BUILD A 348HP 302

DYNO-TEST PROVEN

Mustang Monthly - - FRONT PAGE -

WHETHER YOU FOL­LOWED ALONG FOR PART 1 OF THIS WAL­LET-FRIENDLY SMALL-BLOCK RE­BUILD OR NOT (mus­tang-360.com/how-to/en­gine/ 1806-bud­get-350-horse-302-part-1the-ma­chine-shop), you won’t want to miss out on Part 2. This time around it’s all about adding a healthy dose of power to a run-ofthe-mill 1971 302 small-block. We’re tak­ing what could be an av­er­age re­build and putting a small af­ter­mar­ket spin on it by toss­ing out the stock top end in fa­vor of some good­ies we picked up from Speed­way Mo­tors.

With a set of rea­son­ably priced alu­minum heads from Flo-Tek as the cat­a­lyst, we spec’d out a hand­ful of other top-end parts in hopes of bump­ing the lit­tle 302 up near 350 horse­power. That num­ber might not sound im­pres­sive in the days of 1,000hp In­ter­net he­roes, but if you’ll re­mem­ber, small-block Fords from the early 1970s weren’t push­ing too far past the 200hp mark. So if you were be­ing pulled around by a stock 302 like we were, you know you’re go­ing to feel an in­crease of 100plus horse­power.

So what was the plan of at­tack, you might ask? Well, the afore­men­tioned Flo-Tek heads were what re­ally got us think­ing. Pre-as­sem­bled (valve seats, valves, valvesprings, and re­tain­ers), these things are go­ing for around $400 each, so at $800 for a pair of per­for­mance alu­minum heads, we were off to a great start. At that point it was about pick­ing the right as­sort­ment of sup­port­ing mods, start­ing with the in­take man­i­fold. This was prob­a­bly the eas­i­est de­ci­sion, and since street-driven per­for­mance was the goal, an Edel­brock Per­former RPM Air- Gap was a no-brainer. Time and time again we’ve seen these make solid power at the top of the power­band with­out sac­ri­fic­ing low-end torque and driv­abil­ity.

Next up was camshaft se­lec­tion. We wanted some­thing that would take ad­van­tage of the higher-flow­ing heads and in­take man­i­fold, but again, not give up too much down low. We also wanted to keep it cheap and sim­ple, so we stuck with a hy­draulic flat tap­pet. What we got from Speed­way Mo­tors was a cam with an in­take and ex­haust du­ra­tion of 219/233 at 0.050 and .477/.510 lift with 110-de­gree lobe sep­a­ra­tion. Fin­ish­ing off the val­ve­train, we went with a set of Speed­way Mo­tors 1.6:1 roller rocker arms with a 3/8-inch stud to match the Flo-Tek heads.

To get fuel and air into the en­gine, we could have gone EFI, but since the word “bud­get” is in the ti­tle of this story, we de­cided to keep it sim­ple and af­ford­able. Thus, we opted for a Hol­ley 650-cfm Dou­ble Pumper. Then to dress things up, we went for a set of Speed­way Mo­tors black alu­minum, fully finned valve cov­ers and match­ing 12-inch oval air cleaner. And no, we didn’t for­get about spark; our 302 was al­ready fit­ted with an af­ter­mar­ket HEI all-in-one dis­trib­u­tor that was work­ing well, so we just cleaned it up and got a set of MSD Street Fire plug wires and fresh plugs.

The end re­sult was not only nice to look at (yes, we’re a bit bi­ased), but it also met our ex­pec­ta­tions in terms of per­for­mance. Keep on read­ing to see how we got from a bare block and a pile of parts to a 350hp mill that’s ready to go.

First up we get ready to check the crank­shaft jour­nal clear­ance by in­stalling our Cle­vite main bear­ings in the main jour­nals and caps. Re­mem­ber, in­stall notch to notch and press firmly into place, en­sur­ing each end of the bear­ing sits flush.

Un­less you re­ally trust your­self, it’s best to have a sec­ond set of hands when drop­ping in the crank­shaft—don’t for­get to thor­oughly cover all bear­ing sur­faces in en­gine as­sem­bly lube. Adding some lube on the in­side of the rear main seal is also a good idea so it doesn’t catch on the crank.

This could have been done ear­lier or later, but next we tapped in the core plugs us­ing non-hard­en­ing avi­a­tion sealant on the edges.

Set all the main caps in place and then torque to spec, start­ing from the cen­ter and work­ing your way out.

Next we in­stalled the two-piece rear main seal with the groove fac­ing in­ward and used non-hard­en­ing avi­a­tion sealant on the back and the top edges. Whether you in­stall it flush or off­set is up to you, but some claim that leav­ing one side higher than the other is bet­ter at re­tain­ing oil.

Af­ter torquing all the main bolts to spec, we checked crank­shaft main jour­nal to bear­ing clear­ance us­ing a dial bore gauge and mi­crom­e­ter. If the clear­ances are too tight or too loose, it’s bet­ter to find out now than just cross your fin­gers and pray it all goes well when you fire the en­gine for the first time.

Newspapers in English

Newspapers from USA

© PressReader. All rights reserved.