(Image/Jeff Smith)

In Part 1 of our story on building your own small block Chevy, we outlined the plan and detailed the assembly of the short block that included the rotating assembly, camshaft, and lubrication system. In this second installment we will cover the remainder of the engine assembly along with information you will need to successfully break-in the camshaft and ensure your engine will live a long, healthy life.

Compression, Piston-to-Head Clearance & Quench

In Part 1 we discovered that the pistons were sitting a little deeper in the cylinders than we anticipated, even after the block was decked 0.008 inch. After measuring all eight cylinders, we had between 0.025 inch and 0.032 inch of clearance below the deck. When combined with a 0.041 inch composition head gasket, this was not only going to lower our desired compression but also drastically increase the piston-to-head clearance—also called the quench.

Ideally we want somewhere around 0.035 to 0.040 inch piston-to-head clearance. This creates a tight space between the flat portion of the head to the piston which pushes or squishes the inlet air and fuel into the chamber, creating a more homogenous mixture which will burn more rapidly and completely. With a much wider quench area, much of the energy of this squish is lost and combustion efficiency suffers.

Given this, we decided to substitute a thinner 0.016 inch Fel-Pro steel shim head gasket in place of the composition head gasket that came with the gasket set. This improved our static compression ratio to 9.85:1, which should make for a very responsive street engine. This might also require a slightly better grade of fuel like 89 or perhaps to 91 octane. So if your plans include 87 octane fuel, the thicker head gasket will lower the compression to 9.3:1.

Inspecting the Valvetrain

Before bolting on the Summit Racing Vortec heads, we tested the valve springs to double-check their seat pressure. The springs looked hefty so we removed one spring and checked it in our digital valve spring tester. The load came in around 110 pounds at the 1.710 inch installed height. That number is acceptable for a flat tappet camshaft with an open load of around 285 lbs. at 0.470 inch of valve lift for break-in purposes. We wanted to make sure the break-in on this cam was as smooth as possible, so we so we dug up a near-new set of stock small block springs that tested at 95 to 100 pounds at the same installed height with even less load at full valve lift.

We will use these springs for the initial cam break-in period and then return to the original springs once we know the cam and lifters are fully seated. We have to emphasize this is us just being paranoid but we wanted to make sure the cam and lifters had every chance to break-in properly. We also checked the retainer-to-seal clearance and found that the Summit Racing heads will accommodate as much as 0.500 inch of valve lift with 0.025 inch for retainer-to-seal clearance. This won’t be a concern because our max lift is 0.466 inch on the exhaust side.

We painted the stock shim gaskets with silver paint (which was all we had) and torqued the heads in place using thread sealer and ARP’s Ultra Torque lubricant under the bolt heads. We also torqued the rocker studs that came with the heads. The next step was to slip the lifters into place and then drop in the pushrods and stamped steel rocker arms.

These new rockers also need some attention since these will also need to break-in properly. The exhaust rockers can get hot because of the exhaust valve’s elevated temperature so we coated the rocker balls and bottoms of the rockers with the same lube used on the cam lobes. This and a full engine pressure pre-lube will ensure they break in properly.

We prefer to adjust valves before the intake is installed just to monitor the lifters and pushrods and make sure everything is arranged properly. We then used our normal exhaust-opening / intake-closing (EO/IC) method of setting the valves. In this procedure rotate the engine until the exhaust valve just begins to open. When this occurs you can then preload the intake valve. Next rotate the crankshaft until the intake valve is halfway down on the closing side and then set the exhaust valve preload. We generally set it between a 1/4 to 1/2 turn on the adjusting nut once zero lash is achieved.

Installing the Intake Manifold

With the valves adjusted we moved on to painting the entire engine before installing the Summit Racing Vortec intake manifold. The Vortec heads require a specific intake manifold bolt pattern and also a specific length 5/16 NC intake bolt. These bolts need to be roughly 1-1/4 inches long. If they are too long, they will bottom out in the blind bolt holes in the head. If they are too short, they could possibly strip threads in the heads. We found GM Vortec intake bolts at SummitRacing.com but we cheated and used a set of ARP stainless bolts we had on hand. The Mahle gaskets require only 11 ft.-lbs. of torque to prevent overly compressing the intake gasket.

