| Big block Chevy engine projects |
Last updated on September 28, 2013 |
The coupe engine
While the
327 engine serves as living room art until it gets installed in something, these engines are both based on
big block Chevy blocks. All of them make use of a variety of quality
speed equipment: some current, and some classic.
The polished 496 engine shown here was originally intended to go in my roadster project, but that was before I found an original '32 three-window coupe. That's
where this one is going.
The foundation for the coupe engine is a big block Chevy tall-deck block, which originally had a 4.25-inch bore. At their upper limit, if you notch the oil pan
rails, these blocks can handle a 4.5-inch stroker crank. The combination for this engine will be a 4.31-inch bore and a 4.25-stroke, providing 496 cubic
inches.
This block's casting number is 473478, which indicates that it's a 427 tall-deck block with four-bolt mains that was produced from 1977 to 1990. Tall-deck 427
blocks were produced from 1968 to 1990 and used in big trucks.
This particular block showed up on eBay in October of 2004. It was owned by a drag racer who had just brought it back from the machine shop, where it had been
torn down, hot tanked, and bored .055" over but not honed for the pistons. The main caps had been fitted with a complete set of ARP studs.
The seller was in Virginia and said that he didn't want to ship it. Since I have
polished front axles for a hot rod shop in Virginia, I called them and they said that they'd be
happy to strap it to a pallet and send it on its way. The total cost of the block and the freight was about $325. (Since then, I bought a second tall-deck
427 truck block locally for $150.)
I spent the better part of a day deburring the entire inside of the block, getting rid of any casting flash, and making it easier for the oil to drain back
into the pan. While I was in there, I also used abrasives to clean up the oil passage in the rear main cap.
Next, I sanded the outside of the block with a variety of abrasives, working all the way up to 1,500-grit.
The pictures here were taken in March and April of 2006, and show it as it is now, with all of the polishing work virtually finished.
All of the fasteners will come from
ARP.
The ignition system includes an
MSD 8571 billet aluminum distributor with a slip collar so we can dial it in precisely.
Other ignition parts include an MSD 6AL with a built-in rev limiter.
Custom headers with equal-length primaries will take some time to fabricate but the work will provide worthwhile results compared to generic production street
rod headers that are simply designed to fit. The biggest challenge in designing and building the headers will be getting them to fit inside the stock '32 Ford
hood. While "block-hugger" headers (which were inspired by the cast iron "ram's horn" exhaust manifolds found on early Corvettes and Chevy passenger cars) are
readily available from several manufacturers, the goal here is a pair of true equal-length headers with correct-length primary tubes that don't compromise
performance, while fitting between the frame rails and staying inside the narrow '32 hood.
Cermachrome thermal barrier coating on the inside and outside of the headers, as well as the rest of the exhaust system, will help get maximum power out of the
engine. If the coating is applied properly, it will not discolor from engine heat, and can be kept shiny with the same polish that you'd use on aluminum, as
long as it's not too abrasive.
The car will use a race-prepped Turbo 400. A very trick, bolt-together torque converter will come from
Neal Chance Racing Converters.
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Rob's Speed Shop in Mena, Arkansas provided a Brodix single-plane intake manifold for a 4150 carburetor on a tall deck block in October of 2004, in exchange
for advertising on the site.
These pictures show the engine after a lot of filing and sanding, and some handwork with metal polish. The outer surfaces of the Brodix intake, the Pro Topline
heads, the Chevy block, the Donovan gear drive, and the Milodon valve covers are completely smooth and shiny, with no ripples or waves. These parts were
sand-cast, so their surfaces were pretty rough. Getting this kind of finish on sand-cast parts isn't easy, but that's what I wanted for this car. I had the
time, and I knew how to do it. You just have to really want
results like this.
The Brodix single-plane intake manifolds for both engines were sanded the same way that
the wheels were.
I started by filing off the nitrous bosses and then worked it by hand to get everything including the top of the valley cover uniform and flat. I roughed it
out with files and 60-grit and 80-grit emery cloth. Here are the basic steps involved in doing it:
When you start to shape metal, use emery cloth with a stiff backing, not sandpaper. Don't press down with any more than a few ounces of pressure.
