Over the last week I've had the pleasure to host one of our forum's Engine Masters heroes, Royce Brechler, as he dynoed a 510" MEL engine for one of his customers. It's hard to believe that the FE could be considered mainstream these days, but compared to the MEL engine the FE is positively everywhere. So it was a real treat to see this close FE cousin on the dyno for some power pulls.
This engine is destined for a 56 Thunderbird race car but is a fairly mild piece with something like 9.5:1 compression and a fairly conservative solid roller cam (252@0.050", about 0.550" lift). The engine does feature an Offenhauser tunnel ram with a single four barrel carb, which is actually a 429 piece that fits to the engine with the aid of a couple of adapter plates. Bore is 4.41" and stroke is 4.175" for a total of 510 cubic inches. Here's a photo of the engine on the dyno:
The engine required some special attention to get installed on the dyno, including a custom bellhousing that Royce came up with and some spacers between the bellhousing and the dyno plate, because the bellhousing was fairly short. It was a little more difficult to get installed than a normal engine because the bellhousing didn't have a hole in the side for a clutch fork; apparently it had been adapted from an automatic bellhousing. Normally when lining up the dyno's input shaft to the engine I reach through that hole to help with the alignment, but since that wasn't possible we had to work a little harder to get the engine installed. Eventually it slid into place, and after fabricating a custom bracket to mount the motor mounts to the dyno stand we were in business.
As we got the engine hooked up Royce pointed out all the improvements of the MEL (Mercury-Edsel-Lincoln) over the FE, including the top exhaust bolts which were through-bolts with nuts, not threaded for normal bolts (and prone to rust in place) like the FE, and the valley pan, which bolted in place in the valley and sealed, making every MEL manifold an air-gap manifold (Royce was to later regret bragging about the valley cover, because it ended up having to come off...) Bore spacing on the MEL is a whopping 4.900", which of course makes for a very dimensionally large engine. But just like the 348 and 409 Chev engines, the head is flat; the whole combustion chamber is in the cylinder, and the decks are not square with the piston tops.
After getting it hooked up on the dyno we set the timing at a very conservative 30 degrees, partly because the timing was locked in the distributor, and started the engine. It fired up with no drama and after warming it up we ran a checkout pull from 3000 to 4500 RPM. Everything seemed fine, but the engine was not making near the power we expected, something like 540 foot pounds and 440 horsepower. Royce decided to run it higher to 5500 RPM and see how it did before starting any tuning. We basically got the same numbers; power peak was fairly low in the RPM range. When we started the engine again, we noticed what sounded like a valvetrain noise. We decided to pull the valve covers, lash the valves, and check everything out. Lo and behold, on the #8 cylinder we found a broken valve lock! One of the pieces had come out, and the valve was hanging on by a thread. We figured this was where the noise was coming from.
Here's where the trouble started
I told Royce I had spare valve locks; what size were the valves? Royce said 3/8" stem, so I dug out my valvetrain box and found a couple of valve locks for a 3/8" stem valve. Royce and I installed them. We buttoned the engine back up and it sounded fine again. We went into the next pull and at about 4500 RPM, the engine made a much louder and unusual sound. I backed out of the pull instantly, but thought that the exhaust pipe had just come loose from one of the headers. But on inspection the pipes were still tightly attached. We pulled the left valve cover again and saw a problem with the same valve; this time it had pulled all the way through the retainer. I measured one of the valve stems and it turned out that they were NOT 3/8", but 11/32". We pulled the spring off that valve and it was stuck in the guide, clearly bent.
Well, we weren't going to make any more power that day, that's for sure. Royce tore down the engine, and before he took off the head he cursed his way through removing the valley plate, which bolts to the cylinder heads. I avoided any snide remarks in light of the situation
When the head came off it was all pretty much good news. The valve was very lightly jammed into the guide, and with a few taps from a plastic hammer it came out. The piston only showed a slight mark where the valve had hit. It looked like we could replace the valve and the locks and be back in business.
Royce took off for the day with a plan to get the parts he needed within a few days, then come back and finish with the engine. Sure enough, five days later he was back, and got the engine reassembled and running this past Thursday night. Friday was looking good for finishing the dyno tests.
On Friday, overall everything went pretty well. The big power gainer was the timing; when we went from 30 degrees to 33 degrees, the engine picked up a full 25 HP! I've never seen that big of a bump with a 3 degree timing change before. We finally got dialed in at 40 degrees, then we tried a 1" Super Sucker carb spacer under the 1000 cfm 4150 Holley. Nearly unbelievably, we lost 25 horsepower with that spacer! We took it back out and re-ran the baseline pull, and the engine came right back to where it had started. Go figure. Several times during the day we were spooked with noises coming from the dyno room, and out of an abundance of caution we'd pull the valve covers, check the lash, check the cam timing, etc. In the end we attributed any noise we heard to exhaust leaks (there were no gaskets on the headers), because after getting the engine dialed in with timing and fuel, it ran pretty consistently. Peak numbers were 584 foot pounds of torque, and 495 horsepower. Here's a graph of the best pull:
We did try one more test, replacing the 1000 cfm Holley carb with a 750 carb, and got nearly identical results all across the RPM range. It made sense, because the engine just didn't need all the air that the 1000 cfm carb could provide. I thought that a dual carb setup may have gotten us to 600 foot pounds just because of a smoother path for the air into the engine, but we didn't have a setup that would work so that was that.
Royce has more MEL engines planned for the dyno over the next several months, including his Engine Masters entry for the year, so I will be posting more info on these engines as they come across the dyno. Stay tuned...
