Building Chevy 4.3 liter V6 - 1994 with balance shaft
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== THE PARTS == | == THE PARTS == | ||
| − | One of the downsides of this engine is the fact that nobody | + | One of the downsides of this engine is the fact that nobody seems to take an interest in serious builds on this base. Although this engine has seen a myriad of applications and has been produced in millions it has never been seriously considered for racing or builds, except for some bracket race or dirt track cars. It shares a great deal of common parts with the SBC V8 so a lot of parts can be sourced from there. The hot-rod magazine has probably built the ultimate 4.3l V6 showing the potential. |
| − | + | Here is the experience with the various important parts of the build: | |
| − | Cranks are available as cast cranks for as little as 150 $. For a more serious build a forged crank would be nice. All the OEM cranks including those used on the marine engines producing 200+ hp are cast cranks. All the V6 are external balance cranks. | + | '''CRANKSHAFT''' |
| + | Cranks are available as cast cranks for as little as 150 $. For a more serious build a forged crank would be nice. All the OEM cranks including those used on the marine engines producing 200+ hp are cast cranks. All the V6's are external balance cranks. | ||
Most suppliers would supply a billet crank for this engine from 3'000 to 5'000 $. | Most suppliers would supply a billet crank for this engine from 3'000 to 5'000 $. | ||
The problem is: Then you have a monster crank able to withstand 1'200 hp in a two bolt cap block able to put out 500 at max. | The problem is: Then you have a monster crank able to withstand 1'200 hp in a two bolt cap block able to put out 500 at max. | ||
| − | So I'll have to go with the factory crank properly balanced (internal balance) which should easily withstand 300 hp. As the goal is below that number I should be fine with that. Found a crank from an older version of the engine. As the lenght's and the nose are the same we'll go and try this one. Belongs to a marine shop close by which had it available. I'll see with my machine shop once the internal parts are defined if we can balance it. That would help a lot as the bearings only need polishing. | + | '''MAIN BEARIN CAPS''' |
| + | Some say (various sources internet) that one could use the 4 bolt mains of a V8 (aftermarket) and modify the block accordingly. But this would mean major machine work on the block surface, the caps and align bore and hone for new bearings. Not worth the hassle for a mere 250 - 300 hp build. | ||
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| + | So I'll have to go with the factory crank properly balanced (internal balance) which should easily withstand 300 hp. As the goal is below that number I should be fine with that. Found a crank from an older version of the engine. As the lenght's and the nose are the same we'll go and try this one. Belongs to a marine shop close by which had it available. I'll see with my machine shop once the internal parts are defined if we can internally balance it. That would help a lot as the bearings only need polishing. | ||
'''CYLINDER HEADS''' | '''CYLINDER HEADS''' | ||
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It would be cool if somebody with access to a flow bench could flow a pair of these heads. | It would be cool if somebody with access to a flow bench could flow a pair of these heads. | ||
| − | The 1.94 Intake and 1.50 Exhaust valves should have acceptable flow at low lifts which would be a nice thing for a daily drive and low to mid rpm power band modifications. At the same time this will keep the cost way down. Modifications for screw in studs and decent roller rockers should deliver more power and a sturdy valvetrain. | + | The 1.94 Intake and 1.50 Exhaust valves should have acceptable flow at low lifts and low rpm which would be a nice thing for a daily drive and low to mid rpm power band modifications. At the same time this will keep the cost way down. Modifications for screw in studs and decent roller rockers should deliver more power and a sturdy valvetrain. |
| − | As of 2016-04-21 I got my order from Summit with the majority of parts for the build. I'll | + | As of 2016-04-21 I got my order from Summit with the majority of parts for the build. I'll give a short brief on the parts and the reasons for ordering them. The part number in brackets () is the SUMMIT part number, all others are OEM numbers. |
'''CRANKSHAFT''' | '''CRANKSHAFT''' | ||
| − | Got one from a guy close by who does marine engines. The crank is nearly brand new. As it may only need some polishing I'll go for this one. I consider this an option also for a build when simply buying a new crank OEM casting. It is a huge step up to a billet crank and I would consider that only if building an all out racing engine or a serious hot rod build. | + | OEM - Got one from a guy close by who does marine engines. The crank is nearly brand new. As it may only need some polishing I'll go for this one. I consider this an option also for a build when simply buying a new crank OEM casting. It is a huge step up to a billet crank and I would consider that only if building an all out racing engine or a serious hot rod build. |
'''CONNECTING RODS''' | '''CONNECTING RODS''' | ||
| − | + | EAGLE rods CRS570063D (ESP-570063D) which is an H-beam rod. C to C is 5.700" for standard pins. Careful when building the V6 - the big end bore is 2.225" not the V8's 2.125". As for my research this holds true for all the even fire engines in the 4.3l V6 series. The odd fire may have the 2.125" big end bores. Even at summit they list rods with the wrong big end bore for this application. (The solution is - measure - measure again - order) | |
'''PISTONS''' | '''PISTONS''' | ||
Will be a custom order JE forged pistons as pointed out below. As soon as I get them I'll list the item here. | Will be a custom order JE forged pistons as pointed out below. As soon as I get them I'll list the item here. | ||
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| + | '''TIMING SET''' | ||
| + | COMPCams 56-440-8 (CCA-3202) Standard near stock link belt with iron sprocket. The reason for this order is the balance shaft which I will retain. All other sets are not for the balance shaft engine and would most probably require a new timing gear cover. I'll leave that to a V8 build should the opportunity ever arise. | ||
'''CAMSHAFT''' | '''CAMSHAFT''' | ||
| − | COMPCams mildest grind will be used to be compatible with the stock TBI and computer and still be within emissions limitations. It is a 260/266 degree duration cam. Lobe separation 112 deg and durations of 206/210 deg at 0.050" lift. For the V6 with balance shaft. | + | COMPCams 260-AH (CCA-56-440-8) mildest grind will be used to be compatible with the stock TBI and computer and still be within emissions limitations. It is a 260/266 degree duration cam. Lobe separation 112 deg and durations of 206/210 deg at 0.050" lift. For the V6 with balance shaft. |
| − | ''' | + | '''LIFTERS''' |
| − | + | COMPCams 875-12 (CCA-875-12) hydraulic lifters are my choice because of their near stock dimensions and fitting with the stock plastic retainers. CompCams lifters should be a bit better than stock and prevent lifter pump up within the range of 6'000 rpm. Plus they should work with the camshaft and rocker arms. | |
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| + | '''PUSHRODS''' | ||
| + | TBD | ||
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| + | '''ROCKER ARMS''' | ||
| + | COMPCams 1618-1 (CCA-1618-1) Ultra Pro Magnum Rocker Arm at 1.6:1 ratio. I have ordered just a single one to be able to check the valvetrain geometry for the machining of the studs and check rocker arm height with the OEM valves. At the same time I want to make sure they do not interfere with the OEM plastic covers. With the new camshaft I should already have about .100" more lift at the camshaft. I'll see during a test assembly if it fits. | ||
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| + | '''ROCKER ARM STUD KIT and a warning''' | ||
| + | ARP 100-7201 (ARP-100-7201) Set of screw in rocker studs. If correct they will feature a 3/8 by 24 thread for the rocker arm to be compatible with the adjustable nyloc nuts. WARNING - I have ordered studs with M10x1.5 mm threads for the screw in portion. This metric thread is common at my place and will make machining easier but may cause confusion in the US. One review actually stated that the buyer found out he had no tap for this thread. So make sure you get the correct one for your application. | ||
=== MACHINING AND PORTING === | === MACHINING AND PORTING === | ||
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