HOT ROD to the Res­cue

Hot Rod - - Contents - Mar­lan Davis Norm Bran­des

THE COMBO

As orig­i­nally built back in 2006, this 1969 Ply­mouth Road Run­ner clone was pow­ered by a thump­ing 11.3:1, Chrysler 440-based en­gine, bored 0.040-over, and equipped with a 4.15-inch-stroke crank to yield 496 ci. Since then, the en­gine had been re­freshed at least once be­fore present owner Ray Lane got his hands on it in 2012. The Ply­mouth had laid dor­mant for sev­eral years with a rep­u­ta­tion for break­ing rocker arms, an an­noy­ance that per­sisted un­der Lane’s stew­ard­ship.

En­ter Chicago-area res­cuer, Westech Au­to­mo­tive’s Norm Bran­des. Ini­tially, Bran­des thought it was a ran­dom, oldage-re­lated prob­lem: Like highly stressed alu­minum con­nect­ing rods, alu­minum rock­ers have a fi­nite fa­tigue life. Ex­plains Bran­des, “I thought the rock­ers were just cy­cled out.” He re­placed the orig­i­nal shaft­mount val­ve­train with Dave Hughes shafts, rock­ers, spac­ers and shims. Chrysler spe­cial­ist Hughes is a fa­natic about parts longevity and proper valve-

train setup, and his parts have a great rep­u­ta­tion for strength and dura­bil­ity. Tune-up ace Bran­des also ad­justed the valve lash slightly tighter (the owner said it sounded too noisy) and per­formed a few tim­ing and car­bu­re­tor tweaks. The car ran great for sev­eral hun­dred miles.

THE FI­NAL DI­AG­NO­SIS

Two months later, Lane called Bran­des back: “I told Norm I was sud­denly hav­ing en­gine noise and the en­gine had a miss. Bran­des told me to get the car down to his shop ASAP.”

Bran­des picks up, “When the car ar­rived, we re­moved the valve cov­ers. The stronger Hughes rock­ers had held up fine but now two in­take pushrods and two valves had bent—the next weak link. Those pushrods had dropped clear down off the ad­juster nuts into the val­ley, and cylin­der Nos. 3 and 5 in­take valves were no longer open­ing. Later, talk­ing to Lane, we re­al­ized those were the same two cylin­ders where he and pre­vi­ous own­ers were break­ing the rock­ers.”

When Bran­des re­moved the driver-side cylin­der head, he dis­cov­ered mas­sive car­nage in the val­ley: The bent pushrods had fallen out of the lifter cup, break­ing the lifters in cylin­ders 3 and 5, goug­ing the cam lobes, and scratch­ing a cylin­der wall. There was de­bris through­out the mo­tor, but the main and rod bear­ings and jour­nals were still OK. “Our in­ter­ven­tion got to them in time,” Bran­des says. “But

we needed some valves, and the one dam­aged cylin­der re­quired over­bor­ing, so we’d have to or­der new pis­tons.”

But what caused the fail­ures in the first place? Valve-to-pis­ton con­tact! On a big­block Chrysler, the cen­ter two ex­haust ports and valves are ad­ja­cent to each other, mean­ing the in­take (I) and ex­haust (E) valve or­der is re­versed (I-E-E-I). To match this valve lay­out, there are two dif­fer­ent pis­ton top con­fig­u­ra­tions. It turned out the pis­tons for Nos. 3 and 5 cylin­ders had been swapped, caus­ing con­tact with the in­take valve.

THE FIX: PIS­TONS

Bran­des bored and honed the al­ready 0.040over en­gine another 0.015-inch over­size (0.055-over a stock 440 bore), suf­fi­cient to clean up the dam­aged cylin­der while match­ing the next larger Icon Pis­tons’ PN IC826 shelf-stocked over­size. To­tal dis­place­ment rose to 499 ci. Icon’s forged pis­tons were or­dered as a com­plete kit with duc­tile plasma-moly rings as well as Icon’s op­tional Line2Line abrad­able skirt coat­ing. Sprayed onto the pis­ton skirts, the coat­ing’s added thick­ness de­vel­ops es­sen­tially zero pis­ton-to-

wall clear­ance for re­duced pis­ton rock and qui­eter op­er­a­tion. Dur­ing ini­tial en­gine runin, the coat­ing wear-mates to the cylin­der, de­vel­op­ing mi­cro­scopic high/low spots that ac­tu­ally re­tain ad­di­tional oil for re­duced fric­tion. Icon weight-matched the new pis­tons to the orig­i­nal set, so there was no need to re­bal­ance the en­gine as a whole.

