The Stovebolt Site Forums The Shop Area Engine Shop Manifold issues

I'm putting a '53 235 in my'46 big bolt. I thought I checked the '46 exhaust manifold and that it would fit, but the bolts at the heat riser don't line up with the '53 intake. Now what? Is there different manifold that I should get? Or do I have to make some modifications to what I have?

216's and 1941-49 235's have a different bolt spacing then the 1950-62 235 manifolds.
If you want to keep the straight down dump manifold you need to use the complete early assembly.
There will be a mismatch on the intake port size, but that can be dealt with.

OK, so how do I deal with the mis-match of the intake manifold? I will have to get another one, because I think my old-style one has a leak in it. Would I be better off having a different exhaust pipe made up?

Here are some adapter rings.
Keep in mind 216 and 235's use a different carb bolt pattern.

Thanks, Dave. Next question, I had a lot of trouble ( I believe) with the 216 manifolds I have. How can I test the intake to see if it has a vacuum leak? I am thinking to duct tape over the openings for the carburetor and the head ports then submerge it in water to see if there are any bubbles. I'm not sure if that would work. If there's a better way to go about it, I would like to know what it is.

.....and maybe even shine a light around inside it on a dark night?

Intakes themselves won't have vacuum leaks, unless they are cracked. The vacuum leaks will usually be where the intake meets the head.
Complicating matters, is the union between the intake and exhaust manifold. If you ever separate the two, you will need to keep the 4 nuts and bolts loose while you bolt the intake/exhaust manifold assembly to the head without the manifold-to-head gaskets in place (for the purpose of mockup and alignment). Once you tighten the manifold bolts to the head, you can tighten up the bolts that hold the intake and exhaust together. Any gaps between the head and the manifolds can be found by probing with a thin feeler gauge.
Carl

What I have decided to do is use the '53 manifolds and have a custom-bent exhaust pipe made. The pipe on the truck is in rough shape anyway. The original manifolds should make the engine run better and give me less problems down the road. Thanks for all the advice.

I had a similar question on how to test for vacuum leaks...I found this on the Jim Cater's Truck Parts website and I quoted it to its entirely:

" Even the smallest vacuum leak on an internal combustion engine can prevent it operating to the level of its capability.

No matter how well you rebuild the carburetor, adjust the timing, or clean the gas tank, the engine will continue to operate below what it should even with a small vacuum leak.

On older engines a quick, easy way to check for leaks near the cast iron manifold will often uncover the problem.

Place a large piece of cardboard behind the radiator cooling fan. See photo. This stops fan air flow in the area of the meeting point of the manifold, carburetor and engine head.1
Use a spray can of starting fluid (available at auto parts stores). Let engine idle, and lightly spray in areas of where air flow will let into the carburetor through.2
If you have even a small vacuum leak the starting fluid will be pulled incorrectly into the engine combustion chamber. The engine RPM will instantly increase. Your engine problem has been found! A new gasket or insulator plate will usually make all well."

Has anyone tried this?