I was able to compare my '71 MGB engine parts with Scott Fisher's known stock
'71 MGB engine parts last night and the verdict is in:
ALERT ALERT ALERT
Car: MGB
Part: Pushrods, long, aftermarket chrome molly.
Vender: The Roadster Factory
Manufacturer: Unknown
Problem:
The pushrod cup that pushes against the ball end of the adjuster screw on the
rocker arm tapers down to a smaller diameter than the adjuster screw ball. The
Adjuster screw ball rides on the tapered sides of the pushrod cup.
This results in the sides of the pushrod cups breaking, dropping small metal
chunks down onto the lifter and cam followed by catastrophic failure of the
pushrod :^0
SYMPTOMs: If the pushrod on an intake goes, one cylinder suddenly stops
working. If a pushrod activiating an exhaust valve breaks, everytime that
cylinder's spark plug fires, the explosion travels out the cylinder, into the
intake passages and out the nearest carburator. You suddenly lose power and it
sounds like your engine is about to go for the long distance piston throw
record.
Some history:
I have a '68 MGBGT that does not pass its SMOG test, even after a new valve job
and Roadster Factory refirbished SUs (Excellent job). I took it to to my local
English car mechanic who deturmined that the famous dreaded previous owner had
installed an aftermarket cam. By loosening the valve lash and retarding the
timing he was able to get the car's emmissions down to acceptable levels for
about 30 seconds before it drifted too high. I ordered some new exhaust gaskets
and lower header to transmission clamp (mine was missing - see: dreaded previous
owner). One of the cups on a pushrod broke from the excessive valve lash before
the parts came in and I was to go back for further SMOG adjustments. I ordered
a pushrod from Moss and was accidently sent a pushrod for a Spridget (it was in
an adjacent box, i'm told). Several calls to Moss and the Roadster Factory
varified that 1. I had the wrong part sent. and 2. The engine in my car is a
'71 that came with long pushrods and not the short ones I had originally ordered
from Moss believing I had the original engine (see dreaded previous owner).
I ordered a set of chrome molly long pushrods from the Roadster Factory. I
noticed that the cups were taller and shaped differently from the pushrods in my
car (which were also after market chrome molly pushrods installed by the dreaded
previous owner). I installed them, retorqued the head, adjusted the valve lash,
idled the engine for about an hour, then retorqued the head & reset the valve
lash.
The pushrods lasted about 200 miles before two damaged pushrod cups caused the
engine to stop working.
ALL the parts that broke off the pushrods fell down the pushrod tubes. Fishing
around with a magnet on a rod got one large chunk out of one hole and small
chunks out of both holes. I estimate that I was able to retieve about 1/3 of
the lose metal. The rest of it went down onto the lifters, cam and beyond :*(
Last night I took my rocker arm assembly and pushrod collection to Scott
Fisher's and compaired them to his known stock parts. The adjuster screws are
the stock correct part for my '71 engine (at least the previous owner left
someting alone). The pushrod cups on my old pushrods matched the shape of the
stock pushrod cups.
So the problem is with the aftermarket pushrods. Looks like I'm in the market
for another set of pushrods AND crossing my fingers that the metal debris has
not caused damage to the bottom end of my engine.
TeriAnn
Why me?
TeriAnn Wakeman One of these days, I'll be old enough that
twakeman@apple.com people will stop calling me crazy and start
LINK: TWAKEMAN calling me eccentric.
408-974-2344 TR3A - TS75519L, MGBGT - GHD4U149572G, 109 - 164000561
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