GM crossram intake-valve cover interference

[VintageMusclecar]

What's the trick to get a set of OEM cast Z28 valve covers past the base on a GM (repro) crossram intake? It appears the valve covers will need "massaged", but I don't want to do that unless it's absolutely necessary. http://www.yenko.net/ubbthreads/images/graemlins/dunno.gif

Eric

[Jeff H]

The factory manifold has a small area machined just above the ports to allow the clearance. I'm guessing the repo manifold doesn't have that machined area.

http://home.comcast.net/~jeffhansbury/JL8/xrammachining.jpg

[VintageMusclecar]

Jeff;

I see what you're referring to, but the problem I have is the valve cover won't even go between the (factory) rocker arms and the "lip" on the base where the top plate bolts on. I tried to snap a pic of the area I'm referring to, but that didn't go so well.

It's definitely looking like I'll have to remove the lip on the top side of the valve covers if I ever want them to go on. http://www.yenko.net/ubbthreads/images/graemlins/thumbsdown.gif

Eric

[plumL78]

You will need to trim the edge of the valve cover. You have to trim them with a real gm crossram intake too. I believe you will have to cut about .060-.070 off the covers

[VintageMusclecar]

Kerry;

Thanks, that's what I figured.

Eric http://www.yenko.net/ubbthreads/images/graemlins/beers.gif

[DarrenX33]

Whoa whoa, put on the brakes….

You should have that machined area on the repop manifold. Having a crossram is a maintenance nightmare. The manifold and valve covers (namely the drivers side as I recall) have to be put on at the same time. No cutting needed. However, like I said when you need to adjust your rockers its a little more work than just removing the valve covers.

Your intake gaskets too thick?

[VintageMusclecar]

Darren;

The repop intake has the machined relief just above the ports, but that isn't the area of interference--there will be enough room there once the valve cover makes it down that far.

The problem is that valve cover is binding up between the pushrod side of the rocker arms and the lip on the manifold base where the top plate bolts down. The only way they're going to fit is by finishing the factory partial reliefs on the tops of the covers the entire length of the upper edge.

I'm really appreciating the simplicity of a good ol' single 4bbl dual plane manifold right about now. http://www.yenko.net/ubbthreads/images/graemlins/crazy.gif

[plumL78]

If you don't trim them you can't get them back off with out taking the intake off. Valve covers come off a bunch more times than the intake needs to.

[VintageMusclecar]

Now that my "assistant" is back home and I have a 2nd pair of hands available, I managed to get a pic of the problem.

http://www.yenko.net/attachments/256652-valvecoverinterference1.jpg

[plumL78]

Eric you may want to buy a set of the later covers. As you see in the pic. you neet to cut past the notches that are in the covers. Mine is a real GM intake and I've al ready been through these problems years ago

[DarrenX33]

You can certainly cut if you want to as it will be easier to perform adjustments later. I'm not an expert but I have been around for 2 xram installations. One I did myself and the other I watched someone do. Never cut a thing. The manifold just needed to be tilted to let the valve cover on the drivers side slip in. The removal is the opposite of install. Quite a pain but whatever works best for you..

In your picture if you pick the manifold up a bit the valve cover will slip in..

Just my 2 cents...

[VintageMusclecar]

Kerry;

I don't think another set of valve covers are an option as this is a customers engine, and I don't think they'll consider replacing them with a newer set. Just out of curiosity, is there a significant difference in the offending area between the original covers and the newer ones?

Thanks again.
Eric

[69L78]

I just had a NOS pair of valve covers machined so I could get them off without removing the manifold, I did not want to machine my original non-dripper valve covers....I also had the NOS set refinished to give them that original look as opposed to the shiny polished look.

[plumL78]

Eric I'm not sure about that but I'm guessing they are close. The question I have is to Darrenx33 how are you going to tilt the manifold to get the valve cover on. You will have to take the top of the manifold off to get to the bolts that are in the plemum and then loosen up all the bolts and break the intake gasket seal and take a chance of the intake leaking water or air. All that just to get the valve cover off. If you are using the factory steel shim head gaskets and its a new motor what are you going to do then about re torking the head bolts take the intake back off again? I can't believe that somone has a 69Z and isn't willing to buy a set of covers and send them to Jerry and let him reskin them so they look orig. At least they would have drippers on them . This setup done correctley is not a maintance nightmare. I bought my intake in 1971 and put it on my Z 7 years ago I've put over 16k and haven't turned a screw on it in over two years The only time the intake been back off is when the top of a valve got chipped from a bad rocker arm. Bottom line is you can't have the crossram WOW factor if you're not willing to give up something.

[DarrenX33]

[ QUOTE ]
The question I have is to Darrenx33 how are you going to tilt the manifold to get the valve cover on. You will have to take the top of the manifold off to get to the bolts that are in the plemum and then loosen up all the bolts and break the intake gasket seal and take a chance of the intake leaking water or air. All that just to get the valve cover off.

[/ QUOTE ]

I don't see anywhere in my posts where I have disagreed with what your saying. I just stated that it can be done without cutting. And yes it is a pain to maintain if you don't. If you read again you will see.

Also based on your comment I quoted your adjusting valves with the car running. Not everyone does it that way..

[plumL78]

Daren I agree that you can do it the way you say. I just don't know why anybody would want to do all that work when you don't need to. I just don't understand that. No I don't adjust the valves while the motor is running but I do adjust them hot. As for the orig problem that Eric asked about I guess he has to either cut some covers or take the intake back off and use a single carb or bolt it together like you do. I'm guessing that Eric's customer isn't a hands on guy so when the valves need adjusting or it needs valve cover gaskets or what ever he will have to go back to Eric and have it taken apart. I guess none of this matters because it more than likely wont get driven anyway

[Jerry@CHP]

The best and easiest way to do this is the way Kerry has told you. Machine the edge of the V/C. You will never see this. We have done several and this is by far the best way to access the valves to do adjustments. Having to take the engine half apart is not the best way.

Jerry

[VintageMusclecar]

Thanks for the replies everyone. http://www.yenko.net/ubbthreads/images/graemlins/beers.gif

The valve covers will be relieved (as I'm sure the owner will be when he's told he won't have to pull the intake just to adjust the valves http://www.yenko.net/ubbthreads/images/graemlins/wink.gif )

The customer actually is a hands-on guy, and I'm quite certain the car will see plenty of road time.

More to come as soon as this project is wrapped up and off the dyno.

Eric