HOT ROD to the Res­cue

Hot Rod - - Contents - Mar­lan Davis Brett Tur­nage


Last month, a miss­ing 25¢ oil­gal­ley plug cost 1998 Bronco owner Tevete (“T”) Usumalii his cylin­der block, al­though L&R En­gine was able to sal­vage the 349ci small-block Ford ro­tat­ing assem­bly. Swapped into a good used, pre­ci­sion-ma­chined cylin­der block us­ing Mahle-Cle­vite bear­ings, the as­sem­bled short­block was re­turned to Ad­vanced Engi­neer­ing West (AEW) for camshaft and top-end assem­bly be­fore re­in­stal­la­tion in T’s 1998 Ford Bronco. It should have been a rel­a­tively rou­tine process—but “Mur­phy” al­ways gets a vote! In this case, many votes: AEW owner Mark Sanchez would find mul­ti­ple val­ve­train, fuel, oil, cool­ing, and elec­tri­cal prob­lems.


The Bronco’s ex­ist­ing Air Flow Re­search (AFR) Rene­gade cylin­der heads (PN 1456) are its largest small-block Ford cast­ings. AFR’s 220cc in­take run­ners were prob­a­bly way overkill for a mild 349ci street en­gine in a 6,000-pound Bronco, but the heads were nearly brand new and the ex­ist­ing valvesprings had 140 pounds on the seat, plenty for a hy­draulic-roller cam. Bolt­ing on the heads re­vealed yet an­other ma­jor is­sue: The orig­i­nal in­staller used the wrong ARP head-bolt set, one de­signed for use on 289/302 pro­duc­tion-style heads ma­chined for “nor­mal” 7/16-inch fas­ten­ers that screw into the block’s threaded 7/16-inch holes. But the big Rene­gades

have ½-inch holes for com­pat­i­bil­ity with the ½-inch cylin­derblock head bolt holes found on many OE 351W blocks and af­ter­mar­ket race blocks. ARP’s special stepped small-block Ford head bolt was the easy prob­lem­solver here. New bolts in hand, the heads were mated to the block us­ing Mahle Orig­i­nal head gas­kets.

The Bronco’ s com­put­erop­ti­mized hy­draulic roller grind sur­vived the pre­vi­ous en­gine’s de­ba­cle, but as­sem­bling the up­per val­ve­train re­vealed over­looked lat­eral mis­align­ment be­tween the roller rocker tips and the valve-stem cen­ter­lines, fixed by ad­just­ing the AFR heads’ in­ter­lock­ing pushrod guide­plates.

The val­ve­train ge­om­e­try was off as well. Every en­gine is dif­fer­ent. Many fac­tors af­fect ge­om­e­try, in­clud­ing head brand and de­sign, head gas­ket com­pressed thick­ness, head or block milling, valve-stem lengths, valve-seat lo­ca­tion and height, lifter cup heights, and cam-base cir­cle di­am­e­ter. Go­ing to slightly shorter pushrods was the an­swer here.

The Bronco’s alu­minum tim­ing cover was cor­roded, so Sanchez re­placed it with a good used one at­tached with ARP bolts. Now it was down to the oil pan; in the­ory, all Sanchez had to do was clean and in­spect the old oil pump and oil pan, then bolt ev­ery­thing to­gether us­ing a Mahle one-piece oil-pan gas­ket that, Sanchez says, “fits any Ford small-block mo­tor, not just se­lected late-mod­els.” But noth­ing was sim­ple on this rig. The pre­vi­ous en­gine had no dip­stick or in-block dip­stick tube, so Sanchez mod­ded a Fox­body Mustang tube and dip­stick to work. He threw in 6 quarts of Lu­cas 10W-30 mo­tor oil, then pre-primed the mo­tor us­ing an elec­tric drill and a gut­ted dis-

trib­u­tor. “Pre-prime be­fore in­stalling the in­take man­i­fold,” Sanchez firmly rec­om­mends. “That way, you can be sure that oil gets to where it needs to be and not where it shouldn’t be.”

