HOT ROD to the Res­cue

Hot Rod - - Everyday - Mar­lan Davis Jeff Smith

THE COMBO

Eric Sch­miege bought his 1965 Chevy Bel Air for $1,700 back in 2000, a time, he says, “When you could still buy old Chevys for cheap.” As orig­i­nally built, it had a lowly Chevy straight-six, but over the last 18 years, he and his hot rod­ding bud­dies have in­cre­men­tally up­graded it in­side, out­side, and un­der the hood— where big-block Chevy power now re­sides. “I wanted a big en­gine with an old-school vibe,” Sch­miege says. “So we built a 0.060-over 454 with Edel­brock Per­former RPM alu­minum heads topped by an old Offy dual-quad man­i­fold, then mod­ded a pair of 600-cfm, vac­u­um­sec­ondary Hol­leys to work prop­erly on it. I also put a fairly big flat-tap­pet hy­draulic cam in the mo­tor.” Be­hind the en­gine is a TH400 au­to­matic and 2,600- to 2,800-rpm stall-speed torque con­verter. A 3.08:1-geared 12-bolt Posi rearend gets the power to the ground. Used as an oc­ca­sional week­end cruiser and driver, the car is a reg­u­lar at­tendee at lo­cal SoCal car shows and usu­ally man­aged to make an an­nual so­journ up to Hot Au­gust Nights in Reno, Ne­vada.

THE PROB­LEM

Af­ter the Bel Air came out of the paint shop re­cently, Sch­miege says, “The en­gine sud­denly had a lot of vi­bra­tion; it seemed to be run­ning strange. I had a lo­cal shop in­spect the cylin­ders. They re­moved the spark plugs and stuck a camera in there. It turns out there was a ¼-20 nut in No. 5 cylin­der, prob­a­bly from the air cleaner re­ten­tion bracket. My friends and I pulled the pas­sen­ger-side head off to see how bad the dam­age was. The pis­ton top was roughed up. We smoothed out the dam­age in the car us­ing a Dremel tool, then cleaned out the shav­ings. The head went down to To­tal Per­for­mance in San­tee, Cal­i­for­nia, who fixed up the cham­ber. We re­in­stalled the head, but the en­gine wasn’t run­ning right. There was lots of blowby, and the com­pres­sion in Cylin­der No. 5 was still way down. The en­gine was toast.”

No shop wanted to take re­spon­si­bil­ity or get in­volved. For­tu­nately, Sch­miege knew Jeff Smith, for­merly editor at var­i­ous times of HOT ROD, Car Craft, and Chevy High-Per­for­mance.

In turn Smith con­tacted HOT ROD, and an­other Res­cue was un­der­way.

THE DI­AG­NO­SIS

The ail­ing Bel Air was de­liv­ered to Smith’s Los An­ge­les–area shop, where Smith says, “The en­gine was lit­er­ally huff­ing smoke out the breathers, a pretty good in­di­ca­tion of a pinched top ring. A ‘pinched’ ring does not seal. A ton of pres­sure is pushed into the crank­case and ex­its out the breathers as mas­sive blowby in ‘huffs’ each time the cylin­der fires.” At first, Smith thought that per­haps he could just re­place the bad ring and still sal­vage the pis­ton, so he pulled the prob­lem­atic part out of the mo­tor. Once fully ex­posed, Smith saw the pis­ton had been de­formed by the dam­age, and its ring lands had par­tially col­lapsed.

Still not the end of the world: Get one new pis­ton and ring pack­age, then slap the mo­tor back to­gether. Un­for­tu­nately, Smith says, “We dis­cov­ered the No. 5 cylin­der bore had at least 0.0005-inch taper in and out. That’s ex­ces­sive, so it needed to be prop­erly honed square. That meant—to do a pro­fes­sional job—the en­gine had to be com­pletely dis­as­sem­bled for a trip to the ma­chine shop. Af­ter com­plete dis­as­sem­bly, we mea­sured the other seven cylin­ders and they were also out of square. So now we needed eight new pis­tons and rings and an over­bore.

“Then the block failed a pres­sure-check,” Smith con­tin­ues. “You guessed it: Al­though not im­me­di­ately ob­vi­ous—to the ex­tent the en­gine over­heated— Mag­nu­flux­ing later con­firmed the cylin­der was cracked and it would re­quire a cylin­der sleeve.”

Adds Sch­miege, “When the en­gine was vi­brat­ing and mak­ing noise, there were no bub­bles in the ra­di­a­tor and no milky­look­ing stuff in the en­gine oil.” Go fig­ure.

