The Stovebolt Site Forums The Shop Area Engine Shop Setting Up Offy Intake???

Well; I finally installed my Offy 2x intake and Fenton headers. This will be my first attempt at setting up multiple carbs. So far, it's not right.

The exhaust isn't installed yet. I had 18" pipes made and they're on it.

No matter where I adjust the air/fuel mixture, it only runs when the choke is closed on one of the carbs. It seems like it has a vacuum leak somewhere; doesn't it? I have a vacuum line going from the vacuum advance on the distributor to the second carburetor (near the firewall). That's the same carb that has the choke connected. The vacuum on the other carb is blocked. I've also blocked the vacuum hole on the face of the intake.

What are your ideas for solving this problem?

Thanks.

Did you leave the rings outta the intake?

No. Was I suppose to?

Jerry,

Are these new headers and intakes? If so, they do not correctly bolt-up together unless you grind off a little metal where the intake rides against the exhaust (I dry fitted and kept grinding, mostly off the intake, until I could slide a piece of paper between the manifolds). I used the intake inserts with no problems.

This problem will result in the exact situation you describe - an intake/vacuum leak.

If these are new and you bought them together from the same vendor, I would have expected them to provide a warning about this situation.

Try a search on "Offenhauser Fenton" in this forum and you will find a few discussions on this topic.

Tim

Not at all but that's the first place to check

Start your truck and spray WD40 around all the joints
When the engine note changes there's your leak
Please try to not get too much on the exhaust It'll smoke you our

Another idea!
Have you sync'd the carbs? Are they open the same at idle? You have to disconnect the linkage between them to do this.YOU MAY BE RUNNIN ON ONE POT!

And the choke goes on the front carb....don't ask me why but I've noticed it does make a difference

I did have to grind off the intake to make it fit. I may try the paper trick to see if I got enough clearance. It was pretty close.

The header is touching the intake in the rear. I guess I'll have to remove it again. I'll also move the choke up front. Does it make a difference where I get the advance vacuum?

J.H. can you talk a little more about synching the carbs? I currently have the idle screws turned out so they're not touching. I'm also not sure I have the linkage set right. I'm going to have to play with that a little. It seems like it's pushing the rear carb more than the front.

Jerry - I would suggest using chokes on both carburetors.

If you have trouble with synchronization, give me a call during normal telephone hours, and I will walk you through the process.

Jon.

Jon,

Are you talking about two choke cables? If not, how do you tie them together? Thanks.

Jerry

Mine is set up with one choke that has never been needed since dual carb install. I took other choke blade completely out. Vac. from one carb to dist. No probs setting up. I have tube headers instead of Fentons with no intake heat. Followed the mods described in tech section of inliners.org site just for fun. Good luck, G.H.

Jerry take Jon's kind offer....Yes IT WILL TAKE TUNING

This isn't plug and play

Good news is once you got it all sorted out your way ahead of building your own stuff

Sorry Jim, but I am asking.
Has anyboddy an idea why?

Frank

If you're using the linkage that comes with the Offenhauser intake,it's very crude,but can be made to work ok.Adjustments to the carbs should be made with the throttle linkage disconnected between the carbs.You didn't mention the type of carburetors ,but are they matched? same part numbers?Even Rochester B's have a multitude of variations in air bleeds,idle transition, power valve and main jets.
I had dual Rottenchesters on my 37, both carbs were matching mid 50's models,the larger size.The carbureted great with no changes at all ,used the stock #57 jets.
I hooked up the choke on the rear carb, the cable wouldn't reach the front one But the choke wasn't needed ,just pumped the gas pedal a few times, started instantly,a little foot feathering on the gas got it going until a few miles warmed the engine.
Multiple carb adjusting is easy using a carb Sync tool or simply a large rubber hose.With the hose to your ear and on the carb opening,adjust the idle speed screws so both carbs make the same sucking noise.Then adjust the idle mixture screws for the best idle quality. You may have to repeat the procedure a few times to get the idle speed and mixture correct.Then hook up the linkage, checking for proper operation ,both open at full throttle, both open together off idle, both close against the idle speed screws.

I think I've got it close.

1. The intake and headers were touching. I had to grind a bunch off the intake to get it to clear. That stopped the vacuum leak.
2. I put a T in the vacuum advance line and connected both carbs to the distributor.
3. The air/fuel mix was too lean. Fixed that using a vacuum guage.
4. Choke is attached to rear carb (cable is to short for front carb)
5. Tweaked the timing a little.
6. Voila! She runs.

Way to go! Always a good a feeling, huh? I guess that's a problem with the Offy intakes. I had to grind mine down also. You gonna post some pics on your albums page? Like to see it.

I do need to update the pictures. Those were all 'before' pictures that I got when I was negotiating the purchase. A lot has changed since then.

I'm not happy with the detail under the hood right now. I need to pull the Offy valve cover; change the gasket (235 to 216); install the rubber seals on the top; and, install the acorn nuts. I spent a lot of time bending and fitting steel lines all the way from the fuel pump to the carbs. I couldn't get the right flare fittings so I used compression fittings in some places. They leaked so I took all of that off and put rubber lines on it. I don't like it. I think I'll go to the braided lines. I'm using Wirth's finned air cleaners that match the Offy valve cover. I think the cleaners look to small. Any ideas?

I guess you want something chrome, but my plan is two stock aircleaners when I install my dual carbs. I think that will look cool. I still need a matching carb. So I guess I should take the numbers down on the one I have huh guys?

Jerry, do yourself a huge favor, and spend some more time on the metal lines!!! Flare fittings should be available at the local auto parts store. If not, what do you need?

Get rid of the rubber hoses BEFORE you have a problem.

Jon.

