Mustang MonthlyHow To Engine
How to Build an Easy 400hp 333ci Small-Block on a Budget
How to build a 400hp 333ci small-block without getting too fancy
The 289 engine in our 1965 Mustang G.T. 350 clone sounded good and ran OK, but it just didn’t seem right. The bottom-end power was decent but as rpm rose, the 289 felt lazy. The guy we bought the car from was in the midst of totally restoring it and said that the engine was fresh. Yet, something wasn’t quite right. Maybe a few cam lobes went flat or the valvesprings were allowing for valve float. We didn’t know, but we decided to install a new set of Air Flow Research 185cc Renegade aluminum cylinder heads, COMP Cams roller rocker arms, new Fel-Pro gaskets, and some other tidbits to hopefully wake up the engine.
The 289 was pulled and then we tore down the top end and noticed small flakes of metal in the engine. Thinking that the cam could be flat, we pulled the lifters for inspection and then removed the timing cover to get a look at the cam numbers stamped on the nose of the (supposedly) solid-lifter camshaft. After removing the cover, we saw massive amounts of aluminum shavings. We took the chewed up timing chain cover and the timing gears to a Ford expert for his insight. He said, “They paired a later-style raised-face timing chain gear set with an early-style fuel pump eccentric.”
Things got worse after removing the cylinder heads as the piston tops looked like salad bowls with big, negative-cc dishes. Moreover, the markings on the front of the cam indicated it was not a high-performance solid-lifter camshaft but rather a medium-performance hydraulic lifter bumpstick.
There were too many issues with the old 289, so we decided to start from new by building a stroker V-8. The goal was to build a 400-plus horsepower engine that ran on 87-octane fuel without the use of a bunch of exotic parts. Furthermore, we wanted to reuse many of the ’65-’67 Shelby G.T. 350-spec parts fitted to the previous engine.
The purpose of this story isn’t to highlight things like checking crank endplay, main bearing clearance, and such. Rather, it is to highlight the parts that we used and then to show the final result—as in, how it performed on a dyno. If you like what you see, then you can copy what we did, which should net you about the same results. Or, you can modify elements of the build to suit your particular needs.
01. Thanks to today’s wide array of aftermarket parts, building a stroker engine is just as easy as building a stock engine. Thus, rather than a 289 V-8, we opted to build a stroker small-block V-8 that delivered 333.3 ci.
02. To generate a 333-cube stroker V-8, we used a Scat lower end kit (3.250-inch stroke steel crankshaft, 5.4-inch-long Pro Stock connecting rods, Keith Black forged aluminum pistons, King rod/main bearings, and more). Added to the mix were new Melling parts (oil pump, pickup, and heavy-duty driveshaft), a bunch of Fel-Pro gaskets, all-new COMP Cams valvetrain (solid lifter camshaft, lifters, timing chain, hardened pushrods, stainless steel roller rocker arms), Air Flow Research 185 Renegade CNC-ported aluminum cylinder heads, and more.
03. The Windsor block was taken to an engine shop where it was hot-tanked and inspected. It was bored to 0.040-over and then final honed with a deck plate using the pistons for each bore. The block was decked 0.010 to achieve smoothness. Installed were new oil gallery plugs, new cam bearings, and new brass core plugs. Upon returning home, the cylinder block was cleaned up with an electric wire wheel tool to remove any existing paint and casting flash. Each bolthole on the block was tapped to remove any grime as well as to straighten out any bogus threads. Then, the block was thoroughly cleaned. Afterward, the block was taped up to be readied for a coating of VHT hi-temp gray primer and then some VHT high-temp black paint.
04. The Scat stroker crankshaft (PN 9-302-3250-5400-2123) incorporates a 3.25-inch stroke length versus a 3.00-inch stroke length as used with a 289 V-8. The crankshaft is a cast-steel design that is better than a cast-iron crank, but not quite as good as a forged-steel crank. The Scat crank is lighter than a stock crank and incorporates Aero-wing counterweights, straight-shot oil holes, chamfered oil hole openings, and lightening holes in the rod throws. We also used ARP main studs for added strength. Not that the engine was designed to be a high-rpm race engine, but for the nominal addition in cost we figured the ARP main studs would be safe insurance.
