4-Bolt Splayed cap 383 for a 6-Speed Impala SS
LT4 Heads, Eagle forged Crank and Rods, Mahle -16cc Pistons
499hp @ 5900rpm, 508tq @ 4200rpm
Right now I'm dressing down the engine core which came out of the
customer's low mileage 1995 Impala SS with 6-Speed. Curious to
see how the rods and bearings and piston look.
The core is not an LT4 but the customer has a very-cherry set
of LT4 heads for this project. These will top the typical
ERE-383 with splayed caps and forged rotating assembly.
The oil and the inside of the oil pan looked great. No
dirt or debris. Very clean oil.
In the video linked to the right I'm just trying to show a close
up of the block and bores and the stock rods and pistons.
Although the piston tops are dirty with carbon that is a very
reasonable amount of dirt. The skirts on the pistons are
almost new and the bores are likewise almost new. The crank
main and rod journals are in great shape. This block will be
machined for 4-bolt caps (center 3) and 4.030" bore.
Valve job by Fast-Cat Porting Service. Head resurface and
valve spring installation. The photo to the right shows the
valve job and bowl cleanup. The heads flow 258 cfm @
.550" lift intake and 202 cfm @.600" lift exhaust.
This is un-ported but with a nice valve job (stock valve) and bowl
The cam is custom spec by Fast-Cat Porting Service at 226/234/113 duration
and .584/.568" lift with 1.6 ratio. Billet core camshaft from Erson.
Fresh from the machine shop and main cap shop.
Block cleaned and oiled on the inside and surface prepared on the outside.
Fire red supplied by customer. Good stuff. KBS paint. Brushed
Let's get busy and assemble. First I make sure I don't forget to
install the oil galley ball bearing.
The next step is crank/rod/piston mockup. This is to make sure there
will be no more clearance grinding needed. If more is needed I mark
the spot and take it all apart and grind and clean. All this is
required to be verified before installing the cam bearings.
Already found that most of the rods need additional clearance at the
bottom of the cylinder. They don't touch but they are close.
The black sharpie is where I need to grind.
This tool that Gerry Charlesworth made for me has paid for itself 1000
times. I really like these wire clips that come with the Mahle
piston. They install much easier than spiro-lox.
All 8 rods/pitons installed for mock-up. 6 out of 8 need additional
clearance. Next step is to tear down and work on the block. Then
measure for bearing clearance and install the cam bearings and complete the
Here is a quick photo of the additional grinding It is the
smoother spot. Now I'm ready and confident that I can put in the
G0-NoGo allen wrench lets me know if the cam bearing is aligned with
the oil galley slot.
Then one of the cam bearings did not give a good allen wrench go-nogo.
I broke out the boreOscope to see which way I needed to move the
bearing. Later I found the switch to access the side camera
and I could just stick the boroscope right in the cam tunnel.
Billet core camshaft designed by Dennis Staff at FastCat Porting
With an everwear gear.
Setting main bearing clearance. I ended up needing to mix the
.001" X bearings with the standard size bearings. This give a
bit more bearing clearance. Cannot be too tight with a performance
The main journals measure at 2.4479" #5 and 2.4484" #1,2,3,4
Crank main thrust bearing and end-play is .006" with the main cap
loose and with the main cap torqued to 80ft-lb.
New gear on a refurbished water pump drive gear. This photo also
shows the oil galley plugs.
I decided to gap at .020" 1st ring and .020" 2nd ring.
Mahle 1mm rings.
I measured one rod for bearing
clearance and I get 0.0022". The crankshaft rod journals
all measure to 2.0993"
I put #1 piston/rod into the hole just to see what deck height
is. Right now it looks to be 0.018" in the hole. I
have the machine shop only deck as much as needed to make the block
square. That give better intake fitment.
#1 piston/rod installed and rod bearing clearance is .022"
That's it for today. Check back
That stain or discolor on the deck surface
(in some spots) is WD40 and it soaked in when the block was masked off for
painting. It is just cosmetic but unfortunate that it shows.
Well, a minor set back. One rod bumped the bottom of the block
at the inboard area, (cam tunnel). Yellow marks the spot.
Tear-down to bare block and grind in that area and on all the bores
just to be safe.
Here is a photo of the rod shoulder and bottom of block interference
area. #6 rod is the one rod out of 8 that bumps.
Cam bearings being removed.
Here is that spot. Just a little more grinding was performed. Not a
New cam bearings. The set that was removed is sorta ok and can
be used if someone wants a free set of cam bearings.
Proof that I re-installed the steel ball.
All rods/pistons installed and now torqued. Also .020"
feeler shows the rod side clearance.
