Tom Welch
Enthusiast
CNC = consistancy.
Tom
Tom
Remember the old Boss 429 Mustang with Hemi heads?
Along came a very clever chap whose name just escaped me, and they reworked those heads - filling in the ports and reshaping them, until they obtained supersconic air speeds on the bench. The result was the SHOGUN 429. That head on the 429 set track records across the USA and those records stood for about 15 years. It was so successful Bob Glidden went and bought every single inventory item up so no one else could run them - that's why no one could beat him for so many years.... not very fair - but that's life
I have a set of GTS-r heads that I just got. They are not stock from the factory however. I have found that they have larger valves and I think they have had some additional port work and Larger valve seats installed. They should make a difference on a race engine but I am not sure how much of a benefit they would be on a stock engine. I bought a whole GTS-r engine to rework for racing and limited street use using race fuel.
Unfortunately, the stock cam doesn't offer enough lift to really take advantage of the heads. The cam I am using only has .560 lift which is the reason I want to increase the low lift flow of the heads.
If you are looking to simply swap the GTS-R with the stock heads and pick up a lot of power, I'm afraid you will not be happy.
Don't want to discourage you, just trying to save you some time and money. If these heads are re-worked, I think they can give you 75+ extra HP. I'm not sure that a set of reworked stock heads can't give you the same gain though.
Ron
It's not the lifter you're worried about, but the valve. The higher you go on the rocker ratio, the higher the acceleration the valve sees. Don't picture the engine sitting on an engine stand and you're rolling it over with a wrench. Consider what's going on at 6200 rpm. The valve has a lot of velocity, or inertia, on opening and closing. The higher ratio rocker increases the velocity of the valve and make it harder to control.
Also, a weak pushrod will make the valvetrain harder to control because it will flex on valve opening, then "unload" at the top of the lobe, giving the valve extra motion. When this is happening you can put more spring pressure on it with the hopes of reducing it, but this usually won't fix it, and it may even make things worse, because the pushrod responds by flexing more, and consequently "unloading" more at the top of the lobe.
There's a lot I need to learn about all this valvetrain stuff. I've learned a good bit from friends that run Spintron machines. One thing I've learned about is spring surge. That's when the iniertia of the spring is so high on valve closing that the bottom of the spring actually raises up off the spring seat of the head. A good valvetrain guy can look at the bottom of a valvespring and tell if it has been doing that or not. If the bottom of the spring is pretty shiny and worn, it's probably been surging.
A customer that has a small block Chevy brought me his heads after last season to freshen up. He had somehow let a 1/4" valve cover stud get into the valley of the head. When I took the heads apart IT WAS UNDER ONE OF THE SPRING CUPS and had chewed the spring pad all up on the head. Evidently the springs on those heads were surging enough for that stud to get under a spring seat. I never would have believed if I hadn't seen it. I told one of my Spintron buddies about it and he wasn't surprised.
Anyway, sorry for highjacking this thread.
Stugots, thanks for the kind words, but I'm probably pretty far from being the man. I just try as hard as I can to do good work for people. Call me at 713-290-1103. If those Ford heads are cast iron, call my other number, 1-800-NO-WAY.![]()