The Stovebolt Site Forums The Shop Area Engine Shop Intake/exhaust Manifold weirdness and troubles

Hi everyone - Vehicle is a 1960 Chevrolet P-20 Step Van.

235 Six, Carter Ball & Ball Up draft Carb and Up Draft Intake and exhaust Manifold set up.

I recently had the Head rebuilt...when removing the Head for this I noticed the 'Rings' which are ( supposed to be ) inside the Intake/Head port counter-bores...the Rings were all mashed and dragged 'down' one might say.

I noted this, but did not analyze it critically at the time.

When installing the freshly rebuilt Head, I did look at this aspect critically, and, long story short, the Intake-Exhaust Unit, the intake Manifold is too low and a little ways back ( maybe .010 or so back from the plane of the Exhaust Port Flanges faces ) also.

It is as if the Intake Manifold had shrunk.

Anyone else ever seen such a thing?

No way can I get a good seal like this...the Intake Manifold is 3/16ths of an inch or so too low to register/align with the ports in the Head.

When the Manifold Unit-combo is bolted on, you can see right into the intake Ports.

How it ever ran this way, I have no idea...but, it ran great.

I need to solve this problem now...so, writing in to see what you all may think.

I had this same alignment problem with my GMC 270, after I machined the 2 surfaces between the mating surfaces, when bolted together with the 2 bolts and 2 studs. I kept them together and installed the alignment rings into the intake and put the gaskets on and then was able to determine how thick a spacer I needed to make and put between the 2 manifolds. My spacer was 3/16 thick. This made the gaskets and ports align almost perfectly. Then left them bolted together and machined them that way. Or find different manifolds and start over. Either way its a pita.

Joe

Thanks 1940GmcJoe!


What you describe makes sense to me.

I did get the two apart, which meant breaking off the Studs which held them together.

The Exhaust Manifold Heat Riser Baffle was long since frozen in the 'Block exhaust, Warm-up' Position...and, I removed it and gave it the Heave Ho. I will Plug it's Axel Hole of course.


Cut the broken off Studs off flush, and Drilled them out in stages, stopping right about where I thought the Threaded Hole Thread edges would be...

Took a nice crisp 90 degree end Round Nosed Punch, and tapped the 'shells' in and they fell out, showing no Threads in the Holes at all.

What the heck??? I guess the Studs were a press fit.

So, I grabbed a 3/8ths national Coarse Tap and I tapped the Holes.

I figure I will use some new Studs of course, or else Bolts.

However, to get the intake Manifold 'up' as much as it needs to be, I will have to have it's Holes Milled a little to be 'Good & Plenty' shaped.

My intake needs to come up about 3/16ths of an inch or so.

I will also need to have the respective mating surfaces, where the Intake and Exhaust Manifolds bolt together...have those 'surfaced' and this will likely need a thicker than original Gasket then.

I can likely make a Gasket using some thin Sheet Copper and some sort of heavy Hi-Heat material.

Once I get all this bolted up to align right with the ports on the side of the Head...I can then get all Manifold Flanged Surfaced, as an assembled 'Unit', so the assembled 'Unit' can be on a true flat plane same as the port Flanges of the Head are.

"PITA" is about right!! Lol...

Just seems mighty odd it would be so far 'off' like it was...but, I guess such things happened somehow.

Another fast question -

The alignment Rings I bought for the 235 are ridiculously too small in diameter.

They almost fall into the Ports.

Did they send me the wrong size? Or, should I just get some thin wall Steel Tubing and make my own so they fit nice and snug?

Since I am the Up Draft set-up, finding a replacement Manifold combo would likely be a little difficult.

And, if I found one, it might be no better than the one I have!

So, I figured I may as well take the plunge, and see what I can do with this one, to get it into a right alignment and so on.

Link to an image of earlier to-day before I had cut the old Studs off flush and drilled them out and Tapped the Holes, and removed the old frozen sold Heat Riser -

http://images42.fotki.com/v1630/photos/9/901917/4085747/IMG_0217-vi.jpg

Is it possible that they sent you rings for a 216 manifold? They are smaller. I wonder if your setup is so different that the rings they sell are not correct.

