Thread: Common Engine Building Mistakes

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You are probably right Pat.

Don

WARNING: the following statements are based entirely on my opinion

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.

What's cool is one's opinion.....this is 2009, 350 and "cool" don't fit in the same sentence.....build something else.

Using an engine (or block or heads or manifold) because you already have it.

That eliminates all the 350's...everybody has one or ten.

Choosing parts because of low cost.

Does this apply to a 350? I thought that's why 99% of the people built them.

Buying used parts without verifying what they are.

Probably fits a 350, like the one in my car

On a more serious note....the worst mistake I ever made was not properly setting quench on my engine. I just changed head gaskets to correct it and the difference is amazing. There is so much information out there, and so many people willing to help, I don't see why there are so many poorly built combinations out there....asking questions is easy.

[QUOTE=techinspector1;360936]

Secondly, it must be because there is some romaticism surrounding the camshaft that causes newbies to buy the cam first, before they have any clue about anything else in the motor. As Robot said, you need to sit down and line out everything as a COMBINATION based on the intended purpose of the vehicle, the weight of the vehicle, the rear gear, the suspension systems front and rear, the transmission, the converter (if auto), the piston crown volume and combustion chamber volumes, gasket volumes, piston deck height, block deck height, compression height of the pistons, etc., etc. so that you can calculate the static compression ratio. You CANNOT intelligently choose a cam without knowing the static compression ratio of the motor. The cam should be the next to last purchase, with the converter being the last.

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I've seen so many engines fall flat on their face because of cam selection..... I guess it's too be expected when the only consideration given in selecting the cam is that it has to have a lopey idle!!!!!! Just a minor change in cam specs can make a huge difference in the engine's performance!!!

Next thing I've seen is poor cylinder head selection.... Bigger is not necessarily better!!!! Properly sized and shaped runners and combustion chambers are critical to engine performance.

I still defer to the experts on both cam and heads....Never have spent enough time studying to know what is the best. There are some very knowledgeable folks on this site, so with them and some input from the manufacturer's tech (not sales) people selecting the best components for the application is much easier....

My last observation is that so many people think performance is all about just the engine, when in fact the engine is just a part of the package!!!! It requires a good chassis, good suspension, the right pieces in the drivetrain, and most importantly a good set of binders to slow the whole thing down!!!!!

Planning and research BEFORE starting an engine build will result in much better performance then just collecting a hodge podge of parts from the swap meet and the clearance rack at Jeg's!!!!!!!

a good set of binders-----

Awwwww--I have only had one parachute fail to blossam and once had a stuck throttle---


Of course---they both happened on the same run

push rod length

Originally Posted by jerry clayton

a good set of binders-----

Awwwww--I have only had one parachute fail to blossam and once had a stuck throttle---


Of course---they both happened on the same run

Yeah, trouble comes in bunches, huh Jerry????? /Then there's always the 30 mph crosswind just past the grandstand---with the chute out!!!!

Great stuff! All I could add is that your whole drivetrain should be designed on the same concept of designing a package deal for your car. If you're building a mild street motor, take your transmission parts, stall speed and rear end ratio into consideration on the whole package. A 5,000 rpm stall would be just as bad as a 1050 dominator on your 250hp 283 smallblock.

Originally Posted by jerry clayton

a good set of binders-----

Awwwww--I have only had one parachute fail to blossam and once had a stuck throttle---


Of course---they both happened on the same run

I gotta tell you Jerry, my first thought was "wow - when I was in the Air Force, I always made sure that I took real good care of the guys in the chute shop!" But then I realized, "different chute"......

Either one (plane or dragster) would be a bummer if if didn't deploy, but from 20,000 feet up, it would really tend to mess up your day! Never had to punch out - but have had a few nightmares over the years about having one wrap!

You gave me a good laugh - at myself - Jerry!!

Regards All,
Glenn

Some advice my father gave me a long time ago, do all your math in advance before you ever buy a single part. Calculate what all the parts and machine work will cost you, write down that total, then double it. heheh

i think the biggest mistake is over carb. the engine. puting a double pumper(850 cfm) on a 2300 ford 4 cylinder just dose not cut it but it was one of the problems i was hired to straighten out. and over caming putting a race cam in a stock engine is another.

Originally Posted by glennsexton

I gotta tell you Jerry, my first thought was "wow - when I was in the Air Force, I always made sure that I took real good care of the guys in the chute shop!" But then I realized, "different chute"......

Either one (plane or dragster) would be a bummer if if didn't deploy, but from 20,000 feet up, it would really tend to mess up your day! Never had to punch out - but have had a few nightmares over the years about having one wrap!

You gave me a good laugh - at myself - Jerry!!

Regards All,
Glenn

No problem on the chutes Glenn!!! Mine never failed, and even if it would have every chute comes with a money back guarantee from the chute packers!!!! If it did fail, the next one was free... See??? no problem!!!!

Excellent posting, Robot. It should be printed off and tacked to the shop wall (or tree trunk, or whatever the working area might be) of anybody who isn't a plenty experienced engine builder.

The first engine I ever rebuilt was a Model A Ford. I was probably fifteen and of the opinion that I knew just about everything. When I got to the point of installing the head I asked an old goat down the road how much I should tighten the nuts. He told me as tight as I could get 'em then tighten them another quarter turn.

Ole Dumbutt here took him at his word and promptly twisted off a stud.

I'm still mad at him even though he has been dead over fifty years.


Jim

I am no engine builder for sure but from hish school auto shop, college power mechanics, Army track vehicle repair and 40 more years wrenching on my own stuff I feel one really big mistake is the act of not numbering bearing caps etc and failure to keep the valve train in a way all parts are reassembled in the hole for which they came.

Secondly access to a service manual for the specific to that year is sometimes VERY important .... a guy can build early vintage chevy small blocks by the hundreds but toss a 87 and newer at him and he sure as heck better know the setup.

Originally Posted by jerry clayton

push rod length

.....yep a very big deal.... every one makes there roller rockers geometry a bit different .then some of the retro roller lifters and solid rollers have there pushrod cup in at different heights .small base cam s milled heads deck s longer valves moved valve angles .i spend about 3 +hours getting the right push rods length alot longer on the big chief stuff.

Back when My dad helped me build my 1st motor, he made me wash the whole socket set untill they were spotless. you only have to look at the crap a well used socket can leave on a nut/bolt to see the logic behind it. (As mentioned previously) Also the bit about having a well lit work area is a great point too. I just took to the fluro tubes in my workshop with a rag and a can of brakeclean. It's amazing how much more light they throw off when they are clean.