Head Swap
Mike Reilly, Arnold, MD: I have a '68 Mustang that I am going to put a 302 in. My question is, will heads from a 351W fit on the 302, and if so, is there anything I should do to the heads as far as machine work beforehand? I should tell you that the 302 is from a Granada-not sure what year-and the 351W is from a late '80s Bronco, I think. Thanks for the great magazine; I have subscribed for seven years, and I still get excited every time a new issue arrives.
'CC Quickies
We don't know why we never thought of this.>>>
Jeff Smith:
The simple answer, Mike, is yes, the 351W heads will bolt on to a 302 Ford. Back in the '80s, the 351W head swap was a good plan for early 302 engines. The ports and valve sizes for the '69-'70 351W engines (DOOE casting) were larger and offered a flow advantage over the stock 302 heads. But somewhere in the malaise of the late '70s, the heads used on the 351W engines were closer to 302 specs with the same size ports and valves, so there's no real advantage to those heads. In fact, the combustion chamber is, at best, the same size, which means the compression won't change.
We bolted on a set of Racing Head Service aluminum heads on our boneyard 302 last month and along with a healthy hydraulic roller cam, the little motor made 392 hp at 6,200 rpm. Not bad for a couple of bolt-on parts.>>>
This takes us back to the stock heads on your existing 302 engine. These heads have 1.78/1.46-inch intake and exhaust valves with a chamber size of around 68-70 cc, assuming the casting number is D9AE-AA. As with most small-block Ford iron production heads, these suffer from restricted intake and especially exhaust ports. While a rebuild with larger 1.94/1.50-inch valves and a pocket porting job will help, the simple truth is that this is just investing money into weak heads. If your budget is set on stock iron, the '97-to-current Explorer GT-40P iron head is the only choice. These heads are still only fitted with 1.84/1.45-inch valves and have a drastically different spark plug location that will affect header choice. Many stock spark-plug-location headers will not fit, although there are some companies now making headers specifically for the P head, but you can expect to pay more for those, too. The land mines concerning these heads are the same as with any used cylinder head. You have to assume that you will need to replace all the valves, have the guides lined or replaced, pay for a valve job, and convert over to screw-in studs and guideplates so that you can use a decent rocker arm. If mods also include deck surfacing, it's easy to have $600 or more invested in a set of used iron heads. We've seen castings for sale on eBay for around $650.
Given this situation, it's worth considering a set of new World Products Windsor Jr. heads. These bigger 180cc-intake-port iron castings come with larger 1.94/1.60-inch valves and 58cc chambers for decent compression on a 302, and PN 053030-1 sells for $939 per pair through Summit Racing. We've seen some published flow numbers that indicate the World heads may not be quite as strong as a set of good GT-40P heads. There is also a world of small-block Ford aluminum heads out there including AFR, Brodix, Jon Kaase, Racing Head Service, World, Dart, TFS, and many more. While the investment in a new head is significant, the reward is much-improved power, and the last time we checked that was a good thing.
More Info
Summit Racing
Akron, OH
800/230-3030
summitracing.com
World Products
Ronkonkoma, NY
631/981-1918
worldcastings.com