There's a long-standing assumption that the Chevy 348/409W engine is a nostalgic relic from days gone by. But as we showed last month, fresh aftermarket goodies have breathed new life into the W--576 hp, to be exact. Best of all, much of this attention is aimed at the inexpensive-to-buy 348, which was produced in far greater quantity than the more-sought-after 409.
So far we've watched as Joe Jill and the Superior Automotive crew packed the 348 block with an Eagle stroker crank and H-beam rods and forged Ross pistons to transform it into a rugged 434-cube torque maker. Now let's pick things up with a close look at Edelbrock's new Performer RPM 409 heads and perform the final assembly and dyno test.
What We Did
Built a 434ci stroker
The proof is in the numbers
In a collaboration of Lamar Walden and World Products, a new cast aluminum W engine block has just been released. With 4.50-inch bores it is a 509 right out of the box but can be stoked all the way to 609 ci. The bottom-end architecture, oil pan rail, and front cover are adapted from the big-block Chevy, but otherwise it accepts all W-engine external bolt-on parts and looks virtually stock. Just spray it orange and nobody will ever know. Stuff it with just-released forged pistons from Keith Black. There has never been a better time to build a W engine!
The 348/409 oiling system...
The 348/409 oiling system is identical to the '65-and-up Mk IV big-block except for the external oil galley plugs. Where the Rat uses screw-in pipe plugs, the W has press-fit cap plugs that can pop out and lead to rapid oil loss. Cut the threads with a 1/8-inch tap, and install pipe plugs for safety.
Like all pre-'68 Chevy engines,...
Like all pre-'68 Chevy engines, the W block uses a canister-style oil filter with a replaceable cartridge. This Trans-Dapt adapter (PN TRD-1059) bolts to the block and allows modern spin-on filters for added convenience and filtration. The existing bypass valve is retained.
Though GM likely experimented...
Though GM likely experimented with aluminum 409 heads, none made it to production. Edelbrock rewrites history with its new Performer RPM 409 heads for all 348 and 409 applications. Sold completely assembled (PN 60819, $1,075 each) or bare (PN 60809, $823 each), they are cast from high-quality T356 aluminum and weigh 31.5 pounds each, half what an iron stocker weighs.
This Edelbrock R&D cutaway...
This Edelbrock R&D cutaway shows the revised port floor short turn radius that's incorporated into these new heads. The exhaust port floors feature similar refinement. Edelbrock R&D design engineer Ulises Gonzalez says, "We added plenty of extra material so porters looking for the ultimate airflow can experiment."
Patterned after OE big port...
Patterned after OE big port L80 (409/425hp) heads but with improvements, Edelbrock heads flow 285/222 cfm at 0.700 inch lift right out of the box. The generous exhaust ports measure 90 cc.
The 220cc intake ports are...
The 220cc intake ports are delivered with machined steps (pen points) that can be ground smooth for extra flow capacity. Superior's Fred Simpson spent an afternoon touching up the rough spots and was rewarded with 319/281-cfm flow at 0.700 lift. That's 34/59 ticks over box stock.