Finally

Sorry it's been a while but I am working in a different job now and I just finally got a replacement 250 for the Comet. It ended up that the block was cracked not the head like I first hoped. Anyway I have the new 250 dropped but now I can't get the thing to time right. I went top dead center dropped the dist. In on number one but it is idling really rough. Any advice for me??
Thanks,
Tim

 

Used block

Need some advice.... the used block (250) is from a 1977 and I transferred everything over to the new block. Now she won't run right!! I timed it, rechecked / cleaned spark plugs, I went over everything again. Vacuum is killing me!!! I have all lines on but the spark line on carb to dist. when I hook it up it stalls out quickly. While running that line has alot of sucktion on it. Even if I put my finger in front of it the engine stalls. What the hell?? What if I remove the EGR...what do I keep and what gets removed?? What gets plugged?? Has anyone done this and if so you can even email me to help me out.
By the way when it's full throttle it's shuttering and backfires. Sometimes the carb spits back and stalls out too. Is it possible the timing gear needs to be re-timed?? It seems to be getting fuel fine but is it possible the fuel pump is messed up, it is original.

Tim

 

your hooking the dist vac. advance line to the wrong port. it needs to goto a ported vac. port on the carb. this port wont have a vac. siganal at idle. it will once the throttle starts to open.
now the idle should increase when you do hook it up to the manifold vac port. you may have a carb issue.
have you set the timing with a timing light?

 

vacuum

I have tried hooking up the vacuum lines every way possible and it still runs like crap. When I get it started it is very shaky and almost stalls out at first. Then it sounds alright and runs ok, but when you hit the throttle it acts like it can't keep up with the throttle position and full throttle doesn't work at all (choking). Sometimes it will spit fuel back through the carb upon stalling out. I have two carbs and I am going to rebuild the newer of the two. They are both 1 barrel, but the newer is from the 77 motor and the other is the 74 from the original car.
As far as the vacuum I did try to use the diagrams someone posted previously but I am missing the vacuum modulator that hangs next to the coil.Three lines are supposed to come and go to this. Is this nessesary?? If so where can I get one??

Thanks for the help.

 

oh yeah

I forgot to tell you...yes I timed it with the timing light and it's timed right. If I hook that dist. vacuum line to the carb it kills the motor instantly. I might need that DIST MOD VALVEto complete the vacuum.

 

Might pull the valve cover and check that the valves are working, and maby run a compression check.

 

Timing is still off. How did you confirm you set the distributor in at cylinder 1 top dead center/compresison stroke? Id start the procedure over from scratch.

Also get the vacuum for the dist in the right port before setting the timing. Then cap off that port to set your initial timiing. when you plug the hose back to the dist. you should notice a difference in timing or engine speed at idle, sometimes you get a slight difference if your idle is high.

 

you can cap off all the vacuum ports on the carb and intake manifold. the motor will run just fine if every thing else is correct.
if it still runs bad then vacuum is not your problem.
i would do a compression test to make sure you dont have a valve adjustment problem.
also is the cam timing correct. ive never looked at how the I6 cam is set up but i think its a gear set.
gear set, belt or chain it still is easy to get the cam in wrong and you will never get it to run right if thats the case.

 

You thinked right. Same as a small block but skewed to the right.

 

Plugged all ports, retimed, and it runs a little better than before. When I drive it I still can't full throttle it and still shutters some. Obviously it wouldn't shift due to vacuum and throttle can only go 1/2 to 3/4 down or it kills itself

 

WoooHooo

Thanks for all the input and sorry it's been a while. I finally got time take her apart and check timing. Timing was off about 180 degrees. She runs like a beast now!!!
My final fixes are reverse lights inop, 4 way flashers inop, and heater / a/c not working properly. The heater / a/c only comes out the top and no other controls are working. I haven't refilled A/C yet.
Thanks again for all the input.

Tim

 

If the heater/AC only comes out the top....then you have a vacuum leak somewhere. More than likely it is either the switch itself or the vacuum canister under the hood.

 

pull your valve cover off and check to see if your pushrods are in place ,you may have a stuck lifter