Pulling the manifolds - How far do I go?

[woodie49]

Need some input from you guys familiar with these flatties:

I have a P18 I am assembling in my garage to drop into my '49.

My current engine is a P23. It has good compression, and runs "OK". Lots of valve clatter and I just figured out my exhaust leak comes from the heat riser.

So, this weekend I am going to pull the manifolds (which don't appear rusted at all, so I am hoping for the best, but some of these past threads are scary) and put on the bright and shiney ones for my rebuild. Then I will pull the valve covers and see what the tappets, etc look like. Hopefully, I'll just adjust them cold and live with the small clatter.

Here's the problem, I won't get around to completing my rebuild for several months, and I want to drive dependably (but not far) until them. So, I am thinking, "gee, while I have the manifolds off, it is just a few bolts to pull the head and see how everything looks". If it looks bad, I have a newly milled head to drop back on that I can reclaim later. If it looks OK, I put the old one back on. Obviously, I can inspect the pistons and cylinders at the same time. (I am not planning on rebuilding the P23.)

Of course, then, while I have the head off, and if the valves look bad, maybe I should replace them, along with the tappets and springs. And then, at that point, maybe I should pull the radiator and change out the cam and timing gears (I have those ready too).

By the time I am done, I might have the whole top end rebuilt.

I really do feel it makes sense to pull the head to have a look, but it probably isn't necessary.

Given that I want to drop the P18 in within the next 6 months, do I just stop at the manifolds and be happy, or pull the head? If I do that, where do I stop?

Other than a compression test, should I do a few other tests before I start to help me decide?

Also, does anyone supply chrome plated head bolt sets to dress these engines up a bit?

[BobT-47P15]

I'd say pull the manifold and adjust the valves.....see where that gets you.

Is it leaking at the heat riser or the gasket where the exhaust pipe fastens

to the manifold? Does the riser move, or is it frozen either open or closed?

There are 13 or 14 bolts on the manifold....a couple kinda

hidden......if you recall the previous posts. If it runs pretty good otherwise,

I don't know if I would do much else to it.......since you are planning to replace

the engine before long anyway. Just my 2 cents.

[woodie49]

It is definately leaking at the shaft of the heat riser. Nothing is frozen, but the shaft works away from the manifold when the car is running. I could probably just wire it to the manifold. When all the way in, it is pretty quiet. But it really bugs me.

[BobT-47P15]

With the shaft working away from the manifold, I wonder if it might be

broken inside. It would seem it should only rotate when opening or

closing the flap inside.....not move in or out.

I agree, little noises like that are aggravating. You might just make

do for now......

[woodie49]

Looking at my replacement manifold, it must be that the flap is no longer attached to the shaft. Also, it appears that the inside end of the shaft has a washer or someting to act as a seal, and the there appears to be another washer at the outside of the flap that might help to seal that side. I think all those parts must no longer be attached. So. as long as the shaft is fully in the manifold, it is quiet, once it begins to work loose, the inside hole become an exhause leak, and the outside hole probably leaks a little around the shaft. Since it can't be operating at this point, I am tempted to simply wire the weight against the manifold to plug all the holes and call it good.

I was concerned with having the flap loose in the mainfold, but I am now questioning whether it is even present, since there is no corrosion, etc. evident around the manifold. It might be that it was recently pulled and, instead of fixing the riser, the previous owner simply relied on the shaft to plug the exhaust leak.

I do hate to waste a few hours swapping manifolds for something this small.

[Don Coatney]

Line in the sand? Only you will know where to not cross it:cool:

[Don Jordan]

I have a 48 Chevy - I took off the back fenders just to clean them up. Once the fenders were off and I got a look at the frame I figured I'd just touch that up. Well it seemed silly to just do the sides so I took the bed off because I was going to buy a wood kit anyway. This story goes on an on - I now have a frame in the garage, cab in the front yard, and parts scattered all over.

I tell you - if you're going to do one thing - do it. If you take the head off you're going to find a worn out ring so you might as well take the pan off to pull the piston. If you go that far you might as well do all the rings. If you do the rings it would be silly not to replace the bearings. Believe me it can get out of hand. Before you know it you have a project.

[laynrubber]

I took the front seats out of my Mustang to reupholster them and fix some rusty floor pans.....18 years later the car is still in boxes. carefull with the "while I'm at it syndrom"

[RobertKB]

If it ain't broke, don't fix it. Stop at the manifold. If you were going to use the engine them maybe the head but you are doing a rebuild on another engine so what's the point? My two cents worth.

[Normspeed]

I agree, leave the head on. You run the risk of busting one or more head bolts on removal. I'd enjoy the dual setup and keep the other new stuff for your new motor.

You'll have an easier time checking the valve adjustments with the manifolds off. These motors aren't known for clattering valves, but a little tick isn't a bad thing.

Chrome head bolts, some folks have posted that there is a Chevy head bolt that fits. I don't recall the part #.

[woodie49]

I think you guys are right. I should leave well-enough alone. I don't have a ton of time, and if the motor gets fairly quiet after adjusting the valves, I'll be pretty happy until its time for the change-out. I do have a lot of valve clatter, which makes me worry that I might have some issues with the tappets or springs. I am used to small block Chevy's with solid cams, and you almost need to adjust them after firing up your motor to check your oil pressure. Hopefully an easy fix. I am tempted to hard-wire the heat riser and just address the valve clatter. Even though everything looks pretty good, I am concerned with the few threads that talk about huge issues pulling the manifolds. Seems like a good thing to avoid.