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L98 to LT-Wonderful

Fortifying our Project ’85

Andy Bolig Jun 1, 2001

Step By Step

The block started out as a ’92 Camaro LT1. It came with the purchase of the car, and all of the machine work was already completed.

Since this is going to be supercharged, the machine shop installed billet, four-bolt main caps. We’re using Clevite 77 bearings, and we plasti-gauged them to make sure we had .0015-inch clearance.

The inside bolts were torqued to 75 lb-ft and the outer bolts were torqued to 65 lb-ft.

The crankshaft spent some time at the machine shop, too.

They inserted heavy material into the crankshaft, where needed, to balance the rotating assembly.

We used Clevite 77 connecting rod bearings and, again, used plasti-gauge to check clearances. Our clearances checked out between .0015 and .002 inch.

The pistons are forged, standard bore, TRW flat-tops. The rings must be oiled well as they are installed into the bores.

A benefit of using the LT1 is this one-piece rear main seal. Care must be taken when torqueing the flywheel bolts to prevent distortion of the crankshaft—and inviting leaks.

We installed Comp Cams’ 266HR-14 camshaft. It has .500/.510 lift intake/exhaust, and 210/220 duration intake/exhaust at .050 lift.

We installed the windage tray, oil pump, and pickup tube.

A 5/8 wrench fits over the pickup tube and gives a good place to tap it in place. After installing it, we checked the oil pan for clearance and welded it to the pump.

We installed a new gear onto the water-pump driveshaft. We heated the gear and froze the shaft so the two would slip-fit together.

Then we installed the retainer plate, and the bearing simply pressed onto the shaft.

We installed the water-pump drive and the cam timing chain so we could check the cam timing. The cam timing was retarded a few degrees, so we drilled out the holes in the cam gear and installed a bushing to give us one degree of advanced cam timing.

When we finished, we used a cam bolt locking plate and thread locker on all of the bolts. The locking plate also helps hold in the cam timing bushing.

The LT1 heads were hand-ported with a fresh valve job.

Before installing the timing-chain cover, we needed to install this tool onto the water-pump driveshaft. This keeps the seal in the cover from folding, which would result in a leak.

Once the cover is in place, simply pull off the tool.

We located an LT1 intake at Corvettes at Carlisle last summer that had all of the hoses and fuel rails for $350. LT1 engines are plentiful, but the owners rarely want to separate the intake from the engine. We used the gasket as a template and opened up the ports slightly to get better flow.

Once again, we’re not looking for ultimate performance, but a nice, driveable car.

Because the LT1 uses the Optispark distributor on the front of the engine, we had to install this oil-pump drive where the distributor would normally go or we’d have no oil pressure. Aligning the oil-pump shaft into the drive can be tricky. We put a line indicating the direction of the groove on the drive to help us line up the two correctly.

Make sure the gasket surfaces are very clean. We cleaned our intake-gasket surfaces three times before we even thought about installing the intake. Use a good-quality gasket sealant on the front and rear rails of the block.

Once the intake is installed and torqued to 35 lb-ft, let the engine sit overnight to allow the sealant to cure. Not a problem for us, since our engine won’t be installed for another week or two.

We’re using Comp Cams roller-rocker arms for our LT1. We put 1.52-ratio rockers on the intake and 1.6-ratio rockers on the exhaust.

We also found a set of composite valve covers at Corvettes at Carlisle. We paid $40 for the set and painted them semi-flat black. The biggest modification was removing the oiling dimples inside the covers. We ground them flat with an air grinder so they wouldn’t interfere with our rocker arms.

Here’s the finished LT1 waiting to be placed in our Project ’85 Corvette.

When we first started on the ’85 Corvette, dubbed Project ’85, it was merely a shell of what it had once been. Parts were located in, on, or around the car awaiting the opportunity to be put to use. The downside is that the car had to be put together before we could enjoy it; but, in putting the car together, we could build it exactly the way we wanted it. That included upgrading to an LT1 with a supercharger. We made a few improvements while building the engine, which helps with engine longevity and also adds a few horsepower. Here’s what we did to make a driveable, supercharged LT1.

Note that there is no throttle body on this engine. We have a special installation we’ll be bringing to you in our next story: the engine and transmission, along with the supercharger. Stay tuned—this is where it starts to get fun.


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