My Offy Intake & Reds Headers Transplant

[Mark D]

Moose - you'll need to add this to your post... http://instantrimshot.com/

As for time - we got from now til March. Maybe I'll invite a few other local forum members over and we can combine it with a beer tasting. I'll call you to chat on a saturday in the next couple weeks.

[Mark D]

So yesterday I grabbed the keys and headed up to the garage to hook up the water line to the manifold. I replaced the hose and had to get a couple more fittings to reduce to the inlets on the offy header. All went well until I re-filled the coolant...

As soon as I topped off the radiator I heard a drip on the floor. Couldn't for the life of me see where it was coming from so I stuck my hand in under the intake and it was immediately apparent. There are two freeze plugs (which I had assumed where water tight from the foundry) which were leaking at a pretty good rate. So I disconnected the hose from the intake and patched the two hoses together to by-pass the intake for the time being.

[Mark D]

Here's a link to a video of the car running. I've tried to adjust the carbs a couple times with the draft guage, but I'm missing something in the process.

Disconnect one side of the linkage, and tune the opposite carb, then vice versa, then reconnect the linkage and adjust for draft. But dropping eithere side of the linkage causes the engine rpm to run wild.

Frustrating the heck out of me that I can't figure this out. I am seriously thinking about taking Mark A's advice and pulling the carbs and replacing them with a pair from Geo Asche.

[Don Coatney]

First off my thanks to you for keeping this all in one thread. Makes it much easier to follow.

The flow meter is for adjusting the linkage to insure both carburetors have the same flow at idle.

When I did my dual carburetor linkage adjustment the first thing I found was the stock return spring was not strong enough to pull and hold both throttle plates at the fully closed position. I replaced the spring with a stronger one. Then I took a flow reading on both carburetors. I left the carburetor with the highest reading alone. I then shut the engine off, removed the linkage from the other carburetor, made one round of adjustment on the linkage, reinstalled it, then re-started the engine and took another reading on both carburetors. I had to do this a few times until I finally got the linkage dialed in showing equal air flow on both carburetors. Then I set the idle stop adjustments on both carburetors and re-checked the readings. Lastly I set the idle mixture and took a final reading. This may not be the best way to do it but it worked for me.

On a side note back in the day it was a common practice for repair shops with low scruples to replace the throttle spring with one of lesser tension when doing a tune-up. This made it appear that the engine ran much better as it took less foot feed pressure to acheive speed.

Edited January 17, 2013 by Don Coatney

[greg g]

The other deal is that your choke buterflies are not fully vertical, they should be adjusted to be fully open. I would remove the connection from the throttle pedal to the bell crank, then determine visually that the return spring is fully closing the throttles. Then start the engine and let it idle. Then do what Don suggests, leave the dominant carb ( the one withthe highest flow) alone and adjust the other to it. Also Have you checked real well for air leaks on the engine side of the carbs?? As any air entering after the throttle plates will nullify any and all adjustments. Can you post some detailed still pics of you linkage?

I will echo Don's contention that the stock throttle spring doesn't cut it for two carbs. I have an auxiliary on going from the rear carb linkage to the pass side inner fender.

[Mark D]

I thoroughly appreciate the pointers gents. I am bound and determined to get to

the bottom of this.

Greg I used a bottle of LP gas to do leak detection at the carb to manifold connections - no rpm gain at all as a result. As for the throttle plates, I did a visual flashlight inspection and everything looks tight. It's been a few weeks since I did that and I did not remove the connection from the pedal to the bell crank, so I will recheck throttle plate position again this weekend.

As for the return spring; straight out of the gate I noticed that the linkage was not returning to the full park position and as Don states the original spring was not strong enough. So I created a secondary return on the back side of the rear carb. It's a temp solution I came up with to get me by the issue.

Ideally I will create a better solution with even force on both carbs, but this seems to do the trick for the time being. I was at the Napa store last week and one the counter was a large sorter tray filled with springs of all sized and lengths..When and if I get these carbs synced I will probably rework the spring situation.

Don - I will give your tuning method a try and see how it works out.

[greg g]

One other item to check on each carb. Only one of my carbs has the step up cam for the high idle with choke on setting. There is a piece of linkage that goes from the choke butter fly linkage, down to the base of the carb. It attaches to a piece that wraps around the throttle shaft and provides one or two notched detents for the idle speed adjustment screw to hold it open a bit more than "normal". On my carb, it hangs up sometimes and does not return to the "normal idle" setting even when the choke is fully opened. I have disabled it with a piece of mechanics wire, so that on both carbs only the "normal" idle rest is available for the screws.

[james curl]

I have found that it requires a spring for each carburetor as well as the original spring.  I attached a small diameter spring from each carburetor throttle arm to the inside of the fender and still occasionally have them not close all the way.

