Which fuel is recommended for an orignal (50.000 miles only) 472 fitted in a 1968 eldorado ?

As far as I know, anything prior to '73 should require lead.

Run unleaded. It won't need lead, however at 10.5:1 or so it will require 93 or 91 octane.

That year won't have hardened valve seats so unless you run a lead additive, you WILL tear-up the heads. Don't be "fuel-ish".

It has been said that with the nickel content of these motors, hardened seats are not necessary.

Leaded fuel isn't needed in the 472 family of engines. The earlier 429's I don't even think required it.

Leaded fuel isn't needed in the 472 family of engines. The earlier 429's I don't even think required it.

That's good, because where the h&ll can you find leaded fuel anymore nowadaysa!!!

they sell a lead additive at autozone and wallmart I figure it could hurt to use it

That's good, because where the h&ll can you find leaded fuel anymore nowadaysa!!!

The airport... ;) I ran a couple tanks of 100LL in my stock 472 without any problems. The exhaust had a nice sweet scent to it too...

so a 74 472 should run on unleaded without any headwork?

As far as I know, anything prior to '73 should require lead.

I read that my Dad's 442 had the hardened valve seats in 1971, but I'm not sure if all GM cars that year had them. 1971 was the earliest year that I've heard of.

so a 74 472 should run on unleaded without any headwork?
Yes, any '71 and newer can.

To meet emission standards specified in the Clean Air Act of 1970, automobile manufacturers introduced catalytic converters requiring un- leaded fuel beginning in the 1975 model year. The Environ- mental Protection Agency (EPA) issued regulations in 1973 establishing requirements for the availability of unleaded fuels and, as the new cars entered the fleet, unleaded gasoline began to displace leaded fuel. EPA continued the lead phase-down, further restricting the lead content of motor gasoline in 1982, 1985, and 1986. The Clean Air Act Amendments of 1990 banned lead use entirely, effective January 1, 1996.
'68 engines were not designed to run on un-leaded fuel.

Kev

I am repacing a 1974 with a 1969 472. I intend on running Hi Test (93 Octane). Do I really need to add lead, and if so, how much per tank (25 gal).

I am repacing a 1974 with a 1969 472. I intend on running Hi Test (93 Octane). Do I really need to add lead, and if so, how much per tank (25 gal).
You don't need lead....period.
As for the octane needed....unless the engine is a high compression engine, premium fuel is a waste of money. Would you happen to know what pistons were used in the rebuild of the '69 472?

10.5:1 is stock for 69 so unless you know it's been rebuilt with a lower CR use whatever premium is in your area.

The engine is a low budget $156 replacement from a junk yard. I did hear it run and it was strong and did not smoke. I intend to just drop it in after all of the periferals are replaced. It should be a 10.5:1. I have convinced my son to not use the '74 heads, but stay with the '69 as it was.

We have 92 and 93 Octane in Ohio.

If its just a wrecking yard replacement I wouldn't worry too much about getting hardened valve seats. It'll eventually wear down some, but it'll do it without changing the seats too...just takes a bit longer. Put it together and don't worry about it!

The early heads are a small chamber head. The '74 heads are a larger chamber head. Swapping the two will give the engine really low compression numbers.....lower than what you want. Leave the original heads on it.......they should be a xxxxx250 casting. The seats should be fine as they are. You will have to run high-test fuel though.

I have run regular unleaded in my 69 472 with no problems.

A 10.5:1 engine on 87 octane with no detonation?

No detonation. HEI with 10 degree vac. advance can and go go go.

Well I remember reading something on the CB7 about the early engines not being as high in compression as advertised..

By detonation we mean what is commonly know as "ping"?

Correct. Now out of curiousity, has your engine ben rebuilt, or maybe had the heads off? Older engines tend to get octane creep due to carbon deposits, and the octane requirements go up with age. Also, driving style might be a factor. I can tell immediately what grade is in my car on the first takeoff.

Regarding the nickel content, I thought the heads were plain ol' cast iron, and the block was made out of the nickel alloy?