451Mopar
Well-Known Member
I'm not totally sure on the Hughes Heads, I got them like 7 or 8 years ago.
I just recall checking if the ICON pistons valve reliefs could be cut deeper, but there is not alot of thickness in that area. I think around 0.150"?
I got the Hughes heads after I tried cutting deeper valve spring pocket in my original set of MW Victors and just slightly broke through into the intake port.
Found that on the first intake and stopped, so only had to repair the one spring pocket. That is why we used the 0.030" thick spring locators on the Hughes heads.
Got them from PAC and they milled down some 0.060" thick locators.
On the first set of heads, I was using the PAC-1325 valve springs but noticed some bumps in the power curve around 7,000 RPM? I probably should have tryed the stiffer pushrods first, but with the Hughes heads we used the PAC-1326 valve springs and thicker walled Smith Brothers pushrods. Didn't dyno the engine with the changes, but seems real smooth at 7,000 RPM. The stiff springs and larger cam puts alot of strain on the stock rocker shaft system / hold downs. We didn't mess with the stock rocker stands, just milled them off, installed 3/4" TimeSerts into the heads for the ARP rocker shaft studs and used the billet aluminum rocker stand blocks. This also allowed adjusting the rocker height.
Anyhow, just food for thought because this setup gave me a bunch of valve train issues that needed to be fixed.
On the first set of heads I broke the rocker stands off the head with the smaller cam and lighter springs.
On the second Hughes heads, I was waiting for the ARP rocker studs (the length I needed was back ordered), so I used a Doorman "Grade 8"? studs, and one of the rocker shaft end studs broke, which broke the rocker shaft, and put a hole in the valve cover.
I just recall checking if the ICON pistons valve reliefs could be cut deeper, but there is not alot of thickness in that area. I think around 0.150"?
I got the Hughes heads after I tried cutting deeper valve spring pocket in my original set of MW Victors and just slightly broke through into the intake port.
Found that on the first intake and stopped, so only had to repair the one spring pocket. That is why we used the 0.030" thick spring locators on the Hughes heads.
Got them from PAC and they milled down some 0.060" thick locators.
On the first set of heads, I was using the PAC-1325 valve springs but noticed some bumps in the power curve around 7,000 RPM? I probably should have tryed the stiffer pushrods first, but with the Hughes heads we used the PAC-1326 valve springs and thicker walled Smith Brothers pushrods. Didn't dyno the engine with the changes, but seems real smooth at 7,000 RPM. The stiff springs and larger cam puts alot of strain on the stock rocker shaft system / hold downs. We didn't mess with the stock rocker stands, just milled them off, installed 3/4" TimeSerts into the heads for the ARP rocker shaft studs and used the billet aluminum rocker stand blocks. This also allowed adjusting the rocker height.
Anyhow, just food for thought because this setup gave me a bunch of valve train issues that needed to be fixed.
On the first set of heads I broke the rocker stands off the head with the smaller cam and lighter springs.
On the second Hughes heads, I was waiting for the ARP rocker studs (the length I needed was back ordered), so I used a Doorman "Grade 8"? studs, and one of the rocker shaft end studs broke, which broke the rocker shaft, and put a hole in the valve cover.