THE FIX: CAM AND VAL­VE­TRAIN

Cam tech has evolved since the en­gine was first built 12 years ago. Hy­draulic-roller cams are usu­ally to­day’s pre­ferred choice on the street. Bran­des re­placed Lane’s me­chan­i­cal roller cam with a Howards hy­drauli­croller that, com­pared with the orig­i­nal, has sim­i­lar mid-240s 0.050-inch tap­pet du­ra­tion but sig­nif­i­cantly higher lift, par­tic­u­larly when the solid’s valve lash is sub­tracted from the the­o­ret­i­cal lift num­bers. The cam is ground with a con­ser­va­tive 112-de­gree lobe-sep­a­ra­tion angle (LSA). Bran­des says, “The lobes are ag­gres­sive enough, and 112 is bet­ter for low-speed per­for­mance.” The grind was de­liv­ered as a cam-and-lifter kit that adds Howards retro­fit-style link-bar hy­draulic roller lifters. Bran­des added PAC Hot Rod Se­ries dual (with damper), 1.540inch od valvesprings to match the new cam. They fit Lane’s ex­ist­ing used re­tain­ers, which were OK for re­use.

With se­ri­ous high-perf val­ve­train parts, you must val­i­date both pis­ton-to-valve clear­ance as well as val­ve­train ge­om­e­try (the rocker arms’ roller-tip con­tact point on the valve-stem tip dur­ing the cam cy­cle). With the right pis­tons in­stalled in the right holes, pis­ton-to-valve clear­ance was fine. But the ge­om­e­try it­self can be af­fected by a cam change, block and head sur­fac­ing, dif­fer­entlength valves or valve seat heights, dif­fer­ent lifter heights or cup depths, and/or head gas­ket thick­ness vari­a­tions. Valve length wasn’t a fac­tor here be­cause the lengths of the two re­place­ment stain­less Com­pe­ti­tion Prod­ucts valves listed for a 429/460 Ford were the same as those they re­placed. Valveseat height con­sis­tency is crit­i­cal on a shaft-

mount en­gine, so Bran­des fresh­ened the valve job on all 16 seats, not just the two af­fected by the car­nage.

There are sev­eral the­o­ries on proper ge­om­e­try, ba­si­cally boil­ing down to whether you want max per­for­mance or bet­ter dura­bil­ity. For ul­ti­mate per­for­mance on pe­ri­od­i­cally torn-down race mo­tors, Hughes sets up the ge­om­e­try to ob­tain full cam lift. Pro­vided it doesn’t ac­tu­ally roll off the tip edge, the amount the roller tip is off-cen­ter as it wan­ders back and forth across the valve-stem tip as the cam cy­cles is less im­por­tant than max lift. For max longevity on pri­mar­ily street-driven en­gines, Bran­des likes to see

“This was a clas­sic BFO: a blind­ing flash of the ob­vi­ous. If the same parts keep break­ing, you need to go deeper and find the cause.”

— Norm Bran­des

the push point on the valve stem as cen­tered as pos­si­ble dur­ing the open­ing/clos­ing cy­cle, even though this may not gen­er­ate max lift on some com­bos. “It of­fers a straight push, cen­ter­ing the force. It’s eas­ier on the valve; the guides last longer,” he says.

On shaft-mount rocker sys­tems, both the rocker shaft height, rocker po­si­tion on the shaft, and the pushrod length af­fect ge­om­e­try. With Bran­des’ method, at rest (valve closed, pushrod not lashed), the tip is cen­tered over the valve-stem tip both lon­gi­tu­di­nally (edge-on) and lat­er­ally (side-on). Shim the shaft spac­ers and shaft pedestals as needed to get there. Then, us­ing an ad­justable check­ing pushrod and light check­ing springs, set the pre­lim­i­nary valve lash to zero, and ad­just pushrod length to achieve min­i­mum mo­tion off-cen­ter through the cam cy­cle.

