Technical 261 Complete Tune Up | Drives Like Crap

I'm back everyone, but we keep fixing things one by one.

- New Tom Langdon dual carb with Offy intake put in.

- New spark plugs and wires.

- Timing set and idles perfect at 600 RPMs (see video).

- Not finding any vacuum leaks and vacuum advance works on the distributer.

Whenever I drive and let off the gas it backfires, pops, gurgles all the time. ;(

What am I missing?????? I'm so close to enjoying this thing.




https://goo.gl/photos/b6zzZK8dMjDRzgR18






Sent from my Pixel using The H.A.M.B. mobile app

 

What are you using for exhaust?

Sent from my Moto G Play using The H.A.M.B. mobile app

 

Nothing right now.... Right of the new Williams split headers.

Sent from my Pixel using The H.A.M.B. mobile app

 

Probably why it backfires and makes funny noises when you back off of it.

Sent from my Moto G Play using The H.A.M.B. mobile app

 

Do you have proper heat on the intake supplied by the heat riser? Chevy sixes run better with heat on the intake manifold.

Is it too lean (is combined venturi area too large for cam and displacement)? Try enriching mixture.

(Dan's ghost writer)

 

The manifold is water heated and working correctly.

Sent from my Pixel using The H.A.M.B. mobile app

 

You haven't done a compression check yet, have you? Did you buy a vacuum gage when you bought tools last week?

 

Yes, compression checked out good. I have a vacuum gauge but how would I use that to troubleshoot my problem?

Sent from my Pixel using The H.A.M.B. mobile app

 

Do a quick search for carb tuning using a vacuum gage and you will find tons of write ups at your destination of choice. Lots of good info on what your readings should be and what to look for. Etc...

 

Will do!!

Sent from my Pixel using The H.A.M.B. mobile app

 

And if you think about it, you ARE enjoying it. If problem solving isn't something you enjoy, then you probably wouldn't be here cuz it's a huge part of the ol car and truck game.

 

You probably should at least get a couple of those bendable exhaust tubes and channel that heat and exhaust out of the engine compartment under the truck.... at least! You gonna burn something up! And your ears and eyes will thank you....

 

As soon as I get it running will be going to the exhaust shop.

Sent from my Pixel using The H.A.M.B. mobile app

 

Not wanting to be a jerk but it would probably be helpful if you didn't close and then start a new thread every time something different comes up. It makes it difficult for people to help you when they can't see what has been previously suggested. Also those that were helping and may have subscribed to the old threads so they new when new posts came up might not see your new posts. Makes it much easier when all the info is in one place.

Sent from my SM-G950W using The H.A.M.B. mobile app

 

go to exhaust shop first. then tune

 

Thanks but I respectfully disagree. I like trying to solve one issue at a time instead of multiple under one post.

Also, I think this helps others (easier indexing and searching) when they go to someday search the same issue and not have to read through 50 pages of other issues within one post.



Sent from my Pixel using The H.A.M.B. mobile app

 

no exhaust isn't helping you, fix that and dont drive around like that with the windows down...

 

So a car will not properly Drive halfway decent when you don't have full exhaust on?

Sent from my Pixel using The H.A.M.B. mobile app

 

It would seem that logically they are designed to run best with all the necessary components.

 

it is driving halfway , you want it to run full decent. put exhaust on first

 

Tomorrow, you said we was going on Wednesday.

Sent from my Pixel using The H.A.M.B. mobile app

 

Okay everyone. Sounds like I should have exhaust on first before I go any further. I hope this is all it is...

Sent from my Pixel using The H.A.M.B. mobile app

 

It may or may not be but you will be one step closer to driving it down the road with a big smile!

 

That's what I figure also.


Sent from my Pixel using The H.A.M.B. mobile app

 

Let them pipes crackle all the way to the muffler shop

 

Have we covered valve adjustment yet ? Do it as a quick check ... I wouldn't bother getting it hot, just pull the plugs back out, & spin it over by hand. Needs .006 on intake valves (the ones that stick straight up), and .016 on exh. for test purposes.

 

Naw, time for him to start building his own set of curved feeler gauges

 

Sounds like ignition to me, I would check the underside of Dizzy Cap and look for Carbon Tracks or Cross firing carbon marks between 2 wires. Make sure the Rotor button Lead is not so wide that it's catching to Firing Off 2 wires. Pull Plugs out and with Dizzy Cap removed grab the Crank pulley and turn back and Forth and see how much Delay is between Pulley turning and Rotor moving. If there is a lot of movement without rotor movement there some wear in the Timing set.

 

I'm not very smart on this particular dual carb set-up (done lots of others with older style carbs and intakes)......and I'm surely not familiar with this new style carbs......but, the kinds of symptoms you are mentioning could be throttle butterflies not closing properly.......carb butterflies not properly synched (as someone has already mentioned).......or fuel entering the venturi area from some carb source when vacuum rises abruptly with closing butterflies.

 

I haven't gotten that far because the car ran great before I did the upgrades. Other than the original carburetor went to crap.

Sent from my Pixel using The H.A.M.B. mobile app