A set of new hydraulic roller lifters is soaked in oil prior to installation. It's a basic tip every amateur engine builder can use. | 
The oil-soaked lifters were slipped into their respective bores and capped with retainers. |
Here's a close-up look at one of the LT4 aluminum heads. It's a good-flowing head, with 195cc intake runners. The stock valve-springs, however, won't stand up to the lift of the new Crane Cams camshaft, so Crane also sent some appropriately weighted springs. |
The LT4 heads have smallish 54.4cc chamber volumes, which make low-compression heads all the more necessary when using them with a supercharger. The stainless valves measure 2.00 inches on the intake side and 1.55 inches on the exhaust. | 
Accommodating the new Crane valvesprings required a little surgery on the heads. Shorter valveguides were required because of the higher-lift camshaft. Some machining was also required to ensure adequate retainer clearance. | 
To keep the LT4 heads under pressure, we used sturdy head studs from ARP and ditched the conventional head bolts. It was an easy, inexpensive insurance policy. |
Here, von Hentschel torques down all the cylinder head studs. ARP supplied just about every fastener on the engine assembly. | 
With the long-block assembled, attention was turned to the intake system and buttoning up the engine. We pulled off the 350's stock intake to scavenge parts for the new, Pace-supplied LT4 intake. | 
The raised runner design difference of the LT4 intake bottom is visible when compared with the stock LT1 intake top. The raised runner design enhances airflow velocity. |
The stock fuel rail system was pulled off the old intake to be used on the LT4 manifold. | 
With the fuel rail removed, von Hentschel pulled off the stock injectors and, in anticipation of the blower's needs, popped on a set of new injectors. The chubby, 38-pound squirters were supplied by MSD Ignition. (Yes, we were surprised to learn they offered injectors, too.) | 
Cleaned up and wearing its new set of injectors, the fuel rail was installed and bolted down on the LT4 intake. The red-painted manifold sure is an attractive piece--much better than the black plastic appearance of LT1 intakes. |
After the fuel rail was installed, von Hentshcel used the rest of the LT1 intake's components to fill-out the LT4 manifold's assembly. The lesson here: don't throw away the old stuff too quickly. | 
A new, larger-diameter throttle body will be installed, but the intake bores of the LT4 manifold were too small to match. So, the bores were carefully measured and hogged out to match the new throttle body. | 
The shiny, new intake was lowered on to the long-block assembly, bringing the first stage of the project very close to completion. Note the 1.6-ratio aluminum rocker arms--they were retained from the Pace LT4 conversion kit and worked with the new Crane Cams valvesprings and camshaft. |
TPIS supplied the large-diameter throttle body, which has a pair of 58mm throttle blades. Getting the most flow from this piece required enlarging the intake bores of the intake manifold. | 
Here's the finished engine, sitting patiently on Hardcore Racing's engine dyno while the ProCharger P-1SC kit is readied for installation. We'll pick up that part of the story, as well as all the dyno testing results, in the next issue. In the meantime, we've got a hot, LT4-izied 383 small-block--a combo that should be good for about 500 hp without the supercharger. | |
LT4 Kit at a Glance
As we mentioned in the primary story, the LT4 conversion kit available from Pace Performance Warehouse is a complete system that can pump a stock LT1 to about 425 normally aspirated horsepower. The kit retails for about $2,400 and includes the following components:
* Fully assembled LT4 aluminum heads (2.00-in. intake/1.55-in. exhaust valves)
* Red-painted LT4 raised-runner intake manifold* LT4 "Hot" camshaft (0.525/0.525 lift; 218/228 duration; 110-deg. lobe centerline)
* Aluminum roller rocker arms with 1.6 ratio
* Head gaskets and intake gaskets
* Bleed pipe seals
* EGR gasket and EGR pipe gasket
* Throttle body gasket
* Miscellaneous additional gaskets
What the kit doesn't include is the necessary upgraded throttle body, which maxes the performance of the combination. Computer tuning also is required, as the stock LT1 program won't dig what the LT4 parts are trying to tell it. In all, it's a thorough kit that gives LT1 owners a leg up on the LS1 competition. Check out www.paceparts.com for more information.