The Stovebolt Site Forums The Shop Area Engine Shop Comparing carburetors

Fellow Stovebolters,
Do any of you have experience with using a small 4 bbl, dual progressive 2 bbls and a single Webber progressive 2 bbl.
I'm building a new motor and have all the details worked out except for carburetion.
Performance and mileage are both concerns.
Any feedback is welcome.

Thank you

Do a search on the forum. There is a lot of information about these.

also for 4 bbl info try Clifford @:
http://www.cliffordperformance.com/

for Webber info try Tom Langdon @:
http://www.stoveboltengineco.com/

Don't know what kind of power you're looking for. On my friend's 261 we put on dual Holley-Weber two bbl. progressives, which gives him great low end power. With a full race cam, he got the idle down to about 550 rpm. I love it, he thinks he can do a little better on the top end with a 500+ cfm 4 bbl. Horsepower is over 250, engine will turn over 6,000 rpm, and it will burn the tires into 4th gear.

Here's a picture.
http://www.myoldtruck.com/gallery/files/2/3/8/Engineleft.jpg

Nice pic Fred,
I use my truck as a truck and it has a granny 4 speed with 3:90s and a posi rear end.
I want low maintainence, good power and decent fuel economy.
I read a fair amount of the archives and it seems like a call to the carbking may be in order.

Thank you

Fred,

It will be few months before I am ready to fire it up but I have a similar set up.
261 w/ 848 head / medium cam
Dual Holley-Weber progressives
Dual Fenton Header Exhuast

I may be asking you and your friend some tuning questions in the future.

Aaron

I assume you guys are putting your 2 bbl progressives on an Oppenhauser. Where is a good source for those carbs (= good price). I'm probably getting the 3/4 M4F grind cam from Patrick's (when he gets them).
What pistons are either of you using and what did you do to the head exactly. I'm boring .030 over.
-jeff

I purchased my Holley-Weber two bbl. progressives from Tom Langdon I think the were about $80 each.

http://www.stoveboltengineco.com/

I have the 3/4 M4F grind from Patricks. I am running a stock piston and as for the head I took it into a shop that does all of the engines for Patrick's. I think all they did was drill the steam holes. I also bored mine .030 over.

.030 over for power is wasting money. You pay the same for a .060 setup (boring/pistons) and end up with more power. The m4f is a good cam but after my experiance with it almost the same as a 261 stock cam. I would go for Tom Langdons "Bulldog" cam wich is a solid improvement over the M4F and still maintains good idle and low end power.

If you get this rebuild carbs from Tom, open them and check if they are the same inside (little bores and holes/float/jets and so on)

They made this carbs for a zillion applications and they may look the same outside but my be different inside.
If they are not exactly the same you never will get them syncronized.
If possible get two with the same numbers.

Bin there, done that and ended up ordering 2 more Holley/Webers.

Frank

you will have a little more power but also a block that will be junk when it needs bored again.also some engines run hot when the cylinder walls are too thin.

I'm with Zenish on the overboring.
I see no clear reason to take more meat of a cylinder than it needs.
I'd rather have a block that has another rebuild left in it.

My 261 is .040 over and has a cam that has the same grind as the early Corvette motor as well as a port and polished head, balanced motor and the head has been shaved a bit, not to the maximum as I once again would rather it had another rebuild left in it.

I was looking at 370cfm Webber but they don't seem to be available.
I may use the Holley 390 with a Clifford manifold.
I'm still undecided.

The M4F isn't much of a cam for the 261. It is real close to the stock 261 cam, which is the cam used in the vette 235. I don't recall the grind code in my freind's 261, it is what we used to call a full race cam. He got it from Patricks, some 10 years ago. I have the M4F in my 235, it is what was called a mild, or 3/4 race cam. It still has good low-end torque, and I have had the engine up to 4,500 rpm. For comparison, the 261 has exceeded 6,000 rpm.

Has anybody out there ever looked into sleeving the cylinders on one of these once they have been bored .060 over? Thats where I am & I need to either find a new one or sleeve it if possible. Any thoughts out there?

By the time you pay parts and labor on sleeving 6 holes, you can buy a couple of core blocks. I do it at times on 350 V-8 race engines with lots of machine work on the block, but I've got a couple of thousand bucks' worth of labor in one of them. For a street engine, it's not worth the effort or the cost.
Jerry

As far as I know giong to .008 and even .010 is possible without striking water. So why sleeve it and pay a fortune for that?

Frank

Thanks for the info on sleeves. I'll keep lookin for a cheap block.