Muscle Car Engine Rebuild Tips
Race Engine Rebuild Tips That Can Save You Time And Money
Published November 15, 2017
Whether it’s a muscle car, a race car, or just a daily driven beater, the engine is the heart of the vehicle, without exception. With muscle and race cars, however, it basically defines your ride, and what it’s capable of. When you have the right lumpy cams and loud exhaust, people know you mean business. As all dedicated wrenchers know, every muscle car starts out with an engine rebuild. Unfortunately, building a great motor can be expensive as hell. Yes, the market is flooded with crate engines with plenty of horsepower already installed, but there is something about building your own engine that appeals to most gearheads.
Few are born with the knowledge needed for an engine rebuild. Even the people who are lucky enough to have someone around who knows their way around an engine may run into a few hiccups. That is why we decided to put together a list of engine rebuild tips for the novice gearhead. Hopefully, these tips will help you over a few of the hurdles you might encounter.
Clean Your Work Area
Having a clean work area prior to, and during, an engine rebuild is essential. It will help keep foreign material out of a clean engine block and it makes for a safer work space. Having said that, you should never sweep the floor or wipe down your workbench table during the build. Doing so can put dust and debris in the air and in your engine. You should never grind metal near you build area for the same reason. If possible use a metal topped workbench. It is easier to clean up after the build and you do not have to worry about oil soaking into it, potentially contaminating future non-engine projects.
Organize Your Space
Keeping your items neatly organized will help you grab what you need quickly and easily. Ziplock bags are a great storage solution for smaller items; you can write down measurements and specs on these bags with a permanent marker, helping your engine rebuild go faster.
Clean Everything Before Installing
When you are doing an engine rebuild, you have to be a clean freak. The tiniest bit of dust or debris can prevent a gasket from sealing correctly and you do not want to risk finding a leak after the build is complete. The worst is to have a head gasket not seal, leading to a blown head gasket or worse. The best way to avoid these problems is to have the head and block surfaced by a professional. After surfacing, the pros will clean up with acetone, brake cleaner, or degreaser.
As your engine build progresses, you may have a need to do some additional cleaning. Keep in mind that you should never use a wire brush or an abrasive on surfaces. Either can leave an uneven surface that will not seal properly. Some areas, like the oil galleys and the journals on the crankshaft, can be tough to get to. Try using a gun cleaning kit. The tools in the kit can make degreasing, cleaning, and removing metal shards much easier.
You will need to clean your pistons prior to installation. Acetone is a great cleaner but may leave some contaminants behind. A better cleaner is a mixture of warm water and Simple Green. With a soft bristle brush, you can get all of the material out of the piston ring and oil groove channels. Be sure to blow dry the pistons with an air compressor immediately after cleaning.
Take The Stress Off New Connecting Rods
It is very important to have the right clearance between the rods, main journals, and bearings during any engine rebuild. A huge part of that is making sure the housing bore on the big end of the rod is correct. Most manufacturers are going to make sure that the rods they ship you measure up right, but…
You may get a set of rods with the right housing bore diameter and think you are ready to rock. Maybe not. Honing rods puts a lot of stress on the material. This stress can be relieved by unbolting the rod caps. Unfortunately, some manufacturers do not do this as part of the honing process. That means it is up to you to do so. After unbolting and rebolting the caps to the proper torque, you may find that you now have a gap of as much as much as 0.0005 along the line where the rod and the cap connect. This can put more stress on the bearing, potentially causing a spun bearing. If you find a gap after de-stressing your rods, take them back to be re-honed.
Get The Pins Right
So, there is no bearing between the wristpin and the bore in the rod or the piston. That means the rod and piston bore have to be perfect. Many manufacturers leave the pin bores a tad tight. This is done because professionals doing an engine rebuild prefer to ensure tolerances personally and will hone everything themselves.
If your measurements indicate that the tolerances are too tight, take your components to a machine shop for honing. Additionally, the pin towers on your pistons may measure out right, but not be straight. There is a simple test for that. Insert the wristpin into one pin tower and spin. Now, push the pin into both towers. If the wristpin catches going into the second tower or does not spin as easily as it did in just one, then you have an issue. If this happens, more honing is required.