05. The main caps were deburred, cleaned, bearings installed, and then set in place. With the ARP main studs comes assembly lubricant that needs to be applied to the threads, the topsides of the washers, and to the bottom sides of the nuts (see arrows). Know that the torque specs differ depending on the type of lubricant applied to the threads (dry, engine oil, or assembly lube) as well as the type of fastener (bolt or stud).
06. The Scat stroker kit includes a set of Pro Mod connecting rods. Constructed of forged steel, the rods (right) are bushed for floating pins (as opposed to stock-type pressed-in pins) and feature a 5.400-inch center-to-center length that is longer than stock 289 rods (5.155-inch, left) or stock 302 rods (5.09-inch). A longer rod length generates more piston dwell time at Top Dead Center (TDC).
07. With floating piston pins it is easy to assemble the piston and rod combo. Simply align the small end of the connecting rod with the pinholes on the piston, then slide in the pin. Afterward, install the retaining clips that hold the pin in place. With the Scat stroker kit come easy-to-install Truarc snap rings that should be installed with the open end facing up.
08. The connecting rods have one side that faces the crankshaft counterweight and one side that faces the adjoining rod. With the Scat forged steel rods, the crankshaft end of the connecting rod has one side with a small amount of chamfer and one side with a noticeably larger amount of chamfer (arrows). When installing the connecting rods, the large chamfer side goes toward the crankshaft counterweight while the small chamfer side goes toward the other rod.
09. Part of the Scat stroker kit (PN 1-94055BE) are Keith Black forged aluminum pistons that generated a pump-gas–friendly compression ratio of 9.8:1. On the top of each piston is a small arrow that indicates the direction the piston should be oriented in relation to the front of the engine. If the pistons have two eyebrows (versus four eyebrows like ours), the eyebrows would face up toward the lifter valley.
10. After mocking up the piston/rod combo for each cylinder, it was determined that the Scat 3.25-inch stroker crankshaft and 5.4-inch rods will fit an original 289/302 cylinder block without issue. If you are worried about clearance when using a 3.25-inch stroke crank, you may wish to slightly notch a few of the cylinder bores (indicated with a black marker, see photo) to generate added clearance.
11. After the KB forged pistons were installed, we checked the height of the pistons within the cylinder bores. Although a stock 289 Windsor cylinder deck height is 8.20 inches, during the machining process of the cylinder block it was decked ten thousandths of an inch. Thus, the new deck height is 8.19 inches.
12. We talked with the camshaft experts at COMP Cams and they recommended a solid-lifter cam that would generate great all-around performance for combination. The COMP 282S solid-lifter camshaft has 282/236 duration at .050-inch lift, 110-degree lobe seperation, and .528-inch lift on both sides.
13. Once the camshaft and mechanical lifters were installed, a new COMP Cams Hi-Tech double-roller timing chain set was fitted. When it comes to building an engine, spend a few extra bucks to buy a quality timing chain set, as it not only directly affects cam timing but it will also provide years of trouble-free operation.
14. Although most aftermarket aluminum heads are significantly better than the best-flowing iron heads from years ago, we have had great luck with aluminum heads from Air Flow Research so that’s what we bought. A few years ago AFR redesigned their small-block Ford Windsor heads and the new Renegade design flows notably better than the previous AFR heads. The AFR heads have fully CNC-ported 58cc combustion chambers, 2.02-inch intake, and 1.60-inch exhaust valves (compared to stock 289 heads’ 1.78/1.45 respectively), CNC-ported 185cc intake runners and 70cc exhaust runners that flow 291 and 212 cfm at the 0.528-inch valve lift that our camshaft generates. By contrast, a set of vintage ’65 G.T. 350 R-model race heads (as ported by Mondello or Valley Head Service) flowed around 215 cfm on the intake, and a set of vintage ’65 G.T. 350 R-model cast-iron race heads flowed around 150 cfm on the exhaust. The AFR aluminum heads (PN 1388) will also shave about 40 pounds off of the nose of car.