Lane’s old pushrods were about ½ inch too long, so Bran­des got some made-to­order pushrods from spe­cialty pushrod maker Trend Per­for- mance. Its en­try-level ⅜-inch hol­low pushrod has 0.080-inch wall-thick­ness (com­pared to 0.049 for the pre­vi­ous ones), and is made from 4130 chrome-moly steel with a pro­pri­etary case­hard­ened heat-treat process. “They’re much stouter than the old ones,” Bran­des says. The re­quired pushrod length us­ing the “over-ball” mea­sure­ment method came out to 7.816 inches (yes, they’re that ac­cu­rate).

THE RE­SULTS

Af­ter in­stalling prop­erly ori­ented pis­tons, the val­ve­train was fi­nally sta­ble and re­li­able. The en­gine makes even more power than be­fore, and at a more us­able rpm, too!

LESSONS LEARNED

Don’t mix Miller time with en­gine as­sem­bly time. Be­fore in­stalling the heads, com­pare the pis­ton’s valve-notch ori­en­ta­tion to the cor­re­spond­ing com­bus­tion cham­ber valve or­der. Seem­ingly ran­dom parts fail­ures may not re­ally be ran­dom at all. Care­ful record keep­ing would have shown the same part failed in the same in­stalled po­si­tion, pro­vid­ing a clue some­thing may be wrong in­side the par­tic­u­lar cylin­der and cham­ber. A pis­ton-to-valve clear­ance check could have con­firmed the is­sue be­fore cat­a­strophic fail­ure.

01–02] When Lane’s wife, Jan­ice, broke a rocker ( 01) while idling in home­town Burling­ton, Wis­con­sin, Lane knew he had to get the pesky prob­lem solved. Westech Au­to­mo­tive’s Norm Bran­des ini­tially chalked it up to age and fa­tigue, re­plac­ing the en­tire shaft-mount val­ve­train with new, stronger Hughes En­gines parts ( 02). De­signed specif­i­cally to solve Chrysler rocker arm is­sues, the CNC rock­ers have re­vised oil­ing that pro­vides pos­i­tive oil flow to the pushrod cup at any angle, elim­i­nat­ing the need for a rol­ler­ized shaft.02

01

[ Un­der the Plum Crazy–painted Road Run­ner’s air-grab­ber scoop re­sides a 496ci big-block Chrysler Wedge, run hard by the pre­vi­ous owner.

[ Ray Lane has owned this 1969 Road Run­ner clone since 2012. Be­fore he got it, the car had ac­quired a rep­u­ta­tion for break­ing rocker arms.

[ Af­ter up­grad­ing the shaft-rocker sys­tem, the next weak link failed: bent pushrods cas­cad­ing into lifter, cam, valve, and pis­ton dam­age.

03–05] Hughes’ rock­ers usu­ally clear 1.625-inch-od springs, but Lane was run­ning 0.050-inch pos­i­tive-off­set valve locks to get the right in­stalled height with the springs needed to con­trol his ex­ist­ing solid roller cam, leav­ing lit­tle clear­ance be­tween the re­tainer top edge and valve-stem tip ( 03, ar­rows). Bran­des had to deepen the re­lief on the new rocker bod­ies’ un­der­sides. “With the valves closed, I used a piece of 0.030-inch-thick ny­lon fish­ing line to floss un­der­neath the rocker. The check gauge must be flex­i­ble to fol­low the un­der­side ra­dius ( 04). At the clos­est ap­proach point, I had to deepen the as-re­ceived ra­dius by 0.075 inch in the mill ( 05). You could do this at home with a die-grinder, or even on a drill-press with a fly cut­ter.”

