ok so here's the thing, i'm not much of a ford guy, chevy's and rotaries i know but not fords.

my little sister wants a 64 mercury comet this particular on has a straight 6, 4 door hard top.

whats the deal with leaded and unleaded fuel, obviously there is no more leaded fuel in New York, unless yo're willing to pay 7 dollars for AVGAS.

So my questions are, what do i do besides stickin an lt1 or ls1 in the thing-is there a "new Model" motor i can put in there while keeping the rest of the drive train stock, is there a conversion of some type to do to the existing motor, if so what does it consist of... I'm thinking to maintain the car as a 6 cylinder/carbed.

most likely it'll be anywhere from an everyday driver to a "hangout" ride for her, she won't be goin down the highway at 150 MPH....

Thanks for your help guys and girls

The only difference unleaded makes to the older engines is with the valves. Until the Gov't started mandating unleaded fuel, manufacturers used softer steel in the valves and seats. Under hard usage, high temperature, they would tend to stick to each other and pull off tiny bits of metal, eventually destroying themselves. The lead formed a soft film that prevented that. That's one reason that engines used to need a specific break-in procedure. They needed time for the lead to build up. The worst that will happen to your sister's car is that the valves will eventually burn and need to be replaced with newer components. End of problem. How long that takes depends on her driving style and the engines current condition. If I remember right, the 6's were 144cid. I suggest you find a head for it at a scrap yard. Should be cheap. Have a shop rebuild it and you can put it on at your convenience. What part of NY? I'm in eastern NY and may be able to locate a head if you go that route.
Hope your sister enjoys the car. In '67 I had a '64 Comet Caliente with a 289. I still miss that car.

If memory serves me, I think they also came with a 170 c.u. straight six. Cat-Man-do, please correct me if I'm wrong.
I had a '63 Comet conv., a'63 Falcon, and a cherry '64 Falcon Sprint with the 289 Hi-Po. Wish I still had that one!

First, a note to the OP: There are lead substitites available to put in the gas. I don't know how effective they are, having never used them. Can't hurt to try.
As far as the 170cid, you are correct. I knew there were 2 different 6's but couldn't remember the 170. I had one in a '62 Falcon beater I used for work. It broke a rod one night on my way home from a night of partying. Ran it for 2 weeks like that till I got around to changing the engine. It vibrated and had even less power then normal, but it ran.

Cat-Man-Do - 27 February 2009 08:32 AM

The only difference unleaded makes to the older engines is with the valves. Until the Gov't started mandating unleaded fuel, manufacturers used softer steel in the valves and seats. Under hard usage, high temperature, they would tend to stick to each other and pull off tiny bits of metal, eventually destroying themselves. The lead formed a soft film that prevented that. That's one reason that engines used to need a specific break-in procedure. They needed time for the lead to build up. The worst that will happen to your sister's car is that the valves will eventually burn and need to be replaced with newer components. End of problem. How long that takes depends on her driving style and the engines current condition. If I remember right, the 6's were 144cid. I suggest you find a head for it at a scrap yard. Should be cheap. Have a shop rebuild it and you can put it on at your convenience. What part of NY? I'm in eastern NY and may be able to locate a head if you go that route.
Hope your sister enjoys the car. In '67 I had a '64 Comet Caliente with a 289. I still miss that car.

Well, unless the car was taken off the road when leaded fuel was taken off the market, chances are someone's been driving it on unleaded gas for years already. So either the valves are damaged already, or have already been redone. Or, by some trick of fate, maybe they're just still good.

You can get lead additive to put in the gas.Another option is to get the valve seats replaced with hardened valve seats.

Mr. dB - 02 March 2009 08:30 PM

Cat-Man-Do - 27 February 2009 08:32 AM

The only difference unleaded makes to the older engines is with the valves. Until the Gov't started mandating unleaded fuel, manufacturers used softer steel in the valves and seats. Under hard usage, high temperature, they would tend to stick to each other and pull off tiny bits of metal, eventually destroying themselves. The lead formed a soft film that prevented that. That's one reason that engines used to need a specific break-in procedure. They needed time for the lead to build up. The worst that will happen to your sister's car is that the valves will eventually burn and need to be replaced with newer components. End of problem. How long that takes depends on her driving style and the engines current condition. If I remember right, the 6's were 144cid. I suggest you find a head for it at a scrap yard. Should be cheap. Have a shop rebuild it and you can put it on at your convenience. What part of NY? I'm in eastern NY and may be able to locate a head if you go that route.
Hope your sister enjoys the car. In '67 I had a '64 Comet Caliente with a 289. I still miss that car.

Well, unless the car was taken off the road when leaded fuel was taken off the market, chances are someone's been driving it on unleaded gas for years already. So either the valves are damaged already, or have already been redone. Or, by some trick of fate, maybe they're just still good.

+1/ That was what I was gonna say, if it's running one of the three apply.

I've heard that unless your running the dog **** out of your engine the unleaded gas would have little effect on heads without hardened seats. Those old low compression, slow turning, straight sixes generally aren't prone to self destructing.
I bought a 72 Cutlass when I was a senior in high school(love those Oldsmobiles ) and ran Sunoco 94, beat arse out of it, and never had problems.
If you want to change the motor, go with an '87-93 5.0L. They're cheap to buy, cheap to build, tons of aftermarket support, and will snap to swap. If you stick with the six, Cliffordperformance.net has heads, intakes, cams, headers and so on... Please don't put a Chevy in a Ford

^ If memory serves me right, the manufacturers started switching to hardened valves and seats in the early '70's. Your Cutlass may have already had them. As far as the Comet, it just depends on it's current condition. Maybe, as someone suggested, the valves & seats have been changed. A good possibility, or maybe it just hasn't had enough use to show signs of any problem. At worst, a simple head rebuild will cure the problem.

^You're right, Olds started phasing them in '70, by '72 they would have had hardened seats.

If I had only had the internet back in '94, think of all the money I would have saved on gas! haha yeah right

Higher octane means more timing Fair amount of timing is a good thing. Advance it till it pings and back it of a degree or two. Wonder if I still have my old dwell meter??? The old Accel Super Coil would smoke through points... sorry, I got to reminiscing

I was a mechanic at the local Ford dealer in '67 when the 1st '68 T-Bird arrived on the lot. Everyone at the dealership was amazed at how cluttered the engine compartment was! If we only knew!