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By 55blacktie - 4 Years Ago
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The PCV valve included in Casco's Tbird road draft conversion kit will not seat, thereby causing a vacuum leak. Casco recommends using a socket and extension to "pound down the valley under the road draft hole." Although this might work, I know the valley pan is prone to leak; deforming the pan by pounding on it might not be a good idea.
Is there a pcv valve that will properly fit in place of the road draft tube, without pounding on the valley pan?
Thanks
P.S. I think Casco's solution is to insert the socket into the hole and expand the baffle on the underside of the valley pan by pounding on it, thereby providing additional clearance. They weren't clear, but nothing else makes sense.
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By DANIEL TINDER - 4 Years Ago
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Been a long time since I did that, so…’grain of salt’.
Just be careful not to break loose the female-threaded part (and thus knock it into the valley). I believe the baffle is thin enough to not cause the pan edges to bend/leak when being depressed.
I also recall (details escape) I needed to restrict the PCV hose airflow some.
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By 55blacktie - 4 Years Ago
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DT, was your conversion on a 55-57 Tbird? I don't recall any part of the road draft tube remaining on the valley pan. A Rubber seal is inserted into the hole, and the pcv valve is inserted into the seal. There are no female threads that I'm aware of, unless the hole, itself, is threaded. I'm speaking from memory, but it's a member of another forum who is actually doing the conversion; I'm just trying to help. Considering what's involved in registering on this site, I didn't suggest he post here himself.
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By charliemccraney - 4 Years Ago
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For the valley pan with the baffle, there is a thread fitting spot welded to the baffle, for mounting the road draft tube (or in the case of later engines, a PCV hose fitting). That threaded fitting is probably the part getting in the way of the push in style PCV valve.
The options are:
Remove the pan in order to remove that threaded fitting. If that is the only issue, I suggest welding it back in place but upside down so that factory parts could be reinstalled, only requiring a longer screw.
Take a chance and hammer the clearance needed.
Make an adapter fitting which will allow installation of the PCV valve and avoid altering original parts..
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By DryLakesRacer - 4 Years Ago
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My experience there are threads but they are on the bottom of the lower deflection plate and the PCV doesn’t hit it. I would test fit the valve into the grommet before putting it in the valley cover and use some lube on it. I believe there are offset grommets for the aluminum valley covers. I also seen the draft tube cut off just behind the mount, a washer welded on and a PCV installed in the washer with a smaller grommet. When installed there should be 1-3” of vacuum at idle in the crankcase. I tested mine at the dip stick and sealed the oil fill tube. |
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By 55blacktie - 4 Years Ago
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Thanks for jarring my memory DLK. Yes, the road draft tube cap (if you will) that attaches to the VP, has a long screw that goes into the deflection plate/baffle. Assuming he doesn't put the RDT back into service, the threads in the deflection plate shouldn't be an issue. I'll pass on the 1-3" vacuum at the dip stick.
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By DANIEL TINDER - 4 Years Ago
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Obviously, CASCO’s instructions suggest the mentioned ‘socket’ should somehow surround (?) the threaded fitting, so only the baffle is depressed. But, if you want to be certain nothing amiss should occur while pounding (sloppy/partial spot weld?) and thus totally avoid the grief of removing & replacing the pan should the fitting come loose and drop, you could always buy a long threaded rod at the hardware store, screw it into the fitting, use a thin hollow pipe to to surround it, and then bang on that.
I suppose viewing a clear photo of an OEM valley pan’s underside structure before the attempt would help though, since I seem to remember the baffle has a hole in it, but not specifically where/how the fitting is attached.
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By charliemccraney - 4 Years Ago
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Here is a pic of the underside of a valley pan with the baffle. The circular bit with the 3 dimples toward the bottom left is that threaded fitting.
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By 55blacktie - 4 Years Ago
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I slightly bent my OEM valley pan while removing it/w both heads in place. Although I'm sure it can be straightened, I bought an Aftermarket Ace polished, cast-aluminum pan. It has recesses to allow for installation/removal without removing a head. Although it has the hole for pcv valve, there is no baffle. Ace leaves it up to owner/builder to make and install a baffle that works with whatever pcv valve is used. I'm happy with its quality and price. I think I first read about Ace products on this site.
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By charliemccraney - 4 Years Ago
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You can try a baffled grommet. I use those for the breather and PCV Valve in my valve covers. They work. Take a look at the bottom of the grommet to make sure it has an opening. I've had one or two that had a thin bit of rubber where it should have been open and had to trim that with an xacto knife. It's just a minor defect from manufacture..
https://www.summitracing.com/search/part-type/valve-cover-grommets/universal/yes/baffled-grommet/yes?PageSize=100&SortBy=Default&SortOrder=Ascending
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By DANIEL TINDER - 4 Years Ago
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charliemccraney (11/2/2021)
Here is a pic of the underside of a valley pan with the baffle. The circular bit with the 3 dimples toward the bottom left is that threaded fitting.
OK, now I remember. Forget the ‘threaded rod’ idea, since if the fitting ever comes loose, it couldn’t be retrieved without removing the pan.
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By Florida_Phil - 4 Years Ago
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I ran into this issue when I installed the Casco PVC kit on my Tbird. The PVC valve must fit all the way into the valley pan or you will have a vacumn leak. As mentioned by others, the pan has a threaded piece welded in where the road draft tube screws down. In time, this threaded piece gets pulled up by the tightening of the screw so that the valve will not seat all the way. As Casco suggests you use a socket and a hammer (small) to drive the threaded piece back down. It did bother me at first to beat on the pan in this way. With a little nudging, I was able to fully seat the valve.
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