Building a 261

I plan on replacing my 216 in my 1949 Chevy 3600.

I picked up a running (supposedly) '55 261. Motor #3733950. I also picked up a 235 with a bad lower end. The 235 has the good 848 head.

I also got a set of Fenton headers.

Besides that I am looking for some advice on cam, intake, ignition, carb etc.

On a budget of course.

****** is yet to be determined. Right now it is a SM-420. Would like to go with a variation of a 5 speed OD manual.

Thanks guys.....you are a wealth of info!!

 

Hey, Coach,

I don't remember the overbore amount ( 0.040, 0.060? ), but one of the old tricks was to take the 261" up to 270" while using common oversized rings, cast pistons, etc. Maybe someone will chime in on this.

Before you have your 848 head worked on, drill out the steam pocket holes between #3 and #4 bores; 261 had 'em, 235 didn't. Look at the 261 head when you take it off, or compare the 848 to a 261" head gasket, you'll see what I mean. The 848 is not a real high performance head, so to speak, but it will give you an extra half a point or so on your C. R.

Also, before the rebuild on your block, look at going to full flow oil filtering. Take a look at the p***enger side of the block for two pipe plugs near the horizontal oil galley casting, one above, one below. These can be removed in order to route the oil out through a remote filter and then back in before it goes to the bearings and lifters. Get a remote oil filter mounting kit, and have you local tractor supply place make up the to/from hoses for you. Near these pipe plugs there is a small stud, maybe 1/4" or a little bigger, this gets pushed in to block the oil flow and forces it out through the lower pipe plug. It may take some soaking in WD40 or Gibbs to "un-stick" it. You close off the internal route so it can be filtered.

Take a look on the Inliners.org and the Stovebolt old trucks websites for more tips on these engines.

Good luck with it! *****6

 

Coach,

There are a few threads on hopping the 261- will try to find them, but you can also do it with the search. There was a great article some years back that my dad used for his: using the 848 head (best compression), overboring, etc that is in one of those threads...

Here's one of the threads:

http://www.jalopyjournal.com/forum/showthread.php?t=655586

 

Since the standard bore of a 261 is 3.75, it's no problem to find rings in either standard or oversize; lots of engines used a 3.75 inch bore, including Chevy 265, Buick 300 and 340, and Ford 292. If you punch it .125 oversize, you've got a 3.875 inch bore, which was standard for Chevy 283, Oldsmobile 324 and Pontiac 350.

 

Not exactly....If you use stock oversize 261 pistons you'll find the two upper rings are wider than the stuff mentioned above.The rings are available but limited to cast and chrome.You may find a limited supply of better moly rings...and they are more expensive...

 

The block will have large pipe thread ports [1/2 NPT] if it was setup for full flow from the factory. The stock 261 truck cam was what was used on the 6cyl Corvette's ,good mid end punch. I ran a warmed up 261 years ago in a 54 210. .060 over bore ,.030 off the 848 head ,Corvette 3 carb setup and truck cam. Wish I would have used more cam as at 4K it started to run out of breath. Thing will fly with a 5 speed and about a 3.70 rear. I broke more stock 54 3 speed trans than I can count and several rear axles with that engine.

 

Is there an intake and carb set up that is preferred for general street use?

Budget and ease of set up is my primary concern!!

 

Put in hardened seats on the exhaust and enlarge the exhaust valves to 1.6 using SBC valves and do some port matching. I used Clifford stuff; cam (hydraulic), and cam kit all worked well. I also used the Clifford intake and adapted GM TBI. A 2X1 intake works well too.

 

Any feedback on a 1954 Corvette exhaust manifold?

What intake will it work with?

 

The Corvette exhaust manifold should work with just about any aftermarket intake, as the heat riser connection is the same as a stock single outlet exhaust manifold. I ran one on my first '53 Chevy with a McGurk dual intake with no problems.

 

You've got a budget... I hope it's big... my buddy rebuilt his 261 all stock and spent $4K.

 

From what I have seen it should not take anything near that.........I would like to see a break down of his expenses.

 

Wish I had a few customers like him! Difficult to understand how a stock build could be more than $2500-3000, with everything new.

But having said that one guy I know spent $5,000 with a big-rep east coast restoration shop on a little flathead 6-cyl and the rear main seal leaked when he installed it!

jack vines