Another useful way to identify your GM Industrial engine
This Tech Tip is one in a series of we publish for engine professionals. This Tech Tip builds on an earlier ones we published about GM industrial engine identification. These include our

Tech Tip #43, GM 4.3 Industrial Engine Identification Made Easy
Tech Tip#63, GM 5.7 Litre Industrial Engine Identification Made Easy
Tech Tip #81, Identifying the 8.1L GM Industrial Engine.

The 5.7 GM Industrial Engine recently has been adopted more and more by OEMs including generator and material handling manufacturers. Both Hyster ( a division of NACCO) and Hoist Manufacturing make forklifts that use this engine. While the 5.7 is derived from the popular small block Chevrolet engine and can look a lot like it when buried in a forklift, there are important differences. These differences are critical when it comes time to order a replacement engine. In Tech Tip #63 we gave some handy hints about how to identify exactly which GM 5.7 industrial engine you have. We indicated that you should identify the following features:

The stamped number on the deck on front passenger side of the engine block
The number of bolt holes that hold on the intake manifold (8 vs. 12)
If you have the late style serpentine belt system. We now have an additional characteristic that is important.
Is the front timing cover plastic or metal?

These four identifiers of the GM 5.7 engine are helpful when you call us to order an engine. To support our customers we stock both new and factory reman GM industrial engines and have them ready to ship. If you would like more info and specs on these engines, we stock GM workshop manual. Call us toll free at 800 233 6539 to order your manual. Because we always include a free Workshop Manual with every engine we ship, we will deduct the cost of the Manual from the engine price if the Manual doesn’t solve your problem.
We at Foley Engines recognize our responsibility to pass on to the larger engine community information that we have developed over the last 93 years. We hope that these kinds of Foley Tech Tips and Tech Tips will raise the professionalism in our industry.

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How to identify your engine
The 496 cubic inch GM 8.1 liter engine has quickly found success in the industrial engine market. After all, with the Ford 460 out of production, this is the only V8 gas or natural gas fueled industrial engine of any size now available. This large V8 engine is found powering stand-by generators, many produced by Kohler. We have packaged the GM 8.1 for use in co-generation applications in laundries and correctional facilities. The GM 8.1 engine has also been used in forklifts and other industrial applications. Because it bears more than a passing resemblance to the earlier 7.4-liter GM engine, people often need help identifying it as an 8.1 and which specific 8.1 GM it is when ordering parts. Here is how.
All GM 8.1 industrial engines will have a serial number stamped in on the ear protruding from the rear (i.e., the non-water pump) end of the engine. There are two style 8.1 engines. One has a serial number format that begins as 81L followed by 5 digits. The other, later style 8.1 GM Industrial serial number begins as 8P1L followed by five digits.
This Tech Tip the third in our series on GM Industrial Engines.  Please see

Tech Tip #43, GM 4.3 Litre Industrial Engine Identification Made Easy
Tech Tip #63, GM 5.7 Litre Industrial Engine Identification Made Easy

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How to get around a few troublesome issues
This Tech Tip discusses a weakness in GM 4.3 V6 Vortec industrial engine camshafts and related components under certain conditions and recommends a retrofit kit.
The GM 4.3 V6 Vortec industrial engine is a rugged engine that has been used in a variety of applications. See Foley Tech Tip #43 for tips on how to identify which GM 4.3 V6 you are working on. This is important if you wish to order the correct overhaul parts or to exchange it for a new or reman engine. (Note: pricing on new 4.3 V6’s is so low that rebuilding a GM 4.3 V6 industrial is often not cost effective.)
We have noticed problems with the roller camshafts on the GM 4.3 V6 Vortec industrial engine if the GM V6 is used in a low RPM, constant speed application. This includes applications such as constant speed 1800 RPM generators, oil well pumping units, or in an application such as a forklift or wood chipper where the engine idles for long periods of time at very low RPMs. Under low RPM conditions, the roller cam in the GM 4.3 V6 Vortec doesn’t get enough lubrication from the oiling system and soon fails. The solution for this problem is to swap out the roller cam for the older style, flat tappet camshaft and related components.
Foley Engines markets a complete kit to do this. This kit includes a reground flat tappet camshaft with the base circle reduced by .060, new flat tappets, new push rods, and a brass bushing to replace the front cam bearing. The kit installs easily. The new bushing presses in using the cam retaining plate as a guide and the rest of the parts install quickly.
When you install the new cam, we strongly suggest that you use camshaft assembly lubricant (molybdenum disulfide) and petroleum-based oil, not synthetic, for the initial break in of the cam and lifters. See our Tech Tip #25, Break In Lubricant, Not Synthetic for more information on break in oils. At the first oil change, change the oil filter to remove any residual cam assembly lubricant which can easily clog an oil filter. Then switch to a high quality synthetic oil. If the engine is not in regular use such as in a standby generator application, we recommend a 50/50 mix of synthetic and petroleum based oil to avoid dry starts. See our Tech Tip #1, Blend the Oil for a discussion of the benefits of petroleum based oil in preventing dry starts.