While production polishers get the high points and the low points shiny, the goal here is to bring the high points down to the level of the low points.
Begin by sanding at 45 degrees from the direction of the part (or the imperfection that you're removing). You have to sand the entire surface of the area that
you're working on in that same, diagonal direction.
Then sand it again, at 90 degrees to the direction you just sanded. Again, sand the entire area, and sand out all of the scratches left from sanding in the
previous direction.
Keep working at it by alternating between those two different directions until you have the contour and smoothness that you're after. Every time you change
directions, remove all of the scratches that were left from sanding in the previous direction. Then do it all over again with 100-grit emery cloth.
Once the entire surface is done that way, and there are no ruts, pits, or ripples left in the part, you can use 100-grit again, working in the direction of the
part, until there are no scratches left from sanding in the diagonal directions, and then use a 3M sanding pad to get a brushed finish.
From that point, it's just a matter of going over it again with finer abrasives, without changing any of the contours, until the scratches are gone.
I've done a lot of parts with these techniques, but this intake took more time than anything else I've done.
If I ever polish another big block intake, it will be for an 8:71.
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The Brodix tall-deck intake has a recessed mounting base for the distributor, to accept a standard Chevy distributor.
Here is the pair of nicely-made titanium distributor hold-down clamps that were CNC-machined by Jimmy Kosowski at Z-Tek Manufacturing in New York. Jimmy sold
me these titanium clamps for twenty bucks for the pair.
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The aluminum cylinder heads came from Pro Topline Cylinder Heads in New Zealand. In 2005, Pro Topline became a division of
Racing Head Service.
Thanks to Pro Topline's sponsorship, which was arranged by Greg Stokes, a pair of their Pro Thunder aluminum heads with rectangular intake ports arrived in
February of 2003. As they are made, without any porting or cleaning up, these heads will outflow virtually any other ported streetable heads.
Pro Topline's big block Chevy heads were available with a choice of 320, 360, or 400cc intake runners. (If you're building a big-inch engine strictly for
racing, their monster 400cc heads are also available with CNC-machined ports.) The 320cc versions will keep the velocity up and be much better-suited to
something other than a really big-inch race engine, so that's what I went with for this car.
The intake ports measure 1.64" by 2.4" and take a Fel-Pro 1275 gasket. The combustion chambers are 119cc. They use 2.25" intake valves and 1.88" exhaust
valves, rolled over to 15 and 24 degrees.
When you consider their quality and the technology that goes into them, and the amount of work that would be required to get lesser heads to flow like these
do, these heads are a good value. They sure make the old factory iron large oval-port "781" heads that came with the engine for the truck look cheap,
compromised, and obsolete.
Another benefit of the aluminum heads is that at only 31 pounds apiece, they will take a lot of weight off the front end of the car. (And by using an aluminum
water pump and an aluminum block, the complete engine would actually weigh less than a cast-iron 350.)
To minimize carbon build-up, I've polished the combustion chambers and the exhaust ports, and will finish the chambers when we CC them.
The next step was blending the valve pockets, smoothing out the ports, and then giving them the correct surface finish.
To help the heads flow, I've removed the casting seams that run along each side of the intake ports. To provide better fuel atomization, the intake ports were
worked with nothing finer than 80-grit.
To make the heads match the rest of the engine and to make them easier to clean, I spent some time using files and emery cloth to get the rough-cast areas of
the outside surfaces smooth.
Other valvetrain parts will include stainless steel valves from Ferrea Racing Components, a hydraulic roller cam, rocker stud girdles, aluminum roller rockers,
and titanium locks and retainers.
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We have two sets of tall, cast-aluminum valve covers for the race car engine, from Keith Black and Milodon.
These sand-cast Keith Black valve covers were made in the late 1970s and early 1980s.
Although KB has made several styles of their own breathers, the pair shown here has been fitted with four aftermarket "no-name" breathers that used to be on a
426-powered drag car in eastern Canada.
These valve covers were NOS, and came fully polished, complete with some nasty ruts and waves courtesy of a polisher who was in too much of a hurry. I
sanded them smooth, bead blasted them, and then coated them with
Gibbs Brand to protect them from fingerprints and oxidization.
