Well
FE fans, here it is, the last segment of the 428 buildup. We wanted
the final article to not only cover the last few steps in building
the engine, but to also reveal what the engine ran at the strip.
So two weeks ago our FE guru, Victor Silva, finished up the engine
and loaded it into his Mach1. We broke the engine in for about an
hour on a Friday evening, and had our first timeslips the very next
Saturday. How's that for trying to meet a deadline?
Unfortunately, things did not go without some "minor"
complications. After breaking in the Crane solid cam for over half-an-hour,
we noticed two of the sixteen rockers arms had loosed up significantly.
It is expected for the lash setting on a solid flat-tappet cam to
need readjusting immediately after break-in, but it was odd that
two had loosened up by over twenty-thousandths of an inch. Since
oil pressure looked good, and the engine sounded good, we figured
that perhaps we simply didn't tighten up the poly-locks enough.
So we readjusted all the valves, and called it a night.
The next day we trailered up the car and headed off to Sacramento
Raceway.
A few minutes after firing up the motor at the track, we heard again
what sounded like a loose rocker arm...or two. At this point all
of us, except Victor, were thinking the same thing -the cam was
going flat. But, as all of our mothers had taught us, if you don't
have anything nice to say, don't say anything at all. So we all
proceeded to help Victor readjust the lash three more times over
the course of the evening, before Victor finally agreed the cam
was flat.
So that's the bad news. However, there is good news...very good
news. Even with the intake lobes on cylinders five and six going
flat after each pass, the 428 was making great power. On the very
first run, with Victor baby-footing the throttle and shifting at
a paltry 5500, the car knocked off a 12.50 at 114.
A quick readjustment of the lash on five and six, and the Mach 1
lit up a 12.30 at 115 on it's second pass. Again, Victor's driving
the car with a light foot. Another lash setting -this time we can
visibly tell the lobes are flat, as the two valves are traveling
half the distance of all the other intake valves! On what would
be the final run of the day, the car rips off a 12.18/115 on a 1.80
sixty foot. While this is nowhere near what we expected out of the
428, it was far more than anyone expected with basically only six
cylinders working properly!
We wrapped up the day happy about the promise of much faster ET's,
but scratching our heads as to why a properly broken-in cam would
go flat. To make us loose even more sleep was the fact that oil
pressure at idle was now at 5 psi.
The very next day, with a few hours of restless sleep, Victor began
the investigation. The engine was stripped apart (while in the engine
bay!) and every component was analyzed for possible clues into the
failed cam. While nothing seemed wrong with the cam or lifter bores,
one of the lifters had a hole ground through the bottom! |
According
to Crane, if a lifter gets stuck in its bore during break-in,
and thus can't spin, it will result in a wiped cam. In any case,
we'll send the cam back to Crane for a hardness test. For the
record we've never had any problems with Crane cams, and as
you've probably seen, FORDMUSCLE pretty much exclusively uses
Crane cams. We know we didn't screw up the break-in, so we'd
really like to find out if something in our block (i.e. tight
lifter bore) was the culprit. When we get the results from Crane,
we'll pass them on to you.
As is typical with a wiped-out cam, the oil pump gets bombarded
with filings and metal particles from the worn lobes. We suspected
this as the cause for our low oil pressure, and sure enough
upon disassembly of the oil pump, the pump rotors were scarred
up from the cam disintegrating. We also pulled several main
caps to check for bearing damage, fortunately they checked out
okay.
To get the FE back on track, we put in an old custom Crane hydraulic
cam, which we had used in our 390, with slightly larger specs
(253 degrees duration at 0.050", and .585" lift.)
This time the cam broke-in without any glitches, and sounded
even stronger. Oil pressure at hot idle was at a perfect 35
psi,, letting us breathe a big sigh of relief - it's one thing
to blow a motor, but when thousands of people are expecting
to see the results of your build up...well, let's just say that
this could have been a huge let down.
The following Sunday the Mach 1 visited Sacramento Raceway again
for a local bracket race. Immediately the car nailed a string
of 12.00's. Since this was a bracket event, and since we don't
yet have the car NHRA legal for 11's, we deliberately kept the
car dialed-in at 12.00. Unfortunately Victor red-lit in the
sixth round, so knowing the race was over, he decided to increase
the shift points to 6300 rpm and see what she'd do. This yielded
the fastest ET to date, an 11.88 @ 117. We're very pleased
with these results, especially since this was accomplished through
the mufflers, with no carb tuning whatsoever! The previous engine
would run two to three tenths faster through the headers, so
we know the car is capable of mid 11's once it's all dialed
in.
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