LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

sanity check on rebuild plans....

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Old Mar 6, 2008 | 11:42 AM
  #1  
dougg01's Avatar
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Joined: Apr 1999
Posts: 191
From: Central KY
sanity check on rebuild plans....

Budget build w/ slightly improved performance

current in my '94 formula, daily-driver -
190,000 mile stock short-block and heads
LT4 HOT cam, crane 1.6 RR
elec wp
SLP 1 3/4 headers, 3" exhaust
it's had relatively low oil pressure since I picked it up (one-owner) in '97 w/ 13K on the clock. Inside the motor still looks like new)
we'll be reusing all accessories and stuff from this motor on the new one. The long-block will largely be left intact for a future rebuild.

On the stand getting ready to be cleaned and taken to the shop -
Unknown mileage 94 LT1 with virtually perfect stock bores (checked w/ gauge). Bearings, pistons, etc all looked really good during disassembly.
pair of heads, unknown vintage and I don't have the casting numbers with me.

Plan for the short-block-
check and clean block
hone cylinders
deck if needed
KB hyper pistons 11:1, std bore, press pin
check and resize stock rods, new ARP bolts
check and polish crank
balance
new, stock GM pump w/ white spring (we're already using this setup on my father-in-law's race car)
new ARP studs
new cam bearings
new dual roller timing chain
new freeze plugs
new CC305 cam (that's my choice...this isn't a thread about cam choices)

Plan for the heads -
check and clean
3-angle w/ backcut on stock valves #see note below
10308 spring kit (again, this is my choice...this ain't a thread on valve spring choices)
mill if needed
new cast guides
new ARP head bolts
new pushrods (length determined by amount of milling/decking)
head gasket choice will be depending on decking and milling numbers to achieve a 11:0-11.5:1 comp ratio

##note - I understand that certain head casting numbers have a larger intake seat and therefore can use a 2.00 valve. Can someone tell me what those numbers are so I can check against mine...? If'n mine match I'll go this route and scape together $$$ for new valves though it might prolong the project.

Heads are being mildly ported w/o gasket matching now. This isn't a thread about heads, porting services, or who's head flows what. Let's keep focused pleased.

Car is full-weight and driven all year in all sorts of weather. I have a 3,000-3,200 yank stall and 3.42 gears. The car is bracket raced and autocrossed though I haven't done either the past couple of years for a variety of reasons. I'm going back to the track this year.

Since I have SO much stuff I need to replace on the car (aside from motor work like radiator, brakes, shocks, etc) and my goals are not lofty, then I'd think this is a prudent plan to get things back in shape.

Anyone got the part numbers for the main studs and head bolts...? I used to have them, but now can't find that file.

The car has gone 8.1 in the 1/8th (1.71 60ft) and high 12s in the 1/4, but mph has always been weak (84 and 104 respectively). It's a torquey LT1 that's a blast on the daily commute, but gets stomped on pretty hard from any rolling start above 45mph. I don't care if that changes much because I don't really speed, don't street race (except the occasional stop-light challenge), and want to maintain mileage as much as possible.

That's it. See any glaring issues with my plans other than it's fairly cost-conscious...? Essentially it's the same motor that's in the car just freshened and perhaps a little better breathing.

Side note...the motor in the car now had 1/2 a drill bit laying the lifter valley that must have been left there at the factory as it had never been off the car before (including warranty service). I have no idea why it would have been in there or why a drill bit would even be near the motor as it was assembled at the factory.

Thanks for taking the time to read....
I know...I have a problem with brevity.
Old Mar 6, 2008 | 12:06 PM
  #2  
truedualws6's Avatar
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Joined: Jan 2004
Posts: 1,406
From: Downey, CA
Other than needing a ton of part numbers for all the stuff, I suggest you have the
spring pockets in the heads opened up to accept the 1.55" spring seats and then
use the Comp 4776-16 seats with the springs you selected (99893). Don't deepen
the pockets, just open them up.

Note that you may need to grind a bit on a 1.55" spring seat in the center bolt area
to clear the bolt. It's just a small amount of grinding. Another option is to use the
Comp 4784-16 seats which are 1.50" and may fit in the stock pockets. If you open
up the pockets now you will have a lot more options for springs/seats.

Last edited by truedualws6; Mar 6, 2008 at 12:10 PM.
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