Good looking motor.
|
Lots of RTV on the back of the valve covers probably to help fix an
oil leak
|
|
Nabil Guffey noticed quite a few header gasket leaks, (Felpro).
|
Time for tear-down: These Crane Gold 1.6 ratio rockers are
very high quality.
|
Right away I noticed something. I have a hunch the rocker body
is hitting the valve spring retainers, (slightly).
|
The rocker outer tip-edge look like they touch......
|
You can see marks on almost every valve spring retainer where the
rockers touched but it is only a slight mark. It's a sort of
1/2 moon mark. I don't remember hearing rocker ticking so this
was probably no problem what-so-ever.
|
Other spring retainers have full circle marks from the rockers.
(evidence that valves rotate while in operation). I think just
a little sanding of the rocker edges will give clearance and fix
this.
|
Photos of the heads. Intake ports look fine.
|
Combustion chambers look fine. they also look to have bone
stock LT4 valves, (which are very good valves).
|
Here is the view of the lifter valley and the oil looks great.
There is no debris what-so-ever.
|
The builder installed debris screens and there is no debris stuck on
any of the screens.
|
The piston tops look normal. They look to be SRP brand
(-16cc).
|
Another view.
|
Very interesting oil pan. (I like it). Nab Guffey thinks
it is a Chevy Truck pan. It has a longer sump area.
|
Very good looking bottom end. No signs of trouble here.
|
More photos of the bottom end. Here is the crankshaft part
number (35340006000). Yes that is a true 4.000" stroke
1-piece rear, 4340 steel Eagle crankshaft. I wondered how a
4.000" stroke could fit under that oil pan.
|
Inside of oil pan. There is no metal or debris. Very
good. The pan is messaged in the back left for stroker
clearance but that's the only area.
|
Looking for a smoking gun. The motor had a rod knock sound at
start up which got quieter after a few seconds. Kind-a sounded
like a spun bearing or just loose bearings.
|
All rods out. The bearings looked like they were pounded from
detonation. But they were all intact and they were NOT spun.
|
The crank rod journals are good. Very good actually. The
bearings used are Clevite H-series by the way, (I'm pretty sure all
were "standard" size but I did not look at all of them for
size).
|
Another view of the crankshaft.
|
Here is where Baker Engineering stamped a logo and serial number.
|
The main caps are off and all the main bearings look great.
|
Here you can see the cam and it looks "STOCK". I
have a hunch that really is a stock GM Impala cam or maybe a
Corvette LT4 cam...(not the Hot cam).
|
Looks like maybe they notched the hub to clear the crank timing
sprocket key. The hub was not so tight on the crank
though. It was way too easy to remove.
|
This LT4 timing set is always too loose.
|
Nothing really wrong. Just that the LT4 set is so
sloppy. You can almost remove the chain by hand.
|
Good view of the main bearings and cylinder bores.
|
Again.
|
Don't know why I took a photo of the cam but here it is. There
are no part numbers on the end or the front. There is just a
GM looking part number behind the fuel pump lobe,
(GMPT-BC-17***142*GMPT-BC-17***14_2). It has that stamped and
the "14_2" looks like maybe it is
"1422". Well, whatever. It is about a
.460" lift lobe.
|
Never got a good photo of the pistons before taking to the machine
shop. About 4 of the pistons have skirt shrinking and
scuffing. (talked about that while at the machine shop). The
Lunati rods look very nice.
|
While at the machine shop we found the piston to have 1.150"
compression height so that looks up to be part number 144994.
In the SRP catalog that matches the application too. 408ci,
4.030", 4.000" stroke, 5.850" rod, -16cc D-dish.
|
Talking things over with Bill Koustenis at the machine shop, he and
I both think the motor has detonation damage because all the rod
bearings were pounded and some of the pistons had shrunk
skirts. If the pistons were stock they would have been
cracked. The 54cc combustion chamber of the LT4 heads make for
about an 11.7:1 static compression ratio which is ok but possibly
the cam made too much dynamic compression. Possibly the motor
just needs a bigger cam with less dynamic compression. One
good thing about the motor is that it was not run after the rod
knock sound began. That kept an expensive bottom end in good
shape and very re-buildable.
|
Block fresh from a soap and water cleaning. The machine
shop looked it over and found all good. Just a quick hone on
the cylinders. I pushed out the oil cam bearings and put in
new Dura-Bond cam bearings. The old cam bearings were in good
shape though.
|
I'm putting Clevite "P" series bearings in because
they comply, "flex" with the soft stock main caps.
