Does anyone know where on earth I can find a set of forged pistons for my 454's that have two valve reliefs in them like the stock pistons do? Everyone keeps telling me that the one relief (intake I believe) is good enough and that unless I have some radical cam (which I don't) I don't need the other relief. These same people say that unless I am turning over 5000 RPM I don't need to balance it. I don't care, it is getting balanced anyway - well as soon as I can find a set of pistons to balance with! Reliefs and balancing points may be true, but I am the kind of person that likes to do something right the first time - maybe even a little anal. I can find pistons with dual reliefs - but they are hyperutectic, not forged. Aside from having pistons cut, does anyone know where I can find what I am looking for? 454ci/7.4L Chevrolet V-8, .030 oversize, forged with dual reliefs. I have tried Jegs and Summit. Any leads would be appreciated, can't start the engine work on the starbord until I find a set. Then once she is done, I will do the port to match! Also, maybe I should start a new thread, but wondering if anyone knows lift, duration, and separation of a stock cam - I am looking at a comp cams marine extreme 270 roller and was curious as to how it compares to stock...
Thanks for reading!
Dustin
89' Pachanga32 Twin Merc 7.4/330
Note sure those exhaust reliefs do anything as the seem to be cut at the wrong angle for the exhaust valve. I have them on my engine also and am going to replace with forged.
Take a look a few threads down and I have the 7.4L 330 Hp cam specs posted. I am considering the XM270HR also, although I am also looking for something closer to 230 deg exhaust duration which is the general rule for maximum duration for stock exhaust. I just purchased an EMI exhaust system, with short ss risers but it turns out they also recommend 230 deg max.
Location: Omaha, Nebraska. Boat on the Mighty Mo! Longest river in the USA!
Posts: 1,397
Pachanga-27 Twin 502s
Spunner, are you at Dodge Park?
I am starting building two new engines for my Pachanga. I don't know if I will use the 454's (built by previous owner). I have been looking for a pair of 502 then thinking of selling the 454s. I have built several 496 strokers in the past and they worked great!
Personally I would not worry about the two valve relief. But I recommend talking to RMBUILDER about a nice roller cam. And, yes I would get it balanced
Note sure those exhaust reliefs do anything as the seem to be cut at the wrong angle for the exhaust valve. I have them on my engine also and am going to replace with forged.
Take a look a few threads down and I have the 7.4L 330 Hp cam specs posted. I am considering the XM270HR also, although I am also looking for something closer to 230 deg exhaust duration which is the general rule for maximum duration for stock exhaust. I just purchased an EMI exhaust system, with short ss risers but it turns out they also recommend 230 deg max.
I have that camshaft and I am satisfied with it. Its got a decent idle, not real radical, but it has excellent docking and slow speed manners. If I had known in time, I would have contacted RMBuilder for a cam, hes got a hell of a following around here ...
I have forged dual relief pistons, Im trying to remember what brand they are...
I'm pretty sure you have a directional piston. They will face forward on either bank, therefore they have 2 valve releifs depending on which bank the piston is installed. BBC no not usually need exhaust reliefs.
RHM 253, you are da man! Finally it makes sense. Yes, they are directional and the dual reliefs have nothing to do with the exhaust. I feel so much better now that I know this because I said to heck with oem today and bought a set with one relief anyway Thank you for making sense of it.
Platinum Member
Thank you for making sense of it.
