CLASS OF 1968

We turn the clock back 50 years and build a small-block Chevy with only what was avail­able in 1968

Chevy High Performance - - Con­tents - TEXT: Jim Smart | PHO­TOS: Jim Smart AND Sum­mit Rac­ing Equip­ment

We turn the clock back 50 years and build a small-block Chevy with only what was avail­able in 1968

The Viet­nam War was in full swing. It was an elec­tion year and a piv­otal time for the na­tion. There were two world-chang­ing po­lit­i­cal as­sas­si­na­tions. The Earthrise im­age was shot from Apollo 8 on Christ­mas Eve above the sur­face of the moon. “Hey Jude” by the Bea­tles was the num­ber one hit song. Hot Wheels was in­tro­duced by Mat­tel, launch­ing a phe­nom­e­non that lives on to­day. The Green Bay Pack­ers de­feated the Oak­land Raiders 33-14 in Su­per Bowl II. Rowan & Martin’s Laugh-In de­buted on NBC.

Do you re­mem­ber?

The year was 1968.

Sum­mit Rac­ing Equip­ment re­mem­bers 1968. That was the year it was founded.

Jeff La­timer, who was just 3 at the time has had this project brew­ing in his imag­i­na­tion for years. What if you could turn the clock back to build a 327ci small-block Chevy based only on what was avail­able decades ago? How much power could you make on the tiny bud­get you had in 1968?

For­get af­ter­mar­ket alu­minum heads, cur­rent-day dual-plane in­take man­i­folds, elec­tronic fuel in­jec­tion, ni­trous sys­tems, roller cams, mul­ti­spark ig­ni­tions, and the rest of it.

These items weren’t avail­able to the novice in 1968. The best you could hope for were dou­ble-hump iron heads or per­haps the clas­sic 283 Power Pack cast­ings ev­ery­one wanted.

Jeff found a stan­dard-bore 1963 327 block (cast­ing num­ber 3782870) and brought it to JGM Per­for­mance En­gi­neer­ing in Va­len­cia, Cal­i­for­nia, for ma­chine work to con­ceive a 1968-vin­tage 327. From here, the block could have been turned into any­thing from a rad­i­cal roller stro­ker to the old-school flat tap­pet street beast we’re about to build.

While he was shop­ping, Jeff un­earthed a pair of 3890462 cast­ing heads, one of the two most pop­u­lar “dou­ble-hump” cast­ings out there in 1968. He took these heads and had cus­tom port work per­formed by Chris Brint­nell along with the larger 2.02/1.60-inch in­take/ex­haust valves. He limited his ef­forts to what you could do in 1968.

Jeff’s search for pe­riod parts in­cluded an Edel­brock Street­mas­ter sin­gle-plane in­take man­i­fold, which wasn’t avail­able un­til 1973 but we’ll bite be­cause he had it in his stash. Jeff also found a well-worn Edel­brock C3B dual-plane in­take man­i­fold on eBay, which is a close cousin to the pop­u­lar vin­tage C4B dual-plane man­i­fold also avail­able in 1968. He did some re­pair work on the dam­aged C3B and pressed it into ser­vice.

We learned on the dyno the Street­mas­ter and C3B sport re­mark­ably sim­i­lar power curves con­sid­er­ing one is a sin­gle-plane and the other a dual-plane, with peak torque and horse­power num­bers ar­riv­ing in the same rpm range.

Both man­i­folds, though of dif­fer­ent dy­nam­ics, have long in­take run­ners. The Street­mas­ter, as its name im­plies, was con­ceived for street use. It is the darnedest com­bi­na­tion of midrange torque and horse­power from a sin­gle-plane man­i­fold. The C3B, as de­signed, is a ter­rific street/strip man­i­fold. Great low-end torque, yet it makes horse­power at 6,000-6,500 rpm. In dyno test­ing, we tried three dif­fer­ent car­bu­re­tor sizes: 600, 650, and 750 cfm. The great­est dif­fer­ence in power came from the 750-cfm Hol­ley (PN 0-80783C).

You’re go­ing to look at this retro 327 and catch the PerTronix Ig­n­i­tor, which was not avail­able in 1968. How­ever, solid-state ig­ni­tion was avail­able. You’re also go­ing to see three con­tem­po­rary Hol­ley at­om­iz­ers. We de­cided to opt on the side of con­ve­nience of get­ting new car­bu­re­tors from Hol­ley. Tay­lor ig­ni­tion wires like these weren’t avail­able ei­ther, but they look sharp. CHP

02 | Most of us who re­mem­ber 1968 will ad­mit we didn’t know how to choose a camshaft for our­selves at the time. In­stead, we looked to the ad­vice of speed shops and en­gine builders. We’ve opted for a typ­i­cal high-per­for­mance flat tap­pet hy­draulic camshaft you would have found on the shelf in 1968 with 228/228-de­grees du­ra­tion at 0.050-inch, 0.512/0.512-inch valve lift, and a 108-de­gree LSA that would make our en­gine go “rumpity-rump-rump” like in the good old days.

06 | With the crank prop­erly seated and the main bear­ings hit with en­gine assem­bly lube, Ryan torques the main caps to 65-70 ft-lb be­gin­ning with the in­ner main caps in one-third val­ues, check­ing for crank­shaft free­dom of ro­ta­tion as he goes. The crank should turn freely us­ing two fin­gers with the mains torqued.

01 | We’re work­ing with a 1963 327 Chevy block (cast­ing #3782870) with 4.030-inch bores that has been ma­chined and is ready for assem­bly. JGM Per­for­mance En­gi­neer­ing in Va­len­cia, Cal­i­for­nia, has align-honed the mains, honed the lifter bores, cut the decks, and power-honed the bores us­ing a torque plate.

03 | Jeff found a small-jour­nal forged steel 327 crank­shaft for this early 327 block. The crank was bal­anced by Doug Treutelaar with the cor­rect bob weight re­quir­ing two small pieces of Mal­lory metal due to the use of heav­ier forged pis­tons.

05 | Ryan Peart of JGM Per­for­mance En­gi­neer­ing checks crank­shaft end­play be­fore assem­bly con­tin­ues. We want a range of 0.002-0.006-inch ide­ally, but no more than 0.010-inch.

04 | The main caps are set in place and snugged to check crank­shaft end­play and free­dom of move­ment.

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