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I've never seen it attempted but if the TF heads have raised valve cover rails, interference seems likely. A possible semi-Bubba solution would be to trim the bottom edge of the Piezometer ring to gain clearance.
I've never seen it attempted but if the TF heads have raised valve cover rails, interference seems likely. A possible semi-Bubba solution would be to trim the bottom edge of the Piezometer ring to gain clearance.
Hi Jim, yeah, the rails are higher than standard. I suppose I can mill a new ring, if I need to. Did anyone ever make repro rings? if so maybe I can find one to experiment with.
Hi Jim, yeah, the rails are higher than standard. I suppose I can mill a new ring, if I need to. Did anyone ever make repro rings? if so maybe I can find one to experiment with.
JD had some rings repoped many years back and he learned a painful lesson from doing so. As simple looking as the Piezometer ring is, there are some critical dimensions of which he was not aware. In short, an FI unit with one of his rings installed would NOT work.
There may be other repop rings out there but JD's ring is the only one with which I have 1st hand experience. His ring made me gun-shy, if you get my drift.
The safe approach would be to find an original ring, preferably one which has already been cut off. They show up on EPay every so often and usually for bargain prices because no one wants them.
JD had some rings repoped many years back and he learned a painful lesson from doing so. As simple looking as the Piezometer ring is, there are some critical dimensions of which he was not aware. In short, an FI unit with one of his rings installed would NOT work.
There may be other repop rings out there but JD's ring is the only one with which I have 1st hand experience. His ring made me gun-shy, if you get my drift.
The safe approach would be to find an original ring, preferably one which has already been cut off. They show up on EPay every so often and usually for bargain prices because no one wants them.
Jim,
Didn't John come back later and have some changes made to the rings? Seems like he did. I bought one to replace a trimmed ring and the unit worked OK.
This is a trimmed ring that Jim is referring to.
This one was trimmed waaaaaaaaaay too much!
Wow. I learned something today. The well used FI unit I bought to convert to electronic had a ring that looked almost exactly like that. I couldn't figure out the reason. I actually filled it with JB Weld then cut it down on the lathe to be uniform so it seals any air leaks. Color even matches so it's hard to tell even with the air hose adapter removed.
Jim,
Didn't John come back later and have some changes made to the rings? Seems like he did. I bought one to replace a trimmed ring and the unit worked OK.
I'd bet money he fixed the problem after I brought it to his attention. That said, I never tried a repop Piezometer ring from JD or anyone else so I don't know for sure how the issue resolved itself.
From your experience, Tom, it does sound like later rings were dimensioned correctly.
The safe answer is still to locate an original RP ring, preferably one that's already been chopped off.
I'd bet money he fixed the problem after I brought it to his attention. That said, I never tried a repop Piezometer ring from JD or anyone else so I don't know for sure how the issue resolved itself.
From your experience, Tom, it does sound like later rings were dimensioned correctly.
The safe answer is still to locate an original RP ring, preferably one that's already been chopped off.
I have a 63 ring I could use, but I guess maybe I’ll see how much interference there is when I get the heads on. If altering the valve cover fin is adequate, I have a few extra covers I could chop up.
I remember talking about this before . My suggestion was to have the tops of the rails milled to provide more clearance .
I don't know if it would interfere with the rockers .
There doesn’t seem to be an interference. This is assembled with no head, valve cover, plenum, or intake gaskets. I think it’s going to be OK, with maybe a small relief on one valve cover fin, when I get all the gaskets in. (Please ignore the fact that the plenum is on backwards, doesn’t matter for this)
Last edited by Vettrocious; Sep 7, 2025 at 12:24 PM.
If you lower the rails on that side it will lower the valve cover and you won't have to mess with the fins .
Thanks, but I’d prefer not to alter the heads until I decide on a cam. Probably need all the rail height I can get if I go with a roller, which is what I’m leaning toward now. Milling the valve cover fin locally is a pretty innocuous change so I may just do that, no matter what.
I’m faced with the same problem. I’m building a rare 0- experimental aluminum engine and want to use the Trick Flow aluminum heads and my dual air meter FI unit. After closer examination, I don’t think machining the valve cover rail on the heads is an option due to the raised boss area where Trick Flow is embossed. Not sure what I’ll do now. Maybe a combination of modifying the piezometer ring AND removing the upper fin on the valve cover.
I’m faced with the same problem. I’m building a rare 0- experimental aluminum engine and want to use the Trick Flow aluminum heads and my dual air meter FI unit. After closer examination, I don’t think machining the valve cover rail on the heads is an option due to the raised boss area where Trick Flow is embossed. Not sure what I’ll do now. Maybe a combination of modifying the piezometer ring AND removing the upper fin on the valve cover.
I hadn’t noticed that boss - so much for milling the heads. Are your air meters mounted at a height similar to that of the stock one?
Trick flow heads