With the drill still run­ning, the hy­draulic-roller lifters’ valve lash on the ad­justable val­ve­train was set to zero lash plus ¾ turn. But af­ter the drill was turned off, sev­eral lifters quickly bled down, in­di­cat­ing pos­si­ble in­ter­nal lifter dam­age caused by the orig­i­nal miss­ing oil-gal­ley plug. Play­ing it safe, Sanchez re­placed all 16 lifters with new Ford Per­for­mance lifters.

Sanchez next bolted up the lower half of Edel­brock’s two-piece EFI in­take. A special in­take gas­ket set is needed to match the big 220cc AFR head’s in­take

ports (best fit: AFR PN 6812 or equiv­a­lent). Next in was the distrib­u­tor (now equipped with a hy­draulic-roller-cam-com­pat­i­ble Mel­o­nized gear), new ACCEL fuel in­jec­tors, and the up­per in­take half.


Af­ter drop­ping the mo­tor back in, Sanchez found se­ri­ous fu­el­sup­ply sys­tem is­sues. The Bronco was us­ing a fab­ric-cov­ered, rub­ber-cored, AN-style fuel hose and fit­tings. With to­day’s street fu­els, the core can rot from within, even­tu­ally clog­ging the fuel in­jec­tors. Of more im­me­di­ate con­cern, the too-short, poorly routed hoses hit the ex­haust pipes. Check­ing this out, Sanchez saw the ⅜-inch feed hose and the 5/16-inch return hose had been re­versed at the tank in a crude at­tempt to make a higher-ca­pac­ity, longer, 5.0L-H.O. Mustang fuel pump fit in the Bronco’s tank. But on a Bronco, the in-tank unit serves as a low-pres­sure lift pump that feeds an in­line high-pres­sure pump the builders to­tally for­got about! Sanchez in­stalled a new, cor­rect Bronco lift pump in­side the tank and high-pres­sure in­line pump, re­do­ing the fuel lines us­ing stock-type plas­tic tub­ing and crimp-on fit­tings. At the en­gine end, the AN-style fuel logs were re­placed with fac­tory fuel rails.


En­gine top-end is­sues were suc­cess­fully re­solved and the fuel sys­tem was fixed. But there were

“It’s lucky the orig­i­nal en­gine only lasted 15 min­utes. If it had run any longer, the fuel hoses would have burned down the whole truck!”

— Mark Sanchez

still elec­tri­cal, in­stru­ment panel, and cool­ing prob­lems. We’ll tackle them next month and fi­nally (we prom­ise!) get the Bronco up and run­ning on the chas­sis dyno.


Sanchez doesn’t mince words: “Noth­ing on the Bronco was done right. Who­ever worked on the car pre­vi­ously and built the mo­tor has a re­verse Mi­das touch: Ev­ery­thing they touch turns to crap.” Use rep­utable techs with a proven track record!

01] For more low-end torque on the big-tire, 6,000-pound Bronco, Sanchez re­in­stalled and de­gree’d in the Bronco’s com­puter/EFI-com­pat­i­ble hy­draulic roller camshaft on a 108-de­gree in­take cen­ter­line us­ing the ex­ist­ing multi-key Ford Per­for­mance tim­ing...

03–04] Lat­eral mis­align­ment: The rocker arm’s roller tip wasn’t cen­tered on the valve stem ( 03, right, com­pared to cen­tered, left). If not fixed, this causes ex­ces­sive valveg­uide wear. AFR uses two-piece, in­ter­lock­ing, fin­ger-style pushrod guide­plates...

02] Us­ing “nor­mal” 7⁄16- inch-od 289/302 head-bolts and wash­ers in the AFR heads’ ½-inch bolt holes re­sults in a loose fit that causes brinelling, de­grades torque val­ues and head-gas­ket seal­ing prop­er­ties, and (as the threads go into wa­ter) cre­ates a...


Comp Cams 05–07] Cor­rect val­ve­train ge­om­e­try en­sures the cam’s events oc­cur as de­signed and pre­vents ab­nor­mal parts wear and break­age. On the Bronco, the rocker arm roller tip con­tact pat­tern across the top of the in­take and ex­haust valve stems dur­ing...

BAD 05


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