The Stovebolt Site Forums The Shop Area The HiPo Shop 261 Rebuild Project

Hello Stovebolters!

Thanks for all of the excellent technical advice that's posted on the forums.

I'm in the process of building a 261 Chevy six (1959 vintage) for my '49 Chevy 3/4-Ton truck. I'm planning to go with Fenton dual exhaust manifolds and an electronic ignition, but I'm not sure what to do for the intake. The single 4-bbl setup seems nice for drivability, but the 2-1 bbl setup has the "cool factor" to it. I have heard some stories of dual carbs being a pain to adjust and maintain, but maybe they're just stories. Does anybody have some recommendations for intake manifolds and electronic ignition? Other than that, this 261 will be basically stock.

If it matters, I will be using a GM New Process A-833 OD transmission with 4.10 rearend gears.

Thanks in Advance!
Dan M.
Omaha, Nebraska

tom from the stovebolt engine co.... has a nice dual two barrel set up.... im using it on my stroked 261 in my 39 1/2 ton

Thanks. I called Tom yesterday to get some of his recommendations. Are you running an Offenhauser intake? What type of carbs and what exhaust manifolds?

Dan,

I have used two original Rochesters on an Offenhauser intake using water warming (on a 261). No problems.

I am now setting up two 2-barrel Carter-Webers on a Fenton intake (on a 261) and will use exhaust heat (from dual Fenton exhausts). The only difficulty I am having is fitting the accelerator rods.

You should heat the intake manifold by some means. The Offenhauser intake is set up to allow a flow of water into and out of the manifold. The Fenton intake is not set up for flow in and then out (after passing from one to the other - as is the case for the Offenhauser). Thus, heat is simply "conducted" into/through the Fenton intake whether you use exhaust air or water (no matter what style of adapter plate that you use).

If you get a chance look at the heat chamber at the bottom of a Fenton and of an Offenhauser intake. It looks to me that the water plate that Tom Langdon sells for the Fenton intake does not result in water flow when used with a Fenton intake. The Fenton intake does not seem to be cast for water/air flow - it simply has a chamber. The Offenhauser intake has a divider in the middle of the chamber, allowing water to flow in one side and flow out the other. If you use the Offenhauser intake with a water-heat adapter plate, make sure the plate is the style that is flat on the bottom, so it will seal against the divider in the Offenhauser's heat chamber.

Maybe this has been to much information.

Nonetheless, both set-ups will heat the intake manifold and that is what matters.

Tim

When I get to that point, I am thinking four barrel. I don't want the hassle of two carbs, and I am counting on a little fuel savings with the (smaller) primaries.

John

I saw an inline with a four barrel on this site or another in the last two weeks. I thought it a better choice than multiple carbs if only for the tuning balances that seem to cause some to pull their hair out.

i will soon be struggling w/ the same dilema. 1960 261, stock internals. 2 carbs vs 1, tuning vs cool. some depends on the look you are trying to achieve. my 46 1/2 ton will be a resto rod, w/ my intention being as many 50 /early 60 rod parts as possible. personally nothing looks nicer than two carbs dressed to the 9's. as for tuning, i don't have much hair left anyway. . fit is an issue, i have heard there are some grinding requirements when you use an offy intake w/ fenton exhaust. mechanically, to me anyway, the water heat of the offy seems easier and more reliable than the heat transfer from the risers off the fenton exh headers. but who knows, i've been wromg once before, i think.

I've been running Langdon's dual Carter/Weber/Offenhauser/Fenton header setup with exhaust heat on my 235 for the past 6000 miles. The initial setup required some massaging of the intake and also some minimal trimming on Tom's heat plate to give me full throttle movement.

The C/W and H/W initial synchronizing is made easy by fabricating a "cap" that allows you to use a Uni-Syn on the irregularily shaped carb tops. Granted, it takes a bit of ingenuity, some scrap sheet metal, and duct sealer, but once you get the carbs in sync and your linkage operating smoothly, the setup is troublefree. I check mine periodically and they stay in sync. I've also noted that using a fuel pressure regulator set at 3.5 psi will insure that you don't develop excessive fuel pressures. This also works on the Rochester carbs. Should have some pics of the "caps" in my album.

The exhaust cooling works....although Tom recommends the water heat. The Offy intake requires sealing of the two core plugs in the understide for water heat, and requires some creative plumbing. I've found that the exhaust heat is easier to install, quicker to heat, eliminates any chance of coolant loss, and is a cleaner installation.

Granted, a dual setup is going to require more tweaking than just slapping on a 4 bbl, but the esthetics of a dual carb setup make it a viable option.

Dave