With the en­gine out of the car and ma­chine shop bound, Smith de­cided to also ad­dress two other nag­ging is­sues plagu­ing Sch­miege since way be­fore the “great demise.”

• Oil pan con­tact: The Bel Air had been low­ered 2 inches with dropped spin­dles, caus­ing the oil pan to bounce and rub against the steer­ing re­lay rod.

Part-throt­tle det­o­na­tion:

The 3,450-pound Bel Air (as weighed with half a tank of gas plus driver) pinged at part-throt­tle. This could be caused by any com­bi­na­tion of ex­ces­sively high com­pres­sion, a cam not matched to the app and/or an overly ag­gres­sive spark curve.

THE FIX: BLOCK AND RO­TAT­ING PARTS

But first things first. The block went out to Jim Grubbs Mo­tor­sports (JGM), where the cracked cylin­der was sleeved, the decks milled square per­pen­dic­u­lar to the crank, and the 0.060-over a

10–12] Ex­ter­nally bal­anced 454 flex­plate and damper un­bal­ance amounts are usu­ally stan­dard­ized, al­low­ing easy field re­place­ment with stan­dard 454 parts as needed. But the Bel Air’s ex­ist­ing flex­plate and damper weights were way too heavy; the bal­ancer alone was off by 65 grams! In­stalling a new Sum­mit 454 de­gree’d bal­ancer ( 10) and flex­plate ( 11) put the ex­ter­nal balance within 10 grams of blueprint specs, an amount eas­ily han­dled in­ter­nally when JGM re­bal­anced the mo­tor. ARP’s 190,000-psi har­monic bal­ancer bolt ( 12) fea­tures an ex­tratall 12-point head that ac­cepts a deep socket so it won’t round-off when hand-ro­tat­ing the mo­tor. stan­dard 454 mo­tor’s 4.25-inch bore was taken out an­other 0.010 inch to square up the cylin­ders. With the now 4.320-inch-id cylin­ders and the ex­ist­ing 4-inch­stroke crank, this yielded 469 ci. JE’S Sports­man Rac­ing Pis­tons (SRP) divi­sion sup­plied 0.070over forged pis­tons, rings, and pins that fit the new bore di­am­e­ter. The slightly domed pis­ton de­vel­ops just over 10:3:1 com-

pres­sion with a 110cc cham­ber.

The 0.010-un­der crank and rod jour­nals weren’t dam­aged, but mea­sured bear­ing clear­ances were a lit­tle higher than op­ti­mum and slightly in­con­sis­tent. Metic­u­lous Smith put the clear­ances in ex­actly where he wanted by se­lect fit­ting and mix­ing and match­ing Speed-Pro/Fed­eral Mogul 0.010- and 0.011-inch un­der­size Com­pe­ti­tion Se­ries main and rod bear­ing shell halves on the same jour­nal as needed. Smith says the larger clear­ance shell should go on the top side of the mains and the bot­tom side of the rods. “This is to en­sure good oil flow into the bear­ings. The mains are loaded on the bot­tom while the rods are loaded on the top, so the ex­tr­a­clear­ance shell should be placed in the sides op­po­site to the load.”

The new pis­tons re­quired re­bal­anc­ing the ex­ter­nally bal­anced, 454-based mo­tor. Dur­ing this process, Smith’s bal­anceshop, Treutelaar Equip­ment

Sales (TES), dis­cov­ered the

Bel Air’s ex­ist­ing flex­plate and har­monic bal­ancer had much more ex­ter­nal weight added than nor­mal for Mark IV 454 parts. In­stalling a new Sum­mit 454 bal­ancer and SFI-cer­ti­fied, 168-tooth, 14-inch-od flex­plate solved this lat­est glitch.

THE FIX: CAM

To bet­ter com­ple­ment the driv­e­train gear­ing, mod­ern “star­burst-sym­bol” mo­tor oils’ lack of zinc, and Sch­miege’s driv­ing pro­file, Smith re­placed the ex­ist­ing hy­draulic flat-tap­pet cam with an Isky hy­draulic roller pro­file. Com­par­ing the cam specs (see ta­ble, right), Smith pro­vides a telling anal­y­sis: “At ev­ery data point on the lift curve, the roller will achieve lift ear­lier in the duration curve—which es­sen­tially makes the cam larger within the lim­its of the lift curve. This is the ad­van­tage of a roller cam over a flat-tap­pet.

