A
Anonymous
Guest
Just bought a 67 coupe w/inline 200. Do these run on unleaded or do I need to mix in lead?
It will depend on the head's age and what your intended driving regime is.
Light use on any motor - not to worry about it. Heavy use on an older but original motor - either add the "medicine" to your fuel or have the head rebuilt with hardened valve seats.
Should your engine have been retrofitted with a 1976 or later head, you'll find the valve seats are already hardened, and you're good to go.
Regards, Adam.
Light use on any motor - not to worry about it. Heavy use on an older but original motor - either add the "medicine" to your fuel or have the head rebuilt with hardened valve seats.
Should your engine have been retrofitted with a 1976 or later head, you'll find the valve seats are already hardened, and you're good to go.
Regards, Adam.
My old iron runs on unleaded fuel just fine.
8)
8)
pedal2themetal45
Famous Member
Yea Jonny Ray It well run fine but its what you can't see or hear thats hurting the motor. It was the lead in the old gas the lubercated the valve guides. So with less lead the are running hardend valve seats and guides.. Check you head ID code it is D6 or higher you should be OK.
tim
tim
Jamie Miles
Well-known member
I have been running unleaded in the 1974 250 thats in my '72 Maverick for over 20,000 miles with no problems. The guy who had the car the engine came out of before me ran unleaded in it for years also. The engine is totally stock and never been rebuilt.
When did ford start switching to hardend/unleaded stuff? 74 would have to be in the range of the change over. By 76 all american CARS were unleaded with cat converers wernt they?
Like someone pointed out to me when I asked that question, back in the 60's it was rare to get 100K out of an engine without at least a 'valve job' so chances are at this stage 40 years later many of these engines have been apart. From what I understand a higher compression (vs. the early model t's and farm equipment that was 5:1 or lower) engine if it worked at all will develop valve/compression problems without lead in a fairly short peorid of time like a few thousand miles? At first the lifters will compensate but at some point the valves just wont seal.
The shop manual for my 73 cadillac says that 'low lead' and 'no lead' fuels are fine. Im not sure if that was a GM wide thing or cadillac just trying to stay ahead. My '76 mercruiser book says to use lead but I never have, back then it seems that all the little motors were GM and the V8 were mostly fords. Not sure if they would have built the 'marine' heads differnt. I would imagine they were exempt from all the emissions back then so maybe they wanted to get the most out of the old molds before they converted? When did they redesign the 200 head? Maybe thats when they changed?
TJ H
Like someone pointed out to me when I asked that question, back in the 60's it was rare to get 100K out of an engine without at least a 'valve job' so chances are at this stage 40 years later many of these engines have been apart. From what I understand a higher compression (vs. the early model t's and farm equipment that was 5:1 or lower) engine if it worked at all will develop valve/compression problems without lead in a fairly short peorid of time like a few thousand miles? At first the lifters will compensate but at some point the valves just wont seal.
The shop manual for my 73 cadillac says that 'low lead' and 'no lead' fuels are fine. Im not sure if that was a GM wide thing or cadillac just trying to stay ahead. My '76 mercruiser book says to use lead but I never have, back then it seems that all the little motors were GM and the V8 were mostly fords. Not sure if they would have built the 'marine' heads differnt. I would imagine they were exempt from all the emissions back then so maybe they wanted to get the most out of the old molds before they converted? When did they redesign the 200 head? Maybe thats when they changed?
TJ H
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