I have a straight six that I was told is a 235. It has a 3836850 head on it (261), but I do not see any Captains bars and it looks like the bypass filter not a full pressure system. runs fine, doesn't overheat... just not sure what I have
Some Pontiac 261 had bypass filters You need to see the capitans bars above the starter area And basically in the middle of the intake manifold on the left side
Check the block casting number. I have a 54 model 261 with no captains bars on either side and no oil filter at all. So, there must be a few of these around. Eddie
casting number is behind the damn motor mount. Nothing comes up for the one stamped next to the distributor. Intake is a Offy, so no bars.
Chev 6's did not have a full flow filter until 1963 with the introduction of the 194-292 style engines. If you know a race guy or organization with an engine cubic inch pump and they know how to use it; you only need to remove 2 push rods to do the test. 39 inches per hole on a 235 and a little over 43 on a 261.
what is the number stamped next to the distributor? There are not many truck motor codes on the internets...but I have books.... and post some pictures.
and he didn't mean the captains bars are ON the intake manifold, he meant they are on the block right near the center of the intake manifold.
'54 - '55 first series 261 looks so similar to a 235 that most of them got scrapped. They seem to have a higher quality iron alloy than little brother - the '54 235 block is famous for being soft.
Very early 261s had a bypass filter. After the first year or so they were fitted with a full flow filter fed by 1/2" lines from/to the block and look similar to the bypass type. I actually got a couple of new short blocks that a Chevy dealer had installed in a dump truck. The replacements came with a plug installed for bypass and had to be changed to full flow by the installer. They failed to do that, twice, and ruined the bearings while setting the valves.
I have a '54 261 block in my panel truck, it runs the a 235 water pump (in stock form), has captains bars and the numbers are by the fuel pump.
In the picture Jim posted you'll see the two 1/2" pipe for the full flow filter and the push pin above the lower one that blocks the galley to make the oil have to go out one fitting and in the other via a filter, this is the later 261, the question I have is the later 235 set up the same way.
the later 235 has none of that full flow filter plumbing. There are 1/8" pipe plugs for the bypass style filter.
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