-   Classic Mustangs (Tech) (
-   -   68 302 4 barrel after market carb (

danhiman 03-08-2012 08:31 PM

68 302 4 barrel after market carb
My Dad had a heart attack and I am now trying to help get his Mustang in order. Some time ago he had someone, he can't remember, change his carb. When I got it, it Idled super hi in park/neutral, and hi in drive, clunking bad when shifted. His tranny leaks bad, seems to be tore up. The car on the road is a beast, I connected the vacuum lines, tuned down the carb as much as possible, but I can't control the idle to a reasonable idle. I have a feeling the carb is to big for the car, help. I use to work on carbuatored cars in HS, so Its be awhile.

oxfordbp 03-08-2012 08:39 PM

What size carb is it? If you can get a part number we can find out. Also check the timing and look for vacuum leaks.

Sorry to hear about your Dad!

The_Dude 03-08-2012 09:13 PM

Looks like it's this carburetor, which should be fine if properly tuned.

oxfordbp 03-08-2012 09:22 PM

If it is that 570 cfm then its right on for your 302. However being a holley cant you change the internals to get more cfm? If someone has, how can you tell?

danhiman 03-08-2012 09:23 PM

I tried to post pics, heres a link

The_Dude 03-08-2012 09:27 PM

I did see your pictures and looked up the list number. It's a 570 which should be perfect for a 302.

danhiman 03-08-2012 09:38 PM

I read some where that 1.8 per litre only applies to modified engines. My brother did say that he remembers Dad telling him you can't time it to factory for some reason. He had a stoke as well a Quad by-pass. There really isn't alot of vacuum lines, I did check them, found no leaks, but the timing? I see the 80570 part # on the front. The tranny does not have OD. Is the Trans Linkage hardware required?

danhiman 03-08-2012 09:40 PM

I have to admit, it hauls butt, Just the idle and going into gear is not so good. I'm thinking it will need a new tranny and if so maybe an OD would be nice.

oxfordbp 03-08-2012 09:54 PM

Why wont it time? there may be another hidden issue there.

I was wrong about vacuum. If it was a leak it wouldnt idle very well and would pop and sputter.

I still think carb adjustment or timing.

danhiman 03-08-2012 09:57 PM

I'll have to check the timing this weekend.

oxfordbp 03-08-2012 10:02 PM

Also, If it is idling real high, when you put it in gear it will defiantly clunk. Hopefully that is solved when you fix the idle. Make sure there is oil in the tranny, low levels will cause clunking and much worse issues.

my77stang 03-08-2012 10:19 PM

I had a 570 once, the 600 holley was SOOOOOO much better. That being said you should be able to get 'er dialed in with what you've got. +1 for clunking while going into gear because it's idling high. Even if the trans is leaky the front and rear seals and new pan gasket are super cheap so if it shifts ok once you idle it down i wouldn't worry about shelling out for a replacement (especially a piece of **** AOD)

danhiman 03-08-2012 10:20 PM

Sure will, thanks for the input. I will post when I make progress. I just bought a timing gun. I've been working on 944s so I didn't need one.

groho 03-09-2012 11:25 AM

Your high idle and clunk into gear is the same symptoms seen when the vacuum line is bad or split at the tail end of the tranny, into the vacuum modulator. That line runs between the vacuum modulator, passenger side of the tranny's tail, up to the rear of the intake manifold. It's a quick check, and simple to correct. I suggest you take a glance before get too deep into your carb.

danhiman 03-09-2012 12:39 PM

I am planning on lifting the car to inspect the tranny for cracks as well. Thanks for the info.

danhiman 05-01-2012 06:36 PM

I checked the vacuum line and it seems fine. The belly tray on the tranny was loose so i gently tightened the bolts. When I disconnected the vacuum line next to the trann vacuum line going into the intake manifold, the idle in park did go down slightly. The idle while in gear is good, its high while in park.

danhiman 05-01-2012 06:38 PM

Am I suppose to have the automatic transmission bracket for this carb?

gjz30075 05-01-2012 07:25 PM

A vacuum leak doesn't necessarily have to come from a vacuum line. The carb may not be sitting tight down against the manifold (or spacer). If the carb is snugged down fairly tight, it may need a gasket between the carb and manifold.

djklein21 05-02-2012 10:43 AM

spray some carb cleaner around all the connections to check for a vacuum leak. If the idle changes when u spray it, u know u found the leak.

68dustin 05-02-2012 12:04 PM

Do you know where the idle adjustment is? are you turning the correct one? Did someone open the secondaries too far at that adjusment? There are many adjusments that could have been made. i would first spary carb fluid around the base to check there for vac leaks.

if this screw has been turned too far it will make the idle high as well

All times are GMT -5. The time now is 01:40 AM.