LS4 exhaust valves from Rockauto, Melling/Enginetech (Page 1/1) BHall71 MAY 06, 08:27 PM Just thought I would post this because I wish I would have found this type of information before ordering. I am going through the heads on the LS4 that I plan on installing into my 88 formula. The exhaust valves were very pitted so they are getting replaced. Looked on Rockauto and found the Melling V1935. Well I received this... Doesn't look much like what is in the picture and has quite a large ditch on the back side. They are also made in India, didn't get a pic of the box though. So I sent them back and ordered the Enginetech variants, p/n:V4371S for what looks like a better valve (STELLITE) at a cheaper price. Well I received this... They don't look much like the picture either but are way better looking than the Mellings. The Enginetech valves are made in Taiwan. They also have a ditch on the back side but it is not as pronounced as the Mellings. I have heard that a ditch on the back of an exhaust valve is a good thing as it reduces reverse flow/reversion. The machine finish on the Mellings was not near as good as the Enginetech's. However, the Mellings were not their stellite version so I can't beat them up too bad. Both pictures rockauto depicts has some form of black coating, neither the Melling or the Enginetech valves received had this coating. Post replies if you would like but my main goal here was to get this information out there for anyone else wondering where these may be made and what they really look like. Brian pmbrunelle MAY 06, 08:39 PM quote Originally posted by BHall71: I have heard that a ditch on the back of an exhaust valve is a good thing as it reduces reverse flow/reversion. It is interesting you say that. Recently on the forum, ericjon262 was talking about going the opposite way and making that area smoother with a turning operation: https://www.fiero.nl/forum/.../119122-20.html#p786 BHall71 MAY 06, 09:33 PM Yea, you definitely don't want that ditch on an intake valve, that is where a 30deg blend is usually done after the 45deg seat. But on an exhaust valve the preferred flow is the other direction. What little I have seen regarding the ditch on the back of an exhaust valve says it helps with reversion as long as it isn't too big. The Melling valves ditch was noticeably larger. Brian sleek fiero MAY 06, 09:46 PM on the performance engines we built we would tulip and polish the valves both intake and exhaust to increase top end flow and lighten the valves for higher rpm capability. sleek