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Old 02-25-2016, 11:18 AM   #1
WarpathEngineering
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Can you walk me thru this?

OK, let's all make the assumption that I don't know what the hell doing.....it's been a looooong time since I've been this deep in an engine compartment and what I learned as a teenager about working on engines is probably best lost anyway!

The Victim: Recently purchased 1978 Chevy K20 350, 4bbl (#17058503), California emissions, HEI, 4spd manual, air conditioning, 140K miles.

It's Condition @ Purchase: Engine started ok but ran with a rough idle, drove rough and the mixture was very rich.

Work Already Completed:
1) Replaced carburetor with rebuilt carb from Guaranteed Carburator (#17058204)

2) Removed smog pump, check valves, manifold injection tubes & associated piping, A/C compressor & associated hoses, EGR & install block plate

3) Replace and vacuum lines to brake booster, heat door accumulator, vacuum advance, 2 fuel canisters (dual tanks), hot air choke & capped all open ports.

4) Replace dead alternator & intermittent starter.

Work Yet To Be Completed:

4) Tune up with new rotor, cap, wires, plugs (Bosch #7973, gap 0.60), pcv, oil & filter change, belts, hoses.

5) Install Sanderson CC17 headers & dual exhaust w/ h pipe.

What's Up In The Air:

I know that with a manual transmission my initial timing should be set at 8 deg TDC and roughly 32-36 deg @ 2500 - 3000 rpm total timing. My question is, with the age of the vehicle and the likelihood that it is still running it's original distributor how do I check to see if my vacuum advance is working properly? Should and how do I adjust my carburetor? Should carburetor adjustment be done before or after setting total timing if at all? Should all this be performed before mounting the headers? Any thing else I'm missing?

Thanks for the help!
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1978 Chevy Silverado K20 2016-Present
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Old 02-25-2016, 11:39 AM   #2
geezer#99
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Re: Can you walk me thru this?

1. Gap your plugs at .045.
2. Install headers, then tune.
3. More initial timing. Try 14. Adjust mechanical to give you 32 at 3000 rpm.
4. Put vac hose on vac pot and use your lungs. If it snaps back it's working.
5. Vac gauge and adjust mix screws for highest vacuum. Start at 1 1/2 turns out.
6. Timing first, carb second.

Link for your hei mods.
http://www.crankshaftcoalition.com/w...EI_distributor
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Old 02-25-2016, 05:08 PM   #3
Tom
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Re: Can you walk me thru this?

Removing all that cali smog crap will make you a happy man if you can.
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Old 02-25-2016, 05:52 PM   #4
GASoline71
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Re: Can you walk me thru this?

Quote:
Originally Posted by geezer#99 View Post
1. Gap your plugs at .045.
2. Install headers, then tune.
3. More initial timing. Try 14. Adjust mechanical to give you 32 at 3000 rpm.
4. Put vac hose on vac pot and use your lungs. If it snaps back it's working.
5. Vac gauge and adjust mix screws for highest vacuum. Start at 1 1/2 turns out.
6. Timing first, carb second.

Link for your hei mods.
http://www.crankshaftcoalition.com/w...EI_distributor
This^^^

Amazing what getting your timing nailed down before doing anything to the carb can do.

Gary
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My 1972 GMC 1500 Super Custom (Creeping Death) "long term" build thread.

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Quote:
Originally Posted by LONGHAIR View Post
I would never rebuild a 305.
Quote:
Originally Posted by prostreetC-10 View Post
I love using vacuum gauges as part of the carb tuning process. I hook the gauge to the inside of my garbage can and leave it there.
Quote:
Originally Posted by Marv D View Post
Remember Murphys 2nd law of mechanical relationships... "OPPOSING COMPONENTS ATTEMPTING TO OCCUPY THE SAME SPACE, AT THE SAME TIME, GENERALLY END UP OCCUPYING ADJOINING SPACE AT THE BOTTOM OF THE OIL PAN"
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Its cheaper to listen to advice given when you ask for help than it is to ignore everyone and wait for carnage.
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Old 02-25-2016, 08:23 PM   #5
slotard
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Re: Can you walk me thru this?

I'd probably have gotten rid of the evap stuff if I was in your shoes.
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