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These Milodon cast aluminum valve covers were made in the late 1970s. They're the only pieces I plan on using that are a little later than the theme of the
car.
As far as big block Chevy valve covers go, these are among the hardest to find. I started looking for a pair of them back in 1989. Eventually, on eBay in 2005,
I found two sets of them.
This pair is NOS, bought from six-time world champion drag racer Pat Musi in New
Jersey. One of Pat's customers brought in an engine that had been built many years ago. The engine had never been run, but he wanted it updated. Pat always
puts his own valve covers on the engines he builds, so he asked the customer what to do with the old ones. When he was told to throw them away, Pat put them on
eBay, and I won the auction for $55.
When they were made, these sand castings were extremely rough. This is what they look like now, after a lot of work with files and abrasives.
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Thanks to Ronnie Besselman at Allied Motors, the coupe engine has a new Scat Enterprises
4.25-inch-stroke forged 4340 crank. This crank is Scat's part number 4-454-4250-6385-2, from their Pro Comp series. These cranks are made with knife-edged
counterweights that reduce windage, and lightening holes in all of the rod journals. They are CNC-machined with an eighth-inch radius on all of the rod
journals, and have chamfered, "straight-shot" oil holes. Then they're stress-relieved, shot-peened, and nitrided. These Scat cranks are excellent quality and a
very good value.
There are hundreds of cast 454 cranks that are being used with passenger car connecting rods in junkyard, two-bolt-main 427 and 454 blocks that power Super
Comp and Super Gas dragsters reliably without being the weak link. But once you want more than 600 horsepower, an aftermarket crank is called for. The cost of
aftermarket cranks ranges from a low end of around $400 for something lousy from China, to around $1,100 for this one, and on up to a high end of over $2,000
for something strong enough for nitro and nice enough to display in your living room. A quality aftermarket crank is the way to go in a serious race engine.
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Back in June of 2001, a nearly-new Donovan Engineering "Pro Stock" gear drive showed up on eBay, and I bought it for half the price of a new one. Changing cams
is easy with one of these.
The Donovan gear drive uses an idler gear, so it uses stock-rotation cams, and has an adjustable roller thrust bearing for the cam. It has a five-way,
split-Vernier adjustment for dialing in the timing, allowing you to split one tooth five ways.
Donovan still produces gear drives, but now CNC-machines them from aluminum plate. This one, a Pro Stock version that was made back in 1968, has a sand-cast
housing and cover which I have now sanded and polished by hand.
This particular Donovan gear drive has an interesting story behind it. Back in 1968, when stock-block engines could be run in
the Indy 500, Kent Woolley in California built a radical, destroked 396 Chevy for Indy, designed to run 9,500 rpm
on 50-percent alcohol and 50-percent nitro. It used a set of half-inch-longer Carrillo rods and a 180-degree Moldex crank with a three-inch stroke. Kent spent
about a hundred hours welding a pair of Chevy aluminum heads, relocating the exhaust ports, and then built a set of upswept headers that mounted with machined
copper O-rings. The oil filter boss on the block had to be ground away to clear the
Lola chassis.
And then, when the engine was almost finished, the rules changed. The era of racing stock-block engines at Indy had ended. To see how the engine ran, Kent
installed it in a friend's McLaren Can Am car
and drove it on race gas for four laps around the old Riverside Raceway. The engine was run for less than half an hour. And then it ended up sitting for over
thirty years until Kent parted it out.
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This steel Canton "shoebox" oil pan with a widened sump and a windage tray is ready to have its inside coated. The pan, which I bought from a drag racer in
Texas, will be used along with all of the usual oiling system improvements.
A pair of braided stainless lines will run from a pair of remote oil filters to an adapter that replaces the stock oil filter.
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This spun-aluminum air cleaner top has a spot-welded insert on the bottom for the mounting stud. It's extremely light. I sanded the anodizing off the top and
have started to polish it.
The fuel system includes a modified Holley Dominator carburetor on a CNC-machined adapter, an electric fuel pump, an old Hilborn fuel filter, and braided
stainless steel fuel lines everywhere.
