Technical 235 Idle issue

Guys, I'm try to get my '61 235 broken in but she's not wanting to run smooth or idle. It has a mild cam, Fenton dual exhaust, offy dual intake with Carter Weber carbs, Langdons HEI distributor. Everything is fresh but after I get it started, I have to keep both hands over both carbs before it smooths out and runs pretty well. I've adjusted the idle screws in and out but it makes no difference. It did start the first time and ran pretty well without any adjustments, etc. but it's been downhill ever since. This is in a 1950 Fleetline w/ manual trans. Sure could use some help. Thanks, Mark

 

My friends all run 235's and when this problem pops up, it always seems to be choke related.

 

It has electric chokes and they appear to be working fine. I have to choke it even more with hands over the carb venturi's to make it run smooth. Help!!

 

Let me see, if I can reach a friend with your basic set up by phone. I'll get back.

 

No answer, he must be away from his phone. I'll try again later and get back. This guy is an engine guru and just built your same basic setup for a customer. Stay tuned. No pun intended.

 

Have you sprayed around with some car cleaner to check for vacuum leaks?
If they are new carbs there could be some machining particles in there causing problems.

 

Sure does sound like a vacuum leak. 235's can be a little tricky to get the intake to seal especially when have aftermarket intake/exhaust manifolds. The little 'C' shaped things that bridge between the 'ears' on the two manifolds sometime have to be ground on one side so they sit flush.

You did put the positioning/sealing rings in the intake?

And check your carb base gaskets.

Good luck....!

 

I did put the rings in guys, but that doesn't mean there isn't some problem at the gasket. This is my 1st 235 and although the engine was pro built, I bolted the intake and exhaust on as well as the carbs. I really need to check for a leak but can't use carb cleaner as there is fresh paint everywhere. Thanks so far for the help. Any tricks on checking for an intake/vacuum leak will help. Mark

 

You can use water out of a spray bottle.

 

Very common for the manifold alignment rings to get cocked or tilted and the manifold will not pull down against the gasket and head. There will be an intake leak then, most usually at one end or the other before center of manifold. With the adapters for the Webers there are few more gaskets to worry with also. Try spraying starting fluid at gasket areas on intake?
You do have the windshield wiper vacuum sealed up? Good luck

 

You got both carbs covered with your hands to make it run. You got to be getting air in from somewhere. Get a helper to use heater hose and place one end to their ear and listen around the intake for an air leak. WD 40 will find a leak also.

 

Okay, here's what my guy says, "Sounds like a vacuum leak. If it's a HEI, check the vacuum canister and all your hoses. Also, keep in mind, that a dual carb setup is tricky in it's own right. You will need to play with the carbs a bit."

Hope that helps.

 

Me too on the vacuum leak. I have that exact set up (check that, really close) on my '56 235, fentons, dual Carter-Webers on an Edelbrock intake, etc.



I had to replace that pos gasket you see on there, got that from Larrowe's (in Oregon I think) did I say pos? I meant pos gasket burned off and had several breaks (gaps) after a couple months. Got a new age intake/exhaust man. gasket and 'Bob's your uncle'. Spray bottle with soap solution, have at it, find the leak(s). This is a daily driver only vehicle and she runs like a top.

 

You can use an un-lit propane torch to check for leaks, doesn't make a mess; just turn the propane on and hold the tip near the joints

 

I've seen clothes pins on fuel lines before but the horse shoe has me puzzled.

 

At least the clothes pins are the traditional wooden ones.

 

Thanks again guys. It was what I think is a quality gasket at the cyl head. I'll try the propane trick 1st and hope i find something.what will the engine do if the propane finds a vacuum leak? Also, i think i mentioned that this has been a progressive downward turn for the engine as it started for the 1st time 4 or 5 weeks ago and ran great, 2 weeks ago it started running crappy but i was able to adjust out the idle mixture screws and it got better. Know it wont stay running unless hand are over the carbs tightly. Would spray bottle of soap and water actually work instead of propane? I loved Cosmo's horseshoe deal also and maybe its for luck??? Thanks, Mark

 

The horseshoe is attached to the fender brace to go around the back carb.

 

Here are a couple of pics of my set-up just FYI. Thanks again, Mark

 

Looks good hope you get it lined out man.

 

I ran the propane check and it was very hard to tell if aiming the gas at the intake/head area and base of the carbs made any difference. I did pull the carbs last nite to check the gaskets and they both appeared to be sealing well. I'm going to replace them both with new and start the engine to see if there is any difference. Mark

 

Had similar issues on my 235. I found I needed to break the carb linkage loose and set the idle independently and reconnect the linkage. You might try using a Unisyn to sync the carbs if you can locate one.

 

Well... i finally got it figured out. It ended up being a combination of bad fuel (I let a very small amount sit in the tank for a long time) and rust in the main fuel line, from the tank to fuel pump. Both my bonehead for not replacing the line a long time ago and for letting the fuel sit so long. I flushed both carbs, replaced the line and she runs bitchen!!! Thanks for all your help and suggestions. Mark

 

I love a happy ending!

 

PLUS, the propane, being a gas and not a liquid ....... the gas finds leaks so much easier and is CLEANER than water and or spray fluids.