Leaded or unleaded for '57

[dn010]

Hello everyone. As the subject states, how much harm will I do if I run unleaded in the original 365? I have new valves and ground seats but if the engine was not designed for unleaded - the seats are still soft and would require the lubrication. Thank you for any help.

[Wayne Womble 12210]

No need to worry at all. It will not be a problem.

[Otto Skorzeny]

What he said.

My '56 burns unleaded without any problem. It's my daily transportation.

It's a bit of an overblown myth about the lubrication of the valve seats requiring leaded fuel. While I don't dispute that the lead helped, the over-all negative effect of unleaded fuel on old engines will be marginal at the worst.

By the time your valves show any ill effects from unleaded fuel (if they do at all) it will be time for an engine overhaul anyway, and that will be 150,000 miles or more away.

[Philippe M. Ruel]

Unleaded fuel is a terrible thing for old european engines featuring valve seats inserted in aluminum alloy cylinder heads, and running at 5,000 or more rpm.
My 1971 Peugeot 404 stopped working when exhaust valve seats recessed up to 4 mm (5/32", no mistake) into cylinder head. I exchanged the head 2 years ago, and valve seats are recessing back again.


Relatively slow U.S.-manufactured engines with integral cast iron valve seats will handle unleaded fuel for a looong time before failure.

[Otto Skorzeny]

Is it possible to have hardened seats installed in aluminum heads, Phillippe?

What about lead additives from the local parts store?

[Dave Shepherd]

Most info out there points to high speed driving, racing,  (LOL), or pulling a trailer as being issues with valve seats, I would say normal driving, short of 100 mile 70 mph interstate trips, that unleaded shouldn't be a problem, to salve the worries use the synthetic additive avalaible.

[dn010]

I only drive about 12 miles a day, 2 trips of 6 miles so I was not too concerned but still concerned. I didn't think it would be too bad on the engine, but it is nice to be reassured; it is a pain to put in lead every gas stop anyway. I wish I could travel 70+MPH for a length of time, I don't have too much faith in the steering to go fast for a long time. Currently my power brake booster just gave up with the piston stuck on stroke leaving my brakes locked so I won't be driving anywhere for a while.

[kelly]

My question to dn010 is simple. When I sought out a source for new valves for my 57, I ended up with a very expensive set of Stainless Steel valves, custom made I believe, through Kantor. $240 for the full set. The machine shop that fitted them replaced the guides and put new hardened seats in at the same time. Couldn't have added $60 to the overall cost of the job.  Why would your machinist not have just done new seats as a safety measure? Since they did (or didn't do) the work, ask them the question you are posing here.
  Iv'e seen valve seats on older vehicles, that were worked hard, pounded in to the point of no longer sealing, running unleaded fuel, and you have people here saying it is not an issue. But I guess I fall on the side of caution when I'm having the work done anyway. If you get good service out of "ground seats", you will have an opinion to share with us. If not, you will find a better shop to do your work in the future. No easy answers to be had, I would surmise at this point. If it goes badly, deal with it. If it doesn't, you won't have to. It's never "roadside sudden and catastrophic" with valve seat wear. Best wishes, and good motoring.
Kelly Martin
1957 Fleetwood 75
Michigan

[dn010]

Are the valve seats not part of the heads on the 365? - I was under the impression they could only be ground. I have never seen any seats for sale anywhere, hardened or not. It is difficult to compare a destroyed old engine's valve seats to a 365, as they may have had a different kind of lifter system some of which are harder on valves and seats, and it is difficult to view valves and seats which are destroyed not knowing the history behind the engine and the abuse the engine had from it's operator unless the engine was yours from the beginning to end. Nonetheless, the reason the shop did not change the valve seats is because there was no shop working on these particular heads to begin with. I have two 365 engines, one early engine with high miles and one late one with lower, both from '57. The high mileage engine's valves and seats were nearly destroyed after years of sucking in dirt, apparently being driven with no air filter (and no oil filter as well for that matter!) and the lower mileage engine had nice heads with great seats. I had a set of NOS valves on the shelf for years so I didn't need to spend a ton on the stainless valves although it would have been nice to have them instead. I ground down the valves to spec, installed the new valves and they seated with dimensions described in the manual. While I don't have brand new machinery or machining technology, I have equipment that gets the job done. The engine was rebuilt (along with the high mileage engine aside from the sad heads), test run and there are no leaks or any peculiarities. I will eventually fix the other set of heads and place them on the other rebuilt engine, that way if I ever have a problem I can just drop the second engine in and keep going. I have the same deal going for my Ford, 2 spare rebuilt 5.0 engines just sitting in case they are ever needed.

I would also like to mention that I have been running these ground seats for a months daily on unleaded with no issues (I was just concerned with issues to come in the future). I have machined several other valve seats on my current cars years ago and still have no problems. The Cadillac manual gives you specifications on where to grind your valves to so don't be afraid of grinding them.

[Otto Skorzeny]

Any competent engine rebuilder will be able to install hardened valve seats on any cast iron engine.

[TJ Hopland]

I thought seats was something that shops had in a basic assortment and they were not make or model specific.   Seems like I remember them being only a couple of styles and then different diameters.  After they are installed they then cut them to what ever is need to match the valve which is what you would do even if there was no insert.

I have also heard the same thing about lead, its not worth worrying about unless you have a high performance engine that you are regularly pushing to its limits.   

[dn010]

I was previously only under the impression they could only be ground for '57 365 specific heads, but they obviously can be replaced as Kelly described already having them replaced in the heads. Besides, anything is possible with engines these days. I know that some seats are easily replaceable and vehicle specific; as far as a generic assortment I am not sure how the seats come but I know it would be beyond my capabilities to install them on the 365 heads with my equipment. Thank you kindly to all your posts and info everyone, keep it up!

[Dave Shepherd]

Keep in mid the exhaust valve seats aare really the only issue here, the intakes do not recede or deteriorate from no lead, heat is the issue, of course.

[kelly]

Dani,
  Just remember, it isn't bad until it's bad. Won't cost any more if you do have a seat problem in the future than it would to do a repair you don't presently need. Just drive and enjoy. If you set up a back-up engine, probably worth the expense to have hardened seats installed, for peace of mind if nothing else.
Kelly

[dn010]

Kelly - Thank you for the advice, I'll definitely look into a shop that can install the hardened seats in the extra set of heads I have. It will be a while before I build up that 365, prices for bearings for it are really high so I usually wait until someone has some NOS ones to sell for less. Thanks again!