[DeTomaso] DAN JONES YOUR INPUT REQUESTED

[Brian Dudley]

Hi Chris,
Sorry to hear about your engine problems. 
FYI. I recently got my engine back from Kuntz and Company.  It is running the PAC 1255X springs with a 0.640 lift mechanical roller camshaft without lightweight valve gear, revved to 6,700rpm. It has only had dyno time so I can't comment on longevity. 
Hope you get to find out the cause of the problem without further breakages. 
All the best,
Brian

> On Jan 7, 2014, at 11:50 AM, "clewis at dmn.net" <clewis at dmn.net> wrote:
> 
> Dan when are you available for a phone discussion? 
> 
> Last year middle of the season a beehive spring broke and dropped the valve. 
> 
> I am ready to rebuild but have a number of things I would like your input on. 
> 
> The springs were PAC Beehive 1220XX. Good for .650 lift. They had started to experience cascading failures. Broke one and replaced 
> it and then a second different one failed and dropped the valve. 
> 
> The actual lift is .665, but a phone call with PAC when the engine was built said this should not be a problem. I spoke with them 
> myself as did Jeff Lawrence. Clearly either this was wrong or somehow the engine was over revved. 
> 
> PAC has provided a full set of replacement springs, the same 1220XX. 
> 
> I am thinking if I don't change the cam I need to use 1255xx, good for .700 lift or 1295xx good for .750 lift. 
> 
> I suspect the damage to the bottom end is relatively minor. The valve dropped after the engine had stalled and I was trying to 
> restart the engine (clutch was disenganged and there was no weight of a moving car against the drivetrain. 
> 
> Should I consider titanium intake valves to take weight out and stress out of the valve train? 
> 
> Will the reduction in weight enable the valve train to have better control? 
> 
> Will titanium valves with the proper coating be durable in a street application? (Isn't this what the new Corvette uses?) 
> 
> How would you approach this rebuild to address the obvious and maybe not so obvious issues? 
> 
> Best Regards, Chris Lewis 
> 
> 
> 
> 
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