Maybe this is some inspiration.

I went to a shop that does hydraulic lines.

Bought a view pipes (easy and much better to bend than the steel pipes) and fittings.

Those fittings don`t need no flare. Just screw them on and that`s it - they never leak cause they are made for high hydraulic pressure

The fittings have what we call cutting rings here in Germany (They work only one time - if you dissasemble you have to get new rings - 29 cent for one) - I´m sure you can get that stuff in the US too.

[img]http://www.thesavoy.de/assets/images/Enginedriv.jpg[/img] [img]http://www.thesavoy.de/assets/images/Carbdetail.jpg[/img]

more pics are here:

http://www.thesavoy.de/html/status.html

have fun, Frank

There ya go, two stock airfilters. How much space is between them?

TonyM - The side view of the air cleaners looks like they're two different sizes.

I agree. I'm just trying to get this thing running enough to get it to the muffler shop and then into storage. I'll dress her up next spring.

I should be able to get the fittings I need. It's just that local parts stores seem to be out of stock on these items. I can get one here and another over there, etc. I just need to lay this thing out and assemble the parts before I get back to it.

Thanks.

Jerry

These Webers seem to have a problem with the accelerator pump. No matter how I adjust them, they still hesitate when you first push the gas pedal. They idle fine and accelerate fine afer you feather through the bottom end of the push. Will this work itself out as I drive it? What should I be doing?

There is almost no space at all. I use the hole for the PVC hose to bolt them together with a rubber washer between them.

Those are the heavy duty oil bath filters from a truck(The car is a 41 sedan) but I love the look.

The different size filters you see on the side view picture on my website was just a test setup.
Those here are equal size.

Had some problems with hood clerance, but I grinded the neck down to the felt ring and now it works

Jerry, the Holley/Weber has 3 holes at the pump pivot where you can change the ratio of the pump lever, make sure you got both levers at the same hole.

but your problem sounds more like the strange choke mechanism that provides a kind of second idle stage and relases when you push the pedal to the bottom - hope I could make that clear with my limited english.

Frank

Ok; this thing is driving me crazy (some of you know how short that drive is).

I just went out to start the ole girl. It's about 45 degrees and partly cloudy. I choked her and tried to start. No luck. I had to use starting fluid to get her to jump. Once started, she was a little cold-blooded but ran. Still have the accelerator pump issues. Once warm, I turned her off and tried to re-start. No way. No choking or pumping would get her to fire? What are your thoughts?

Jerry,

Are you heating the intake manifold? An unheated manifold (of even a warmed-up engine) gets cold from the vaporization of the gas. The cold manifold can cause the gas to condense and this can result in hesitation.

Search this forum on "heating intake" for several discussions of this topic.

The hesitation of my 261 with Offy intake and Fenton headers completely disappeared after I hooked up water flow (from below the thermostat housing).

Stovebold - nice looking engine. I also used tubes and ferrules with brass fittings. Mine do not look as nice as yours. I used fittings for right angles rather than bending the tubes (brake line tubes, I think). Also, the oil bath cleaners are a nice touch.

Tim

Frank, Engine compartment looking first class! That dual exhaust you are running, Kansas Kustoms??? Lots of guys posting questions about that type of set up vs. Fentons.

Also, are those carbs Webbers or Holley-Webbers, neat job all around.

I'm not heating the intake. I was hoping not to have to do that. I've read a few posts where people said they didn't need it. So.... I have the plate that takes water. I guess I could hook it up to see how it goes.

Jerry

Jerry,
I too was going to forego the heated intake. After researching a bit, every reputable source I could find on the subject said, 'it is absolutely essential to supply heat to the intake for a street application'.
I don't know if this is necessarily your problem at the moment but, it may be compounding the issues.
-David

I'm not using heat on mine currently but I think the change over from 3 speed to Hydramatic is going to force me to go from current tube headers to the corvette split manifold I pulled years ago so at that point it will have exhaust heat again. I do notice a slight hesitation but followed tips on inliners.org tech tips page and then Patrick's advised me to drastically shorten or even remove the springs under power valves to experiment and run advance timing up a bit and it made big difference. Also using 2 stock oil bath air cleaners and have plenty of room between them. http://community.webshots.com/user/greg_h
you gotta promise not to make fun of my grubby engine. Thanks G.H.

This thing just keeps getting better.

I installed the plate on the bottom of the intake for water heat yesterday. I haven't hooked it to water yet, but I wanted you to know that I had to cut quite a bit off to make it fit between the intake and the rear Fenton. It would seem that these vendors could have done a better job of fitting their parts together. Also; the threaded holes in the intake aren't nearly deep enough. I was very nervous that I may strip them out. I sure hope this works. (I've been looking back at my stock intake and exhaust wondering what I was thinking when I removed it.)

Here is a set of Kansas Kustoms. No worry about hooking up heat here. Offenhauser bolts right up too when I am ready to install it. Still have more cleaning up under the hood to do, fuel lines etc.

[img]http://www.angelswest.com/_borders/kansaskustoms.jpg[/img]

I was using two Model B's, had several spares, different jets, water heated intake, etc. Never did get it running properly before it swallowed a valve and rappity-rap boom. Now have a V8 Vortec EFI,As Gleason said "how sweet it is"! Zeke

Hi Jim, thanks and yes Mike did the splitting for me, I prefer that setup because of the original heat riser and yes those carbs are Holley/Webers.

Jerry, here is some reading for you on those carbs:

http://www.surpluselectron.com/aaron/holley.htm
Best

Holley/Weber tuning

offy heat plates.... are there different gaskets for water and exhaust to heat the manifold. Im guessing yes. I have the one for the exhaust. Where can i get gasket for water?

thanks