You may also find this article handy too: Ask Away! with Jeff Smith: How to Ensure a Good Intake Manifold Gasket Seal on a Small Block Chevy

Final Assembly, Pre-Lubing & Timing

With the intake in place we used the Allen style plugs to close off all the coolant and vacuum passages with pipe plugs. Next it was time to fill the engine with Summit Racing’s SAE 30 Break-in oil and pressure lube the engine. We like to use our old homemade pressure lubing tool made from an old HEI distributor body and shaft, but there are plenty of commercial oil pump primers available. We spin the oil pump clockwise with a 1/2 inch drill motor and run it until oil exits each of the 16 pushrods into the rockers.

OnAllCylinders contributor Wayne Scraba wrote a good article on oil-pump priming: Oil Pump Primer Tech: Starting Up Your New Engine the Right Way

The next step is to turn the engine until the balancer reads 15 degrees before top dead center (BTDC) on the Number One cylinder on the firing stroke. This can be identified by placing your finger over the spark plug hole and feeling pressure. With the crank at 15 degrees, we install the HEI distributor to line up to the rotor at the Number One spark plug position on the distributor. Make sure to lube the distributor gear with a good high-pressure lube to ensure proper life of the gear. It’s important to always use a new distributor gear with a new cam.

We included new spark plugs and wires with our new engine and made sure the Autolite plugs were the correct thread length. This is important because Vortec heads use a longer 0.700 inch tapered seat spark plug that is in between the short 0.400 inch stock small block tapered seat plugs and the longer 0.750 inch thread length gasketed spark plugs aftermarket heads most often use. We’ve included the Autolite part number for this application at the bottom of this article and we double-checked to make sure they were correct before we bolted the heads in place.

The Engine Break-in Process

To begin the start process, we always use straight water in the cooling system for the initial start because there are inevitably leaks with a new engine. To ensure the engine fires on the first crank, we always pre-fill the carburetor float bowls with fuel and hit the accelerator pump until we have about four or five squirts of fuel in the engine then we wait about a minute or so before attempting to start then engine.

If everything is adjusted properly, your engine should start on the first or second rotation of the engine with the starter. After the engine fires, immediately bring the rpm up to around 1,500 to 2,000 rpm. All pushrod V8 engines use oil splashed from the crankshaft to lube the camshaft and lifters so this high rpm ensures plenty of oil is delivered to the cam and lifter interface. We generally will run the engine for around 10 minutes and then shut if off to allow it to cool for about 30 minutes before running it again.

We bolted our small block to a Summit Racing engine run stand because the truck that is intended for this engine still has its original engine. The point is that after running the cam in for 10 minutes, we don’t want to run it any longer without putting a load on the engine to properly seat the rings. This ring seating process demands higher cylinder pressure than occurs with no load on the run-in stand.

To complete the break-in process, we need to install the engine in the car so we can immediately put load on the engine by continuously applying light to medium acceleration for another 10 to 15 minutes. Allow the engine to cool for about an hour and then, after checking coolant and oil levels, you can perform a couple of short, two to three second WOT acceleration runs not to exceed 4,500 rpm to ensure the rings are fully seated. This won’t hurt the engine but you want to always monitor oil pressure and water temperature.

We recommend keeping the rpm low because remember we are using stock valve springs to make it easier on the cam and lifters and they may not be happy much above 4,500 rpm. Of course, if the engine exhibits mild detonation or pinging, immediately lift off the throttle and retard the ignition timing to prevent this from reoccurring.

With this run-in process complete, it’s generally a god idea to leave the Break-In oil in the engine for 100 to 200 miles before changing it to the proper high-zinc oil like Summit Racing’s 10w30. This oil uses the proper zinc and phosphorous additive to ensure a long lifespan for the cam and lifters. At some point after perhaps 300 miles or so, you can then replace the stock valve springs for the original ones supplied with the Vortec heads.

Our modest small block is now ready for bolting it into our next intended project and we’re looking forward to a long lifespan in our parts-running shop truck project.

