Larry Hutchens
Active Member
Previously I had posted a tread asking about some specs on a Dodge HD 360 engine w/ exhaust valve rotors. Appreciate all the help & will probably join a forum for Dodge motor homes as suggested by one member. I'm listing some hard learned info on that type cylinder head in case someone needs to use them on an A body project or gets roped into helping a buddy, relative, or neighbor build one of these engines. I started to do this previously but was rudely interrupted by a power outage that shut down my computer system. Then got busy finishing up my engine & installing it in the van. First things first. Some suggested that I was being a bit picky on stuff. May be but I have had some engine failures due to poorly made products & bad machine work. A bit gun shy at this point. My regular cylinder head guy has retired so I'm having to try a new one with whom I have no experience. The retired person specialized in cylinder heads & I was familiar w/ his work, always good. New guy an unknown. I checked his 3 angle job by putting dykem one the seats & doing a light lapping in of the valves to check position of the seat contact w/ the valve & the width of the valve seat. All OK. Then checked the valve stem height & they were all OK as well. Good job. Unless you have a machine shop that you absolutely trust it is best to check things & clean prior to assembly. Anyone can have a bad day. Other factors: making mistakes. not properly trained, person is simply lazy, not familiar w/ MoPars (works mainly on Chevys & Fords). Better safe than sorry. Here are some hard learned specs that I managed to obtain. This is relative to the HD heads w/ ex valve rotors. 1) Installed valve stem height 1.907"- 1.937". 1.922" nominal. Both intake & ex. 2) Valve spring free length Intake 2.000", ex 1.810". 3) Valve spring installed height: Intake 1.625" - 1.688". 1.6565" nominal. Exhaust: 1.453" - 1.516". 1.484" nominal. This info comes from Midwestern Engine Rebuilders data sheet. If you want to use a non rotor valve spring retainer on an ex valve that was made for rotors the installed valve spring height will be 1.595" approx. NOTE: this is based on an average measurement made on my cylinder heads only. Others may vary. Another thing to be aware of is the fact that the rocker arm for the valves equipped w/ the rotors are different than standard rockers for non rotor retainers. There is an extra radius cut in the rocker to clear the oversize retainer. On my engine both left & right rockers had this cutout. On a 318 truck engine that I had previously worked on this wasn't true. The intakes had the rockers for the standard retainers while the exhausts had the special rotor type rockers. Be very careful, if you use the wrong type rocker on the rotor retainers there will be metal to metal contact & some weird valve noises. How do I know? Been there, done that. Replacement exhaust valve spring w/ rotors. Midwestern was able to locate a suitable replacement spring. Brand is Engine Pro, P/n RV1061. It fits fine but is a bit different than factory. Factory spring: Free length 1.810", engine pro 1.840". Wire dia factory .193", wire dia replacement .186". Number of coils on each is 5. Replacement spring has a slightly larger inside dia. but fits the head OK. Replacement has no damper spring. Will probably work OK, will see. Box says that it is made in USA. Parts guy thins that it may be the old Elgin brand that got bought out but that is just a guess.
