You couldda zero decked that block and it would have never known it.
Hardened valve seats - do they really matter?
- Thread starter Princess Valiant
- Start date
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It came out to a measured 8.4:1 CR... Exactly textbook. I was hoping for more.
But it's together and running now, not coming back apart for the machine shop to have another shot at it. They took off what I told them to.
I hate to think what the actual CR was on that engine with all original parts as originally built.... I got it in pieces so couldn't measure. It was lacking the pistons and rods. I lucked out on finding a set of NOS rods for it for a too good of price to pass on from one of the "big racer guys" at the /6 site.
I do still have the original drool tube 74 head that hasn't been touched from new except for pulling it off of the engine. Never taken apart or machined.
But it's together and running now, not coming back apart for the machine shop to have another shot at it. They took off what I told them to.
I hate to think what the actual CR was on that engine with all original parts as originally built.... I got it in pieces so couldn't measure. It was lacking the pistons and rods. I lucked out on finding a set of NOS rods for it for a too good of price to pass on from one of the "big racer guys" at the /6 site.
I do still have the original drool tube 74 head that hasn't been touched from new except for pulling it off of the engine. Never taken apart or machined.
Probably 7.2 lol
I purchased a set of Slanty main studs off of a Member here, He has a set of the 1.70"/1.44" stainless EngineBuilder valves, & a set of 340HP springs that I passed on. Most aftermarket stainless valves come with stems that are .001-.002" under stock stem sizes, so if the guides have any wear of note they'll need lined or replaced, but I'm not sure about the EB ones. More importantly, replacing the stock valves w/quality stainless ones greatly reduces the need for hardened seats.
When I had my head done I told them that I wanted anything done/fixed that they saw fit to do.... Including guides if needed. They didn't do anything to the guides except for cutting them down on top to make sure my keepers didn't make contact considering that I put a little bigger than stock cam back in....
That machine shop sounds like they can't get the guides on center. All the MOPAR valve jobs, I've done the seats were pretty concentric. I used to have a guy grind my valves and seats, who blamed Amoco gas for his valve jobs not lasting. My cousin Kelly's dad had a shop in the same small town. One day Kelly told me Marvin's valve grinder was shot. When I looked incredulous, he said to just lap the valves on one of Marvin's valve jobs. Wow! It looked like saw teeth on the valve face. Kelly did my valve jobs from then on, till I got my own valve grinder. I still lap a couple valves to check seal and position on the valve face. As to the original question, I prefer stainless exhaust valves to hardened seats. I feel it keeps the centers better than trying to keep the guide, seat, and now the hard seat on the same center.
Well, that I know of they didn't do any guide work on any of the heads I have sent them, though I tell them every time to go ahead and do so if there's ever a question about them being good or not. So far they've all come back "good" on the guides. They did have to open up the ones on my EQ heads that I took them that were sticking brand new out of the box.... Heads That ruined my last 360 mag rebuild because valves kissed pistons and had to come out again with a whole 6 miles on the job. Those heads are now on another engine with so far 60k miles since they went thru that machine shop
I don't know why I didn't think about this earlier in the thread, I actually forgot I had this head til last nite
And the timing of it having become available couldn't have been worse but I bought it anyway since, well, I haven't come up with anything comparable since, either.
The day after I picked up the head I have on my engine as described earlier in the thread from the machine shop, I saw a /6 head come up for sale on CL a couple of hours away.
and the price was too good to pass up. Asking price was much less $$ than I have in the head im currently running.
A freshly machined peanut head, still in the machine shop shrink wrap, done 30+ years ago and put on a shelf.
All new guides seats, valves, everything //for not much more than junkyard core head price. And it still sits waiting for my next motor.
The relevant part to this thread and that head is this: the guy used to run 2 fishing charter boats on lake Michigan each powered by twin /6s.
He sold the boats and retired some years ago, but had gone to the junkyard and got a couple of heads off of "whatever" with a /6, to have as ready spares. Claims the unleaded gas ate up his valve seats. Boat's down, no money coming in.
He had it down to a couple of hours for a head swap, he said he did them so often. So he always had at least 1 done up ready to go.
And he always had "the works" done to them each time he sent one thru the machine shop no matter what they did or didn't need. And dust? Like snowblowers, most outboards I worked on had no air filtering. Out on the water, no dust/dirt cuz the water "held it down". So though I can see a bad air filter playing a part of eating the seats and burning valves but there's gotta be more to it than that. Granted this was a special application that's basically N/A to many of us. But when these boats ran they ran at a steady rpm most of the time.
And the timing of it having become available couldn't have been worse but I bought it anyway since, well, I haven't come up with anything comparable since, either.
The day after I picked up the head I have on my engine as described earlier in the thread from the machine shop, I saw a /6 head come up for sale on CL a couple of hours away.
and the price was too good to pass up. Asking price was much less $$ than I have in the head im currently running.
A freshly machined peanut head, still in the machine shop shrink wrap, done 30+ years ago and put on a shelf.
All new guides seats, valves, everything //for not much more than junkyard core head price. And it still sits waiting for my next motor.
The relevant part to this thread and that head is this: the guy used to run 2 fishing charter boats on lake Michigan each powered by twin /6s.
He sold the boats and retired some years ago, but had gone to the junkyard and got a couple of heads off of "whatever" with a /6, to have as ready spares. Claims the unleaded gas ate up his valve seats. Boat's down, no money coming in.
He had it down to a couple of hours for a head swap, he said he did them so often. So he always had at least 1 done up ready to go.
And he always had "the works" done to them each time he sent one thru the machine shop no matter what they did or didn't need. And dust? Like snowblowers, most outboards I worked on had no air filtering. Out on the water, no dust/dirt cuz the water "held it down". So though I can see a bad air filter playing a part of eating the seats and burning valves but there's gotta be more to it than that. Granted this was a special application that's basically N/A to many of us. But when these boats ran they ran at a steady rpm most of the time.
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