Anyone have idea

[Angelo]

Carb plate between intake and carb on 707b which I believe was there to prevent freeze up during warm ups. It’s wide open when cold. Is that right? Everything in my head says no 

[mowerman]

Isn’t that a heat riser? It should be closed at first start and there’s supposed to be a spring on it on the outside of the manifold. I think the regular auto engine 707 might be a little different. I’m sure you’ll get more input.Bob

[Angelo]

That’s what I thought too mower man . I had carb rebuilt noticed truck was cold and it’s wide open. I’m gonna heat it and see what it does but I believe it might be closing on me when warm and causing all my issues. 

[tjc transport]

if it is open cold and closing as it warms up, the spring is on backwards.

[mowerman]

good luck bud....probably a dumb question,,,,its not stuck is it.....bob

[Angelo]

I don’t think so I’m gonna take carb off again and mess around with it a bit 

[Angelo]

I’m chasing a lean condition. If I pull choke halfway out she runs good and can throttle it up no problem. If you take choke off and try to rev she hesitates bad. Temp is good. Has new fuel pump, rebuilt carb, fresh fuel filters. not sure what else it could be. I noticed these were open not sure if they are closing when warm. Definitely something to investigate. Didn’t notice any vacuum leaks gonna get into that alittle more too. Maybe I have air leaking in some where. It’s driving me crazy.  Might try to crack a whiper vacuum line and put meter on it see what it’s pulling. When it off for while the whispers sag down soon as you start it they shoot right up so thinking my vacuum is good 

[Angelo]

[Vladislav]

You should check some basic things about the carb. Fuel level and (my guess) correctness of hole sizes of the duses. Both fuel and air. Also air leak in the intake manifold in its portion between the carb and the cyl. heads. But I think you meant that talking about vacuum check. 

Nice L btw, drool😀

[D-Day]

A few years ago I had a C30 with a 454 and 4 speed always had a lean issue it had a holly electronic adjustable throttle body the control was mounted under the dash like a CB you could adjust it while driving but even on max fuel setting it still had the problem take the air cleaner off I could actually see large amounts of fuel being sprayed down the throttle I switched to high quality non ethanol fuel and that helped a lot never did find any other problems and ran pretty good that way

[mrsmackpaul]

Sounds like a vacuum leak

Get some rubber hose and put one end in your ear and run around the inlet manifold and carby with the motor running 

Should be able to hear a vacuum leak pretty easy

Or get some WD 40 or aero start and with it running carefully squirt some around the joints of the inlet manifold, if the revs change your in the area of the leak

Or maybe Im full of crap and completely wrong but these are cheap and simple things to try

Paul

[BOBWhite]

Vacuum gauges sure are handy for stuff like this. They are your best friend for carbureted engines like this.

[mowerman]

Man, that’s a mighty fine looking ride . hope you get it figured out…. Bob

[Angelo]

Well I found one part. Didn’t fix entire but I’m moving foward. Vacuum wipers had crappy rubber line on them. Changed hoses and when holding my finger over it it sucks to my finger pretty hard. 

[mowerman]

All right, I could think we’re getting there. Thanks for the post. Good luck… Bob

[mowerman]

Probably a stupid question you did adjust the carburetor, correct? Maybe it doesn’t even have a screw or mixture.

[Angelo]

Yes was adjusted and rebuilt as well

[mackdump600@yahoo.com]

Hi I have a 70  R608 with the 707C engine and it melted the pistons on me twice ,do yourself a favor and weld in a bung at the exhaust pipe ,couple inches from where the steel pipe connects to the manifold and monitor your pyrometer and see how hot your running ,mine at  1800 RPM would go up to 1300° pretty quick and melted the Pistons ,still haven’t found the exact reason why ,water temperature does not go up ,just exhaust temperature pretty expensive to replace the pistons in that girl ,good luck

[doubleclutchinweasel]

Ethanol-added fuel also makes a carb act "lean".  Can require re-jetting.  Non-ethanol fuel can take that piece out of the puzzle pretty easily, though.

[1958 F.W.D.]

On 5/31/2023 at 8:40 AM, doubleclutchinweasel said:

Ethanol-added fuel also makes a carb act "lean".  Can require re-jetting.  Non-ethanol fuel can take that piece out of the puzzle pretty easily, though.

Yep. Corn gas does that to my 140GZ Waukesha. Not to mention the last time I cleaned the stone-element fuel filter, I pulled out a bunch of crap I can only equate to the snot that comes out of your nose when you have a bad cold. Since then she has only been getting corn-free and she runs so much better. 

[Angelo]

Well redid points again and got it running on both distributors and all plugs gapped right and seems to be running a lot better. Switched rear dry rotted tires over to 10.r22.5 so now it’s time to take her out and see how she does 

[mowerman]

Excellent thanks for keeping us updated