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Old 10-29-2018, 12:01 PM   #24
SRT8-X
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Join Date: Feb 2017
Location: Cypress, Texas
Posts: 42
Re: '69 C10 327 SBC Off Idle Stumble / Misfire Help - I feel like I've tried EVERYTHI

Quote:
Originally Posted by 68 P.O.S. View Post
I think it’s a lost cause and you should give up so I can take that sweet truck off your hands

Yes, your distributor should have 24 degrees….was just trying to verify. Keep your total timing at 36, it should run very well there. Yes, you can plug your vac advance into the manifold vac port on the carb to see how much advance it provides. It should have no more than 10-15 degrees in it and be plugged in to manifold vac for it to work right. Another possibility, did you add the HEI and are you using the original power wire? The stock power wire has a resistor in it and won’t give the HEI the full 12 volts it needs. You can de-pin the wire from the harness and replace it with an un-resisted power wire.

Glad you kept the manual; it has lots of helpful info. Get the 1487 calibration kit, and together with the manual, you’ll have everything you need to set it up correctly.

Geezer is correct on the pressure gauge. The heat under the hood doesn’t agree with the liquid filled gauges and makes them read incorrectly. Maybe your Delco inline filter is making the fuel pump work a bit harder, reducing pressure? He’s also correct on your timing numbers too. I let that go since your total timing of 36 is more important than the initial.

I agree with HO455, make sure your ignition system is good to go, then move on to the carb. Test the distributor to make sure you didn’t get a bad unit. It happens.

Thanks again 68 POS. I appreciate the comments, I love the results and progress we've made with the truck but it just sucks that this off idle issue exists.

I did a full rewire using Painless Performance wiring for the kit so every wire on this truck is new. I've also installed over a dozen heavy ground wires at the proper locations and then some so that won't be an issue. The coil wire is a straight feed for the under hood harness from the bulk-head / fuse panel however I'll give it a shot to make sure 12V+ is at the coil.

I will also try lowering the RPM for initial timing to see if that helps as well. I'll check the advance added under vacuum and run without as well under load so I can weigh the differences.

I can then move on to the carb, noting that the floats need to be verified and rejetting is a benefit that should be done anyway since these electric choke carbs are set up for efficiency more than performance out of the box.

Noting the fuel pressure gauge issues, I've heard that too with the liquid gauges.

I will be calling Performance Distributors too so I can run this by them as well since my ignition is all DUI with the exception of the plugs.

Thanks again for the update and added suggestions. I appreciate everyone's help and the comments about the truck.
__________________
1969 C10 Stepside (PERCY - tribute to CDE)
1996 Chevrolet Tahoe 2-door / 2WD LS5.3/4A (ROBYN)
1998 GMC SLE Regular Cab Short Bed Fleetside 4.3/4A (LUCY) (driver)
2000 JEEP Cherokee Sport XJ 4x4 4.0/4A (RUBY, son #2)
2013 VW GTI Driver's Edition 1.8T/6A (GRAU GEIST, son #1)
2016 BMW X5 xDrive50i MSport 4.4L N63/8A (SCHNEEWITTCHEN)
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