slant and leaded/unleaded gas

-
R

rdb

Well-Known Member
Joined
Apr 25, 2012
Messages
173
Reaction score
2
Location
Maryland
Well we know the slant in my '64 Dart is a later one probably early 70s. Does that make any difference from the original one as far as the problem w/ no more leaded gas... actually when was it.. 1980s? that leaded gas was phased out?

Should I be using an additive of some sort in this engine? Any recommendations on what and how often?
 
No-lead was introduced in '72-'73 and required to be offered at all gas stations in '74. (CA may have been earlier.) Hardened seats came into being in about '73.

Per the experts on slantsix.org I do believe, the /6 heads had a pretty good nickel content, and did not need much hardening. And with the weak stock valve springs, the /6 is pretty easy on everything (And sticks the valves pretty easily too, like so many older low HP engines).

So if you are staying stock, I would not worry too much about it. My local old time machinist does not, and my '62 with 60k miles are overhaul showed no signs of valve recession. (But it only had 3k miles on it beyond '72 with no lead fuel, so is probably not the best example.) I did not get hardened seats at the rebuild last Jan due to all the above.
 
Yes, valve recession proved to be not much a problem in many engines, especially ones not driven hard often like steep mountain roads. It is fairly easy to monitor in a 60-70's slant w/ solid lifters since it would reduce the exhaust valve stem gap. If you do find you need hardened seats, it wasn't very expensive when I did that in my 1965 Newport when having the heads redone in 2001. I recall only ~$10 per exhaust valve, but that was in Atlanta, so probably more here in high-rent NorCal.
 
I didn't remember the /6 had a mechanical cam, but when a Dart I had would slowly lose power and stop running as it warmed up a year or two after I got it, I checked the lash when warm, and it was zero. I figure the valves were recessing.
 
Slant was mechanical from the get-go until 81, when they literally dropped hydros in there and changed the head (not mandatory but it got a different valve cover too) The hydros got oiled with the same old oil path but were fed from the top via hollow pushrods AMC/Magnum style. so to change to hydros youll need the cam,lifters, pushrods and rockers. Regrinds are available hydro or mechanical.
 
Unleaded was mandatory to have available by 1974 for the obvious reason that cars
started using catalysts and then O2 sensors.I worked for a friends dad in '87-'88 between my
wrenching jobs, we serviced gas stations and shops for a local oil co.,which was a fun job to
have... we did almost everything.One of our tasks was to re-decal the pump cabinets,and to
change the leaded reg. pumps from red to blue,the higher grades were lead free for a while
by then.Of course the tetraethyl lead had been mandated to be below a certain ppm level
at that time, and the reality was those who purchased leaded reg. were basically getting un
-leaded w/ barely a trace of lead added for 3 mos. prior to that point.
I believe the consensus is that in most applications,the lack of lead has not had
the degree of negative impact that was expected,and that is my experience, even w/ o/s
valves and no hardened inserts.If you are running stock valve sizes,many OE seats were
induction hardened enough to handle a valve job or two,and will be fine.
 
You must log in or register to reply here.
-

Back
Top