Well I finally found / made time to rebuild the top end on my 91 YJ. The engine has 136,000 miles and making enough lifter noise to bother me, along with exhaust leaks that needed attention as well as low power output due to the 33" tires. I had a 4.0L TB, screaming demon ignition coil already installed.
I installed a Hesco RVOB cam in the advanced position with cloyes double roller timing chain as recommended by Hesco. I also installed a Hesco prepared head with Hesco performance valve springs and milled to 57cc combustion chamber volume, I port matched the head to the intake / exhaust gasket myself. I also installed a pacesetter header and electric fan to finish things off, and used a Chiltons manual for reference when needed.
The installation went well, the only problem encounterd was removing the star screws that mount the timing chain tensioner to the block,the timing chain tensioner isn't used with the cloyes timing chain and must be removed.
The engine runs great, has a nice little lope to it when idling due to the cam, and nice exhaust note also. The first thing my wife said was, "It sounds much more powerful". I would like to be able to say it runs like a small block chevy but it doesn't.
Overall I'm pleased with the outcome of the rebuild, the engine has much more power than before, I'll stay away from HP and torque predictions, but will say it is much, much stonger. It starts great and pulls hard form idle to redline, I wouldn't go to the trouble and expense to do these mod's just to get more power if nothing is wrong with your engine. But if you've got to go into the engine anyway and want to beef it up I definetly recommend Hesco parts and these mods.
When I get 4.88's installed it will be a real screamer, borderline dangerous I hope !!!!!!!!!!!!!
