Topic: 351C gas and oil question

[TheJ]

I have a 73 351C do I need to use a lead additive in the gas?  Also I was talking to a local engine builder and he recommended that I use a zinc oil or zinc additive in my oil.  Do I need do use either of these additives in my engine?

Thanks

[ol dirty doug]

you only need the lead additive if you do not have hardened exhaust valve seats in your heads.  i do not remember the year ford started using them, but most of the time if you have your heads rebuilt they do that as part of the job.

[TheJ]

I do not know if they have been rebuilt and when I had the valve covers off I couldn't tell if they were hardened.  What about the zinc oil, is it needed?

[ol dirty doug]

to be honest i am not familar with the zinc oils, i have always used either mobil 1 regular oil or full synthetic oil even in vintage v8's i use it in a 1940's flat head and run pump 91 octane gas (exhaust seats have been upgraded)

[Jeff73Mach1]

Zinc must be present in the oil for solid lifter cams or the cam lobes will be worn away.  This is true for any engine running a solid lifter cam.

The Cleveland engines have a higher load on the lifters due to the angles created by the canted valve arrangement.  As such it is a good practice to use a oil with zinc in ANY Cleveland engine.

High zinc content will destroy catalytic converters though, so use in engines after 74 is  problematic.

As to the lead substitute additive,  it should be used for track events, and if you are planning to drive your car aggressively.  Cleveland heads do not have a lot of room for hardened seats and usually the 4 V heads, when rebuilt don't get hardened seats unless someone is insistent, as cutting into the water jacket is a bad thing.

For street driving, I don't see it as necessary, though it won't hurt anything.

Cleveland engines have several potential weak points that can be addressed in an overhaul or rebuild.

The stock rods are great, but the nuts on the rod bolts are not great quality and have been known to pull off at high RPM  ARP nuts can be added to eliminate this or you can go ahead and use their bolts as well.

The Stock valves are two piece and likewise at high RPM the head of the valv can separate and destroy the engine.  If the heads are off replace two piece intake valves with one piece units.

You can identify the two piece valves without removing the heads using a mechanic's scope and looking through the spark plug hole at the underside of the intake valve (depending on carbon build up).  If it says ford in an oval-it is a two piece unit in all likelyhood.

Until these items have been addressed RPM's should be limited to under 5500-6000 depending on your risk aversion.

[TheJ]

I have a 2v Cleveland, is there much of a difference between the heads besides the combustion chamber?  This is a more expensive route but are the aftermarket aluminum heads any better than the stock ones?

Thanks for the info

[Jeff73Mach1]

4v closed chamber heads are great for a car with 4.11 gears and up and that is driven like you are a teenager.
2V heads still outflow most any stock small block head with a port matched 4 barrel intake and will actually be better on the street for most people.  All cleveland heads shine as cubic inches are added or as cams allow the motor to spin up the RPM's in the 7000 and up range-as I said it is a lot of fun, but not practical on the street.

Kasse Aluminum heads are great, CHI are supposed to be good, Procomp heads have potential in the hands of a good head builder, but are reputed to be poorly set up  at the outset;

The 4v Open Chamber heads flow as well as the closed chamber heads and there is a myth that they are worse about detonation due to the lack of a "quench" style chamber.  I have run both and the CC heads raise compression a bit, but the OC heads are not detonation prone and the CC heads are no better unless the block has been zero decked.

Building a good set of iron heads will cost about 5-600 bucks with valves, plus the cost or value of your cores.

Aluminum is lighter and can be had for just a little more money, but will require a matching intake in many cases

[TheJ]

For now I think I will keep the heads as is and use a zinc oil/additive and possibly the lead additive provided the availability in my area.

side note: I am a teenager but I probably do not drive like a typical one.  Although this could be because I have a slow car.

Thanks again for the info

[thundertc64]

http://www.summitracing.com/parts/RED-60202/   this is where i get mine