The Stovebolt Site Forums The Shop Area Engine Shop coughing

OK I need help again.. Its coughs when you excelerate even under no load. Idles good, hit the gas and it coughs. Vacuum is good, new distributer, points, dwell is fine, timing is good, new coil, new plugs, new plug wires. The carb is just a year old from chevy duty. It was running fine before I took the intakes off for painting. I put on new gaskets and I don't think there is a lead, I have to get some starting fluid to test it for sure. From what I've read it sounds like the carb, power valve. I have never rebuilt one but I guess I will have to try. Does this sound like an intake leak or the carb could cause this? Oh yea, its a 1961 235 engine. One more thing it starts great, runs good on the road once past the coughing spot which is on initial exceleration. Thanks for the help..

Have you made sure that the manifold heat valve in the exhaust isn't stuck? Otherwise check your accelerator pump. A bad power valve is either rich all the time or stays boggy when the gas is pressed.

I forgot the mention the heat riser spring is new also although I have been fighting with that also. It never opens when it gets warm so I unhook the spring but I still get the same results with the coughing. Not sure how to check the accelerator pump though. Whats a good way to check it? I can use all the help I can get.
Thanks

As a suggestion, I found that adjusting my timing was the key to stopping a hesitation problem..

willib I too am having the same problem. I took my truck to get weighed this weekend and was having the same thing happen too me. When I pulled on my choke it seemed to help but I know that isn't the solution. I adusted my timing last night but I have yet to test drive since then. I will let you know what I find.

Let us know if you find a solution.

53forme and Brian
Thanks for the suggestions, I'll try the timing again tonight. I'm having some trouble getting it correct. I've read from other post to use the pointer on the fly wheel housing about the starter and the ball on the fly wheel. I can't find a ball on the fly wheel but I found a hole where the ball may have fallen out of and have used this as a reference. Accoding to my handy dandy service manual the ball is only on a 261, well I have a 235, it states the is a 5 on the flywheel to use, I have found it which happens to be right beside the hole. There is no maker by the 5 so what do you align it with? Also next to the five is another stamp that appears to look like U|L as best I can read it with my bad eyes anyway. I'm going to play with all three locations and see which one works best. Also should I be able to get close to finding the alignment point by pointing the roter to the number one contact on the distributor and then looking on the flywheel for the marker? Thanks agian and I'll let you know what works and what dosen't.

You might want to check the accelerator pump in the carb. My truck did this till I rebuilt the carb.

I have always adjusted my timing using the vacuum gauge. Try for the maximum rpm and the highest and smoothest vacuum reading..

That method has worked well for me.,.I find it a lot easier than squinting to try and find the ball on the flywheel.

I don't even know if it is accurate, but my truck starts and runs well. That is the goal I suppose, lol..

If the sympton appears while not under load, that is when you hit the gas in neutral, it is quite likely the acc. pump. If you had an air leak in the manifold, it wouldn't idle very well and would ping under load. This I have found from experience1

Willib:
All the posts make sense. I only offer this from my experience; since the trouble started subsequent to removal & replacement of the intake, you may have an intake leak. One way to find out before doing anything of consequence, is (while the engine is off), pour gasoline down the throat of the carb. If you have a poor mating of the intake to block, it will leak out.

That's a good way to fry a ring or hydrolock a cylinder, donz. It's better to use propane or carb cleaner around the manifold while it's running to find the leak

howziit guys!

my 454 coughed twice, in accelerating through a sluggish mid-range. i tweaked it, from 12* to 16* static advance.

now...it only coughs onces, then power comes on like GANGBUSTERS!

i need to fix my mechanical advance...only getting 4*.

JMO, check your ignition timing...AND DO NOT POUR GAS DOWN THE CARB! :rolleyes: :rolleyes: :rolleyes:

willib my was fix with timing adjustment and not takeing off the choke too soon. In otherwords making sure the truck was fully warmed up. The "ball", at least on my 235, is recessed in the flywheel. I took one of my sons white crayons and marked it so when I used my timing light it is really ease to see. I believe and could be wrong that the "5's" are 5 degrees befor and after TDC ( top dead center). For me I found that if I am my timing light down between #2 and #3 plugs I get the best angle for lighting up the timing mark. If I can help let me know! Good luck!

To check the accelerator pump. Remove air cleaner and open the choke. Look down into the carb and pump the throttle by hand. You should see a stream of gas squirting into the carb. If it's only a trickle or not at all, replace the leather (or rubber) on the pump.

Timing on the 235 is easiest with a vacuum gauge. Follow 53 for me's instructions, you should end up just as good as with a light.

[QUOTE]Originally posted by 5-7heaven:

i need to fix my mechanical advance...only getting 4*.

howziit again guys!

with spare distributor nearby, i popped off the cap...figured i'd clean and lube the weights and plate on the existing HEI, before i yanked it out.

that done, i played with the weights...THEN NOTICED THAT THEY WERE NOT FLINGING THEMSELVES OUT!

DOH!!! the last time i cleaned the distributor, i mistakenly installed the distributor weights UPSIDE DOWN/BACKWARDS! hence the 4* mechanical advance.

just cracking open the throttle of the 750 edelbrock, i realize that i am no longer the owner of a LAZY RAT MOTOR!!

Good news guys, I found the problem after trying everyones great advice. I checke the timing, accelerator pump, fuel mixture everything. I was get frustrated and then it dawned on me, after everything I had replaced, all the adjusting, setting of points, dwell, timing, carb I thought, you know what, it was blowing all that black smoke until I got everything right that I decided to check the new plugs again. I pulled one out and it was charcol black. I cleaned em all off and started it up. It runs like a champ, no missing, smooth as silk, no coughing, no dead spots, its perfect. Guess I should have thought of that sooner but look at all I learned along the way. Thanks again for all the great advice and don't worry I didn't poor gas down the carb. I am amazed at how good it runs, it start on the first turn of the engine. I've been driving it all over with no grill or bumper, or tags for that matter. Guess I need to button it all back up and make it legel, time to enjoy it for awhile. Most of the other things I want to do on it I can do here and there.

With the plugs being really black like you mentioned, it tells me that you are running a little rich on the carb adjustment.