06–08] Sev­eral hun­dred miles later, the en­gine be­came noisy and de­vel­oped a miss. Back at Westech, Bran­des checked out the prob­lem: “The Hughes rock­ers were fine, but we found mas­sive car­nage in the val­ley af­ter re­mov­ing the heads. Two pushrods bent and dropped down into the val­ley, where they bounced around and ended up be­hind the lifter link bars, snap­ping them and shear­ing the tops off two lifters ( 06). Two lifters ac­tu­ally turned side­ways on the lobe ( inset).” Good­bye, cam lobes ( 07). De­bris also scratched a cylin­der wall ( 08)

09–11] Big-block Mopars have siamesed cen­ter ex­haust ports; the ex­haust valves for the cen­ter cylin­ders pairs 3 and 5 and 4 and 6 are ad­ja­cent to each other ( 09). Icon IC826 pis­ton sets in­clude two sep­a­rate pis­ton top con­fig­u­ra­tions, each with a dif­fer­ent valve notch or­der and size. On this mo­tor, the Nos. 3 and 5 pis­tons were switched, caus­ing the larger in­take valve to hit the pis­tons above the smaller ex­haust valve notches ( 10, ar­rows). Com­pare to the cor­rect cen­ter pis­ton ori­en­ta­tions on the new, freshly in­stalled, Icons ( 11).

13] With the new cam, Bran­des in­stalled match­ing PAC springs spec’d for hy­draulic roller-cam big-blocks. Shorter than Lane’s orig­i­nals, the 431-lb/in rate springs of­fers ad­e­quate re­tain­erto-rocker body clear­ance with stan­dard-height valve keys. These springs would have elim­i­nated the need to clear­ance the rocker bod­ies. Dig the cool Good­son mul­ti­an­gle spring com­pres­sor.

12] Lane’s old tim­ing chain was slack­ing off, so it was re­placed by a premium Cloyes bil­let steel True Roller tim­ing set with a nine-key­way crank sprocket and three-bolt cam sprocket. Bran­des in­stalled the new Howards hy­draulic roller cam “straight-up” (on the “0” marks), as the cam al­ready had 4 de­grees ad­vance ground-in (108-de­gree cen­ter­line on a 112-de­gree LSA).

14–16] Slide the rock­ers back and forth slightly on the shaft un­til the roller is cen­tered on the valvestem tip as viewed edge-on from the cam val­ley. Once cen­tered, mea­sure the gap(s) be­tween the rock­ers and spac­ers or pedestal re­tain­ing block ( 14). Add shaft shims to take up the gaps ( 15, ar­rows), or shave the spacer if a rocker can’t be moved far enough to cen­ter it. To lat­er­ally cen­ter the roller tip as viewed from the side, ad­just the rocker shaft ver­ti­cal height. Shim the pedestal ( 16, A) to move the rocker to­ward the in­take side of the valve tip ( B); sub­tract shims to move it to­ward the ex­haust side. If all shims have been re­moved and the con­tact point is still bi­ased to­ward the in­take side, mill the pedestal.

18] One way to ac­cu­rately mea­sure Chrysler­type cup-end pushrod length is the “over­ball” method. Af­ter ad­just­ing a cup-tipped check­ing pushrod’s length so it yields proper ge­om­e­try, place a 5⁄16- inch ball in the cup and mea­sure the length from the top of the ball to the pushrod’s other end. Be sure to let your pushrod maker (Trend, in this case) know how you mea­sured. This mea­sure­ment method com­pen­sates for dif­fer­ent wall thick­nesses and cup radii.

17] On street Mopars, Bran­des sets val­ve­train ge­om­e­try to keep the rocker-to-valve con­tact travel point within the cen­ter third of the valve-stem tip through­out the open­ing and clos­ing cy­cle. If the pat­tern’s bi­ased to­ward the ex­haust side, get a shorter pushrod; if to­ward the in­take, a longer one.

19] Lane’s Chrysler big-block-pow­ered 1969 Road Run­ner had pre­vi­ously run 11.30-sec­ond, 121-mph quar­ters on 93-oc­tane un­leaded, shifted by a 727 TorqueFlite that trans­fers the torque back to a 3.23:1-geared 8¾-inch Chrysler rearend with a Sure Grip lim­ited-slip diff.

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