By Jeff Smith   –   Photography by the Author & Cam Benty

Street car engine building is not always about ultimate power. Sometimes it’s more about projecting the right image. Steve Strope had a vision—a Pure Vision, if you will—which happens to be the name of his car building company—to construct an early 327ci Chevy with an early ’70s vibe for a project car that he’s assembling.

One secret to successful car building is to project a consistent theme. Strope had an early 327 small-journal block, crank, and a pair of ’70s large-chamber heads and he wanted those parts assembled into a streetable small-block.

The plan was to build a streetable 327 with its factory steel crankshaft into a suitable little small-block with decent compression, a nice lope to the cam, and a tunnel ram with a pair of Holley 600 carburetors. We’ll be honest and say that most of Strope’s ideas had merit–except for maybe the heads. But that’s what he wanted, so that’s what we built.

The only way to accurately measure bearing clearance is with a set of good micrometers and a dial bore gauge. We measured each rod and main journal and recorded the measurements.

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The heads he dropped off were a pair of 3973487 castings that trace back to 1971 and the low-compression version of the LT1 350 engine. These heads featured screw-in studs, guideplates, 2.02/1.60-inch valves, and decent ports for castings that have survived more than 50 trips around the sun. They are not bad heads, but then neither are they great. But they are what he wanted to use because they take him back to a time in his life when these were sought-after pieces.

002 The only way to accurately measure bearing clearance is with a set of good micrometers and a dial bore gauge
Next, we then transferred the micrometer journal diameter for the mains to a dial bore gauge. With the main bearings torqued in place, the dial bore gauge will display the clearance. On the first main, we have it right at 0.0021-inch clearance, which is very close to ideal.

This changed the packaging of this little 327 when it came time to choose pistons. First off, our compression ratio program spelled out bad news if we were to stick with a generic flat-top, four-eyebrow piston. A flat-top piston with a 3.25-inch stroke matched with a 74cc chamber would drop the compression to a paltry 8.75:1. Since this engine needed to be snappy, we decided to add compression by adding a small dome to the piston.

003 Setting endgaps on rings can take a lot of time
Setting endgaps on rings can take a lot of time. If you don’t build a lot of engines, those inexpensive manual ring grinders are perfectly fine. We bought one of Summit’s new electric ring grinders that really save a lot of time working on the top and second 1/16-inch rings.

We had already decided against a hypereutectic piston as Strope liked the idea of strength from a forged piston. A short search brought us to an ICON piston with a 6.3cc dome that could pump the compression up to 9.8:1 using a 0.010-inch deck and a 0.041-inch-thick composite head gasket.

The issue with a domed piston is that it impedes the combustion process by lengthening the path of the flame front. A much better solution would have been a more modern aftermarket head with a tighter, 62cc chamber and a flat-top piston. This would have created an improved 10.15:1 compression ratio that would also shorten the path traveled by the flame front with no peaks or valleys.

004 Setting endgaps on rings can take a lot of time
Make sure this plug is installed–we used this photo from a different engine, but make sure the oil plug under the Number 5 main bearing is in place or the engine will not make oil pressure.

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If we were searching for ultimate power, we would also have decked the block to bring the pistons up to near zero deck, or we could have ordered a thinner head gasket to improve power. But that wasn’t necessary here.

With compression now settled, we continued the vintage vibe by selecting a flat-tappet, hydraulic camshaft. Summit Racing offers a line of Muscle Car camshafts that dial it back to the bygone era. From a wide list of potential candidates, we selected a cam that emulates the original L79 350hp 327 camshaft that was used in Corvettes, Chevelles, and the Chevy II.

005 Setting endgaps on rings can take a lot of time
Ring manufacturers now recommend using a ring expander instead of spiraling on the top two rings. Place the ends in the ring groove and expand the ring until it just slips into place. This prevents scratching the piston with the ends of the rings.

We’ve included the cam specs in a separate chart but with a relatively short duration of 221 and a wide lobe separation angle (LSA) of 114 degrees, this cam will offer a mild lope, yet still deliver some decent power with valve lift approaching 0.450 inch. This cam seemed like the perfect match to Strope’s visual approach with the engine.

We had Don Barrington at Barrington Engines in Canyon Country, California, just north of Los Angeles perform the basic block restoration routines that included boring 0.060-over, and torque plate honing. This block has seen some rough times and it also demanded line honing of the mains. The 0.060-inch overbore was necessary to clean up a nasty ridge at the top of several cylinders. This is near the outside edge of the bore envelope, but this block was up to the challenge with sufficiently thick cylinder walls.