“We also need to com­pare the difference in ad­ver­tised duration ver­sus 0.050 duration. The flat­tap­pet’s ad­ver­tised in­take duration is 39 de­grees longer than the roller cam while at 0.050-inch tap­pet lift the duration difference has shrunk to 20 de­grees

(238 − 218 = 20)—yet the lift is very close to the same for both cams: The roller has a lit­tle less in­take lift, and a lit­tle more on the ex­haust side. This will make for out­stand­ing torque with bet­ter throt­tle-re­sponse while giv­ing up only a slight amount of peak horse­power.”

“I told Eric it was a risk just to bolt the head back on with­out pulling the pis­ton, but it would be OK to try it. They would know right away if it didn’t work. It didn’t.” — Jeff Smith

It’s bet­ter to in­stall the new cam be­fore the pis­ton and rods to en­sure it fits eas­ily through the cam bear­ings. “Some­times the bear­ings are a touch too tight in the hous­ing and won’t al­low the new cam to fit,” Smith ex­plains. “Al­ways check this first be­fore assem­bly; it’s eas­ier to fix be­fore the ro­tat­ing assem­bly is in­stalled. On a Chevy, you should not need to per­suade the cam into place. If you do, some­thing’s not right. Usu­ally, the cam bear­ing may be tight in the bore. Most times put­ting a dif­fer­ent bear­ing in place will do the job.”

Final short-block assem­bly was fairly straight­for­ward, with an added Smith touch when tight­en­ing the con­nect­ing rod bolts—he uses a spec­i­fied stretch value, not a spe­cific amount of tight­en­ing torque. Rod bolts are your mo­tor’s most highly stressed fas­ten­ers. High-perf, high-al­loy, steel bolts have a rel­a­tively nar­row plateau dis­tance be­tween the the­o­ret­i­cal torque value need to achieve max fas­tener strength and the yield point. Due to the in­ac­cu­ra­cies of well-used (but never re­cal­i­brated) torque wrenches as well as co­ef­fi­cient of fric­tion vari­ables, tight­en­ing to achieve a spec­i­fied stretch value (al­though time-con­sum­ing) is safer and more ac­cu­rate. It may take more than the nor­mal torque value to achieve the spec­i­fied stretch.

THE RE­SULTS (SO FAR)

The block is re­paired, a balance is­sue ad­dressed, and the short­block metic­u­lously as­sem­bled with new pis­tons and a bet­ter cam. Next month: Cor­rect­ing pis­ton deck clear­ance, val­ve­train ge­om­e­try, a new oil pan and pump, and carb and ig­ni­tion tun­ing.

LESSONS LEARNED

Pay at­ten­tion to the de­tails. Cut­ting cor­ners ends up cost­ing time and money in the long run. Con­sider mak­ing a step-by-step pro­ce­dural check-list if you’re new to all this.

02] Noted SoCal en­gine builder Jim Grubbs (Jim Grubbs Mo­tor­sports) has re­tired, handing the reins over to able long­time shop fore­man Ryan Peart, who con­tin­ues the shop’s tra­di­tion of ex­cel­lence. Peart sleeved the dam­aged cylin­der. But check­ing the other cylin­ders with a bore-gauge re­vealed all had ex­cess taper and were out of square.

01] In­di­ges­tion: Swal­low­ing a bad nut can ruin your en­gine’s whole day. Some­how a nut got sucked down into the No. 5 cylin­der on Eric Sch­miege’s big-block Chevy. Bounc­ing around, it pinched the pis­ton ring land, cracked the cylin­der, and dam­aged a com­bus­tion cham­ber—but re­mark­ably missed the valves.

Eric Sch­miege[ Dropped 2 inches, the car re­cently got a fresh coat of Toy­ota Blue Spec­trum Mica paint. Af­ter it left the paint shop, the car ran poorly.

[ The vi­brat­ing, huff­ing, and puff­ing Rat mo­tor’s prob­lem was even­tu­ally traced to a nut in­gested down into No. 5 cylin­der.

[ San Diego’s Eric Sch­miege has been hop­ping up his 1965 full­size Chevy Bel Air in­cre­men­tally for over 18 years.

04–05] SRP’s forged, low-ex­pan­sion, high-sil­i­con, 4032 alu­minum al­loy, pis­tons ( 04) are de­signed for old closed-cham­ber fac­tory heads, but their rel­a­tively small CNC-ma­chined 14cc dome pro­file also fits Edel­brock’s semi-open 110cc-cham­ber alu­minum heads, yield­ing com­pres­sion ra­tios in the 10 to 10.5:1 range with a Rat’s near-zero deck heights and headgas­ket thick­nesses. They’re ma­chined for float­ing pins re­tained by dou­ble Spirolocks, but Sch­miege’s ex­ist­ing Scat rods weren’t bushed, so JGM press-fit the pis­tons and pins onto the rods’ small ends ( 05).