15. Because so many critical factors (decked cylinder block, non-stock head gasket thickness, aftermarket aluminum heads with thicker-than-stock deck, aggressive mechanical lifter camshaft, aftermarket valvetrain) were playing into the 333 stroker mix, we decided to check the piston-to-valve clearance to make sure that there would be no metal-to-metal surprises. You can also see the Fel-Pro PermaTorque composition–type head gaskets (with a compressed thickness of 0.039 inch) that we used.
16. After piston-to-valve clearance was confirmed to be within spec, it was time to install the AFR aluminum cylinder heads. We debated on whether to run the heads in their natural aluminum look or paint them black to match the cylinder block, which would make the engine look more stock. We got numerous responses from friends and the consensus was to paint them black.
17. The AFR heads come with 1⁄2-inch head boltholes drilled in the cylinder heads. As a result, you need to modify your cylinder block with 1⁄2-inch threaded holes for the head bolts, run regular diameter (7⁄16-inch) head bolts with space-filling washers, or use ARP 1⁄2-inch diameter bolts (PN 254-3708) with a unique shoulder that necks down to the original 7⁄16-inch head bolt size. We went with the ARP fasteners (shown).
18. When building a new engine you should verify that the pushrods are the correct length so that the end of the rocker arm is centered on the valve tip. (COMP’s Hi-Tech Master Pushrod Checking Kit, PN 7705, makes it easy). After checking our engine, the end result was that a 7.10-inch long (versus a stock 6.80-inch long) 5⁄16-inch pushrod was needed for our 333 V-8. Remember that when using aftermarket cylinder heads fitted with pushrod guideplates, hardened pushrods are required.
19. A set of COMP Cams Ultra Pro Magnum 1.6:1 stainless steel roller rocker arms (PN 1631-16) were installed. While the rocker arms don’t have any clearance issues, the tall polyloks generate a clearance issue with the original Cobra aluminum valve covers.
20. The polylok retainers hit the oil splash shields fitted to the underside of the Cobra valve cover, but there is a solution. We bought a set of aluminum spacers (arrow) from Blue Thunder that raise the valve covers about 7⁄8-inch.
21. Here is the whole reason why we embarked on the engine rebuild project in the first place—the guy who rebuilt the 289 installed a later-style upper timing chain gear (with a cast-in ridge) with an early-style fuel pump eccentric. As a result, the fuel pump eccentric was moved forward about 1⁄4 inch, which caused it to grind into the timing chain cover (arrow), resulting in aluminum shavings being circulated throughout the engine.
22. With the Air Flow Research CNC-ported aluminum heads, special intake manifold gaskets (Fel-Pro 1262) are needed to properly mate to the oversized intake port runners.
23. Now starts the heavy reuse of the parts from the old engine. First up was the installation of the Blue Thunder “Cobra” aluminum intake manifold. The BT intake incorporates larger intake runners for improved flow along with a revised plenum opening; yet the external look is fairly original. How much added flow (or extra horsepower) the manifold delivers over an original Cobra “S2MS” intake we don’t know, but it is said to be in the 20-plus horsepower range. Then on went the restored ’65 G.T. 350-spec Holley 715-cfm Le Mans float bowl carb that was used with the previous engine.
24. We reused the Cobra aluminum oil pan from the old engine. While nostalgic looking, in reality most any modern oil pan will provide significantly improved oil control. Fel-Pro offers a unique oil pan gasket that is a one-piece design, integrates a steel inner core surrounded by molded rubber gasket material, has small inserts at each bolthole to prevent distortion of the gasket at the bolt, and is reusable. You don’t need to use RTV silicone with the Fel-Pro gasket ... but we always use a dab at the edges of the gasket near the main caps.