006 Early small blocks were not fitted with harmonic balancer bolts relying on the press fit on the crank snout
Early small-blocks were not fitted with harmonic balancer bolts, relying on the press fit on the crank snout. We enlisted our local machinist Lucki Candoff to drill and tap our crank for much more security. Plus, we can now use a generic harmonic balancer tool for installing and pulling.

The cost to rebuild the stock connecting rods was close enough to the price of a new set of Scat 5.7-inch rods, which made the selection easy. Barrington installed the floating pins and opened up the small ends slightly to ensure there was room for lubrication. The ICON pistons were machined for the classic 1/16-, 1/16-, 3/16-inch ring package and we filled those with a set of Hastings rings that we custom set the endgaps using Summit Racing’s electric ring grinder.

007 Long ago we learned our lesson to always torque rod bolts using ARP’s rod bolt stretch gauge
Long ago we learned our lesson to always torque rod bolts using ARP’s rod bolt stretch gauge. This is their newest digital version gauge, but regardless of the gauge, this is a critical step to ensure the rod bolt clamp load is correct.

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We also used a set of Clevite rod and main bearings to complete the rotating assembly after the entire package was balanced by our friends at SoCal Diesel in Santa Clarita, California. Our standard preassembly ritual checked all the important clearances, including rod, main, and crankshaft endplay dimensions. Once the block machining was completed, the assembly procedure went smoothly.

008 We chose a Summit Muscle Car flat tappet hydraulic cam that is a reproduction of Chevy’s original L79 350hp 327 cam for this project
We chose a Summit Muscle Car flat tappet hydraulic cam that is a reproduction of Chevy’s original L79, 350hp 327 cam for this project. Using our degree wheel, we made sure the intake centerline was right at spec with the intake lobe centerline at 110 degrees.

After washing the block, it’s still not clean. We used white paper towels and a splash of Marvel Mystery oil to deep clean the honing grooves. We keep wiping with a new towel until it comes back red and not gray. This will also keep that honing grit out of the oil during new engine startup.

Strope wanted a little flash to bleed through this build so he spec’d a finned, cast-aluminum pan for the small-block and we finished that off with a specific package of a high-volume oil pump with an extended pickup to better use all the oil that this pan could contain.

009 With the deeper cast aluminum pan our initial oil pump and pickup was too shallow
With the deeper cast-aluminum pan, our initial oil pump and pickup was too shallow, so we had to change to a high-volume pump and performance pickup in order to place the pickup near the bottom of the pan. Shoot for a 3/8- to ½-inch pickup clearance to the bottom of the pan. Remember to include the thickness of the pan gasket in your measurements.

Having already chosen the cam to use, the only other requirement was to degree it in using a new Cloyes timing chain set and using our degree wheel to ensure the numbers were all in agreement.

Barrington had also tapped the front oil galley holes for us as well, which makes the plugs less likely to push out under high oil pressure. This is a good idea for early blocks like this one that had already been rebuilt at least once. Now it was onto assembling the top half of the engine.

010 We had Barrington Machine upgrade the heads with better exhaust seats
We had Barrington Machine upgrade the heads with better exhaust seats, new Erson stainless steel valves, Viton rubber valveguide seals, and dual springs. To assist in the cam break-in process we removed the inner springs, which will be reinstalled after the cam is fully broken in.

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We chose to assemble the heads ourselves to reduce the bill at the machine shop and also to ensure that we removed the inner springs in order to reduce the load on the camshaft during break-in. This is an important step because the break-in process is critical and even with high-zinc Summit Break-In SAE30 oil, a reduced spring load will also greatly assist in establishing a proper wear pattern on all 16 lobes.

011 The early small block Chevys used a canister oil filter that is a pain to change
The early small-block Chevys used a canister oil filter that is a pain to change. We used a Trans-Dapt oil filter adapter to convert this block to a spin-on style filter. This adapter uses a Ford-style Fram PH8A filter.

With the heads torqued in place with ARP bolts with sealant on the threads to prevent any coolant leakage into the oil, the final step was to install the intake. Strope wanted an older-style tunnel ram that we found used with a pair of Holley 600-cfm vacuum secondary carburetors. This package looks wild and also harkens back to the early ’70s look that he was after. The final piece is an early small-block distributor to finish off the look with smaller 7mm plug wires.

012 New flat tappet cams must be properly broken in and that require a specialty oil to ensure the lubricant has sufficient levels of zinc and phosphorous
New flat tappet cams must be properly broken in and that require a specialty oil to ensure the lubricant has sufficient levels of zinc and phosphorous (ZDDP). We used Summit SAE30 Break-In oil to ensure this part of the break-in task would be covered.