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This aircraft-style Hilborn fuel filter was made in the 1960s.
The body is a magnesium casting that has been sanded smooth.
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Here the pair of stainless steel tanks that we might use for puke tanks.
These tanks were made by Festo in Germany, a manufacturer of food processing equipment. They are intended for holding compressed air.
The workmanship on these tanks is exceptional. They are supplied with a coarse, brushed finish, but one of the tanks has been rough-sanded with abrasives, and
now you can't tell where the welds are.
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For all of the plumbing on the race engine, we're using braided stainless steel hose and aluminum AN fittings from Aeroquip.
This picture shows one of the two-inch Aeroquip AN-32 fittings that will be used for the radiator.
Buying the fittings surplus, I bought ten new AN-32 fittings and ten feet of new Aeroquip AN-32 hose for less than $110.
In the future there will be lots more information about the rat for the race car, including a complete parts list, and finishing with dyno results and timing
slips.
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The truck engine
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While the coupe engine uses a tall-deck 427 truck block with a 10.2-inch deck height, a Brodix rectangular-port single-plane intake, and a pair of Pro Topline
rectangular-port aluminum heads, the engine for the truck uses a 454 truck block with a 9.8-inch deck height, a Brodix oval-port single-plane intake, and will
probably use a pair of oval-port aluminum heads.
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The truck engine started with a complete 454 from a late-1970s Chevy truck.
Bought for only $350, the engine provided a good block, crank, and rods, as well as the pair of "781" (casting number 336781) open-chamber, large oval-port
heads.
A good 454 steel crank came along in a trade, and it will be perfect for this engine.
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These pictures show the single-plane manifold that I bought direct from Brodix and then sanded and brushed by hand. Like the Brodix tall-deck intake for the
coupe engine, I removed all of the nitrous bosses and then fully polished it.
The Brodix will provide a fine compromise for street driving. Aside from port-matching, polishing, and detailing the manifold, it's basically a bolt-on deal,
if you don't include the two weeks of evenings I spent hand-sanding it with emery cloth to get it to look like this.
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Yet another eBay find was this Stewart aluminum water pump.
It's practically new, having only been used for a few dyno pulls, and cost $55.
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Here's one of the 14-inch Cal Custom finned aluminum air cleaner tops that I was lucky enough to find on eBay.
This one is NOS, and for now it's going to stay the way it was made, complete with the ripples and waves from its production polishing job.
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Here's the second 14-inch Cal Custom air cleaner top and base that I bought on eBay.
I've shaped the top to get it uniform, and then polished it.
It will be used with a new K&N filter.
Yes, I filed it and sanded it between the fins.
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Like the engine for the race car, there are two pairs of valve covers to choose from.
Here is a pair of the first cast-aluminum big block Chevy valve covers that Edlebrock made.
These suit the theme of the truck as well as anything, and they'll be practical.
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Among the very first aftermarket valve covers for the 396 and 427 engines were these from Cal Custom, in Gardena, California. These were die-cast parts that
were high-quality and very popular. The early versions say "Gardena, Calif. No. 40-2100". The later versions say "Carson, Calif. No. 4701-4028". The only
difference is in the logo, which is on the breather knock-out.
These were one of very few aftermarket valve covers to have oil drippers located above the rocker arms. Although Cal Custom made valve covers for many
different engines, the big block Chevy version was the only one that I know of, and the only aftermarket big block Chevy valve covers that I know of other than
Edelbrock, that had drippers.
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While at a swap meet in Pleasanton, California in 1999, I paid for $60 for this vintage
Enderle finned, cast aluminum timing cover, just because I've always liked they way they
look.
It looks even better now that I've sanded out all of the casting imperfections, bead blasted it, given it a brushed finish, and sprayed it with
Gibbs Brand to keep it clean.
Like any conventional timing cover, its disadvantage is that you have to drop the oil pan to change cams, but that won't be a factor on this engine.
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We'll use this old, die-cast, finned aluminum fuel pump block-off plate.
I don't know who the manufacturer was.
I'd like to find another one, so please let me know if you know of a source.
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are Copyright 1996-2013 Dave Mann
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