The Stovebolt Site Forums The Shop Area Engine Shop 848 Head

Nope, it was on 235's from about 1956-62 or so. The 261 has a larger combustion chamber and steam holes between the siamesed cylinders. An 848 head can be used to increase the compression on a 261, but it needs the steam holes drilled to work properly.
Jerry

Does the 261 head use bigger valves?? John

Same as 235.

No.

However, I think that larger Powerglide 235 valves (1.94" dia. GM #3835519) can be used in any high-pressure 235/261 head.

I know the 1950-52 235 with PG list the intake valves as 1 15/16", but all the rest after those as 1 7/8"........

John

Right - there is no 18-bolt head with 1-15/16" valves stock.

I have used the larger 1950-52 Power Glide intake valves in the 1953-62 heads several times.

Dave,

Is the part # I gave the correct number for the 50-52 Powerglide intake valves?

Thanks,

Tim,
It is interesting that my 1950 parts book shows the 3835519 number you showed.
My 1954 parts book shows a new number 3835908.
Then my 1961 parts book goes back to the original 3835519 number.
And yes that is for the 1950-52 Power Glide engine.

Dave,

What angle/angles for the valve and seat?

Thanks very much,

Dave, did going w/the larger valves increase your engines HP and did you do other mods to the 848 head?

I ask as I will be exploreing options to squeeze as much streetable performance as I can out of a 54 235 w/an 848 head.
Dave

I can offer a little insight into valve size increases, supported by lots of dyno runs, but they're all from small block V8's. There's little if any noticeable advantage at low to midrange RPM, and it takes some pocket porting, good carburetion, and exhaust port and manifold work to get a noticeable advantage at higher RPM.

Since a stovebolt engine has all the breathing ability of a sprinter with soda straws duct taped into his nostrils, the gain from lots of valve size increase, porting, dual exhausts, and multiple carbs will be moderate at best. You can actually make a silk purse from a sow's ear, but it makes the pig look really funny!
Jerry

On of the engines that I used the larger valves in was a 261 that received a larger cam, 390 Holley, and Fenton exhaust manifolds.
I do not know how much of an increase the valves accounted for.
I think Jerry is right on this.
I also have used the larger valves on heads with a lot of pitting in the seats or seats that have been ground enough that the valves are sunk in the head. This was done instead of installing hard seats.

Quote

You can actually make a silk purse from a sow's ear, but it makes the pig look really funny!
Jerry

No one will notice any changes in any pig, if the changes are all internal changes using stovebolt parts: 1954 235 with 261 cam, 848 head, and Powerglide intake valves. And, I am not looking for a silk purse (external glam), just slight improvements from cheap and easy changes (each change being related to stovebolt engine "natural history" - that GM presumably used for marginal increases in performance).

I guess I'd go to the HiPo forum if I wanted to growl (and beat my chest) about an engine.

Yeah, I had a bad experience lately with they person who made this slick 4 speed close quarter shifter. He said to me, 'we here in California, the capital of hotrods and all things hotrod, do not put lipstick on a pig! So the answer is NO help for you on your quest to dress up your crappy 6 cylinder and 3 speed transmission from me. Call me when you have an LS engine and a decent trans for that truck."

Mkay, well now. ISNT THAT SPECIAL! So, sometimes in life, we have to deal with complete, and total, with no chance of reversal, absolute IDIOTS. Its one of the tests of our real character. I am thankful for Jerry, Dave, Tim, Gus, Grigg, the list goes on and on because usually they don't judge, they just help. Okay, they judge but they help anyway!

Oh.. Tim.. you said you had an 848 and you would know in a week if yours was cracked or not. How did that come out for you?

It has been at the engine shop a little more than one week. I'll call them tomorrow. If the head is good, I'll celebrate by posting a photo of the manifold assembly - it'll have you scratching your head.

That's a good point about using the bigger intake valves to salvage a head after several valve jobs. Since the exhaust valves have the same dimensions as small block V8 exhausts, the popular 1.6" diameter V8 valve can also be used to get a new seating surface for the exhaust valve. In either case, a 60 degree seating stone or cutter tool should be used to open up the port area just below the valve.
Jerry

Jerry (or, anyone else),

Do you have a part number for that exhaust valve?

Or, what is the year/size/etc of a specific small block V8 that has an appropriate exhaust valve?

I do not want the re-builder to make the wrong choice.

Thanks,

I haven't seen a photo on here yet..... Must have been bad news??

John

No, John, the shop is quite busy taking care of race car engines. Their "old guy" who works on older engines has visually inspected everything (the engine is apart), but has not done a magnaflux on anything.

I'll report on the results - they say they'll start on Monday and be done in a week. I doubt that - getting parts might taking longer than a week?

http://www.huntsmachine.com/index1.htm

I don't have a part number or a brand name, since I usually shop Ebay for the best price. I'll see what's available there, but it's just a 1.6" diameter stainless steel exhaust valve for a Chevy small block V8. Since the PC patrol zaps every Ebay link that gets posted, I'll PM a link to you.
Jerry

Thank you, Jerry

Somewhere I read 292 Chevy valves work in these engines?? maybe it was on here?

John

Maybe the exhausts- - - -stovebolt intakes are a different breed of cat- - - -about an inch or more longer stem than the V8's. Small block V8 exhaust valves are a drop-in swap for 235's and possibly 216's.
Jerry

Almost every exhaust valve since 1941, 216,235,194,230,292,265,283... has the same dimensions.

Follow-up on magnaflux of my "848" head: it is supposedly OK.

I have started another thread with questions about my engine's rebuild. Specifically, what valve springs to use.

There is a question I just thought of.... Are all 261 engine solid lifters or were there any hydraulic lifter versions. Or could they be run with hydraulic lifters by using a 235 hydraulic lifter cam??

John

All 261s sold in the USA were for trucks and had mechanical/solid lifters. The 58-63 USA truck 261 blocks were drilled for use of mechanical or hydraulic lifters.

261 Canadian Pontiac engines supposedly came with hydraulic lifters. The 216 truck engines in Canada (at least in 1954) came with mechanical/solid lifters.

In a Pontiac car they probably would have use hydraulic lifters. Sometimes I wish I'd held out for a 261 engine....

John