The Stovebolt Site Forums The Shop Area Engine Shop what's a 848 head??

What's a 848 head? If I swap it on my 235 block will it boost power? How do you know which heads are "848"? thanks, kyle

Sorry I'm really confused, do i have "848" heads then, my truck is a 56 with a 235 3spd combo.
Where do I find the serial numbers? I'll post them if you tell me where they are hiding. thanks, kyle

If your head is the original, it will be an 848 head. 1956 was the first year of production. It raised the compression from 7.5-to-1 to 8-to-1. It increased gross horsepower to 140. The cast number on the head is on the distributor side of the engine, near the top of head, close to the valve cover. In addition, the 848 head casting also features a larger hole for electric temperature senders. Since you have an electric temperature sender, I would bet you you have an you have an 848 head.

OK ! The "848" head was the head that Chevrolet made for production 235 engines beginning in 1958 through the last year of production for 235 engines, 1962. "848" has become the "term" used to describe that certain head that has the casting number which ends in the numerals "848".
The casting number appears on the driver's side of the engine on a "ledge" of the head which is not covered by the valve cover near the line of head bolts next to the valve cover closer to the front or the left side of the head as you face the left side of the engine.
The significance of the "848" head is that of all of the 216, 235 and 261 heads, it is the one with the smallest combustion chambers thus giving it the highest combustion ratio and makinge it the most desirable of the heads for 235 and 261 engines because it can deliver more power than any of the other heads.
As a side note, it will also produce the loudest exhaust sound, when coupled with headers or a split manifold and glass packed or straight through mufflers, of all of the heads because of that high combustion ratio.
Check the left side of your engine head. I have seen so much grease, oil and crud on some engines you can't see the casting number until you scrape all of the gook away.
Good luck!!!

Now I'm really confused, taskforce dan says that the first year was 56 and the last guy says it was 58. Which one is it?

1956-- 58 to 62 must have been a typo. I have two 848 heads both date coded for 1956.

According to the posting by Ralphy, the web site page at http://www.stovebolt.com , 848 heads are not mentioned until 1958. I have never heard of a 848 head prior to 1958, but Chevrolet may have made and distributed the 848 head earlier as sn over the counter parts replacement head.

No confusion here LOL! -- 1956

Most likely, the only 1953 engines on which the 848 head could be used are the 235 on automobile Powerglide-equipped engines (they had the "new" 235, which was not used in trucks until 1954).

Of course, 235 engines might not have come equipped with 848 heads until 1958 (or 1956) but the 848 head can be used on all "newer" model 235 blocks (and would listed as such in any Master Parts or Parts Interchange manuals).

It is mentioned above that the 848 head could be used on 261 blocks. It is a bolt-on fit but a few holes have to drilled in 848 head (to match holes in the 261 block/head that are not in the 235 block/head).

Tim

And just for clarity, the 848 head will not fit on a 216 or early 235. Only 53 235's for Powerglide and all 54 and later. Count the head bolts, 18 later, 15 earlier.

Just so it's clear . . . 848 heads were used on all new 235 engines from 1958 to 1962.
Chevrolet also sold the 848 head as a replacement head for all 235 engines, over the counter.

Better put: If you are going to a wrecking yard, auto salvage yard or "bone" yard to look for an 848 head, 99% of the time you will find them on 1958-62 Chevrolet vehicles.

It is just so clear, go ahead and walk past a 56 and 57 when looking for an 848 head. It is just that many more parts for people that have "actual knowledge". I know 58 and onward 235 blocks are different. The oil passages are modified from prior years. Maybe the confusion is stemming from that. Go look up casting numbers on the Inliners International it will be enlightening.

Well, what would life be if you couldn't learn something every now and than!!
Here's where I became confused. :confused: Yes, 848 heads were factory heads on 56-57 models, but the compression ratio of that head was not as great as the compression ratio of the 58-62 heads. As I have learned from of my Vintage Chevrolet Club of America friends, in 56-57, the compression ratio of the 848 head was 8:1. In 59-62, the 848 head compression was raised to 8.25:1 , thus making the 58-62 848 head the highest compression ratio head. Therein, is where I became confused. :confused: :confused: Sorry!! I, personally, would still walked past a 56-57 in a bone yard and go to the 58-62 848 head.

Yes, compression was bumped to 8.25 to 1 in 1958. Head castings are the identical. Dig deeper...what changes were made in 1958 to bump the compression? You are missing a great resource if you walk past a 56,57

:confused: :confused:
Well, I probably know what you are looking for here, but without making alot of guesses . . .tell me. I have never owned a 235, so I know less about them than 261's. I've got a 56 - 261 and always wished I would have built the 62 - 261 I have instead of the 56 that's in my 37. :rolleyes: :rolleyes:

The compression was also adjusted by the distance the piston is below the deck at TDC.On engines with original standard size pistons that varies from about .010 on some 235's to .035 on 261's.The actual compression ratio and HP is less than Chevy advertised in it's specs by quite a bit in some engines .Chevy also changed the HP ratings to suit marketing stratagies,if Fomoco raised their HP on 6's GM did the same and vice versa.
Big trucks used a net power rating at a lower rpm than the gross HP the cars used.261's for example are rated from 123-150 HP depending on the RPM and model year.The only actual dyno tests of a 261 comes from a 1955 Hot Rod magizine,a stock 261 had about 115 HP at 3600 rpm.

I have a 747 head on my 235. Does that mean it will go faster and I should be using JP4 fuel? Joking aside I have an 848 on my 235 and I thought it was from a 56 model. I recently saw a bone stock 59 Chev pick up with a 235 and an 848 head.