proform one-wire ignition
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proform one-wire ignition
87-F250-4X4-351W-4bbl
I replaced the duraspark ignition with proform 6003 one-wire HEI distributor/ignition. Engine starts and idles okay; but under load or at high (3000 rpm) engine pings, knocks and runs like a dog. Also, can't climb a hill! I think the mechanical / vacuum advance is way out of wack. Has anyone had any experience with the proform HEI system?
Engine vacuum at idle is good (18-20" Hg); vacuum advance from carb (Holley 4160) appears okay.
Thanks, John.
I replaced the duraspark ignition with proform 6003 one-wire HEI distributor/ignition. Engine starts and idles okay; but under load or at high (3000 rpm) engine pings, knocks and runs like a dog. Also, can't climb a hill! I think the mechanical / vacuum advance is way out of wack. Has anyone had any experience with the proform HEI system?
Engine vacuum at idle is good (18-20" Hg); vacuum advance from carb (Holley 4160) appears okay.
Thanks, John.
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Sounds like the timing is too advanced. I would keep turning it back till it quit making the noises. Then check the timing. If it seems way off with the numbers, your outer ring on your crank balancer could have slipped a little bit. Tuning it by ear and road test is the best anyway though.
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When I set up the timing I manually / mechanically located TDC on #1 cylinder; the timing mark @ zero degrees and the pointer on the cover were well aligned, so I think the balancer is okay. The tag under the hood calls for 8 degrees BTDC; I have reduced it to 4 degrees and 0 degrees with little improvement. Should I try the "dark" side of TDC?
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Do you have the original factory carb, and the egr disconnected? What temp thermostat are you running?
Having the original carb, and the egr disconnected will make the engine run lean and the combustion chamber temps will be high, causing it to ping. Headers and dual exhaust will only make it worse.
I had to go up three jets sizes in my 2bbl 351w, and go to a 180 degree thermostat. I also went with a colder sparkplug. All this started when I put headers on it. Mine runs good now, with just a slight hint of a ping after I get off the interstate(The condition seems to worsen after driving on the interstate for awhile). But I was able to keep the timing at about 10 degrees BTDC.
You are right in the middle of a mess right now if you have the factory system, and have changed something. The whole tune of the engine will have to be messed with to get it right.
Having the original carb, and the egr disconnected will make the engine run lean and the combustion chamber temps will be high, causing it to ping. Headers and dual exhaust will only make it worse.
I had to go up three jets sizes in my 2bbl 351w, and go to a 180 degree thermostat. I also went with a colder sparkplug. All this started when I put headers on it. Mine runs good now, with just a slight hint of a ping after I get off the interstate(The condition seems to worsen after driving on the interstate for awhile). But I was able to keep the timing at about 10 degrees BTDC.
You are right in the middle of a mess right now if you have the factory system, and have changed something. The whole tune of the engine will have to be messed with to get it right.
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New carb & manifold
I installed new Holley 4160 and new Weiand Stealth dual-plane manifold; also, disconnected those pesky pollution pumps; running 180* thermostat.
Is there a typical advance curve for 87-351W available?
Is there a typical advance curve for 87-351W available?
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Is there a typical advance curve for 87-351W available?
Did these problems start when you put this new equipment on the motor? Did it run ok before? I assume it had a holley 4bbl before the switch.
What I would do first is disconnect the vacuum advance, and leave it disconnected till you get the rest of the timing correct. The vacuum advance is for gas mileage only, not power.
I looked up and read a little bit about the dist you have, and am wondering does it take the standard springs and weights the original GM did? If so, you might want to start experimenting with lighter weights and or stiffer springs, so the timing doesn't advance as fast, causing it to ping.
If you get it all dialed in, then the last thing would be to hook the vacuum advance back up, and tune in as much as you can without it pinging. I see that your vacuum advance is adjustable.
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