New to Y-block, Intake Manifold Puzzle

Dobie Gillis

Dobie Gillis

Well-known member
Hey guys. Been a member here since last year but haven't posted much. I acquired a '55 Merc w/292 and have a couple of questions about the intake. There are 2 holes just behind the rearmost runners, 1 on each side that go into the heads. I found them after I bought the car; there were crankcase fumes issuing forth from them. I plugged them with big vacuum caps but I'm wondering what they're for? :confused: Obviously they shouldn't be open to atmosphere. The reprint service manual doesn't show them which leads me to believe the manifold is for some other application. Would they be a good place to install a PCV setup? A previous owner installed a half@ssed PCV system, the road draft tube port on the block is blocked off with a plate and gasket. The thing runs OK but leaks oil more than one might expect, even from a known leaker like a y-block. Any insight appreciated.

I might add that the holes in question are not threaded. The intake is for the original Holley Teapot carb, so it's for a pre-1957 application.
 
Last edited:
Heads are reversable so if it was turned around you would find something on the front that would line up with, I think the intake front runner? If we are talking of the same hole. Gerry
 
Thanks, Gerry. The heads are reversed; the temp sender is located at the rear of the driver side head. It should be be at the front of the passenger side head. I don't see anything on the heads that looks like it would line up with the holes, but they might be covered by the runners. I'll try to get a pic or 2 and post them. I have to pull the intake to replace the valley cover gasket when the weather warms up so maybe I can solve the mystery then. I'm tempted to leave it as is and just plumb a PCV system using those holes. The system the PO cobbled up doesn't seem to work all that well.
 
The early blocks, like yours, have all the extra holes clear though to the valley chamber.
There is one at the rear of each head, and a trio straight down on the rear of the block. If any of them are unfilled, vapor can get out, but dirt and water can get in. Be very careful the hole fillers that are 3/8 USS at the rear of the heads are not too long or they will contact pushrods.
 
The temperature sender should be at the rear, left head. Yours is correct.

The holes at the extreme rear are usually threaded. The one on the left is for a clamp to hold the temp and oil sending unit wires. The one on the right is for a bracket that holds the spark plug wires. As was said before, use a short bolt in these holes.


Dobie Gillis said:
Thanks, Gerry. The heads are reversed; the temp sender is located at the rear of the driver side head. It should be be at the front of the passenger side head. I don't see anything on the heads that looks like it would line up with the holes, but they might be covered by the runners. I'll try to get a pic or 2 and post them. I have to pull the intake to replace the valley cover gasket when the weather warms up so maybe I can solve the mystery then. I'm tempted to leave it as is and just plumb a PCV system using those holes. The system the PO cobbled up doesn't seem to work all that well.
Click to expand...
 
I think you will find that the holes you are talking about are the threaded fixings for the spark plug cradles.
I presume you are not using the factory spark plug lead holders.
Regards
 
I couldn't feel any threads in 'em with my pinky finger. These are part of the manifold casting. I'll see if I can find some freeze plugs that will fit when I pull the manifold. I'm using the stock style plug wire brackets mounted where the pic in the manual shows them.
 
Dobie Gillis said:
There are 2 holes just behind the rearmost runners, 1 on each side that go into the heads.
Click to expand...

Dobie Gillis said:
I couldn't feel any threads in 'em with my pinky finger. These are part of the manifold casting. I'll see if I can find some freeze plugs that will fit when I pull the manifold. I'm using the stock style plug wire brackets mounted where the pic in the manual shows them.
Click to expand...

You have any pictures? Sounds to me like your describing the two rear manifold hold down bolts... with the bolts missing...:eek::eek: There's nothing else back there that could possibly be open to the engine that is on the manifold casting???
 
I'll take some pics tonight or tomorrow. Missing bolts wouldn't surprise me; I've found other fasteners loose/missing and expect I'll find more as I get into this thing.
 
I think he's referring to the hole where we usually find an adapter for the heat sensor on the driverside - and a freeze plug on the passenger side. If you were to take the heads off and swap them side for side, those two holes then line up with the water passages across the front of the intake casting. The adapter for the temp sensor and the freeze plug on the opposite side, if you leave them in place the heads become "RH" and "LH". Otherwise the heads are the same part for either bank.
 
I thought that too, at first. But he says it is on the manifold casting AND "crankcase fumes issuing from them"...
It sounds like he had it running and if so water would be coming out the holes you suggest, not to mention the front water passage would be plugged if the freeze plug was still in it.
I'm confused :confused:, we need pictures.
 
Last edited:
I always thought that one hole was supposed to hold the bolt that holds down the spark plug wire loom bracket. The other side (at least on 55 and 56 Ford Passenger Cars) was used to bolt the engine ground strap/cable that then attached the fire wall.
 
Here's a pic I snagged off the net. The holes in question are at the extreme bottom.


images

^ ^
 
Last edited:
Those holes at the bottom are to torque the manifold down to your heads...

Y block OEM manifolds have four bolts up front (because of the water ports), 4 studs in the heads (with the 4 half-egg washers), and then two bolts in the rear.

Were these bolts not even there when you disassembled the engine? Trust us, the thereaded holes to receive the bolts are in each head.

Apologies about my confusion... I thought you meant the holes in the heads themselves.
 
But the real question dobie is what those 4 holes in the middle are? Nice car in your avatar.
 
Hot Rod Reverend said:
Those holes at the bottom are to torque the manifold down to your heads...

Y block OEM manifolds have four bolts up front (because of the water ports), 4 studs in the heads (with the 4 half-egg washers), and then two bolts in the rear.

Were these bolts not even there when you disassembled the engine? Trust us, the threaded holes to receive the bolts are in each head.

Apologies about my confusion... I thought you meant the holes in the heads themselves.
Click to expand...

Nope, no bolts. I haven't disassembled it. It actually runs. I guess I couldn't feel the threads with my little finger because I couldn't get my finger in there far enough. Any idea how long the bolts are supposed to be? I might have a couple in my collection...
 
You must log in or register to reply here.
Back
Top