Slant Six Forum
https://www.slantsix.org/forum/

This is an offy valve cover mod. quest, not in other threads
https://www.slantsix.org/forum/viewtopic.php?t=32756		 Page 1 of 2
Author:  rock [ Fri Dec 12, 2008 8:47 am ]
Post subject:  This is an offy valve cover mod. quest, not in other threads
Hello,

Before I ruin a nice surface on a new Offy valve cover, I want to see what other modifiers have used to make the PCV grommet hole. I have a fine shop and lots of experience but that hole is large enough that I don't have a bit that diameter. I am afraid a hole saw will cause extra scratches, and I could use a die grinder and cut to a scribed circle.

So, how did you other modifiers do it without making a blemish?

rock
'64d100
Author:  63d100sixer [ Fri Dec 12, 2008 9:40 am ]
Post subject: 
What Ive done in the past to avoid scratches on any surface: If you end up having to drill with a hole saw, use masking tape over the area you wish to cut. That way, any burrs or debris coming from the drilling process, wont scratch the surrounding area. I wish I could be of better assistance, but I have no experience hacing to do this exact thing. Oddly enough, the tape idea is from years of drilling glass, especially mirror that a customer wants to reuse.


Good luck, and Im sure Doc or SSD will be here soon with their knowledge 8)
Author:  66Dart [ Fri Dec 12, 2008 12:05 pm ]
Post subject: 
Rock

I used a 'stepped' drill bit. Harbor Freight had an inexpensive assortment to pick from. I used this bit in a drill press. Worked great.

66Dart
Author:  CARS [ Fri Dec 12, 2008 12:36 pm ]
Post subject: 
I use step bits all the time, they work great.

I second the masking tape also. You don't want any burs scratching the polished surface.



I have been thinking about the PCV mod myself and wondering if anyone is adding baffles? If so how are you attaching them??
Author:  armyofchuckness [ Fri Dec 12, 2008 1:56 pm ]
Post subject: 
Good, someone else is asking these questions too. I'm very interested in hearing how people drill the holes and install the baffles.
Author:  Pierre [ Fri Dec 12, 2008 8:42 pm ]
Post subject: 
I plan on using a hole saw but drilling from the back. Any burrs left on the topside should be easily removed with a file, so the scratches will be really limited and hidden by the grommets.

I don't think the stepped bits I have go that big, I'll have to check.
Author:  CARS [ Fri Dec 12, 2008 9:56 pm ]
Post subject: 
Quote:
I don't think the stepped bits I have go that big, I'll have to check.
Your right, most only go to 3/4". But 1"ers are available.

A quick search: http://www.amazon.com/Neiko-Titanium-St ... B000FZ2UOY
Author:  SlantSixDan [ Fri Dec 12, 2008 9:58 pm ]
Post subject: 
You needn't add baffles if you do the PCV mod with the GM breather as discussed elsewhere.
Author:  CARS [ Fri Dec 12, 2008 10:00 pm ]
Post subject: 
Quote:
You needn't add baffles if you do the PCV mod with the GM breather as discussed elsewhere.
Great! I just assumed that since the factory cover has baffles under the fill and pcv that I would need something.

Thanks Dan!
Author:  Pierre [ Fri Dec 12, 2008 10:45 pm ]
Post subject: 
The cover is pretty thick too, I'm not sure how well the step bits will do. You may have to get to it from both sides, unles the size of the hole is the last step on the bit. I bought the grommets at same time I bought the push on oil fill cover / breather, but haven't measured anything yet.

I'm itching to practice my tig aluminum welding by adding some baffles but I'm not that good with aluminum, I'd smack myself if I ruined the cover.
Author:  CARS [ Fri Dec 12, 2008 11:01 pm ]
Post subject: 
Quote:
I'm itching to practice my tig aluminum welding by adding some baffles but I'm not that good with aluminum, I'd smack myself if I ruined the cover.

It's been a good 5 years since I TIGed aluminum so I understand your concern. The bottom can drop out quite fast. And no matter what, your going to have a bump there that is going to have to be sanded and polished.
The plus side is that metal can be filled so even if you do fudge it up, you could let it cool and try again :lol: .
Author:  SlantSixDan [ Sat Dec 13, 2008 7:00 am ]
Post subject: 
The PCV mod for aftermarket valve covers like the Offenhauser unit is here.
Author:  Pierre [ Sun Dec 14, 2008 3:36 pm ]
Post subject: 
Just took a caliper to it. The 42344 grommet measures at 1.5" for the hole required. Off to buy a holesaw.
Author:  dakight [ Mon Dec 15, 2008 5:29 am ]
Post subject: 
1.5" sounds a little large to me; are you sure you measured it correctly?
Author:  rock [ Mon Dec 15, 2008 5:39 am ]
Post subject:  Yep, mine is 1.501" too
First,

Thanks felllows for taking the time to answer. My experience with hole saws had been that regardless of care a slight wobble out from one tooth will always make a scratch, and I assumed a hole saw would not be stopped by tape. Thus the idea of doing a hole from underneath was very helpful and of course I hadn't thought of it...but that is what the forum is good for (among other things!)

And, Dave and Pierre, yes mine is 1.501 with my caliper, also. That is what occasioned my concern. The breather is dimensioned as per Dan's diagram but once the grommet is fitted over the breather stem, of course the added rubber adds to the overall diameter needed for the the valve cover hole. While tight would be good, sloopy loose by even a 1/16 is bad in my experience, creating a vac leak and sloppy wobbles. So, I am still toying with a hole saw from underneath first, followed by die grinding.

rock
'64d100
Page 1 of 2 All times are UTC-08:00
Powered by phpBB® Forum Software © phpBB Limited
https://www.phpbb.com/