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Useful way to identify your engine
This Tech Tip follows on the heels of one earlier, Tech Tip #43, “GM 4.3 Litre Industrial Engine Identification Made Easy.”
Over the last 50 years GM has made over three million V8 engines known as the Small Block V8. This engine family began as a 265 cubic inch displacement engine in 1955 and continued forward to this day. This engine has had a variety of cubic inch sizes, block castings, cylinder heads, and other variations. We are concerned here though only with the current 5.7 Litre iteration as used in industrial applications and helping to identify any potential problems with a new replacement engine.
Identifying Your GM Industrial 5.7 Engine
Look for a stamped number on the deck of the block at the front on the passenger side of the engine. The number you are looking for will be a suffix stamped after the casting number. It might read as either two or three letters, beginning with an “A”.
In addition to locating this number, it is important to determine if your engine has the late style serpentine belt.
Vortec Version. One easy way to identify the 5.7L Vortec engine is to examine the cylinder heads. The GM Industrial Vortec cylinder head was made by installing LT1 Corvette ports into an iron casting. The intake manifold bolts on with an 8-bolt pattern, unlike most other 5.7 GM heads that bolt on with a 12-bolt pattern. As a result only a Vortec manifold can be used on a Vortec engine unless the heads are drilled and modified. Additionally, these Vortec blocks used a late model center bolt style valve cover. Besides industrial applications these Vortec heads were also used on late model Chevy L31 truck engines.
GM Industrial 5.7 Special Characteristics
As an industrial engine the GM 5.7 industrial’s only problem area is a relatively weak valve spring. For low RPM application such as an 1800 RPM stand-by generator this is not debilitating. However for high RPM industrial applications such as wood chipper or continuous duty applications such as prime power generators or irrigation pumps, we recommend that the valve springs be upgraded. There are various aftermarket solutions to the weak valve spring issue. While it may seem surprising to turn to a racing parts manufacturer to make a GM industrial engine more robust, Comp Cams® has a new valve spring called a Beehive™ to cure this. These springs are canonical, and wound with an oval wire that avoids coil bind. These new springs do an equal job to a dual spring set up but are much lighter (73 grams vs. 115 grams) and use a 14-gram lighter retainer. They are something to consider if you are running your GM industrial engine under severe duty conditions. This upgrade can also be done on the 4.3 GM industrial. The Comp Cams® spring PN is 26918 and for the retainers is PN 774.
The GM 5.7 engine oil lubrication system, Vortec and non-Vortec, is well thought out. Neither “high volume” nor “racing” oil pumps are necessary or even desirable. A “high volume” pump can push too much oil up into engine and quickly drain the oil pan. However if you are concerned with bearing life in a difficult application we recommend switching to the 2 quart Delco oil filter that is available. A larger oil filter means cooler and cleaner oil is in the system. A two quart filter is also more forgiving if the lube system is low on oil. See Tech Tip #23, Oil Filters: Capacity counts,  at for an explanation of the benefits of using a larger filter and even switching to a remote mounted, extra capacity oil filter. Naturally, we highly recommend synthetic oil and regular oil sampling. (See  Tech Tip #18.)
Want to Learn More?
Foley Engines has Workshop Manuals for GM industrial engines including the GM 4.3 and the 5.7 ready to ship. Please call us with any questions or if you would like to contribute to this Tech Tip.

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Helpful guide on how to identify your GM 4.3 V6 Industrial Engine
Over the years General Motors has made many versions of the GM 4.3 V6 industrial engine. So many variations that without good information it can be difficult to exchange a failed engine with the correct new or remanufactured 4.3 Industrial engine assembly. The wrong engine can easily get shipped. But not to worry, Dr. Diesel™ has worked up a Tech Tip to help people identify which 4.3 industrial they have.


96 up


up to 94


Year of manufacture. Locate the GM 4.3 engine serial number on the left (remember, engines are always viewed from the rear; if the engine were in a vehicle, the left side is the driver’s side) front bank under the cylinder head. Record the last two letters of the number.
Is the bolt pattern where the governor mounts to the intake manifold three or four bolts?
How many bolts hold the intake manifold to the block? 12 (1996 and later) or 8 (1986 –1995)?
Are the valve covers and timing cover plastic (1990 on up) or sheet metal?
Are the mounting bolts for the intake manifold straight up and down or at an angle?
Is the water pump belt a v-belt or one large serpentine belt?
Are the motor mounts positioned in the shape of a cradle, with the supports located close to the lube oil pan?
Is there a provision on the block for a mechanical fuel pump?
What is the engine used in? If a marine application remember to change to brass freeze plugs, if in a Hyster check the oil pan. If you are going to change the Hyster pan, check your pick-up tube. Hyster can supply a new one. If in a Tennant, is it a “LT” version?
Is the GM 4.3 industrial engine oil pan ribbed aluminum or made from stamped sheet metal?

Want to learn more? Foley Engines has GM industrial engine workshop manuals covering the GM 4.3 ready to ship. Please call us with any questions or if you would like to contribute to this Tech Tip with another distinguishing characteristic that we haven’t listed. While we would like to be your distributor for GM Industrial Engines, we recognize that we have the responsibility of passing on to the larger engine community information that we have developed over the years. If this Tech Tip is helpful and raises the level of professionalism in the engine industry we will be gratified.

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