Continuing with Wilson's problematic 72 Skylark

Gents,

I recently purchased a fellow board member's 72 Skylark. Haven't had a lot of time to do anything to it yet. He had a lot of issues with it that now fall on my plate. Below is the link to what all he did before I took delivery.

http://www.v8buick.com/showthread.p...g-rough-idle&p=2207223&highlight=#post2207223

So, when the car was delivered, you could tell that the motor wasn't running right. Very choppy at idle. Once you hit the gas, it cleared up.

My buddy stopped down and started messing with carb a little bit All he did was turn needle screw out to add a little fuel. Car seemed to respond to that. Shut it off and left it go for the day.

I came in the next day and fired it up. It puffed through carb and stalled. Once I got it running, it barely ran. Fuel enriched smoke bellowed out and fille my garage. Raising the RPMs didn't help at all; almost like plugs are filed out.

No way a slight twist of a needle screw on a carb can change that motor that much.

From what original owner said, he tried everything all of you fine folks told him to.

Any additional help or information would be great!

Thanks!

Chris

 

Run them both all the way in then back them out 2 full turns, then turn idle speed screw in 2 more turns from where its at now , that if timing is correct and everything is working order will crank it with a high idle , then adjust mixture screws for highest vac and rpm then drop idle speed to desired idle rpm

 

I would try not to put fresh plugs in unless you have to to get it to crank, put fresh plugs in after its adjusted, if need be pull plugs in there now spin a few revolution to push any fuel out, then clean them plugs with brake clean and a little sandpaper

 

Ok. I will give that a shot. This will work on a street demon carb?

Been so long since I messed with a carb. Went FI 20 years ago and never looked back.

 

If its a demon check the air bleeds , needle and seats, and 1turn out on each mixture screw, best approach is to reset carb to factory settings and make sure its clean first and foremost, Demons are touchy carbs, but I like them

 

Speed demon should have 4corner idle and if its mechanical secondary it will have a screw to open the secondary side a little to aid idle adjustment

 

If it is 4 corner idle adjust circuit you should have primary and secondary throttle plates adjusted the same and mixtures should all be very close . Check float level idling after you set these up.

 

Will do gentlemen. Will report back progress. Think it could be anything else? Last owner had a lot of issues. He thought it was misfire. No popping under load when I 1st got it. Did run rough though.

 

There's all kinds of possibilities, but fuel,timing and spark related issues are the culprit 90% of the time, a compression test and rocker arm/spring inspection may be in order also

 

Start from scratch, pull all 8 plugs, test compression on all cylinders and post results, pull valve covers and inspect valve train, watch all 16 rockers go up down uniformaly or not, look for broken valve springs, ohms test all 8 plug wires, and report, its time to get the basics setting on go or find out they or no good, BTW, your correct twisting the carb screw no way is causing what you are seeing,

 

BTW, google ohms testing plug wires, if your not familiar with it, you may have to buy a volt ohm meter, report results

 

Check for stuck float. A few careful taps on the float bowl at the needle/seat location may help. Otherwise pull the bowls and check the to make sure the seats are screwed tight, needles and floats are operating and adjusted properly. Just a few things to check off your list.

Larry

 

Keep advice coming guys. All good things!

The one thing I didn't understand was that this motor has a TA Performance 212 cam with adjustable push rods. Not sure why u would need adjustable push rods...

 

Adjustable push rods would be used where the head was decked to raise compression instead of ordering shorter push rods...

 

I don't know if the heads were decked or not. Should be able to loosen them and then set lifter preloaded. What is preload on these? .040"?

 

Definitely did resistance checks a time or two. I'm a Sparky by trade.

 

.020 to .060 is the window if recall correctly

 

Hoping to dig into this thing by the weekend. Wanna get out and drive it.

 

Here is the link with everything that the previous owner did:

http://www.v8buick.com/showthread.p...g-rough-idle&p=2207223&highlight=#post2207223

 

Start with a basic compression test to verify even compression. If they are not even, verify
the adjustable pushrods are set correctly, one or two that are too long will reduce compression.
If you get different readings after adjusting the push rods you are on the right track.
Then verify your timing is close, and verify top dead center. Check
for vacuum leaks around the carb and fittings on a cool engine with carb cleaner or wd-40.
If you have a massive vacuum leak you will never be able to get it to run right. I would
forget everything that the previous owner tried. Next would be to verify the cam was
put and properly and not degreed too much. If that was done wrong you will never
be able to tune it properly. Next would be to try and borrow a verified carb from
a buddy that is know to run perfectly. Good luck!!!