Thread: Spitting Mustang 429

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I purchased a 1971 Mustang Fastback about a month ago, which runs pretty good and has pretty good tires.

I was told the engine wasn't original and was a 351, but upon further research, it’s a 429, a 69 with C9VE-A heads.

Here are a few pictures.

http://pg.photos.yahoo.com/ph/bigen1...Ol_KFBnC77RJLT

I've got a little bit of work done on.

I’ve changed the distributor cap, rotor, spark plugs, plug wires, thermostat, flushed the radiator, and changed all of the fluids.

Doesn’t sound like much but when you consider we have a 3 month old baby boy in the house, it was hard to get that little bit of work done!

I’m planning on getting a new coil this week and that should about do it in the engine compartment, for now.

However this weekend I took my 15 year old son out for a drive. The car still starts beautifully, idles nice and sounds really good.

While we were out driving it, when I really hit the gas petal hard, the car hesitated, spitted and sputtered. I would let off the gas and it went back to running fine. I tried slowly depressing the gas petal and it would rev up and do fine. But every time I hit the gas petal hard it would spit and sputter. I tried spraying out the carburetor with carburetor cleaner, but it didn’t seem to help.

I’m guessing either the carburetor needs to be rebuilt or some how the timing is off?

Here are some thoughts: Carb needs cleaned/rebuilt. Spraying carb cleaner only hits the throat, need to dismantle and soak and rebuild.

Vacuum leak maybe, or perhaps your vacuum advance is not working right.


Some of the more mechanical minded guys on here may have better info, but I would look at these first.


Don

I've been thinking about doing away with the points, and maybe going with a Pertronix IGNITOR II, but would I be better off in the long run to switch to a good HEI distribuitor?

Take the air cleaner off and look down the carb and pump the gas pedal. Is the accelerator pump squirting?

First things first. Change the fuel filter.

Update:

I took my car to a friend of mine who builds hot rods. He suggested that we change out the power valve in the Holley Carburetor, which we did.

I checked and the accelerator pump is squirting. There is no play in the distributor and the vacuum advance appears to be working properly.

We then changed out fuel filter, points for pertronix igniter, and a flame thrower coil, got out the timing light and adjusted the timing. We adjusted the timing from 0 advance to 10deg advance, did have something strange happen there. The plug wire to the #1 cylinder would only fire when pulled out of the distributor. I could hold it just above the distributor and it would fire like crazy, but when plugged in it wouldn’t fire the timing light? Regardless the car is still backfiring through the carburetor. But I think I have a bigger problem now.

While we were adjusting the timing, I started hearing a loud squeaking or chirping that seems to come from approximately the #4 cylinder.

I’m guessing something is going wrong in that head??

When it rains it pours!!!

Depending on the RPM when the spitting starts, and the chirping noise, you could have a broken valve spring. Easy to see with the covers off.

yup i'd pull valve covers, check the springs and also turn it with the covers off with the ignition disabled so you can watch each valve open and close....if all that checks out.... then do a compression test to see if maybe you have burnt valves.... btw i'd stay away from using that glass inline fuel filter.... i've seen those things crack and cause some pretty nasty fires

Have you checked the plugs since you installed them? I have had problems in the past with a plug that went bad almost right out of the box, it ran fine on idle or slow excelaration but missed on hard accelaration.
If you have a set of torches at home, turn on JUST THE OXYGEN and as the car is idleing run the torch head with the leaking oxygen around the intake and carb gasket area. If the engine picks up RPM, then you have a leak in the gasket and its sucking in the oxygen wich causes the higher RPM.
In a quick check, usually, but not always, backfiring threw the carb is usually a electical problem and backfiring threw the exhaust is a carb problem, unless you have a intake valve not closing properly, then it will blow the compression back up the intake.
One place that alot of people forget about is the bushings for the throttle plate shafts. If they are really worn it will suck air in there also.
A month ago i had a hard time trying to keep my engine ideling between rounds, only to find out that one of the adjuster screws for the idle side was missing. What were the chances of that happening.

1. Pull the valve covers and inspect valve train.

2. Get another set of plugs- I like autolite, make sure that you gap them.

yup... dont use platinum plugs either.... most older style v8s actually will run better with just standard plugs over the platinums.... so they'd just be a waste of money