The wrong size alignment rings could be as truckernix described: all 216 rings and pre-1950 235 rings are smaller diameter (the alignment rings might have been correctly stock-listed as 1941-1949 235 rings).

That is an understandable mistake and an easy fix.

The mis-fit of the manifolds (together and to the block) is more difficult to understand. The two manifolds bolt together in a different plane from the downdraft manifolds (as shown in the picture-link). That should not affect the relative alignment of the two manifolds to the head.

Grasping at straws: finding up-draft manifolds is a challenge. Perhaps the manifold assembly (or, just the intake manifold) is from a pre-1950 updraft-manifold engine? What are the casting codes on the manifolds? Compare them to the codes listed in Group 3.265 in the Master Parts Catalog.

Yeahhh, it is weird!

Intake Manifold Ports are about 3/16ths of an inch too low to properly meet the Intake Ports on the Head.

Exhaust Manifold ends of course, register with an alignment 'Peg' on each end, the Pegs being in the Head.

Exhaust Manifold ports appear to meet the exhaust ports in the head, just fine, no alignment problems with them.

It is as if the Intake Manifold had shrunk...

The way the two Manifolds bolt together, there is no provision for any adjustment of course.

I will post their Casting Numbers here shortly.

It was difficult getting them apart, too! Man, they had really been stuck together a long time.

Opening of Ports of the Intake Manifold, and, of the Intake Ports on the Head...the openings ( where the 'Ring' would go ) are 1-1/2 inch in diameter.

The horizontal alignment of Manifold to Head when the Exhaust Manifold is in proper position( as far as the Intake Ports lining up ) the Intake Manifold is just about 1/4 inch too low.

The old Rings were horribly distorted into whatever the round version is of a 'parallelogram'.

Having thought about all this some more, I think what I will do is to get the Warm Up 'Box' aspect of the Exhaust Manifold welded closed, and the Stud Holes welded up solid.

I will then surface that area so it is flat and even.

I will mount the Exhaust and Intake Manifolds pro-tem to the Head then, with them being separate from one-another and 'floating'...with some small space where the old Gasket had been.

I will mark the Exhaust Manifold through the Holes of the Intake Manifold's Warm Up Box mounting Flanges, to see where the new Stud Holes will need to be, with both Manifolds ( now ) correctly registering to the Head Ports.

I will then Drill new Holes on the Exhaust Manifold Warm Up Box area, and tap them for new Studs ( or Bolts ).

I will decide what thickness of spacers or Washers to use between the Manifolds and, then, Bolt them together tight.

Any slight out-of-plane with the intake and Exhaust Port faces, I can then have 'surfaced' to they will all be dead flat where they go on to the Head.

I can not think of what else to do to solve this problem.

If anyone else has any idea, let me know?

Links to images showing Casting Numbers on the Intake and Exhaust Manifolds.

I was not able to locate these Numbers on the Master Parts List seen at http://chevy.oldcarmanualproject.com/parts/1929_54/186.htm

Intake -

http://images42.fotki.com/v1630/photos/9/901917/4085747/IMG_0223-vi.jpg


Exhaust -

http://images108.fotki.com/v1629/photos/9/901917/4085747/IMG_0219-vi.jpg

Exhaust code: 3835580 is 50-55/57 COE DD 6 cylinder

Intake code: 3835582 is 50-55/57 COE DD 6 cylinder

They should match each other, and they should work OK on 50+ 235 heads and all 261 heads?

You are one good Detective!!

Thanks!


My Vehicle is a 1960 P-20 "Thriftmaster" Step Van.

Now I am thinking to just screw in some Threaded Bolts into the now Threaded Holes in the Exhaust Manifold, and, Braze them in ( rather than to have the Welded Welded closed )...then cut them off flush.

Then make the two Steel pieces to fill in the openings of the Heat Riser and my buddy can Weld those in then...this should work out nicely I think.

I will get that area Surfaced then and, go on from there.