The Stovebolt Site Forums The Shop Area Engine Shop To Lead or Un-Lead

Greetings all,
I've read something a few years ago on this subject but could not locate it. It has to do with what gas to use ( low octane/high octane). I have a stock 1955 235 engine with a single barrel Rochester, the engine was rebuilt by previous owner, however no hardened valve seats
were installed. The rebuilt was about 5 years ago. I've ran the engine through out the years but not hard. The engine seams to idle pretty good, but I'm no expert on these engines, I recall mention of heavy deposits on the valve seats when using unleaded gas? What will this eventually do?
how about adding a lead additive that I've heard about? Jake

I was an old Cavalry Trooper during the late 70's, news images of the 7th Cav charging ahead brought happy tears to my eyes.

The unleaded gas will eventually burn the valve seats and warp the valves. You can buy some instead of lead, or other brand and use it. I had a big bottle that I got at WallyWorld, price wasn't bad there. And it does work.

Fred T,

Wallyworld? autostore? not sure what that is? is there a brand name lead additive for unleaded gas that can be used.
My truck is a sunday driver not a hard driver does damage to the valves come quickly or ?

jake.

Jacob ;
First & formost , _thank_you_ for your military service ! .

The unleaded thing is a red herring , I'm running a stock 235 in commercial service (towing , hauling scrap etc.) and it's never had any valve trouble , either it will or it won't , just drive the damned thing and enjoy it !.

If the valve seats ever recess , then it is time to do a valve job with hardened seats and stainless steel valves but not before and don't worry about it .

If you're planning a rebuild down the road, forget about the lead substitute. If you've been running unleaded through it and it's not giving you trouble, same story. If, on the other hand, you want to keep the existing valvetrain as long as possible, get a bottle of lead substitute. Better safe than sorry.

My preference is 92 octane with a squirt of lead substitute. Zenith-topped 248 runs like new, and I'm not changing the formula until it acts up.

Here is a little write-up about this matter:

http://www.chevron.com/prodserv/fuels/bulletin/unld-gas/

Tim

WallyWorld = Wal-Mart

You mean the place WITHOUT the giant cartoon characters?

Get a bottle of "CD-2" lead substitute. It will say "for off-road use only", but you can ignore that. It will treat 150 gallons (give or take) and has a built in measuring chamber.
Autozone, Kragen etc. About $8 out the door.

According to some grey-beards on the Antique Automobile Club of America website, AMOCO has been offering no-lead gasoline since the turn of the 20th century; tetra-ethyl wasn't added to gas until the mid twenties, and then it was for anti-knock purposes, not valve protection.

The various lead substitutes mentioned won't hurt; my personal favorite is about 6 oz. of Marvel Mystery Oil (also available @ Wally World!) to a 16 gallon tank of gas.

The engines most susceptible to valve damage from lack of lead are high-compression engines run at hard & at high speed for prolonged periods of time.
Are you pushing your stock 'bolt down the interstate at 65 mph for hours on end?

Many engines are ready for a valve job by 100,000 miles, lead or no, at that point (or whenever you
tear your mill down) you can see what kind of shape your valvea are in and go from there....

Be glad you're dealing with an OHV engine here... it's pretty simplt to just yank the head and take it to the machine shop.... MoPar freaks like me, with their flathead-sixes, have to find someone that knows how to do valves in them, and then you've got to send 'em the whole darn block!

Frank McMullen

Frank, I grind those Continental & Chrysler flatheads in the chassis,when the need arises in forklifts.Cleaning the grinding dust out of the ports is obviously very important. The Hall-Toledo "EJ" orbital seat grinder is great for these and any other seats,it is the one seen in all of the old repair manuals that has the offset body and the spring handle on the top side.It delivers a perfect finish every time,with proper stone.Getting back to no-lead,I have not seen too many problems with seats and guides because of it,unless it is run hard and at high speeds.The lead helps to slow the process of the seats and faces pounding out.

I have had good luck with adding a gallon of aviation 100LL to each tank when I fill the GMC up. The 100 octane give me a small boost on the anti-knock factor and I feel better knowing that I'm running at least some lead through the stock 302 mill. I get the 100LL from a buddy who works at the local airport FBO. The stuff he gives me is fuel sumped from aircraft needing fuel tank work. Legaly it can't be put back into the aircraft because of storage requirements but there is nothing wrong with it for the truck!

Fred T, thanks for the wal-mart (wally world) classification, also VWNate1 thanks for your reponse, if i was twenty years younger I'd do it again, Go Cav!

Anyway, the engine was running good using midrange unleaded gas until this weekend, I happened to look down the carb throat and noticed some grayish black residue. I had a bottle of STP carb cleaner close by and poured it down the gas tank in an attempt to "clean" the carb, guess what. massive back fires, flames coming out of the carb, choke closes even at the slightest rev of the engine. what have i done. drain? change carb?

the bottle say's use with upto 14 gal. of gas which it had. Jake.