Cam Question - 400 out of a 68 GTO

[Austringer84078]

The previous owner of my Lemans blew up the 350 it had and put a 400 in it out of a totaled GTO. So after sitting for 10 years or more, it had a lot of leaks. I started to tear down the engine to replace all the seals and gaskets, clean it up and prep for paint.

When I got the heads off I found it has never had a rebuild and decided I better do it. So my question is, How do I know if I need to do the cam as well? I don't want a big loping cam that's hard to start and tune. The one that's in there runs great. Do I need to pull the cam?

 

[Zimgxp]

Might be a good idea to look at the lobes and bearing surfaces. You dont want to have to tear into it again.

 

[Austringer84078]

Ya, I thought about that. I'm kind of torn between, "I'm in it this far, might as well replace the cam" and "If it's not broke don't fix it". I've seen some rebuilds go bad so I hate to replace something that appears to be in good condition and runs fine.

I'll probably replace it. It's out of a '67 and I don't know the history. The motor doesn't seem to be mistreated. The cylinder walls are like glass, just worn down quite a bit. The ridge at the top is still 4.12 so it's not been worked over before.

 

[melsg5]

If you are sending the block out to have it checked/machined by a shop you might as well have them insert new cam bearings and put in new cam and lifters and rockers and pushrods,etc.

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[Austringer84078]

I live in a small town and am lucky to have a good, experienced machine shop. Since everybody knows everybody here, he'll do as much or as little as I want. I'm on a budget (isn't everybody?) so, right now I'm thinking about having him bore and hone the block, replace the cam bearings, clean up the heads and put new valve guides in.

That will get me to the point where I can paint it and work on it a little, while I put some money together for a new cam and a stroker kit. Anybody in the market for an old Jeep? ;-]

 

[Kevlar]

I'm with Mel on this. If it were mine and I was going to rebuild, I'd save until I could do it all the way. Nothing radical, stock specs are great, maybe a mild cam with a slight increase in performance and mileage. You're tearing it down to the block, this may be your last and only opportunity, you never know what life throws your way.
I say go for it!

 

[melsg5]

with the issues people are facing with flat tappet cams and low zinc levels in current oils I would not put back in a used cam and lifters

 

[Austringer84078]

Ya, the more I've thought about it today, I'm going to replace it. I don't know the history on the motor except that it was put in my Lemans when it came out of a totaled GTO, which tells me, early in life it was probably driven like it was stolen.

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[Austringer84078]

Good call guys. I just pulled the lifters. Some of them look brand new. They still have the rings on the tappet. Others were dished out like little cereal bowls. I found a lot of assembly lube in the valve area too. Odd.

The big thing I found was that two of the lifters seemed to be clogged when I was cleaning them out to bag them up. I wish this motor could talk.

 

[melsg5]

whatever you do read up on the issue of flat tappet cams and modern oils or you will have quite possibly the same issue with a new cam. I use Valvoline VR1 10W30 for the high zinc/phosphorous levels required for flat tappet cams.