After removing the tape seal from the Summit Racing Vortec heads, we used compressed air to remove any possible dirt or machining debris. The valve springs looked pretty strong so we decided to test a spring to make sure the load was not excessive for a flat tappet cam. (Image/Jeff Smith)
We established the installed height at 1.710 inch and then tested the springs at that height and measured 110 pounds. This is just slightly on the high side of load for breaking in a new flat tappet cam, so we dug up some used stock springs of the same diameter that tested 100 to 103 pounds at the same installed height. This will give the new cam a better chance of a proper break-in. (Image/Jeff Smith)
Using a lever style valve spring compressor, we changed the springs on the Vortec heads. We re-used the same retainers and locks for the new springs since the spring diameter was the same. (Image/Jeff Smith)
We also checked retainer-to-seal clearance with the Summit Racing heads and measured a substantial 0.525 inch. This would allow up to a 0.500 inch lift with 0.025 inch clearance to the seal. (Image/Jeff Smith)
This oil galley hole just below the deck must be plugged to prevent a massive oil leak before the driver side (left) head is installed because the head blocks access but does not seal the hole. (Image/Jeff Smith)
Our first hiccup occurred when we discovered the worst piston measured as much as 0.032 inch below deck. The average was closer to 0.028 inch, which meant a significant drop in compression if we used a thicker composition head gasket. We needed a new approach. (Image/Jeff Smith)
We decided to exchange the 0.041 inch composition gaskets (black one) for a much thinner Fel-Pro steel shim gasket that measured 0.016 inch. We painted the gasket with some silver paint, allowed it to dry and set the heads in place. This moved the piston-to-head clearance tighter and improved the static compression to 9.85:1. (Image/Jeff Smith)
Again to save money we reused the stock head bolts. We cleaned the head bolts and applied ARP thread sealer to prevent water leaking past the threads and then applied a small amount of ARP Ultra-Torque to the underside of the head bolts for lubrication and then torqued the bolts in three steps to the factory spec of 65 ft.-lbs. (Image/Jeff Smith)
We also placed the moly break-in lube on the bottom of the lifters while putting regular assembly lube on the walls of the lifter before dropping them in place. (Image/Jeff Smith)
With new stamped steel rocker arms, we placed a thin coating of moly lube on the balls of the lifters to improve their chance to break-in properly. (Image/Jeff Smith)
To set the lifter preload, we employed the exhaust opening and intake closing method (EO-IC). This process is detailed more fully in the article and in other tech pieces that can found on the internet. (Image/Jeff Smith)
We used an old aluminum intake manifold to cover the intake ports and also masked off the exhaust ports and used old spark plugs to close off the plugs into the heads, then spray painted the engine with a can of Dupli-Color Chevy orange. (Image/Jeff Smith)
Vortec heads use a different rubberized intake manifold gasket and the directions also call for a bead of RTV at the China wall on both ends along with a small dab of RTV at the corners underneath the intake gasket to ensure a leak-free seal. (Image/Jeff Smith)
Vortec heads use a specific intake manifold pattern so we chose a Summit Racing Vortec dual plane manifold and bolted it down with specific length intake bolts. The intake bolt holes in the head are blind so if the intake bolts are too long, they will bottom out and not compress the gasket. The bolts need to be long enough with a 1-1/4 inch under-head length. These are torqued to only 11 ft.-lbs. to avoid over-tightening the gasket. We cheated here and used a set of stainless ARP bolts we had of the correct length but we’ve included a part number for the correct Fel-Pro Vortec intake bolts. (Image/Jeff Smith)
A very important step is to pressure lube the engine to put oil all the way up to the rocker arms. We first added five quarts of Summit Racing Break-in SAE 30 oil and pre-filled the Wix oil filter. With a pre-lubed engine, all the important areas are lubricated and a dry start is avoided. We run the 1/2 inch drill motor until we have oil at all 16 rockers. (Image/Jeff Smith)
With the balancer set at roughly 15 degreed before top dead center (BTDC) on the compression stroke, we positioned the HEI distributor with the rotor pointing at Number One spark plug position on the distributor cap. We also made sure to place a thick assembly lube on the distributor gear to avoid excess wear on the distributor gear during break-in. (Image/Jeff Smith)
We also included new Summit Racing 8.5mm spark plug wires that require assembly. Decide on how best to route your wires to avoid header tubes and be sure to leave sufficient room to adjust initial timing. If the wires are too short, you won’t be able to move the distributor to adjust initial timing. (Image/Jeff Smith)
Vortec heads use a specific reach 0.700 inch length spark plug with a tapered seat. This photo was taken before we installed the heads and you can see the threads do not protrude beyond the surface of the chamber. A 0.750 inch thread length would protrude by around two threads and could cause pre-ignition problems. (Image/Jeff Smith)
We bolted on a Summit Racing 750 cfm carburetor for our quick test firing on our test stand. This carburetor offers annual boosters in an affordable carburetor that will improve off-idle throttle response. (Image/Jeff Smith)
We ran our engine for about 10 minutes on the test stand mainly to check for leaks and to perform the first minutes of the cam beak-in. The final break-in should be performed under load to ensure the rings are fully seated within the first 30 minutes of engine run time. (Image/Jeff Smith)

