15 Brutally Basic Engine-Building Tips

Builder's Basics

Mike Petralia Jan 1, 2003 0 Comment(s)

We're going back to basics. The more we learn in the engine-building world, the easier it is to forget some of the basics. So whether you're an old pro or just about to bolt together your first engine, we offer a few tips that might save a headache or two.

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Righty Tighty
Everyone tells you to use Teflon tape on threads of any fitting (except O-ring, compression, or flare fittings, which don't require any sealant). The easiest way to apply the tape is to hold the fitting in your right hand and the tape in your left. Twist the fitting, not the tape, as if you were threading it into something. Keep the tape wrapped tightly around the top of threads and it'll apply itself! Two turns is the minimum and no more than four total.

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Timing Is Everything
When installing a new distributor, mark the No. 1 plug wire's location on the distributor, and align the rotor with that mark when you install it. It's also best to turn the crank to about 6-10 degrees at the dampener for the initial advance setting. The No.1 piston should be on the firing stroke; check for air coming out of the spark plug hole as you turn the engine over, and then stop between 6 and10 degrees.

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Set The Lash
Setting valve lash is easy but can be confusing because the valve layout is different on small-blocks than it is on big-blocks. One of the surest ways to set the lash is the "intake opening, exhaust closing" method. Turn the engine over clockwise watching the intake valve's rocker arm for the cylinder you're adjusting. When it begins to open, lash that cylinder's exhaust valve. Continue turning the engine over clockwise and watch for the exhaust valve to open and then almost completely close. Set the intake lash when the exhaust is about half closed. Starting on the left (driver's) side, the first valve on both small- and big-blocks is always the exhaust. The difference is that big-blocks alter intake-exhaust with every cylinder, and the first valve on the right side of a big-block is the intake. Small-block valves flip-flop with each cylinder. So a small-block's valve layout from the front of both heads is: E-I, I-E, E-I, I-E. A big-block's layout from the front of the driver-side head is: E-I, E-I, E-I, E-I. The pattern is reversed on the passenger side of a big-block (I-E, I-E, I-E, I-E) because the heads are on opposite sides of the engine.

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The Prime Of Life
When you build an engine, it's best to prime the oil system at least twice: once before you lash the valves to get lots of oil onto the bearings since they'll be abused during the lashings, and then again just before you start the engine. You should always turn the engine over slowly by hand to uncover all the oil passages and watch for oil to come up through the rocker arms on the second prime. That means the system is fully pressurized. It may take several minutes for oil to get to the top of the engine, and you'll need a powerful 1/2-inch chuck drill for the job.

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Proper Parts Matching
When installing parts from different manufacturers or even when mixing different parts from the same company, there's a hidden danger. Example: This rocker arm nut came from a different company than the one who built the rocker arms. The nut didn't fit the fulcrum pivot correctly and was damaged as a result (shiny spot on bottom of nut). Make sure you source your parts from the same manufacturer, or be very careful that the parts you use match up.

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Check TDC
When you're building a new engine, it's always a good idea to see if your indicator truly shows TDC. The best time to do this is before you install the cylinder heads. With the crank, pistons, and dampener installed, mount a degree wheel on the dampener and use a piston stop to find true TDC on No. 1. Then, bolt your indicator on and line it up.

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Don't Let It Fall Off
This happens way more often than it should. Some guy gets a new oil pump and pickup and presses them together for installation. The darn things fit so tight when pressed together, he'd never believe us if we told him it could, and probably will, fall apart. Well, they do and yours probably will too if you don't weld it first. Summit Racing's Engine Shop (800/230-3030, www.summitracing.com) offers pre-welded pumps, like the one shown, if you don't want to weld one yourself.

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Good-Looking Seal
You should only use high-temp, oil-resistant RTV silicone on the ends of your intake manifold. The author prefers Permatex Black. After torquing the manifold in place, use a few paper towels to wipe off any extra silicone that squeezed out, and your engine will look much better.

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Proper Alignment
It's common when installing new rocker arms on aftermarket cylinder heads not to have the rocker arm tips centered on the valves (note the rockers on left and right are not centered). Isky Cams (323/770-0930, www.iskycams.com) makes adjustable pushrod guideplates that can correct the problem on some heads. Or you can cut your guideplates in half, reposition them, and weld them back together. Don't ever try running cut guideplates without re-welding them or you could have a disaster on your hands.

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Depth Charge
If you've just bought some new cylinder heads and are about to bolt them on, be sure to check your spark plug depth before proceeding. If the plug sticks too far inside the chamber, it could hit the piston. If it does not go far enough into the chamber, its spark will be shrouded, and you might lose some power.

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Not Long Enough
You've just installed that brand-new set of rocker arms, and they hit the valvespring retainers. The way to fix this is with longer pushrods. The same may also be true if you've swapped cylinder heads, installed new springs and retainers, or even installed thicker head gaskets. Any of these could cause interference between the rocker arm and the retainer. Longer pushrods are the answer, and they're easy to get from just about any cam manufacturer.

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Compression Gone
When swapping heads, make sure the heads you install don't have a larger combustion chamber than the ones you removed, otherwise you'll lose power. That's because a larger chamber will lower your compression ratio, which is usually a bad thing. The only time you'll want less compression is if you're adding a blower or turbo, or if your engine pings on Super Unleaded gas. Aluminum cylinder-headed engines can usually withstand about 1 point more compression without pinging than an iron-headed engine can.

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A Little Gap
You should always check your ring gap, even when installing factory-fit rings. If you don't and your rings bind, you'll be in a world of hurt. The industry standard for ring gap in street engines is 0.004 inch of gap per 1 inch of cylinder bore. Therefore, a 4.00-inch bore small-block should have minimum 0.016-inch top ring gap (0.004 x 4 = 0.016). It's okay to use 0.002-0.003 less gap on the second rings. Check out www.federal-mogul.com/sealedpower for more tips on ring gaps.

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Lube For Life
Even though roller-tip rocker arms produce less power-robbing friction than stamped rockers, they still need plenty of oil to live. That's especially true upon startup with a fresh set of rockers. We advise soaking the rocker arms in an oil can for at least 10 minutes prior to installation to allow the oil to seep into and lubricate the roller's trunion. If included, always apply any special lubricant to the rocker arms just before startup.

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Hi-Perf Lifters
You may not want to believe it, but high-performance hydraulic lifters like the Pro Magnum lifter from COMP Cams (901/795-2400, www.compcams.com), shown on the left, can make some power for you. Their special internal valving helps make more power at higher rpm. They're more expensive but worth it, even for a daily driver that gets pushed hard from time to time.


Project Cars
15 basic engine-building tips for beginning Chevy builders
Mike Petralia Jan 1, 2003


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