I've heard both sides of the issue of the stock red or chrome valve covers not being able to be installed on the latest TA Stage 1 Aluminum heads without fixing clearance issues like taking material off the heads or modifying the valve covers or using special thick gaskets. I had these very same valve covers and aluminum heads on the '71 GS455 I sold recently and don't recall any mods having to be made. So, what's the story, if there is one?
I thought the issue was with roller rockers not clearing causing fitment issues, not the head them selves. Others more experienced will weigh in I’m sure....
I have a set on one of my cars,with TA covers. I can pull one off and try a stock steel,but I am pretty sure it has to do with rocker clearance,not the head itself.
Yes, there is an issue. I know Jim Weise has posted about it. They are harder to seal up. Let me see if I can find the thread/post. See JW's post #13, https://www.v8buick.com/index.php?threads/why-dont-both-valve-covers-have-holes.363650/#post-3134560
Most of that thread deals with PCV issues. Just checked with the guy who bought my '71 GS last year and it has the TA Stage 1 heads and stock chrome 455 valve covers with no mods done to either the heads or the covers. Can anyone else weigh in?
This is what I was thinking of, I had reproduction chrome covers and was running roller rockers. When Jim built my engine, he donated a set of iron 3/8" spacer plates to the project. To get them to seal, everything was RTV'd together. I had to beat them off with a rubber mallet when I changed my lifters. I wanted the valve covers to be removable of course, but no matter what gasket I tried, the only way they would seal is if I used RTV again. I always had a leak at the rear of the cover. That is why I went to the Poston covers. I'm sure there are guys who get the covers to seal.
I guess we'll see when my heads come in. My covers are original with correct part numbers so, maybe no issues. I'm also using stock type rockers and pushrods. I'm still gonna use those new thick, reusable valve cover gaskets on this motor.
Those new TA gaskets are AWESOME. I have had my Poston covers off and on several times. They seal right back up every time.
The TA Alum heads lack the undercut on the intake side, just above the ports. This.. The TA head.. Easily seen when they are side by side.. That undercut only has one function.. it allows the lip of the valve cover, on the intake side, to drop into it, so the gasket contacts the head. Like this.. It only comes over the head, into the undercut, about .050 before the gasket contacts the head. But without the undercut, and a stock 1/8 inch gasket, your never going to contact the gasket on the top of the head.. the lip crashes into the valve cover rail, as seen here.. So you either have to bend the lip out of the way, or grind it off, so the gasket can be crushed.. both of those things are not appealing to me, from a detail point of view. The only somewhat clean way to get around this issue is a thicker gasket... if your running roller rockers , then your already there for internal clearance, but not everyone is, I have built more alum head motors without roller rockers, than with them. Now when they were $600 bucks, sure, throw them on.. but at over 1K now.. something to consider.. The use of the new .255? thick rubber molded gasket will sidestep this issue, but we will see how well they seal up on the stamped covers.. That kind of gasket is designed to be clamped between to rigid surfaces, and no one who ever handled a stamped 455 valve cover would accuse it of being "rigid".. For you Stock appearing guys, lack of the undercut is the first thing I notice when looking at the heads, to see if they are aluminum or iron. In Ray's case, he is not running roller rockers, but wants to use the new gaskets.. I am going to recommend that we mount the heads in the bridgeport, and do the undercut.. only really needs to be about half as deep as the factory ones, as just .050-.070 of the lip hangs into it, depending on how much the gasket crushes. My recommendation is based on the fact that I know of no one with a positive experience here using the proposed setup, and no one really could have any long term data, as the gaskets are too new. With the undercut there, he has the option to go back to a nice cork gasket and the sealer we have used for decades on stamped covers, to seal them up. Also.. it looks stock.. and is very noticeable, as long as your neat with your intake gasket installation, and trim off all the excess that extends beyond the casting on a Performer or Iron intake.. which I do, in a stock appearing situation. Thanks JW
If that solution is the clean, most stock looking solution then so be it. I'm still waiting to take a look at the '71 I sold last year (that's still in the area) to see why that issue didn't occur on that motor. I'll post when I found out. Thanks, Jim for the detailed illustration of the problem.
