What's the difference between a 235 & a 261? What's the Horse Power of a 235? What's the Horse Power of a 261? Are they the same block? Are they direct bolt up? Cause we think we have a 235, and if so, we're gonna dump in a 261. Thanks. Anthony
261 is 1954-63 truck and some Canadian Pontiac only - no US cars. Different block, same crank, heads interchange, 261 has stronger rods. Same bolt up year for year (but not early vs. late). HP depends on year, but none very impressive. Very few good 261 out there.
The 261 also has a full flow oil filter, so you need to run the filter or at least bypass the lines. 235's you can get away with blocking the oil lines off. Also been told the 261 heads do not flow very good.
261 crank NOT the same, it has 3 15/16" stroke. Same bore as 235. I have three good 261's. All Pontiac 6's in Canada were 261's, until '63's came out with 230/250. 261 bolts up to '55-up 235 cars, the earlier ones have minor problems, motor mounts, water pump length, nothing insurmountable.
261 and 235 have the same crankshaft,same stroke,same balance,same part number,identical.261 has a 3-3/4 inch bore,235 has a 3-9/16 bore.
The 261 also has a full flow oil filter Only 1958-62 have the full flow, not 1954-57. 261 heads do not flow very good. They basically use the same assortment of head castings. There is no "big valve head" (except 1950-52 Powerglide, and the valve can be installed in any later head), there is no "high flow head", there is no "performance head", the Corvette head is nothing special. The 848 head is used on some 261 already, and is only different by chamber volume. This is a primitive engine, and not related to the later Gen-3 194, 215, 230, 250 & 292. Don't expect to get much out of it. Many comparisons above are confusing annual changes (1941-53 vs 1954-63) with engine changes (235 vs 261).
The 1941-53 cranks are all different from 1954-*... but all 261 are 1954-*. The only shorter stroke is the 216 at 3.75".
If you are trying to source a 261 in the US, best to hit the rural areas. You will be looking for a full size commercial chassis. Common in farm trucks. School buses are pretty common locations, also. Here are some numbers that I have. I recollect that they were from a reliable source. Let me know if anyone knows differently so I can correct my "little black book for car parts". Cylinder Head 3635499 1954 261 261 Engine Blocks: 3703414 54-56 3733340 55-57 3733813 58 3733950 54-55 3737012 55-57 3738365 60-62 3738813 55-63 3739365 58-62 3759365 59 3769717 59-62 3769925 58-62 3788813 55-59 3833340 55-57 383340 55-57 3836012 55-57 3836340 55-58 3837012 55-57 Good luck in your search. They are not the easiest to find these days. Tom
According to my MoToRs Manuals, the 235 AND the 261 BOTH had 3 15/16" stroke. The 235 had a 3 9/16 bore; the 261 had a 3 3/4 bore. Since the difference is in the bore, it would appear that they share crankshafts.
Better bang for the buck would be a later series 292............7 main bearings vs 4........full flow oil filter..........can use a stock HEI.........more cubes right out ot the box.........already fits any V8 chev bellhousing/tranny combo..........lighter weight..........need I go on?
True - the 292 is a bit cheaper to work on, much newer, physically stronger, more speed equipment available, higher potential max power, and weighs about 75 lbs. less. It's pretty tall, and has clearance problems in some newer cars with 230 or 250, but not taller than the 235.
gags* only 2! Strait six's are worth anyone's time. The mopar 225 and the ford 300. You all may now proceed now that i’m done venting my asshole opinion based on biased experience and sheer arrogance. lol <o></o>[/FONT][/COLOR]
That's correct. If you've got a 261 block and rods, you can fake the rest with 235 parts (I assume that you're buying new pistons anyway).
some people just don't have a since of humor. it's a comon failing, possibly a genetic flaw... ought be studdied so it can be cured, life aint worth living if you can't laugh.
So, are the camshaft journals different sized between the early (pre 54) and later motors? I.e. can I use a cam for a 216 in a 55 truck block?...
If you're going to run an 848 head on a 261 you will get a slight boost in compression, but you will need to drill a steam hole to mate up to the 261... so chamber volume isn't the only difference. Anthony would get a lot of information by doing a little research and using the search function first. There are whole tech pages devoted to the 261 on the Inliners board, too.
....just like some people can't spell "sense" or "studied". See, I have a sense of humor; your grammar makes me laugh.
No, 292s use the same bell housing as Chevy V8s, whereas 235s were the same as 216, 261, and '39-'59 GMC sixes.
DAWM skippy there....you can get a ton of horses outta these too.....for less than 2 g's....full bore motor can get a light car into the 10's and be cool doin' it......Check out inliners.org you'll be pleasently suprised...
If you're going to run an 848 head on a 261 you will get a slight boost in compression, but you will need to drill a steam hole to mate up to the 261... so chamber volume isn't the only difference. Unless, of course, it's an 848 from a 261.
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