302 very low vacuum won't run

[Tiko433]

I am helping a friend with a 302 , motorcraft 2 Bl. You have to give it gas to keep it running . Runs very ruff . Then will die . The vacuum will hardly build at all . I have timing close but since it won't idle I did the best I could do . Carb adjustment screws are set at base 1 1/2 out. Even when you give it gas and try to keep it running the vacuum is very low.
My plan is to do compression check to start
Any other things I could look at ?
The carb had some vac ports not connected , I capped them off . I'm not familiar with that carb are there any vac ports I should make sure are hooked up?
He does not have a PVC going into his valve cover .. Could this be a issue ?
He bought it as a project so it has not run right since he owned it

 

[SHX669]

Are there any vacuum ports on the baseplate or intake ? Any port that has vacuum should be plugged or " plumbed' into something.
Is this an automatic tranny - if so is there a vacuum leak in that line ?
Have you checked to see if the timing chain has a lot of slack/slop in it ?
Oh - and it has to be asked - you're using the front passenger side cylinder as #1 ? when setting the timing ?

 

[Tiko433]

I will check all the ports and trans vac line ..yep I'm on 1# and I checked the wires also . I thought dizzy may have not been dropped in the wrong spot but it lined up with 1# . Is there any way to check if the chain has jumped ?

 

[blubuckaroo]

When you've eliminated the other sources of vacuum leak, you'll need to pull the intake manifold to inspect the intake gaskets. They've been known to cause vacuum leaks. A leak there usually contributes to oil consumption as well.
The FelPro 1250 intake gasket (and it's knockoffs) is usually the common denominator. This failure is more common with aluminum intake manifolds though.

 

[broncogt]

......And the carb has to be bolted on flat and even or it will leak. You may want to pull it and check the gaskets....

 

[SHX669]

Did you check the timing with a timing light - and what is it set at? If you turned the crankshaft to TDC then you removed the distributor cap and turned the distributor untill the rotor pointed to #1 then the timing is more than likely retarded.
And yes the timing chain might have jumped .

 

[Tiko433]

I set it with a light , vac hose to dizzy plugged . But with it not wanting to idle it was hard

 

[68stang73]

Bring it up to 3000 rpm and set timing at let's say 32-34 degrees. Then at idle it should be darn close. Then adjust idle screw until it stays running. Then spray carb cleaner around intake and carb and listen for fluctuation in the idle. But you could also have a stretched timing chain or it wasn't set on Tdc and dot to dot when built. Or it jumped a tooth or two.

 

[maverickconner]

Damn Buckaroo strikes again, look at the rear of the intake manifold use a rolled up toilet paper roll or paper towel roll and light it on fire (please no open flames near the carb, use it like a punk for fireworks) just so it smokes, start the motor and see if the smoke goes in at the back of the intake. Yes redneck but have done it for 30 years and I'm cheap.

Sounds like a intake leak

 

[Tiko433]

Thanks for chiming in Maverick . I have not had a chance to look at in again. That is a clever way to see if it's sucking air . I will keep you posted

 

[DirtDonk]

Works best if there is no fan spinning though!
I use carb cleaner or brake cleaner myself, but the smoke is safer on new paint. Older baked on paint is less susceptible to the chemicals, but if in doubt the brake cleaner evaporates too quickly to mess up paint unless you put it on heavy and let it sit.

Is there any way to check if the chain has jumped ?

To check for simple stretch, you use the timing marks and pointer.
Turn the crank one direction to line up marks, then while watching the distributor rotor, go back the other way and count the degrees of rotation before the rotor starts to turn the other way.
A new chain should be less than 2 degrees of deflection. One in good shape is 3-5 degrees. A worn one is 6 or above. If you have 10 degrees it's time to change it. Like NOW!;D

Not sure a good way to see if it's jumped a tooth other than to open it up and look. When it does this it only changes the cam timing permanently. The ignition timing can still be adjusted with the distributor.

Personally, I would advance the timing by hand/ear to see if it helps it run better. Then once it's running do your vacuum leak tests. Then drive it and see how it responds to advancing the timing even more.

Does your friend know any history of the engine? Was it new/rebuilt before he got it? Was it original or had at least some parts replaced?
Replacing the crank dampers is a tricky business with our Fords, as the timing marks and pointers were all over the place and can suffer from mis-matched parts. This leaves you guessing because a timing light does no good if the marks don't match the pointer.

Was the cam changed? Valvetrain converted to adjustable?
Flat tappet cams have to be broken in immediately upon first start-up, so if that was not done by the PO or you guys, it could be messing up the cam lobes. After that nothing normal is going to happen.
If the valvetrain is adjustable, they may have set the rockers too tight or installed the wrong pushrods and they're holding the valves open. That would effect running greatly, and give you low to now vacuum signal.

If it's not a Bronco engine originally, it's hard to say what it's supposed to have.

Good luck.

Paul