Can You Really Put GM LS Heads on a Ford Small Block? – Jalopnik

Technically, with enough cutting and welding, you can probably make any combination of block and heads work for at least a few minutes. Cutting and slicing up a set of Chevrolet LS or LT V8 heads to fit a Ford Windsor 302 or 351 wouldn’t even be the weirdest Chevy head on a Ford block project out there. A guy named Ken Hutchison cut the end cylinders off a pair of LS heads and welded a single straight-six head for a Ford 300.

But what’s amazing about the LS/LT head-to-Windsor-block swap is how many lines are queuing up. The Chevy small block V8 famously has a center distance of 4.4 inches, while a Ford Windsor V8 has a nearly identical center distance of 4.38 inches. Both use 10 head bolts located in approximately the same location. The push cable trails are also relatively close. It’s almost as if Chevy engineers, feeling the wrath after daddy GM had the audacity to allow a marine engine manufacturer’s Lotus-designed V8 into the Corvette ZR-1, didn’t take any chances in making the next-generation small block V8 as beefy as it could be. So maybe when creating the LS they copied a little homework to meet the C5 deadline?

Well, probably not. Pushrod engines already look quite similar, especially when the pre-existing bore center distances are nearly identical and use the nearly ubiquitous 90-degree V-angle. The truth is, mating LS and LT heads to a Ford Windsor small block still requires a lot of work to yield a usable engine.

A 302W/L83-LT head built by manufacturer Mark McDonald and his son Corbin was documented by Hot rodand they used a Windsor head gasket as a template on the head to align the holes in the center. Some of the coolant passages matched quite well, and some had to be filled and re-drilled. Unused passageways in the head were closed off. Since the heads came from a 5.3 liter L83 GM direct injection truck engine, the DI ports were filled in preparation for a conversion to port fuel injection.

According to by Tecmotion’s video, the existing push bars continue, even though they are the wrong length and modified push bars are necessary. There is also the problem of valve angle differences (15 degrees in LS/LT heads versus 20 degrees for Windsor heads) with the valvetrain. Tecmotion put the stock LT rockers in and found they were close, and they theorized that a builder could add clearance for the pushrod in the headstock. Still, knowingly changing valve angles is asking for a valve geometry headache.

Now, zero intake manifolds fit this Ford-Chevy chimera, necessitating a custom build. In addition, Chevy heads require a dry lifter valley, which means closing the exposed wet lifter valley of the Windsor block. And then there are potential lubrication and oil passage issues that need to be addressed.

The aluminum L83 heads the McDonalds picked up came from a flood-damaged pickup, and they scored them both for $280. ​​The stock intake ports flow 253 cubic feet per minute (cfm) with 0.6 inch valve lift. At Ford Performance Parts, a set of aluminum “X2” Street Cruiser 302/351 heads cost $1,250 each and flow 230 cfm at 0.6 inch lift. So saving $2,220 on heads with superior breathing sounds like a pretty compelling reason to give the swap a shot.

But for this to work, you better be a manufacturer or be very good friends with a manufacturer who will give you a big discount. Neither the McDonald nor the GMTgearHDs engine appears to be running yet, so there’s no pudding to look through for proof at this point. Maybe an LS-headed Windsor is a viable way to get Boss-351-Cleveland-level breathing and performance (if you’re interested, here’s the difference between Ford’s 351 Cleveland, Windsor, and Modified engines), or it could be a years-long nightmare that ends in a leaky, rough-running engine with ongoing performance deficiencies. The LS and Windsor V8s are certainly close in design, but anyone who has ever had a ticket where every number was one away from the winning results will tell you that sometimes close isn’t close enough.