new carb and intake runs like crap need some advice.

[chucks1967]

Ok so last night i got my stuff but back together.... new intake (performer),old carb(holley 450 model 4360). it fired right up, but that’s the best part of the story. my friend and I took it for a spin, at first I just wanted to get it up to temp so I was easy into the carb and it ran ok not what I was expecting though. After it warmed up good, I opened up the carb. It fell on its face, sputtered, and then came alive and accelerated really good. did it again and same thing. Like a dead spot in the carb. went to good ol' AutoZone to get a couple fittings and came back out it wouldn’t start very easy, took a couple tries and adjusting the idle air screws to get it running. After that we went to wal-mart for some stuff for the wives. on the way there I really didn't get into the carb because it felt like it was surging. The more gas I would give it the more it would sputter and surge and it had a hard time ramping up the rpm like it was being held back. When we went to leave the wal-mart, I gave it WOT at the red light and it just died. I couldn’t get it started again. Had to push it back up the hill and go get some starting fluid to get it started. After it started it barely ran at all. made it home shut it off, started it back up checked the timing, checked the jets, the air idle screws, al vacuum good, but now I’m stuck. I don’t know what to do now. Please help.

 

[woodsnake]

I know you said everything all your vacuum lines are good, but it sounds like a vacuum problem. Most carb issues are either ignition or vacuum related.
When you checked everything out, was it still night time? Or do you have good daylight now?
Spluttering, surging, all sounds like vacuum advance or a loose ignition wire somewhere.
Did you change anything else besides the intake manifold? Did you put a vacuum gauge on it to get it dialed in?

 

[chucks1967]

I was thinking vacume advance as well but that is starting to fall out of my field of knowledge. how to you adjust that or verify that it is working? I will have day light when I get home this evening and am trying to get all the info I can before then. I dont have a timing gauge on the block it is on a list of things to buy for the car, but I do have a timeing light though that will do me no good. I marked the distribuiter on 2 spots when I removed it from the block. when I put it back everything was exactly the way it was when I remove it. you mentiond a vacuume gauge to dial every thing in, what and how is that done. remember im a little more than a novis at this, and am learning a lot as I go.

 

[Fast63]

are you saying that you had a running car, and just took off the intake and carb, installed a brand new intake, and reinstalled your working carb? Simply marking the distributor in two places and removing it does not cut it. You also have to check the position of the shaft on the inside that the distributor gear and rotor are on. If that thing turns, you can still install the distributor, but your timing will be off, so I would check out your timing first.

 

[chucks1967]

I replaced a 2 bbl intake and carb with a 4bbl intake and 4bbl carb. the distributor was marked on the outside on the shaft as well as marked on the inside. it came out and went in exactly exactly as it came out.

 

[truck90278]

Your sentence states "new manifold, old carb" . How old is the carb? do you know for sure the carb was good before you installed it? when the accelerator pump goes south you get similar situation.

 

[chucks1967]

the carb is old as in the early 70 era. but I rebuilt it with a holley refresh kit cleaned it all out, replaced accelerator pump. it was spotless when I put it back together.

 

[D.Hearne]

It may be spotless on the outside, but did you blow out all the tiny passages in the throttle body, and the main metering block? After I soak these parts for a couple days in carb cleaner, I first blow em out with spray carb cleaner, using the capliary tube on the nozzle (wear eye protection), then blow em all out with compressed air. One little piece of trash can do just what you've described. Also, it's important to verify the gasket behind the powervalve is seated properly. If it is a vacuum leak, that's easy to spot, use the spray carb cleaner and spray all around the intake and carb while the motor's idling. If there's a leak, you'll hear it when the carb cleaner is sucked in.

 

[A67StangMaster]

Sounds like the timing is a little off.

turn the engine on and let it warm up.
unscrew the bolt that holds the Disy.
turn your disy right or left it will smothin out. but to make it accuate you must use a timing light.

good luck

 

[chucks1967]

ok, I put a 650 holley double pumper on this afternoon and it fixed the issue. seems the car was way lean with the carb I was trying to run. but the double pumper fixed it. the timeing was and is still a little off, but i advanced it enough to get it to Idle right.... but still stumbles a little on accelleration from a dead stop. but run it up into the rpm arround 1500 and punch it.... it starts to walk sideways!!! no joke. Im gong to tune it in next week and will get some video.... its a wicked little car.

 

[woodsnake]

Before you get ready to do the final tune up, get a good timing light and a vacuum gauge. Any more, they aren't expensive tools, and really make all the difference with the results of your work.
Also, how old is your timing gear set? They get sloppy with time, and that will have a very noticable, and hard to nail down effect on your engine performance.
How do you tell if you need a new timing gear set? Well, when you point your timing light at the balancer, and have identified your mark, snap the throttle.
If the timing mark on the balalncer 'slides' up and down before settling down, this is the indication of excessive play.
Is it a fun job? no, not really.
However, it's better to replace the timing gear, than to replace all the valves and pushrods when the gear set slips, and parts start making contact.
As far as the vacuum gauge goes, while making your adjustments to dial in the carb, your objective is the greatest amount of engine vacuum. Do one 'side' of the carb at a time, and then check your timing.
Repeat until you get consistant mid teens (in inches of vacum).
Unless you have a particularly lumpy cam, then just shoot for the most vacuum.

 

[D.Hearne]

An easier, more acurate way to check chain stretch, is by turning the crank with a breaker bar and watching the distributor rotor rotation (with the cap off) I don't know what the spec's are for stretch, but I'd say more than about ten degrees crank rotation before the rotor moves would be more slack than you'd want.

 

[dbfarr]

I'd had adverse running effects when the slack in my chain was 5-6 degrees.