I have some left over zinc additive. Would it serve any purpose to use it in my roller cammed 400?

 

would help keep corrosion and oxidation down, if it sits long periods, in between drives.

 

It will reduce startup wear on the crank bearings.. which is the primary purpose of ZDDP

 

My understanding is the zinc is primarily for flat tappet liftrs and cams. Feel free to enlighten me.

 

I uae Mobile ! synthetic oril but I'm not sure of the sinc in it. some say it isn't the same as it used to be.

 

Ok, this is gonna be a bit long, but I think I can answer all your questions..............Ok, ZDDP is not specifically for flat tappet engine, but, when an engine is fired up, that is when the most damage occurs as you know......ZDDP is the additive that all oils have used for decades to (paraphrasing here) coat the cam/crank bearings since they operate on oil pressure, which is essence lifts and separates the cam/crank journals away from the bearings. ZDDP in essence, acts as a miniature roller bearing to prevent/minimize this wear. (Crankshaft/piston rod bearings are metal "shims" so to speak). Flat tappet engines, the valvetrain suffers from similar impacts as compared to the modern valvetrains or roller cams which in this case have "wheels" they operate with instead of 2 pieces of metal rubbing against each other like what happens with the crankshaft.

The reduction of ZDDP in all of the oils (including diesel) is such that flat tappet cam lobes by appearance, are the first to suffer excessive wear as a result of the lower ZDDP levels. Some high volume cam grinders are claiming new cam failures on initial startup are a result of this, IMHO, I suspect the chinese low carbon steel cam billets play more of a significant role in this than anything else.

To reduce cat converter contamination, the ZDDP in the oils was reduced from around 2000 ppm to about 700 ppm (within the last 5 years if you include diesels), which the engineers advise this is plenty for any engine......but this reduction has paralleled with the increase of flat tappt cam failures, valve tick, etc. The one thing that the aftermarket cam mfgs & machinists agree upon is engines need about 1400 ppm of ZDDP, the newer engines (modulars) with cats, about 1000 ppm. While the oil companies disagree, they added another additive to the oils as a "wear reducer" (the name escapes me now) when they reduced the ZDDP content.

With regards to syn vs non-syn oils, today (which someone will eventually bring up), all oils are are considered synthetic. While I am not promoting this company nor their products, they have an excellent, detailed description as to how & why all oils today are considered “Synthetic” Synthetic Motor Oil and was confirmed through legal proceedings http://www.scribd.com/doc/217558103/...s-Day-in-Court. Mfgs such as castrol, are actually using a oil base that is not by previous industry standards to be even considered a "synthetic", was sued (By Exxon/Mobile IIRR) and they won in court because they were able to demonstrate with additives they were essentially delivering a syn product. When looking at all the refineries in the US (2014), the only one really capable of supporting 100% synthetic oil manufacturing is Chevron/Phillips refinery in Texas…and it is not promoted as a synthetic oil.

When all this 1st started 15+ years ago, I discussed this in detail with Ron Eskenderian (yes, Isky Racing Cams), and I add one bottle of ZDDP to my old school engines and 1/3 of a bottle to my mod motors as well (1997 Cougar Sport 4.6 & 2006 Lincoln Mark LT 5.4)- IIRR it is a 9 oz bottle.

Hope this helps!

 

Thanks, pretty much confirms what i've been finding in my searches. I'm still not sure if I should add it Mobil ! in my rollercammed 400. Obviously a performance engine that isn't driven a lot.

 

Understood! Here's the consideration.... I also have a "toy" that sits... and when an engine sits for more than 2 hours after startup that's where the issue comes to be... when they sit for long to extended duration that where a bit more concern comes to play. as while the bearings will not completely dry out, there is dissipation of the oil coating which can create bearing wear.

What I do with my "toy", much like your's, yeah, she's got a moderate build on her too.... in 1985 I spent $3500 on parts & machine work (assembled this one myself).... so I understand......
To ensure I have a coating on the bearings at startup, I add ZDDP to the oil... ZDDP sticks to the bearings after shutdown... then when I go to start it, I always just spin the engine over till the oil light goes out...(which happens very quickly). Now the carb is typically primed, the oil is throughout the engine and we're ready for fire-up.

Hope this helps!

 

Flat tappet cam cores were/are cast iron, not steel. The real culprit was/is the machining of the lifter faces. They need to be convex (slightly domed) to function properly and not dig into the cam lobes as the lobe rubs across the bottom of the lifter in service. This also imparts rotation in the lifter that further reduces the friction/wear between the two parts

 

Agree!.................................