The Stovebolt Site Forums The Shop Area Engine Shop 261 build..848 head and oil pan

just some research w/ the pros...

1. does anyone have a picture of an 848 head they have installed on their 261 AFTER they drilled out the "steam holes". i dont have a gasket set yet but am working on the head to get as much accomplished in the crappy weather here in the NE. I have gone throught the usual 261 build articles but cant find a visual reference.

2. Reading the Mcgurk article Soup that Chev (May 55 HRM) They refer to using a powerglide 53 or any 54 oilpan on the bottom of the 261 for clearnce purposes in the 37 to 54 cars and trucks. has anyone had to do this or is it even necessary? My 261 is going in a 46 1/2 ton pu.

thanks again folks

big ed

There's a picture in the link below of the holes in the block and you would see the same thing on the head. They are 3/16" in diameter, 1 17/32" center to center and paired between cylinders 1&2, 3&4, and 5&6. I have coordinates of all the holes and if you need more data pm me and I can help you lay out the holes without a gasket. Can't help with the oil pan issue though.

http://www.1954advance-design.com/Web%20images/261-engine/index.htm

Curt B. provided all the data you need if there is not a 261 gasket available when it is convenient to drill the holes in the 848. Here is a photo of a stock 261 gasket on a Bob Toros head. The photographs in the May 55 HRM issue show the additional water circulation holes in the 261 head, but no mention of the need to drill the holes in the 235 head is made in the text. Did McGurk not notice this? When I built by first 261 with a 235 head in 1958 I did not notice the missing holes either. I did not have any unusual overheating problems that I recall. I did drill the holes for my next 261 in 1960 after I realized that the holes were there for a good reason.

Hoyt

thanks guys. after looking at the size of the holes and there placement i am going to order the gasket set and drill from it. it is not like i can run to a flap and get a new head if this gets screwed up.

hoyt, i saw that picture as well on pg 16. have read the article several times and as you said, McGurk makes no mention of drilling. another mystery of history in the auto world i guess.

Curt

pm sent....thanks

Ed,

The oil pans are slightly different as shown in this thread:

https://www.stovebolt.com/ubbthread...;Main=72638&Number=521282#Post521282

I finally decided to stay with the 261 pan instead of using the 235 pan even though it was in better shape because of the baffle in the 261 pan for no reason other than I figured Chevy must have had a reason to change the design.

I am installing the 261 in my '51 3600 3/4T. Although the 261 pan is slightly deeper, the entire pan is in front of the axle so I can't see how it won't fit.

I had my rebuilder drill the steam holes on my 235 head (-5913) to my '58 261 block. He asked me why I nnd I said that's what everyone said to do. He just shook his head and said okay. Pics of what he did are in the engine rebuild album on the link below. I have to remember that this guy used to race 6 cylinders at Bonneville and was a GM research engineer for like 40 years. So....steam holes or not? Who knows if they are necessary or not.

GM thought the extra cooling passages were necessary, as was a higher-cooling fan-blade, and a higher flowing water pump, and larger diameter hoses, ". . . to increase cooling capacity for the higher heat rejection of this more powerful engine . . ."

Yes, we might get by with lower capacity replacement 235/216 water pumps and hoses and fan-blades, and no extra cooling passages between the larger siamesed cylinders, but GM upgraded these things for a reason (and, back then the reason was not to sell more/different parts). These engines were meant to be used in the largest trucks, under the highest of loads, often at high rpms at low speeds.

On the other hand, it is hard to understand why different baffle designs were used in pans for various 235/261 engines, especially since the oil capacities do not appear to be significantly different. And, it does not look like the oil pumps and pick-ups are different.

man, i love when a thread starts to get historical. thanks for all the info folks.

joe, i agree w/ you. the pan on the 261 is on it for a reason, right??? looked at the front suspension today and cant see any reason the original engine pan should cause problems. i'll just go w/ it for now and make a change later if necessary.

curt, pm sent again.