Rod Bearing Width
Many performance crankshafts have a larger radius fillet at the journal edges. That means there is more material between the journal and the crank arm, which makes for a stronger crank. Some engine rebuild kits do not take this added material into account and ship stock spec rod bearings. Stock spec rod bearings are too wide for a performance crank. These stock spec bearings are commonly made out of aluminum and do not have a babbitt. These bearings will have a silver finish. These rod bearings have to be pitched because the added width will cause the bearing to ride up the crank, damaging both bearing and crank.
Even if this is not your first engine rebuild, you may not be able to spot these wider bearings by sight. An easy way to test your new bearings is to install two rods with bearings. Afterward, grab a feeler gauge and check the side clearance. Also, check that the cheek of the rod hits the crank first. If the rod stops before the cheek hits anything, your bearings are too wide. The best solution is to buy a narrower set of rod bearings. The hard way to go is to use a bearing scraper and cut a chamfer into the outer edges.
Check The Valves
This tip applies when your engine rebuild involves roller-tipped rocker arms. You will want to check that your entire valve train is under control. Valves should never spin. If they do, they are bouncing off the valve seat instead of closing correctly. Valve bounce will damage valves and valve seats while lowering compression.
You can check for valve bounce by looking at the valve stem tips. When a valve is bouncing, it will leave a star pattern on the tip of the stem. Be sure to check for damage to the valve and seats in the cylinder heads. To fix this, you will want to switch to stiffer springs, lower the rocker ratio, and perhaps use a milder cam.
Check Your Lifters
When you buy an engine rebuild kit, you expect the lifters to be the right size, but that isn’t always the case. So many engine rebuild kits are being made overseas nowadays. Unfortunately, that means the quality is lower from time to time. All it takes to ruin an engine is one incorrectly sized lifter.
If a lifter is too large, it will stick because there isn’t enough clearance between the lifter and the lifter bore. A lifter that sticks at the bottom of the bore will tear up a cam lobe, sending metal through your engine. One that sticks at the top will force the valve open. That means the piston will slam into the valve, bending the valve or breaking it off. If it breaks, you have most likely lost the engine.
Check The Combustion Chamber Volumes
Many an engine rebuild reuses old heads. One good idea, especially if you are building a muscle car or race engine for competition is to check the combustion chamber volumes. This allows you to check your compression ratio and meet all compression and minimum chamber size rules.
There are plenty of kits for sale. Some beginner kits are fairly inexpensive and easy to use. If you do not think you can do this accurately, most machine shops can do the work.
If You Opt For A Double Timing Chain
The engine rebuild of choice for competitors is a Chevy small-block. The stock timing chain is a single width chain, but a double-width stands up better in high-performance engines. The problem is that stock engines do not have enough clearance for a double-wide chain. A double-wide will rub on the block and likely break…almost always at the least convenient time.
All you need is a die grinder. Slowly grind the top edge of the boss of the upper oil gallery until the double-wide fits without contacting the block.
Your machined metal surfaces will have irregular finishes when they arrive. These surfaces will wear together in time, but until the engine oil circulates, you will want to have an assembly lube in place. Assembly lube protects your engine rebuild against micro welding, dry starts, or inefficient oiling issues.
You will want to use assembly lube on nearly everything other than pistons and cylinder walls. You should also use moly or a moly grease as a break-in lube on flat tappet cam lobes/lifter bottoms. A thin layer on critical surfaces is all you need.
The frictional inconsistencies of oil and other lubricants can cause you to get inconsistent torque values while doing an engine rebuild. This is called pre-load scatter and can lead to bore distortion, hamper piston ring seal, and poor head gasket seals. One solution is to tighten and loosen all bolts numerous times. Another is to use a torque assembly lube. Many will allow you to get within five percent of the ideal preload the first time you torque.
Well, there you have it, our list of engine rebuild tips and tricks. Do you have a few that you think should make the list? Hit us up in the comment section!
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