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Hi, after four years of searching, I am picking up my first 327 solid lifter C2 in a few weeks with a full factory drivetrain. The long-time owner tells me that the engine is very original with 75k miles and has not been rebuilt thus it does not have hardened valve seats (he has been adding a lead additive to the fuel).
- What should I add to the fuel at full ups?
- Also heard that you should also include an additive to the oil at changes. If so, what additive(s)?
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Answers to these and all other questions you can think of are in the links listed in the FAQs thread up in the Stickies at top of home page. https://www.corvetteforum.com/forums...aq-thread.html
Short answer, you don't need hardened seats, even with no lead fuel. No need for lead additive to the high test gas you run.
No need for any additive in your oil, if you buy hi zinc, hi phos oil, which you can get anywhere including Wally World.
Thanks for the note very good to know. Looking forward to a 365 car. Took much longer than I expected four years ago to find a real car. Any other suggestions regarding 365, please let me know.
My opinion differs from all of the other responses but as far as I can tell I'm the only one, in this thread, that has actually installed hundreds of seats and repaired heads for many years. The car's together so you drive it hopefully to never have an issue. If I were rebuilding I would wholeheartedly suggest hardened ex seats. I've seen what happens. I've posted pics of members here that posted pics of their heads with the seats recessed.
My opinion differs from all of the other responses but as far as I can tell I'm the only one, in this thread, that has actually installed hundreds of seats and repaired heads for many years. The car's together so you drive it hopefully to never have an issue. If I were rebuilding I would wholeheartedly suggest hardened ex seats. I've seen what happens. I've posted pics of members here that posted pics of their heads with the seats recessed.
If you have installed hundreds of seats in old heads, how many of them ended up being anchors because the cutter breached into the water jacket?
I had 2 sets of 461X heads, one set dated the day engine was built and one set dated a month earlier, So I decided to use the month earlier heads, even though they had not come with the car.
I was given the pitch of hardened seats. The next day I was informed that the heads were boat anchors. From that day forth I swore I would never touch another old set of heads
So my opinion is, if additives work, as they appear they do, do not take a chance on ANY machining . 50+ year old heads should not have one micron of metal removed for any reason other than valve seats. and, even then, remember, machining the "new valves" remove the only hardened surface you ever had, So do anything and everything else that you can before changing valves.
Contrary to the opinion of some apparently, these cars are special. Very special to some of us. If they weren't, we wouldn't pay $50,000 and up for them Old Chevrolet cars can be had much cheaper than that. I think most of us drive them infrequently and when we do, we are not routinely running them up to redline. We are not abusing them all the time like was the case in the 70s and 80s when they truly were just old Chevy cars. My feeling is that when they are only driven 500-2000 miles a year and usually carefully and conservatively with limited bursts of higher rpms, there is little likelihood of hammered valve seats. Others may have a different opinion
Contrary to the opinion of some apparently, these cars are special. Very special to some of us. If they weren't, we wouldn't pay $50,000 and up for them Old Chevrolet cars can be had much cheaper than that. I think most of us drive them infrequently and when we do, we are not routinely running them up to redline. We are not abusing them all the time like was the case in the 70s and 80s when they truly were just old Chevy cars. My feeling is that when they are only driven 500-2000 miles a year and usually carefully and conservatively with limited bursts of higher rpms, there is little likelihood of hammered valve seats. Others may have a different opinion
when I say they are not special its to the point that the ware items are common chevy parts found at any parts store. Its not like a Italian super car where a oil change can set you back around a grand and even more for other ware items. In collectible aspect they made a bunch of them. With that said they hold a very special place in peoples heart and memory's. Most of the memory's dating back to when the owner was a kid (when every that might be). So enjoy them how every that may seem fit. weather that is a garage queen, fun driver, a track monster or what ever your budget sets it at.
If you install them correctly you don't hit water. Yes I had to learn this as well. I cut through about 3 heads a BBC, an SBC, and a Ford. None of which were valuable heads. To do it correctly you must install the correct diameter and most importantly depth seat. Then the seat also must have a radius on it. Your cutter for machining must have the radius also. With all of these things done you don't have to worry about hitting water. What I have seen over the years is old heads untouched have very wide worn seats that have a harder black surface to them. This comes from use the heads never had any type of hardness preparation. When you do a fresh valve job this is gone and the head is more likely to have the micro welding happen.
This is a late vortex head I did a valve job on. This is typical of any unleaded fuel engine. The valves and seats of any of our current vehicles, I'm talking new stuff, look like this. This is what unleaded fuel does and why hard seats are used. The continuous picking up of seat material by the valve is what causes the erosion.
These are pics of 2 different forum members heads that were at machine shops being rebuilt. These are not truck heads being used to haul heavy loads, these are corvette heads being used as corvettes should be. These are not examples of bad valve jobs where the machinist just sunk the seats in the heads this is what valve seat erosion looks like it is precise and sharp because the valve is removing metal as it operates. It only removes metal that it touches which is why the edges are sharp. You will notice that the intake seats are not sunk into the head whereas the exhaust are due to micro welding which is heat causing the valve to pick up microscopic bits of the head with each cycle. If you look you'll be able to see both of these heads, one a 461 casting and the other a 462, at 2 different shops in different areas of the country have been rebuilt in the past. Both have had replacement guides installed when they were previously rebuilt.
If you care to learn you will notice the intake seats are still very narrow as they should be even before regrinding. The exhaust seats have eroded to the full width of the face of the valve and will continue to sink either until the hydraulic lifter is bottomed out or you can't adjust the solid any longer. Now these are facts what anyone chooses to do with the info is their business. Have we fully whipped this dead horse enough, hardly this question will be back in a month or 2. My repsponse. Will be the same then and I will keep repeating it to try and educate members willing to look at facts. Oh did I mention EVERY cylinder head produced since 1973 has hard seats, that's EVERY Chevy, Ford, Dodge, Mercedes, Toyota, Volkswagen, Porsche, Briggs and Stratton, Lycoming, Continental, Honda, Kia, every Brodix, Dart, World Products, Air Flow Research, Trick Flow, and any other I forgot to mention. They didn't do this because someone thought oh this might be a good idea.
Last edited by Robert61; Jun 21, 2020 at 10:08 AM.
I will still maintain that while hardened seats are desirable, there is an extreme risk to cutting 461x heads and a moderate risk to 461 heads. The reward/risk for the intended use on the majority of C2 engines with rare correct dated heads isn’t worth it. I have a pair of 461x heads to prove it. Cut for the smallest insert available to correct a corrosion issue on 2 exhaust seats, both leak, 100% failure rate.
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