Thread: Common Engine Building Mistakes

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I am sure Tech and a few others can add to this list but here is some info for the guys learning how to do their first build:

MOST COMMON ENGINE BUILDING MISTAKES

• Using an engine (or block or heads or manifold) because you already have it. This is a compromise from the start. Before you spend a lot of money on an engine build, define (on paper) what you are trying to accomplish, is it a low RPM street engine in a 3600 lb car or is it a drag-only engine in a 2000 lb car? There is a difference; a big one. Then, build the engine on paper by making a list of every component's specification. Go thru the list to verify that the components are compatible. Sell those incompatible parts to some other sucker.
• Listening to buddies....they are the poorest source of information in the world. Call the experts. If it is a cam choice, call the cam manufacturer and listen to their advice. Just like asking your buddy about sex, your buddy has no experience in building engines
• Thinking you are going to build a superior engine by cutting corners We see this all the time.....guys will argue that they are building a xx horsepower for little money...but the professionals have to spend twice (or more) the money to get the same horsepower....what do you know that the pros don't? There is a reason for almost every step in an engine built. Skipping steps or cutting corners will not result in a higher horsepower engine....it just will not happen.
• Building an offbeat size engine because it is "cool" or because "everyone has a 350." There are valid reasons for building a 265" or 283" Chevy or a 221"/260" Ford. Being cool is not a reason. 99% of the people that look at the engine have zero clue of the size.....build a big engine and tell them whatever....they will be impressed by how well it runs
• Using parts because you already have them. Wow, how many times has someone written this forum and said "I am building an xx and I have these heads that I have had for 20 years. What a disaster! An engine is a system and every part in the system must be chosen with care. Maybe they have been collecting parts for 20 years to build a specific engine...that's a different story and is OK.
• Buying used parts without verifying what they are. Again, how many times have we seen someone post "I need to identify this cam that I bought really cheap at the swap meet." Why did he buy something that he had not already identified? Buying used parts is risky enough but buying unknown used parts is a poor use of money.
• Choosing parts because of low cost. Realizing that everyone has a budget (yes, everyone), it can be said that it is foolish to compromise an engine build by using a questionable part or a part that is just wrong. If you are spending several thousand dollars or more on a build, why risk the entire cost by installing a "low cost" oil pump or a set of "Chinese" hydraulic lifters? If nothing else, think of the value of your time when you have to remove the engine to change a dumb part. I once knew a guy who bought a rebuilt engine for his car. After installing the engine, he fired it up and it had a bad knock. He went back to the el cheapo auto supply and told them the problem. They gave him another engine. It too had a problem so he got to install not one, not two, but three engines in his car. If he was pretty fast, he may have spent 8 hours on each engine times three. No bargain there from the el cheapo supply house.
• Using a cam (or pistons or heads) without consideration of the total system Just because Hot Rod Magazine used a "super thumper double whammy" grind does not mean it will work in your motor unless you are building the exact same thing they did. Do something really smart and really simple....call the part manufacturer and talk to their tech people. Then, do something really revolutionary....follow the manufacturer's advice.
• Not placing enough importance on the piston ring choice and the required bore/hone procedure for that ring package. The current Hot Rod Magazine has a good ring article. Rings are pretty important to the engine's success. Again, ask the manufacturer.....that cell phone plan you have probably has free long distance so use it!
• Choosing the wrong torque converter for the engine A bit of art and science but there are resources that can point you in the right direction. A wrong converter can turn a hot engine into a dog. Converters are not cheap but you should be able to zero in on the correct one without buying the entire range of stall speeds.
• Relying upon the machinist to not make mistakes Wow, what a mistake to make! If the machinist goofs up, he may not notice the error (or he may not care). Nothing like building an engine and finding out that the clearances are wrong after you spend the weekend installing the thing. Trust no one.....including yourself.
• Choosing a machinist using price as the criteria Just because he will bore the engine for $1 a hole will not make your build a better one. Unless you are building an engine for the demolition derby, you should buy machinist services on quality......
• Not checking everything and not rechecking everything Back to don't trust anyone. Don't trust your measurements, measure a few more times.
• Putting the distributor in backwards or one tooth off. Think thru the assembly and know the theory of how the engine is assembled before you do the final assembly. Every engine has a similar operating theory, just figure out how a Ford indexes the distributor relative to the cam.....it isn't the same as a Chevy.
• Adjusting the valves wrong Wow, we have seen this a lot in CHR. When the instructions say "tighten the rocker arm nut until the push rod play is eliminated and then tighten the nut 3/4 turn" means the VERTICAL push rod play. Twisting the push rod is not play, it will still rotate after all vertical clearance is gone. We all have done it, but we all have learned.
• Putting the timing gear on wrong If you don't understand how to line up the little dots, ask someone or read the instructions....the little dots mean a bunch to the cam. After you put the timing gears on, check it again. Then, check it one more time.
• Improper break in procedure. Engine's in....let's go!! Well, the specific components that you used each have a preferred break in procedure. Follow the manufacturer's instructions. Just because your buddy broke in his car by pouring sand down the carburetor does not mean that it is applicable to your build.