25. We reused the 1965-spec, hi-po “button top” fuel pump that was rebuilt a few years ago by a Shelby restoration expert. Most any aftermarket fuel pump would provide greater output and would be more inexpensive to buy. However, we were going for a factory-correct look so we were fine with the old-school pump. We also reused the original Hi-Po harmonic balancer.
26. A few years ago we had the original Hi-Po distributor rebuilt. In addition, the distributor was fitted with a PerTronix Ignitor III module that does away with the factory dual-points setup as well as it incorporates a built-in rev limiter.
27. The 333 engine arrives at Westech Performance, a SoCal-based dyno facility (with numerous engine dyno rooms, a chassis dyno, head flowing rooms, engine building rooms) that we have used dozens of times. Testing was conducted using a Superflow 902C dyno.
28. The engine was filled with Lucas 30-weight break-in oil that contains a high amount of zinc. Then, Westech’s Steve Brule primed the engine to ensure that oiling was proper before firing it for the first time. The engine was broken in for about 20 minutes before any power pulls were made. At Westech, during break in they use a unique computer program that varies the engine rpm as well as the load applied to the engine. After break in, the valve lash was adjusted hot and the engine was checked for any leaks or issues.
29. The 333-cube engine was tested exclusively using Rockett Brand fuel using numerous octane ratings, including 87-, 91-, and 100-octane. However, due to the relatively mild (9.8:1) compression ratio the fuel octane had no real effect on power output. Were the engine to have a higher compression ratio (such at 11:1), the fuel octane would likely have had a significant effect.
30. After break in, the initial dyno pulls revealed that the jetting was lean and that the vacuum secondaries for the 715 carb were opening late. Thus, the purple spring fitted to the secondaries was replaced by a white (softer/lighter) spring that opened the secondaries sooner. The result was better throttle response along with better overall power. We also tested it with 32, 34, and 36 degrees of total ignition advance, but there was no major difference in power. Also, we tested the 0.022-inch valve lash that COMP Cams recommends. In addition, the lash was set tighter (0.016) but the results were mixed. While the top-end power increased by about 2 hp, the low/mid-rpm power decreased by about 6 hp. Thus, for a street engine, you should probably go with the lash of 22-thou that COMP Cams recommends.
31. Being that the Holley 715-cfm Le Mans float bowl carb is 50-year-old technology, we decided to try the latest/greatest carb technology (a Holley HP 750-cfm 4V carburetor with mechanical secondaries) to see if it made a difference. While the engine did make about 5 hp more across the rpm range, it proved that a well-prepped 715 still runs pretty well after all these years.
32. With more than 400 hp on tap, the 333ci stroker V-8 should prove quite fun in our 3,750-pound G.T. 350 clone. The car also makes use of a modern T-5 manual transmission and a 9-inch rearend shod with 3.50:1 gears and a limited-slip differential.
Horsepower: 413.5 at 6,500 rpm
Torque: 387.2 at 4,600 rpm
John Kiewicz: 1970-2015
Just before press time, the author of this story, John Kiewicz, was tragically killed in a motorcycle accident. John wanted to use his pseudonym of Jaye Kaye for the story, which we initially agreed to but now feel that since this may be the last magazine story ever written by him, we should use his proper byline. John was a longtime automotive journalist, beginning his career as a youngster in 1993 at Car Craft magazine (where we became friends), and in later years moving on to becoming a staffer and photographer at Motor Trend before leaving for the public relations world at American Honda Motor Company. He was highly respected by everyone in the industry who he worked with, was always a ray of positive sunshine, and was also a damn good driver. It had been several years since I had seen or talked to John, but when I came onboard at Mustang Monthly we re-connected (that’s his ’65 Shelby clone in this story) and we traded texts the day before his death. As John’s friend Vernon Estes posted on his Facebook page: “Keep it pinned up there buddy.”—Rob Kinnan