik (edited 05-01-2011).]
Fiero2m8
MAY 01, 01:56 PM
Looking for spark plug recommendations (to install when I've got the air/fuel mixture sorted):
Stock is AC Delco double platinum 41-987 for a 2001 Northstar with 0.050" gap. My setup varies from stock since I am using coil wires and carbs.
A new spark plug has been released for use in the above vehicles. The new spark plug has an Iridium tip instead of the current Platinum tip. Due to the different tip design, the gap of the spark plug has also changed. The new spark plug, P/N 12571164 with AC Delco P/N 41-985, is gapped to 1.01mm (0.040 inches) when the spark plug is made. The spark plug gap is set during manufacturing and should not be changed or damage to the spark plug may result. Any new spark plug found to not be properly gapped should not be used. GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information. WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION
wont work with his HPV 1 as it requiers a gap of 32 Thou 40 will cause problems he requiers stock GM AC Delco plugs
Fiero2m8
MAY 02, 09:53 PM
quote
Originally posted by bubbajoexxx:
wont work with his HPV 1 as it requiers a gap of 32 Thou 40 will cause problems he requiers stock GM AC Delco plugs
Ah yes when in doubt read the manual...HPV 1 manual says 32 thous for stock V8 and 30 for hi-performance street. So I guess I need an AC Delco part number of a non-platinum plug that has the right specs for a Northstar (size and heat range) that I can gap to 30-32 thou.
In the meantime, I have reduced the idle jets from 58's to 52's and turned in the mixture screws to half turn out. After engine running at operating temp for a while plugs are changing to a tan colour.
