Judging Question?

[Patrick H.]

Re: Judging Question?

Thank you for your reply. My question is how does and engine not designed to run on unleaded fuel survive. These engines do not have harden valve seats. At the very least the heads would have to have harden seats installed. Where do you find 93 octane. The best I have every found was 92 octane and the next option would be race gas. I am in Southern California living around the eco friendly crowd wack jobs.

Even 92 will work, and it doesn't take much "race gas" added to your tank for 92 to become 93 if you really want.

Regarding the heads, the hardened seats only are useful if your engine will be under high load conditions for long periods of time. Getting back to my previous post about your engine, just how many miles are really going to go on it?

I've found that valve seals and also valve guides are the items mostly likely to need repair on an engine with miles like to yours. My experience is with small blocks but I would suspect that big blocks may be similar.

[Michael H.]

Re: Judging Question?

Even 92 will work, and it doesn't take much "race gas" added to your tank for 92 to become 93 if you really want.

Regarding the heads, the hardened seats only are useful if your engine will be under high load conditions for long periods of time. Getting back to my previous post about your engine, just how many miles are really going to go on it?

I agree with Patrick. I rebuilt the 425 HP in my 66 about 25 years ago and we've driven that car all over the counry. (about 40,000 miles so far) I did NOT add hard valve seats. Absolutely not necessary for a somewhat limited mileage car in my opinion.

Most engine builders won't agree though.

[Paul J.]

Re: Judging Question?

David:

I agree with the others that 93 octane is fine and you can certainly get by with 92. Like John said, you have tune it properly. If you still feel uneasy about unleaded there are people in Driveline advertising additives containing tetraethyl lead, or you can use some of the much cheaper lead substitute products from STP and others. I don't know if any of these products really help but I use them because I'm an old school hot rodder and it gives me peace of mind.

Paul

[David J.]

Re: Judging Question?

It is unfortunate that there is a popular myth regarding the need for leaded fuel in older cars to avoid engine damage- it's false.

As John has stated your car will run fine on 93 unleaded.

BTW- what's the strange looking addition to the radiator overflow hose?

The previous owner made a coolant recovery bottle and that is what you are looking at. He also revited the splash shields into the inner fender panel. I would have to replace the panel inorder to correct the problem.
Not sure if it is worth it.

[David J.]

Re: Judging Question?

David:

I agree with the others that 93 octane is fine and you can certainly get by with 92. Like John said, you have tune it properly. If you still feel uneasy about unleaded there are people in Driveline advertising additives containing tetraethyl lead, or you can use some of the much cheaper lead substitute products from STP and others. I don't know if any of these products really help but I use them because I'm an old school hot rodder and it gives me peace of mind.

Paul

Thank you for your response. I guess with all of the information I have been provided I will have to rethink my original plan. When you say tune the car properly what exactly are you referring to. Beside the basics and I mean correct timing, correct heat range spark plug , vac advance is operating correctly. carburetor has to be adjusted correctly example Float level, idle mixture, idle speed, choke operation. Is there some thing I am missing ?

[Michael W.]

Re: Judging Question?

Thank you for your reply. My question is how does and engine not designed to run on unleaded fuel survive. These engines do not have harden valve seats. At the very least the heads would have to have harden seats installed.

David,

For many years people believed that 'bad things' would happen without lead, one of which was accelerated valve seat wear due to micro-welding between the valve face and seat. GM added to the beleif by case hardening the seats from 71-ish onwards.

Despite the tens (hundreds?) of thousands of performance motors still in service, there's yet to be a confirmed case of valve seat wear due to lack of lead. The engine simply do not run hot enough for long enough to achieve the temperatures required to initate the problem

Forget the lead, it's dead.

[David M.]

Re: Judging Question?

You don't have to replace the whole panel just to fix small rivet holes. You can drill the rivets out then use a counter sink bit on top and bottom ( just a little bit) then use a heavy based resin bondo and put on both sides, this makes a sandwich effect. Then sand smooth, it gets blacked out on both sides anyway. Then you will be ready to go back with the correct staples.

[David J.]

Re: Judging Question?

You don't have to replace the whole panel just to fix small rivet holes. You can drill the rivets out then use a counter sink bit on top and bottom ( just a little bit) then use a heavy based resin bondo and put on both sides, this makes a sandwich effect. Then sand smooth, it gets blacked out on both sides anyway. Then you will be ready to go back with the correct staples.

Thats a great idea. Thank you for your input.

[Paul J.]

Re: Judging Question?

Thank you for your response. I guess with all of the information I have been provided I will have to rethink my original plan. When you say tune the car properly what exactly are you referring to. Beside the basics and I mean correct timing, correct heat range spark plug , vac advance is operating correctly. carburetor has to be adjusted correctly example Float level, idle mixture, idle speed, choke operation. Is there some thing I am missing ?

The only thing that I think you're missing is that you said "correct". If you set it by the numbers you may not get the best performance and might even get some pinging. Some of the others in this forum can probably give you some idea of the right settings, but I tune it by ear. Then I drive it. I primarily work with fuel and air mixtures and timing, after I'm convinced that the plug is hot enough. This takes a while and can be frustrating, but it's the only way that I know how to set up older engines on modern fuel.