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post #1 of 4 (permalink) Old 09-01-05, 12:48 AM Thread Starter
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Location: INVERELL Northern NSW Aust
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Timing and carb choice

Hi all
My first post. A little history. I have a cars a 78 Ford update fairlane with the 351 done 340k and a 77 lwb XLT F100 with a brand new "Betta Built" 351 installed 2 weeks ago.

Today I installed a crane cams optic 700 points conversion kit into the bosch/motorcraft dizzy. I think i did it right cause its running ok. I set it up with the timing on zero and after finishing and starting I set the timing at 7 degrees before tdc. Do you think this timing would be ok for this motor? I am running it on premium and it doesn't ping very much at this. I had it set the same when the points were in it. Our altitude here is about 700m above sea level.

Would changing the standard coil for a high output coil help with the new electronic ignition? And if so what brand would be best.

It has a motorcraft 4800 4barrel carb on it at present I think from memory. Would a 600 vac holley give better fuel economy?

I am considering putting the old truck on gas, I have only one quote at present for a duel fuel installation with a 80litre tank and that was $2500inc GST do you think this is a reasonable price and what are your thoughts on running it on gas? The HM gem people told me the motor is set up for gas and premium unleaded but what quality valves and seats they use I don't know. They also told me I should also still run flashlube in it.

Thanks all and sorry for starting off with all the questions.

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post #2 of 4 (permalink) Old 09-01-05, 01:07 AM
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Re: Timing and carb choice

Welcome to FF gunna.

7* timing is nothing huge - but there should be NO pinging - not even a little. This can damage your motor.

Your high altitude 2300 feet would cause a normal car tuned at sea level to run rich. ie: less air, same amount of fuel. This would reduce pinging, as its the lean (low fuel) case that would tend to ping more. You can get your car tuned using an airfuel ratio meter so the jetting is spot on for your conditions. Drop it back about 2* from where the pinging starts.

Try 98 octane premium BP Ultimate, Mobil Synergy etc (not the 96 stuff). Your 351 doesn't have high comp 302 heads on by any chance?

Another thing to consider is your TOTAL timing. You have 7* static timing, but the dissy has a certain amount that comes in automatically as the rpm increases (eg 35*), which would give a total of 32*. This will all be in at ~3000rpm. Mark your balancer and check the timing whilst revving the motor up.

The only gas I like is gasoline. Not sure on prices. Others can help out here.

MSD Blaster 2 coils aren't too bad.

XE Falcon
393 Tremec TKO 9"
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post #3 of 4 (permalink) Old 09-01-05, 06:21 AM
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Re: Timing and carb choice

Another thing to make sure off is that you have 12V @ the coil. Since you've gone from points -> electronic. You'll probably only have 6-9volts at the coil. Which will case an insufficient burn and detonation.

XB Fairmont (street car) 11.07@123.02mph.
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post #4 of 4 (permalink) Old 09-02-05, 03:58 AM Thread Starter
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Re: Timing and carb choice

Thanks for the replys
So the best thing to do for someone who is no expert in this would be to keep advancing the timing till it starts to ping badly then reduce it so it stops, that way it is advanced to the max without causeing a pinging problem? I have noticed previously when it was set at 7 deg before tdc that when I drove the truck down at sea level it pinged badly unless you gave it some throttle to get the vacume advance going and then it stopped ie when going up a hill you had to feed it to stop it from pinging. I run caltex vortex in it which is the best fuel avaliable here in town. Not sure of the octane though might be 95 ron.

I drove the truck to town today which was the first decent trip since putting in the crane conversion. I only drove it down the road yesterday. The truck runs better now than when the points were in it, and it had new ones and a condensor only 1500km ago when the new engine went in.

I could put a multimeter on the coil terminals to check the voltage, is this correct? if it's not 12 volts how can I fix this. The current coil has external balast resistance which was needed for the crane conversion and was already there.

Thanks Scott
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