Clearance is .002, .002, .0023, .0025, .0025"
|
|
Crank end play is .006"
|
Custom Ross piston for 408ci (4.000" stroke and 5.85"
rod).
|
|
The Ross piston has a -14.5cc D-dish and the top ring land is
.275" down.
|
The pistons are Left-Right and so need to be assembled so that the
intake/exhaust valve reliefs are in the proper direction.
|
The piston was specified to run a small nitrous shot, (150hp).
|
Since this is a 4.000" stroke motor the piston compression
height was specified to be 1.150".
|
Using premium Mahle piston rings. 1.5mm, 1.5mm,
3.0mm
I specified that the pistons be made to fit this ring set. The
top ring is gapped at .022"
|
The 2nd ring is filed to .026" This ring filer is a
God-send.
|
Here is a piston/rod combo with the rings in place.
|
All of the bores are cleaned about 20 times with rags and auto
tranny fluid and Mobil 1 motor oil. After each rod/piston is
installed I rotate the engine and feel and look for trouble.
The oil rings are tricky and can slide off the piston during install
and you can feel that when rotating the motor. I also look for
ring-gap marks on the cylinder walls. There should be no
marks. If a ring has a bur then you'll see marks.
|
Motor posed for photo after installing all rods/pistons. The
pistons are from .015 to .012" in the hole. The block was
decked only slightly if at all. It's ok not to deck a block in
my opinion if the pistons are not too far in the hole. I will
order up a Victor Reinz head gasket at .026" thickness.
That will give .038 to .041" quench.
|
Lunati rod bolts torqued to 65ft-lb. Rod side clearance is
.015 to .017"
|
Installed oil pan for a temporary dust
cover and to see if anything interferes. I wish I had the cam
and heads. Cannot go much further than this until the
cam/heads arrive.
|
Ai CNC ported LT4 head have arrived. Ai billet core custom cam
too.
|
Let's get busy. Ai cam goes in pretty easy.
|
Reused the LT4 timing set but the chain is new. Cam check
with degree wheel. Even with a loose timing chain the cam came
in very close to dead-nuts-on 106 deg lobe centerline.
|
After installing the Ai cam the #2 and #6 rods bump, (higher lobe
lift than previous cam). Clearancing was performed at the side
of the rod shown here. The rod bolt needed to be clearanced
too.
|
The pistons are .015" in the hole so I selected the .026"
Victor Reinz head gasket.
|
New GM head bolts ready to go.
|
The motor had 7.200" Comp Cams pushrods. Now I need
7.000" I tried all different lengths and it seems like
7.000" will work best. Right now I have 6.950"
pushrods installed.
|
 `
Valve train installed
|
One last look at the bottom end
|
Oil pan on. That is a new dipstick tube and indicator
|
Stock hub pressed on.
|
Now I spin the drill to 2500rpm. This is a pre-lube and test
of the oiling system. The Crane gold anodized rockers are good
quality.
|
GM LT4 intake manifold gaskets.
|
LT4 intake manifold
|
This motor had the full LT4 treatment.
|
One or two final things-to-do prior to sending to Nabil Guffey who
will install the motor into the car.
|
Install new rear main seal.
|
Install SCAT flexplate.
|
Mechanicsville EFI Performance: Nabil Guffey
|
Jimmy's 96 SS at Guffey's shop
|
Almost ready for initial start-up
|
This is a very stock looking motor. Stock-ish intake, stock
cats, stock exhaust, stock torque converter, stock 3.08 rear
gears.....all of that needs to go.
|
Nabil Guffey installed the 408LT1 and I
was there for the initial start-up. She runs very well.
Good job Nabil. The motor is actually more quiet than I
expected. The Ross pistons have .006" clearance.
The stock exhaust makes this car quite a street sleeper.
|
