383 Small-block - Lethal Weapon Project - Top Gun

Putting the finishing touches on Lethal Weapons' 383 engine build with a set of AFR cylinder heads and an Edelbrock High-Flo TPI intake

Justin Cesler Sep 24, 2013 0 Comment(s)
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Building any engine from scratch requires a significant investment of both time and money. For anyone who has ever been down this road that should come as no surprise but each and every time we build something here at GMHTP, we're certainly reminded of the effort involved. From the original planning stages to completion, engine building is all about setting concise goals and sticking to a plan. You can't jump into a fresh build without a clear vision and it's important to stick to your plan once everything is underway, even if that means taking a little more time to get everything right.

If you've been following our TPI engine build, you should remember us putting together a stout 383 shortblock a couple of months ago using a low-mileage four-bolt main block and a serious rotating assembly from Lunati. With the 383 shorty complete, it was time to assemble the top half of the engine, but we didn't want to compromise power and performance for time. So, we waited a little bit for all of our parts to arrive and spent the idle time porting our TPI upper plenum for maximum performance. Finally, the UPS man arrived and our goodies showed up, and boy was it worth the wait!

383 Small Block 2/28

Up top, we selected a pair of Air Flow Research 195cc Eliminator cylinder heads for our 383, which flow upwards of 280 cfm on the intake side at .550-inches of lift thanks to a set of 2.050-inch valves, a killer 100-percent CNC ported runner, and a competition five-way valve job. The 195cc Eliminators also feature a 3/4 deck for maximum strength, raised exhaust ports, 23-degree valve angles, and L98 style plugs for plug-and-play performance. These heads were designed by AFR to work on 350 to 400 cubic-inch engines from 2000-6500rpm, which is exactly what our 383 was built to do on the street and strip.

To make those 195cc heads work, we teamed up with Comp Cams, who sent us a set of Ultra Pro Magnum rocker arms, hardened .080-inch chrome moly pushrods, and a hydraulic roller camshaft, which we installed in Part 1 of this series. For a little late-model retrofit fun, we also ordered up a set of Gen III LS style lifter guide buckets, which will allow for quick and easy camshaft swaps in the future, should the need arise… and you know the need may arise!

All the way up top, above those AFR heads, we chose to bolt up a complete Edelbrock High-Flo TPI intake runner system, which will maximize flow to the cylinder heads and create power and torque throughout our 383's power band. The High-Flo baseplate, which can work with stock or aftermarket TPI runners, was optimized by Edelbrock to improve flow throughout the engine operating range and, combined with Edelbrock's TPI runners, is worth over 20hp in stock form. On a heavy breathing 383, we're betting the High-Flo intake will be worth even more…

Of course, in all of the hustle and bustle, we did manage to forget an oil pump, a set of raised valve covers, and the correct oil pan, but we'll drop those on when we go to install the 383 in Lethal Weapon. For now, follow along as Greg Lovell makes quick work of our 383 top end build and tune in next time to see the TPI mill drop into Steve's Firebird.

383 Small Block Build Arp Head 3/28

1. After a month of painting, porting, and running to the front door like an excited puppy dog every time the UPS truck drove by, it was finally time to dig into the top end of Lethal Weapon’s 383 TPI build and finish up the engine! Here you can see the forged 383, topped with a set of ARP head studs, ready for assembly.

383 Small Block Build Lifter Guide 4/28

2. Wait, what? This isn’t an LSX build, what’s Greg doing with a set of lifter guide buckets? He’s installing our new lifter set from Scoggin Dickey Parts Center, that’s what, and he is using a retrofit composite lifter guide (P/N 88958652) that bolts to a Gen I style block while giving users the benefits of a Gen III lifter system…

383 Small Block Build Install Lifter 5/28

3. …which means that our lifters will ride in the lifter guides during everyday operation and stay in the lifter guides when it comes time to do a camshaft swap in the future. That means the intake and lifters never have to come back out for a swap, saving future Greg a ton of time and headache. And for less than 15-bucks a side, well, just do it!

383 Small Block Build Lifter Buckets Guide 6/28

4. As you can see, the lifter buckets install into the early Gen I style block without issue, and bolt down using the same guide retainer (spider) as you are probably used to. No performance gain here (over no composite lifter guides) but this slick setup will be your best friend next time you and your buddies dig in for a camshaft upgrade.

383 Small Block Build Mls Head 7/28

5. With the lifter installation taken care of, Greg moved his attention to the deck surface, giving it a thorough once over and clean before dropping a set of Cometic Multi-Layer Steel (MLS) head gaskets in place. You may need to “shimmy” these down the ARP head studs, but they are a precision fit and will slide in place with a little work.

383 Small Block Build Cometic Street Pro Gasket 8/28

6. In fact, we’re sealing Lethal Weapons’ entire 383 build with Cometic’s Street Pro gasket set, and for good reason. First, the complete set saves us time, money, and trips to the parts store but—more importantly—it features high quality gaskets throughout the entire package. And a leak free engine is a worry free engine.

383 Small Block Build Afr 195cc Sbc Eliminator Street Cylinder 9/28

7. Last month, we hinted at the bad boy AFR heads that we selected for Lethal Weapons’ 383, and this month we’re ready to drop them in place. Say hello to the AFR 195cc SBC Eliminator Street cylinder head (P/N 1038). With a thick 3⁄4-inch deck, 3⁄32-inch raised exhaust ports, 23-degree valve angles, and 195cc intake ports, these heads were the perfect match for our street driven, pump gas friendly, 383.

383 Small Block Build Intake Exhaust 10/28

8. 2.050-inch 8mm intake and 1.600-inch exhaust valves fill the 75cc (65cc optional) combustion chambers, which have been 100-percent CNC machined and treated to a competition valve job at AFR’s machining facility. At .550-inches of lift, these heads will flow up to 280 cfm on the intake side and 218 cfm on the exhaust.

383 Small Block Build 195cc Cylinder Heads Port 11/28

9. That’s a lot of air for a set of 195cc cylinder heads, and a lot of that flow comes from the well-designed 195cc intake and 64cc exhaust runners. Just like the combustion chambers, each port is 100-percent CNC machined, and optimized for power between 2000 and 6500 rpm on engines displacing between 350 and 400 cubic inches.

383 Small Block Build 195cc Cylinder Heads 12/28
383 Small Block Build Afr Heads Angled Spark 13/28

10. Our AFR heads shipped complete to our door, which meant no assembly was required to drop them on the shortblock. Obviously, our heads are also L98 style, which meant they shipped with angled spark plug locations, but you can also order these in a straight plug design, if you so desire.

383 Small Block Build Torque 14/28

11. With the cylinder heads in place, it was time to break out the torque wrench and get to fastening. Using the standard GM 10 ft-lb increment sequence, Greg started by tightening down all of the studs to 40 ft-lb, and then he worked his way around to 50, 60, and eventually 70 ft-lb of torque, using Moly lube between the heads, washers, and nuts.




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