Strope also took the time to remove all the external casting flash from the block and heads and then painted the engine with actual Chevy Hugger Orange automotive paint after making sure the block and heads were surgically clean. The overall effect is stunning and will look outstanding sitting in his ’29 roadster pickup. Even if it is just another small-block Chevy, this one will run as good as it looks.

013 New flat tappet cams must be properly broken in and that require a specialty oil to ensure the lubricant has sufficient levels of zinc and phosphorous
We used a set of Fel-Pro composite head gaskets instead of the older tin head gaskets to ensure a good seal and then clamped them in place with a set of ARP head bolts.
014 To retain the early engine flavor we also used new Summit stamped steel rockers and Summit 516 inch pushrods for this throwback 327
To retain the early engine flavor, we also used new Summit stamped steel rockers and Summit 5/16-inch pushrods for this throwback 327. We pressure-lubed the engine until we had oil on all 16 rockers to make sure they were properly lubricated before startup.

 

015 Strope’s goal was an early ’70s look so he polished the Weiand tunnel ram to produce this image
Strope’s goal was an early ’70s look so he polished the Weiand tunnel ram to produce this image topped with a pair of Holley 600-cfm vacuum secondary carbs, velocity stacks, and Corvette cast valve covers.

Cam Specs

The following are the timing specs for Summit’s Muscle Car cam that emulates the original Chevrolet L79, 350hp 327. Note the wider lobe separation angle of 114 degrees.

Camshaft PN 1121
Adv. Duration Duration 0.050 Lift Lobe Separation Angle
Intake 290 223 0.447 114
Exhaust 290 223 0.447

 

Parts List

Description PN Source
Icon pistons domed pistons, 0.060-over IC793 Summit Racing
Hastings ring set, 1/16, 1/16, 3/16, 0.065 2M5523065 Summit Racing
Scat I-beam 5.7” I-beam rods, bushed 2570020 Summit Racing
Clevite main bearings, 0.010 under MS429P-10 Summit Racing
Clevite rod bearings, 0.010 under CB745P-10 Summit Racing
Dura-Bond cam bearings CHP-4 Summit Racing
Summit Muscle car camshaft, 350hp 350 SUM-1121 Summit Racing
TFS hydraulic flat tappet lifters TFS-21400001 Summit Racing
Erson stainless steel intake valves, 2.02” 2105 PBM-Erson.com
Erson stainless steel exhaust valves, 1.60” 2003 PBM-Erson.com
Summit Racing pushrods, 5/16” stock length SUM-1457800 Summit Racing
Summit stamped rockers, 1.5 G6800 Summit Racing
Cloyes timing set 3023XSP Summit Racing
Summit high volume oil pump 121155 Summit Racing
High volume oil pump pickup 40SB Summit Racing
Melling oil pump driveshaft IS-55E Summit Racing
Melling freeze plug kit MPE-100BR Summit Racing
Dorman harmonic balancer RNB-594-002 Summit Racing
Trans Dapt oil filter adapter 1024 Summit Racing
Fram Ford spin on filter PH8A Summit Racing
Fed Mogul 2-piece rear main seal 2900 Summit Racing
Fel-Pro pan gasket, 4-piece OS5197C2 Summit Racing
Fel-Pro head gasket set HS7733SH2 Summit Racing
Fel-Pro timing chain cover gasket TCS51241 Summit Racing
Speedway Motors cast oil pan, finned 9101760 Speedway Motors
Front timing chain cover 9101736 Speedway Motors
Summit Break-In oil SUM-SAE30 Summit Racing
Summit Muscle Car oil 10W-30 SUM-1-10w30 Summit Racing
ARP head bolts 134-3601 Summit Racing
ARP oil pump stud 230-7001 Summit Racing
ARP cam bolt kit 134-1001 Summit Racing
ARP accessory kit 534-9601 Summit Racing
ARP harmonic balancer bolt 134-2501 Summit Racing
ARP starter motor bolts 430-3505 Summit Racing
ARP flywheel bolts 100-2801 Summit Racing

 

Sources:

Automotive Racing Products (ARP)
(800) 826-3045

Barrington Engines
(661) 298-7790

Federal-Mogul (Fel-Pro)
(248) 354-7700

Speedway Motors
(855) 313-9173

Summit Racing
(800) 230-3030

Click on this issue’s cover to see the enhanced digital version of Old-School 327ci Small-Block Chevy Engine.acp march 2024

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