03] Af­ter Peart milled the decks to square up the block, the al­ready 0.060-inch-over bores for­tu­nately cleaned up by bor­ing the cylin­ders an­other 0.010 over. Hon­ing with a torque plate en­sures the cylin­ders ac­tu­ally stay round when the heads and gas­kets are in­stalled.

[ SRP, Isky, Fel-Pro, Speed-Pro, Sum­mit and ARP sup­plied the needed fix-it parts; Jim Grubbs Mo­tor­sports ma­chined and bal­anced the mo­tor.

[ Jeff Smith to the res­cue. The verdict: a pinched ring, cracked cylin­der, ex­ces­sive bore taper, the wrong cam for the combo, and a balance is­sue.

[ Pa­tient, crit­i­cal. Open it up, stat, and get that mo­tor out of there! Stay tuned next month as “Doc­tor” Smith brings a dead Rat back to life.

09] Fel-Pro per­for­mance sup­plied all the mo­tor’s gas­kets. For this month’s short-block assem­bly, that included this handy R.A.C.E. (Re­main­der to As­sem­bleCom­plete En­gine) kit that in­cludes front and rear main seals, and front cover, water pump, fuel pump and water neck gas­kets.Fel-Pro

Sum­mit Rac­ing

Mar­lan Davis

06–08] Smith checked the crank and rod jour­nals us­ing an out­side mike ( 06), then used those mea­sure­ments to zero a dial-bore gauge to check the in­stalled clear­ances of new Fed­eral Mogul trimetal Su­per Duty al­loy bear­ings. Final clear­ances were 0.0025-inch on Nos. 1–4 main bear­ings ( 07), 0.0032 on the No. 5 (rear) main, and 0.002–0.0026 on the rods. At just 0.0025-inch, crank end­play was too tight ( 08). To open up the thrust clear­ance to the 0.006–0.010-inch blueprint spec, Smith sanded the rear main thrust bear­ing sur­face on a glass pane.

13–14] An Isky hy­draulic roller cam ( 13) re­placed Sch­miege’s old flat­tap­pet grind. Smith: “The shorter-duration Isky roller adds a lit­tle more power down low. We kept the duration short at 218/228 de­grees at 0.050inch tap­pet lift, with a 112 lobe-sep­a­ra­tion an­gle (LSA) and 112-de­gree in­take cen­ter­line (IC). Com­bined with the mo­tor’s 10.3:1 com­pres­sion ra­tio, this should run pretty strong in the area where Eric drives the car.” Us­ing Sch­miege’s ex­ist­ing dou­ble-roller, three-key­way tim­ing chain, the cam de­gree’d in 1-de­gree ad­vanced (111 de­gree IC)—about as close as you can get al­low­ing for nor­mal ma­chin­ing vari­ables ( 14).14

13

16] One just doesn’t have 4.320inch bore ta­pered ring com­pres­sors lay­ing around. ARP to the res­cue: Its com­pres­sors are CNC ma­chined from 6061-T6 bil­let alu­minum tube, have a true ra­dius for each dif­fer­ent bore di­am­e­ter, and are even re­lieved for wire O-rings on the bot­tom. Stan­dard stock­ing sizes range from 3.552–4.750 inches (SAE) and 75mm–100mm (met­ric).16

15] With a roller cam’s non­ta­pered lobes and a Chevy’s rear-mount dis­trib­u­tor, the bil­let wants to “walk” for­ward in the block. Con­trol this with an an­ti­walk thrust but­ton, available in sev­eral dif­fer­ent ma­te­ri­als and lengths. Sum­mit’s 0.940-inch-long alu­minum but­ton (PN 6002) re­quired the least hand-sand­ing to yield the de­sired 0.005-inch end­play. An Isky lock plate pre­vents the cam sprocket bolts from loos­en­ing.15

*Valve lift with Sch­miege’s ex­ist­ing and reused Har­land Sharp 1.8:1-ra­tio roller rocker arms. The stan­dard big-block Chevy ra­tio is 1.7:1.

17] Tight­en­ing high-ten­sile con­nect­ing-rod bolts to a spec­i­fied torque value is pre­ferred over us­ing a torque wrench. Smith uses ARP’s bil­let stretch gauge, one of the most ac­cu­rate available. If you have a known ac­cu­rate torque wrench and the bolt reaches stretch be­fore hit­ting the torque spec, you may have a “stretchy” bolt (dis­card it).17

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