I finally got around to rebuilding and upgrading the Y block for my 55 T-Bird altered chassis dragster. I Originally built the engine in 2010 and it was in the car most of 2011. I broke it the last race of the season. Autopsy showed 2 broked lifters and a wiped out camsaft. I tore it down last spring and sent it to the shop to get checked out. I finally got it back this fall and after upgrading several components it is almost ready to go back on the dyno.
It is 333 cu in 3.83 bore and 3.61 stroke. Cast crank, 2 inch rod journal
Features originally included 6.3 inch Crower rods, Wiseco pistons ,12.1 compression. G heads ported by Joe Craine, an Isky custom cam with 248 duration at .050 and about .500 lift. I ran it with a ported Blue Thunder intake and Hilborn injection. With the 4bbl intake it made 435 horse and 462 hp with the injection. Power peaked at about 6700 rpm. I was within a few 100ths of dipping into the 9's when the valve train broke.
In addition to a broken lifter I had 1 rocker arm seized on the shaft. Pulling the main caps revealed that they had been "walking" in the block register.. When the crank was check it had a couple of stress cracks in it, right at the fillet area.
Given the multiple failures I decided to upgrade in several areas.
I had another cast crank reground, but this time with much more generous fillets in the journals. To prevent further cap walk I had a machine shop turn out some steel main caps that are the same height as the pan rail and fit very snug in the block... I am using an Eaton girdle which sits tight against the top of the steel cap. I am hoping this will give me a very stout bottom end.. I know I should have a billet crank at this point, but the wait is long and the cost is high.. I know of FE guys that put a lot of rpm and horsepower through their 428 cast cranks, so we will see.
I have upgraded to Mummert heads, fully ported by Joe Craine, and flowing like crazy. Also a Mummert intake, also ported by Joe. With the smaller chambers in the heads my compression is up to 13.5
The cause of my valve train failure was not obvious. Some possible causes could be spring harmonics, insufficient guide clearance, material failure in the lifter, or camshaft lobe failure.
To address as many of these problems as I could I did the following..
New tool steel lifters made by Trend Performance. These things are like jewelry with a highly polished and hardened face. full Harland Sharp rocker setup. Comp Cam beehive springs to accomodate .650 lift. New cam by Jones Cam Designs in Denver NC with 268/274 duration at .050 and .635 valve lift. Lobes are nitrided to assure proper hardness.The cam should make max power at 7500 rpm.
Ted says Mummert heads are worth about 70 horse, so I am hoping for 540ish with the carb. The big cam, extended rpm, and higher compression might get me a little more than that. The Hilborn injectors are consistently worth about 30 hp so I am setting a stretch goal of 575 horse for this combo.
Hopefully I will have this engine on the dyno before spring. I will run it with the intake and carb first. Eventually I would also like to switch to Alky with the injectors, and that requires a different setup.
I have attached a couple pictures one showing how the steel main caps and the girdle fit together