Windage tray bending out of the way of the rods.
Stef's-Ellwein oil pan trial fit, (dry run...haha). Fits ok with
no gasket except a minor bump in the usual spot...at the rear
crankshaft counterweight. Will clearance that later.
Oil pan serial number.
While I have easy access I installed the rear main seal housing. The
.003" feeler gauge at all 3 alignment nubs proves positive
Pan is on as a dust cover and because it looks great in photos.
Pistons are .015" in the hole. If using a .026" Impala
SS head gasket that will give .041" quench or AKA piston to head
Head on with a .040" MLS shop gasket. (I don't have an Impala head
gasket yet). I'm wanting to find out pushrod length so I am mocking things
Neat photo of the LT4 roller rockers.
I installed a 7.200" pushrod set for
intake and exhaust and got 3/4 turn to fully tight on the jam
nut. This is a non-adjustable set up and so you set lifter
pre-load by pushrod length. So I have a set of 7.150"
pushrods on order. My thinking is I need 1/4 more turn and also
the head is .014" taller using this .040" gasket (instead of
the .026" gasket). So get this math and correct me if I'm
wrong. 24 tpi stud. 1 turn is .042" and the desired
preload is .050" to .100". Right now with the .040" gasket we are at
3/4 turn or .031" preload. With a .026" gasket we
would only be at .016" preload or not even 1/2 turn. With a
.050" shorter pushrod we would get 0.066" which good.
We shall see when the pushrods and gasket arrive.
Installation of the timing set, (from a video clip). I seemed to forget
about taking photos when I'm rolling video tape. (rolling tape is figurative).
Cloyes timing set at the +4* crank sprocket setting which brings the
cam to +2* (in theory).
Finding exact TDC for the degree wheel.
And now intake centerline is 108 exactly as specified in the cam card
from Dennis Staff.
Still waiting for oil pump pickup. It's Sunday and so I want to get as
many other things finished so that I'm not delayed or rushed for the Saturday
dyno session. Here is a clean and nicely refurbished timing cover. I
tried cleaning up and repainting the customer supplied timing cover and I put a
second heavy coat of gloss black paint on it and it turned into a bubbling paint
mess. So I went with this all natural timing cover and will strip the
other one at some point in the future.
ATI hub for B-body. It requires .001" interference fit
according to ATI. It was at .002" and I took it to
.001" with a bottle brush dingle-ball hone.
ATI damper bolts torque to spec. 30ft-lb for the 3/8"
bolts and 16ft-lb for the Torx 40-plus bolts.
I marked top dead center.
One day I'm going to manufacture a quality and accurate TDC timing
pointer. I'll figure something out sooner than later.
Just for my reference when this LT1 is at TDC the degree wheel shows 35
degrees streight up at 12 O'Clock.
Some things that need to be attended to....the oil pan bump
(slightly) with the crankshaft. I ground in this area at the
pan-to-block rail and then washed the oil pan.
That crank counterweight is what hits.
I put the pan on and spun the crank. No bumping. All
It has been almost 1 week waiting for a set of Johnson lifters. These are
from Brian Tooley Racing. Part number 2110R. Also have the Mr.
Gasket .026" thick head gasket and the oil pump pickup for 8" deep
Measure volume of combustion chamber before I do anything else.
It is 58cc.
The oil pump pickup is a press in and bolt on. It certainly
could not bolt on to this pump with the bolt holes in the wrong
spot. But I ordered a press on and it is a good interference
Final measurement is 1/2" clearance from pan bottom to screen.
Soaking the Johnson lifters.
Mr. Gasket head gasket.
Heads on. Now I need to get right to seeing what pushrod length
A photo for the LT4 head part number and nostalgia.
Pushrod length ended up being 7.200" for 1 turn past zero pre-load.
Pressing up the oil system gives 75psig and oil flowed up the pushrods
pretty quickly, (within 1 minute).
20ft-lb (carefully) for the oil pump drive gear. Oops not yet. This goes
on after the dyno. I need to have it removed for the distributor.
LT1 dual plane intake for the dyno. The intake ports are small
and do not match the LT4 but I don't have an LT4 carburetor manifold.
Here we are at the dyno.
I have found that this is the best Top-Dead-Center indicator for the
LT1. haha. I'm serious.
Carburetor is used for simplicity. Soon I will have an EFI
harness and fuel system for the dyno.
All worked exactly as expected. I was thinking 480 hp at the lowest
and 500hp at the highest. Power and torque are just right. This is a
very mild street motor, but with power and torque right were it's needed.
The camshaft is set up for longevity and reliablilty.