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Mechanic Martyn
Mechanic Martyn, Australia Car Mechanic
Category: Australia Car
Satisfied Customers: 1002
Experience:  Advanced trade certificate in Automotive engineering
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Ford f100 79 model 2wd: I have a 79 model f100 351 clev on

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I have a 79 model f100 351 clev on duel fuel adjusted timing on petrol but it still pings its head off yet on gas no noise and usable power do not have to back off, it's got c6 auto. Thanks mat
What do you have it set on now - how many degrees of advance?
Mechanic Martyn
Customer: replied 3 years ago.

It doesn't seem to matter where its set at as it always pings on petrol but is ok on gas. I can accelerate on gas but on petrol I have to back off on the pedal as it pings too much. Ive adjusted the dizzy in many positions.

Okay - yes I get that but have you been using a timing light to get a reference or have you just been doing it by ear.
LPG will do about 20 degrees or so more advance than petrol without a problem.
The trouble is if you set up for LPG the petrol will pink and if you set up for petrol the lpg will lack power.
There is an electronic box from MSD that does a change over in timing. It's worth the investment.
I have a 84 f100 with a 351c and a electronic distributor in it. I find I set the initial timing to about 6 degrees on petrol. I have an lpg kit for it but I haven't fitted it up yet.
What grade petrol are you using?
I find using an octane booster can help too but it can get expensive.
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