The Stovebolt Site Forums The Shop Area Engine Shop Manifolds for 261 in 2-ton

Where do you find manifold casting numbers listed? I have a 261 engine that needs the pair of manifolds. I have been sent in error a very nice looking pair with intake casting number 3835627 and exhaust casting number 3835988. If these will fit my 261 I'd rather not send them back. I would need to enlarge the vacuum fitting on the intake to accommodate the large service needed for a Hydrovac brake booster and a 2-speed rear end.

Is it very risky to drill out and tap the manifold for a 1/2" pipe thread? With shipping, the cost was $175 -- pretty high, but no truck without them.

Thanks for any advice.

The intake casting number for the 261 is 3836922 and the exhaust is 3835587 based on the '57 261 that I have in the garage. These are the same as what is on the 235 in my '57 truck.

I don't know if what you have will fit or not.

Out of curiosity, I did a quick search on your casting numbers and didn't come up with anything. Rather than try to adapt them, you might try to resell them to recoup your money. They don't appear to be common casting numbers, so they might be rare, or at least hard to find, for someone who needs them. The correct ones that I listed above aren't that hard to find.

Matt

The intake manifold on my 59-62 261 has a casting number of 3535590. It has a half inch pipe fitting that has a pvc, hydrovac and 1/8 pipe fitting for wipers. Sorry I can not see or read the exhaust casting number. The manifold you have may work if the carb. ID matches the intake. I hope this helps you.Mtneermike

Mike: I do have the original 62 261 manifolds from my engine that I would sell for $125 + S&H. Still good paint on them from when I restored my truck 10 Years ago. I went to dual exhaust and don't need these anymore. Dave V

Thank you so much all.

My intake manifold is 3835590 with 1/2" NPT vacuum fitting. The wiper, the hydrovac, and 2-speed switch, are served from another fitting on the firewall. The manifold fitting also connects to a pvc. This is good. The exhaust manifold is 3835587. I have two of these. One has a deteriorated interface with the intake manifold at the heat riser which I can't seem to make good. On the other one the pin that holds the bimetal spring to rotate the heat riser flap has rusted away.

Is there any way to replace the pin that holds the bimetal spring?

Matt:
The shipping worker at rpmclassic dropped and broke the beautiful pair that I bought on eBay and he just took this mysterious pair off the shelf nearby and sent them. He didn't bother to tell the people in charge. The company will take them back and are trying to find another correct pair like the one I bought, but aren’t having much luck.

DaveV:
Do your 62 manifolds have a ½” NPT opening in the center of the intake box? Is the gasket connection between the manifolds good? And are the port faces where they mate with the head all in a plane so they seal well at the head? Could you send me some pictures like the ones they put on eBay?

Clarke

My manifold does have the 1/2" pipe hole, good gasket and flat mating surface but I just noticed when I dug it out that it has a crack in the exhaust manifold so probably not what you're looking for. Dave V

Clarke, I have a good set listed in the 'for sale' section of the Swap Meet forum. It meets all of your qualifications except that it needs a new gasket between the two manifolds. The exhaust matches your casting number, but the intake is 3836922. They should fit your 261. You can try to cross reference the intake casting numbers to verify or perhaps others can chime in with info.

Pix and full description on the Swap Meet listing.

If you want the exact same casting numbers as you have today, maybe DaveV can handle the matching good intake and I can handle the matching good exhaust.

It is against the rules to sell things on this forum, so if you are interested it would probably be better to communicate with DaveV and me with PM's instead of postings.

Thanks,

Matt

Clarke, When I changed my manifolds to a modified split exhaust I found that there is a difference in heights of the intake manifold where the carb mounts. The 261 has a taller larger chamber above the heat riser. DaveV

Here's an idea if you don't like the idea of drilling the manifold.
The 48 235 in the 2 ton had the vacuum supply for the brakes and rear axle supplied by a cast aluminum spacer under the carb. It has a 1/2" hose barb cast off the side. It was maybe 5/8 thick. When I went to the dual carb manifold, I made an identical one for the other carb so they would sit the same, just didn't drill the hole to mount another hose fitting.
You could mill one and use any manifold.

Thanks again all. I hope Matt/Maybellene/Shop Shark will sell me his pair as they look to be just the thing. A NAPA gasket set for mating to the head comes with a gasket for the manifold pair mating, so I should be good there. I don't really care about casting numbers unless they imply some characteristic that affects their doing the job without alteration.

Combining DaveV's comment about height of carb mount on the intake with Mark's about matching exhaust and matching intakes separately, is it possible that Mark's intake is not best for a 261 2-ton? In this case, maybe I should try to follow Mark's suggestion.

I will try to move the conversation to the swap forum or the PM thing I just learned about. Again, thanks!

Clarke

I copied this from one post:

"You can try to cross reference the intake casting numbers to verify or perhaps others can chime in with info."

How does one do this? Where are there listed what the casting numbers refer to? I've spent a good bit of time trying to find this and failed.

C

Clive,

Keep the conversation here - it is interesting.

The only need to use PMs or post in the Swap Meet is with respect to person-to-person "transactions" (personal buy/sell/trade).

I have the 261 manifolds. They are good except the heat riser hole is wallered out. It has a 3 outlet vacuum fitting with a large tube, an inverted flare outlet & a small tube. It has a spacer on the carb mount & new exhaust pipe studs. $40 plus shipping. I can send photos by e-mail.
George

I hadn't seen a 'lower' intake manifold on a 235/261 as mentioned in an earlier post, then coincidentally stumbled across one this morning in '56 with a 235. Here is a picture--

http://s844.photobucket.com/user/ma...20manifold/IMG_1953_zpslwrfrxzj.jpg.html

For comparison, here is a picture of a 'normal' one--

http://s844.photobucket.com/user/ma...vbedwdq.jpg.html?state=copy&sp=false

The lower one has a height of about 3" from where it joins the exhaust manifold to the base of the carb studs compared to 4" on the other one. The threaded bung for the vacuum connection is angled about 30 degrees toward the rear on the lower one compared to straight out on the other one.

Matt