Ok brain trust here we go: I guess the bigger question is how do I find out which version of the Y block does my 1955 C600 really have? How do I determine its CID? According to all Ive read it came with the 256 but as clean as this truck is....who really knows its history after 60 years... Next question, I have an exhaust leak at the passenger side cross over pipe. I see the manifolds are a common area of concern. So while I think its just the pipe currently, I want to plan for the possibility of an issue... I want to keep this engine original so its no headers, or as tempting as it is no rams horns etc. Are all the exhaust manifolds the same, you know those for cars and the trucks? Will an exhaust manifold for Y block 239,256,272,292,312's all interchange? I see the EBAY listings where these platinum plated (they must be platinum plated they cost so much) are listed. EBAY sellers never really let on to what is what except to say "wont fit Tbird". Would it kill them to actually say what is what????? Any clue on where to find the cross over pipe? Has anyone had success with having one made at a muffler shop?

 

No guru, but a good exhaust shop should have no trouble with the crossover pipe itself.

When you say it is leaking at the "passenger side" crossover pipe this is confusing. There are manifolds on each side. Sometimes they (manifolds) will crack. The crossover is, well crossover. The crossover pipe has an expansion joint in the middle, this should not be welded, this helps prevent manifold cracks. Pics might help in determining what you have and what you need, depending on what you want.

 

Quick Google search shows this one. Ford Y-block Single Exhaust Crossover Tube - Car & Truck - Happy Scamper
I bought mine on eBay for around $25.
There are several different exhaust manifolds. You'll have to stay with the stock front crossover manifolds to clear your steering gear. Rear exit Car manifolds won't clear.
Does your passenger side have the factory heat riser? That is probably where your leak is.

 

That and they are often times stuck. If they are closed it will send heat through the intake manifold constantly and cause exhaust manifold cracks.

 

Here is how to tell which motor you have: TECHNICAL

When you shop for replacement exhaust manifolds/headers/ram horns etc the tech page for that product typically says the product will fit the 239, 272, 292 and 312 Y-Blocks. But I think there is a slight difference between the manifolds used on cars and trucks. I'm unfamiliar with the Mercury 256. More great identification info here: Y

I welded up my own using the stock crossover pipe flanges as those are awful difficult to find. I went to a muffler shop and they wanted something ridiculous so I bought two 2" elbows and one section of 2" straight pipe. I think it cost me less than $20.

 

Depending on how the mating surfaces for your manifolds look you could choose to have them machined flat for a better seal. Both the Head to manifold interface and the manifold to crossover interface! This would certainly help keep things sealed if it has been leaking for a long time it has probably been eroding away the iron in that area too.

 

I have one I could sell you. Pm me if you are interested. Doug






Approximately 24" centre to centre on the top bolts. It's on a 62 M100. And I have another one on a 64 M350. Both look to be in very good condition.