Summit Racing Classic Cam Specs (SUM-K1103)

 Advertised
Duration
Duration
at 0.050"
LiftLobe Sep. Angle
(LSA)
Intake
Centerline
Intake288°214°0.444"112°107°
Exhaust298°224°0.466"

***

Jeff Smith's 355 SBC Budget Build Torque Specs
Main Bolts65 ft.-lbs.
Head Bolts65 ft.-lbs.
Crank Bolt65 ft.-lbs.
Rocker Arm Studs50 ft.-lbs.
Intake Manifold Bolts, Vortec11 ft.-lbs.
Rod Bolts, ARP0.0055" to 0.0060"
(bolt stretch)

***

Jeff Smith's 355 SBC Budget Build Engine Specs
Compression Ratio9.85:1
Bore4.030"
Stroke3.480"
Combustion Chamber Volume67cc
Deck Height0.025"
Piston Valve Reliefs6cc
Head Gasket Thickness0.016"

***

Jeff Smith's 355 SBC Budget Build Parts List
Engine Short Block
Summit Racing Coated Hypereutectic Pistons, 4.030" BoreSUM-17351C-30
Summit Racing Piston Ring Set, 5/64"SUM-133-M139-30
Summit Racing Main Bearings (Standard)SUM-172000
Summit Racing Main Bearings (Undersize, 0.001")SUM-172001
Summit Racing Connecting Rod BearingsSUM-171000
Dura-Bond Standard Cam BearingsDUR-CH-8
Summit Racing Oil Pump (Standard Volume/Pressure)SUM-121155SV
Melling Oil Pump Pickup/Screen AssemblyMEL-55-S1
ARP High Performance Series Connecting Rod Bolt KitARP-134-6003
Summit Racing Classic Cam and Lifter KitSUM-K1103
Cloyes Heavy-Duty Timing SetCLO-C-3023X
Fel-Pro Timing Cover GasketFEL-TCS51241
Summit Racing Freeze Plug KitSUM-G1581
Summit Racing Dowel Pin KitSUM-150122
Dorman Harmonic BalancerRNB-594-121
Summit Racing Harmonic Balancer BoltSUM-G1677
Summit Racing Stock Replacement Oil PanSUM-G3503X
Engine Top End
Summit Racing Vortec Cylinder Head (x2)SUM-151124
Summit Racing Chromoly PushrodsSUM-1457800
Mahle Original Engine Gasket SetMAH-95-3488
Summit Racing Stage 1 Intake ManifoldSUM-226018
Melling Rocker Arm (x16)MEL-MRK-651
WIX Oil FilterWIX-51069
Summit Racing ZDDP Performance Motor OilSUM-1-SAE30
Autolite Copper Core Spark Plug (x8)ATL-605
Summit Racing Blueprinted HEI DistributorSUM-850001-1
Summit Racing 8.5mm Ignition Wire SetSUM-881020
Summit Racing Valve CoversSUM-G3319B
Special Engine Assembly Tools
Clevite Rod Bolt SleevesCLE-2800B1
Summit Racing Cam Degree WheelSUM-G1057-16

Author: Jeff Smith

Jeff Smith has had a passion for cars since he began working at his grandfather's gas station at the age 10. After graduating from Iowa State University with a journalism degree in 1978, he combined his two passions: cars and writing. Smith began writing for Car Craft magazine in 1979 and became editor in 1984. In 1987, he assumed the role of editor for Hot Rod magazine before returning to his first love of writing technical stories. Since 2003, Jeff has held various positions at Car Craft (including editor), has written books on small block Chevy performance, and even cultivated an impressive collection of 1965 and 1966 Chevelles. Now he serves as a regular contributor to OnAllCylinders.