[Mark D]

Quick update - I spent an hour on the phone yesterday with George Asche.  Had am informative convesation with him about my car and the issues I am having syncing the carbs.  I am going to take the carbs off the car and send them to him, and he is going to rebuild them as a matched set or rebuild the best that of the two that I have and send me a match for the good one.  Additionally he is going to credit me some cash for the two other spares that I have on my shelf.  Price for rebuilding my carbs into a matched pair was very reasonable using my shelf stock. 

 

On another note, George was very anxious to find out if I had any overdrive transmissions in my stock, (wishful thinking) to which I replied that this was going to be my next question to him.  After we finished laughing he gave me instructions as what I needed to look for as I begin my hunt.  George also gave me some pointers as to a potential desoto or chrysler rear axle swap out if I was not able to get my hands on an OD, which would make highway speeds a little less trouble for a sixty-four year old engine.   George also offered to rebuild my engine for what I thought was a very reasonable price, but the logistics and cost is not in my budget this year.

 

My carbs will be off the engine and in the mail this week.  Already looking forward to getting them back and installed.  Guess this will give me some time to remove and replace the oil pan gasket and main rear seal.

[Don Coatney]

There is no such thing as a short phone conversation with George Asche. He will do a great job on your carburetors and they will be returned to you looking like new. Make sure you tell him hay for me the next time you talk to him.

 

[greg g]

It took me 45 minutes of phone time to order a couple of new acc pump plungers, and that was a short call for George.

[Mark D]

Spoke to George Asche on the phone today. My carbs are done and will be back in my hands in a few days!

 

I feel like a kid waiting for Christmas morning...

[steveplym]

About time to get that Plymouth on the road.  Probably ready to stretch it's legs a bit. 

[Mark D]

Figures, I'm in an airplane on my way to Cincinasty, and I just got an email from the USPS that my carbs have arrived from George's shop and are sitting on my front porch... I feel a case of the Friday flu coming on.

[Don Jordan]

Silly question - what I do best. I also have dual exhaust - how do you adjust the valves? The only way I can see to do it is to remove the headers. I can't figure an easy way to do it.

[Don Jordan]

I will probably get scolded for not doing my own research on this but I'm confused about syncing the carbs. How is that done? Is it best to have George do it? What should I expect to pay? I've never heard of that. Maybe that's why my car is so hard to start cold and it won't idle until it's warmed up. I would appreciate any info on this procedure.

[Plymouthy Adams]

that would be a very long drive...you asked this long ago...here is the link to the thread...

 

http://mopar.pairserver.com/p15d24ph_forum/index.php?/topic/21392-george-asche/?hl=%2Bcarb+%2Bsync#entry206762

[Mark D]

Good information in that thread Tim and thanks for the repost. Kevin, George will redo your stuff for you, but the tweaking and the tuning carbs can only be done on the car.  Last night when I got home from Cincinnati I unpacked the carbs and headed straight for the garage. Installed them and chased a few gas leaks from the carb lid gaskets.  Today I got Moose coming up from southeast Mass to help me tune and balance the carbs.

 

George did a great job building me a fine set of matched carbs. He's forever on my christmas card list now.

 

 

[martybose]

Silly question - what I do best. I also have dual exhaust - how do you adjust the valves? The only way I can see to do it is to remove the headers. I can't figure an easy way to do it.

I bought a pair of Nomex arm sleeves that actually work pretty well for valve adjustments with headers.  It's been a long while, but I may have gotten them from McMaster-Carr.......

 

Marty

[Mark D]

Had a fairly good weekend up until today.  Moose came by on Friday and we tweaked the car until it ran good.  He gave me a few geometry pointers on the linkage, things I hadn't thought about, and today I set about to correct a fuel leak I had at the carb body. Very unhappy to report that I managed to strip the threads in the #2 carb body where the flow valve seats.  Threw my tools on the bench and put the blanket back on the old girl outta frustration.  I doubt theres a way to fix the carb body without replacing it entirely.  Monday I guess I will call George again and see if he can get me that part so I can rebuild it on my bench.  Frustrating to say the least.

[Young Ed]

Hopefully he can fix it for you. Seems odd that a freshly rebuilt carb would be leaking and then strip out. I've got some parts carbs if you need a fuel bowl.

[greg g]

Not good to hear regarding the carb.  What was the discussion regarding the geometry of the linkage.  I remember diddling with mine a bit to get things aligned, carbs synched and levers pulling freely, opening and closing completely.  

[Mark D]

Angles of the throttle levers on the pull rod weren't quite the same as on the carbs. Moose thinks the rod from the head pivot needs the be lengthened a bit. Maybe moose will see this and confirm.

[Don Coatney]

If I recall I had to add some length to that rod on my setup'

[T120]

If I recall I had to add some length to that rod on my setup'

What's happening ?? - No picture, (sarcastic font required).  Sorry,Don I just couldn't resist.