Swing and Sting Engine
Squeezing 74 more inches in a 318
Story Geoff Stunkard / Images John Stunkard - April 12, 2012 10:00 AM
1 Ken tested and found us a nice LA-series block to start with; this is actually a 1985 version, but proved an excellent base since we only needed to go .030-inch over in cylinder size.
2 Other than good block prep, the only major change from OEM was this single notch for rod clearance; the crank throws are fine. The Chrysler LA-series engine almost seems made for a bigger displacement.
3 Jack carefully hand-fit each main bearing shell that we had gotten with our Mancini kit to make sure the crank would ride correctly once we dropped it in.
4 We got a set of ARP bottom studs from Hensley as added insurance (and we would also replace our head bolts). We probably could have used the old main bolts, but this change made sense. It allows cleaner torque readings when installing the main caps
5 The first problem showed up here. Note the large screwdriver wedged down between the block webbing and the crank counter throw, which is used to determine the critical measurement of crank thrust — the amount of lateral movement the crank is allowed to make under load. In this case, we ended up with too little at .003-inch and Jack spent quite a bit of time double-checking the crank and main cap, then massaging the #3 bearing edge to get the proper clearance; extreme cases will require crank machining.
6 Jack used a straight edge to make sure the main caps were exactly right and still double-checked every one of them even though he had done the machine work on this block himself.
7 We first installed a stud on the rear main cap; don’t do it, as it will not clear the oil pump.
8 After heavily adding lube to each lobe, Jack carefully installs the cam into the center of the block; the cam bearings get progressively smaller the further into the block they are, meaning you want to make sure you don’t score them during this step.
9 Here is our first Diamond piston, installed in #1 cylinder and at top dead center.
10 Mancini Racing also sent us a new dual-sprocket timing outfit. With the timing chain aligning the reciprocating assembly, Jack uses a degree wheel to measure the cam centerline based on the degree specs that Hughes provided.
11 Here we are using a dial indicator to determine actual cam lift at the lobe to measure piston to valve clearance.
12 The Hughes valvetrain uses a special guide plate and pedestal-mounted rockers as opposed to the shafts; at a 1.65 rocker ratio, clearance checking is critical. These are PRW rockers that Hughes sells as part of their kit. Jack uses a dial caliper to measure the installed spring height, and then measures the amount of valve lift to ensure the pistons and valves don’t make war.
13 The preparation of parts took almost as long as the build; Jack hand-fitted each ring and bearing set, and then matched them to the piston. This is cheap insurance to make sure the engine is not damaged during break in.
14 A ring compressor makes sure the cylinders wall and rings are not damaged during installation, then the handle of the hammer is gently used to persuade the piston into its new home. Jack installs each rod, and double checks it for fit and clearance.
15 Debris on the screen in the OEM pickup was pretty nasty, but after cleaning it, and everything else that we are reusing in the oil system, it ensured nothing bad is going to get flushed through into the new motor.
16 Because we are using the old oil pan, Jack used the OEM pickup with the new Melling oil pump from Mancini. Ken does not use a windage tray or crank scraper in non-race, lower-rpm (under 6,500) applications.
17 With a quick repaint, Jack installed the original timing cover.
18 This new PRW high-volume water pump looks awesome on my motor with its polished finish. That finishes up the bottom end; next up is the top of the motor.
Having followed our ongoing efforts on the Swing n’ Sting Dart, you may already know that John and I were now at the point of getting another engine assembled.
What started as a freshen-up, turned into a complete overhaul. So, we began gathering pieces for a stroker build. Most of our already-gathered pieces would fit; we would change the reciprocating assembly and cam outfit for the new direction.
The bottom end was a one-stop kit (MRESTROKE318-KIT) from Mancini Racing Enterprises in Roseville, Michigan. Featuring a Scat crank, Eagle SIR rods, .030-inch Diamond pistons, Total Seal rings, Fel-Pro gaskets and Clevite bearings, we went with the basic standard set-up – cast crank, I-beam rods, and cast pistons. Mancini offers these complete kits in a variety of styles and horsepower levels.
This would be augmented by our new AAEQ heads that had been mildly prepped by Hughes engines, our PRW water pump, MSD Pro-Billet E-curve ignition, and the 680cfm Quick Fuel Technologies carb we used before. Mancini had already sent us a new double-roller timing outfit and a Melling high volume oil pump to round it out. The new displacement would come up to a very cool and legendary Chrysler Corp (old and new) displacement of 392 cid.
But we won’t lie. This was a job that we knew we could REALLY screw up. To that end, we were very blessed to have Hensley Performance only about two hours away. Ken Hensley has decades of history with Chrysler engine packages, and chief wrencher Jack Moore would put our stuff together in their clean room. The first step would be block prep.
We could have cleaned up our old block, but Ken suggested a better solution. Having built a number of 318 stroker engines and knowing we’d get an off-the-shelf piston set, Ken had a supply of cores and could simply sell us one that was ready to go. So rather than go through the process of tanking and testing our fairly common 318 only to find out it would not work, we got a circa-1985 318 that was already bored out, notched for crank clearance, and machined for performance. This includes align-boring, truing of the crank saddles, block squaring, hot tanking, and final checks.
The art of engine building is based on a number of factors. For Ken, what we had put together in our pile would frankly not have been his first choice. This had no bearing on the products or their quality, but rather on his own long-standing personal experience and product use. Supplying engines to people across the country for both street and race applications has created several combinations he knows work well.
We say this up front for one simple reason – Ken humored us by agreeing to have Jack assemble the variety of parts we had selected, but don’t call them asking for this combination. Indeed, a 318/392-cid package Jack had just done to Hensley’s own off-the-shelf specs for a customer had made 425 horsepower and 476 lbs-ft of torque; we’d say if you decide to not be mad scientists like us, go with what they desire and you should be in great shape.
For our cam change, we again called our friend Dave Hughes at Hughes Engines for a 392 Whiplash to replace the 318 version we had previously selected. He sent a semi-radical HEH2832AL hydraulic our way, along with a set of his 1111 springs. This thing was stout, .558-inch intake and .576-inch exhaust, with 110° of lobe separation and a 107° installed centerline. This would work well with the AAEQ heads that Hughes Engines already be prepped for us with a competition valve job.
The specs on our pistons coupled with the fairly tight chambers in the iron heads meant compression could be a problem. We wanted to keep the static level at about 9.5 so we could run pump gas; Ken’s calculations led us back to Cometic gaskets for a set of .070-inch multi-layer shim-style units. With our new heads going on, once again the guys at Mancini came through with a crowning touch, the latest design Edelbrock RPM AirGap intake that will keep hot engine oil off the base of the intake, another improvement.
Of course, Hensley has a lot of these same parts in stock; in addition to the work they did, they supplied us with ARP hardware, some other small pieces, and good humor about what we were doing. Ken can help you out on many carefully selected products that have served Ken well over the years. We went with his recommendations wholeheartedly on things like high quality Baldwin oil filters and better fastener technology.
So, with our big pile of parts on hand and throwing caution to the wind, Jack and John would get down to work in Hensley’s clean room putting it all together. John will tell you what he learned. We will cover the bottom end in this story; next issue will be the top end.
Hughes Engines, Inc
PRW Online Store
Cometic Gasket, Inc.