Since, I post one on the same thing with the engine not running after a overhaul I thought I do a new post. Several weeks ago I replace the 250 in my 75 mav with a another 250 that I rebuilt. It has a reman head because the orginal one was crack. I assembed the engine and drop it in and connected everything. Now the big problem. Engine wouldn't start. After setting the timing on the distrubtor and pouring gas down the carb it runs at high rpms no idle. I double checked the timing and rebuilt the carb, swapped new fuel pump with the fuel pump from the old engine and still nothing. Today, I took the timing chain cover off and check the timing marks. They there perfectly aligned than I redid the distrubtor and set it up on number one. It does not act like a timing issue its more of a gas starvation to where it runs out of gas. It only runs for a short time than stops running. I do have gas in the tank. I check fuel lines there good. I cann't see it being a wiring problem because the engine runs and I have spark. The next thing to check would be the reman head. Some how there bad, I don't know. I'm going back to the machine shop and talk with them. OK, now the confusing part. The reman head is differant. On a 250 the vaccum tie is just under the carb. On this one there is a hole on top next to where it says the firing order on the intake manfold. Just under the carb there is 2 threaded holes and a plug in between. I had to plug both holes. I don't know what car it came from or if it mattered. Would a head cause gas starvation? At this point I'm totally lost on the problem. I have been working on this for weeks. If anybody has any thoughts please let me know. The only thing left is to pull the engine and tear it down to find the problem. That part I don't what to do. Sorry if its to long.
I agree with Dennis. checl the compression on all cylinders to make sure they're correct. if nothing else, make sure the carb was rebuilt correctly (not saying that u dont know what ur doing) but just to be on the safe side...
Well some good news. Wednesday I took the heads and one new push rod to the machine shop who did my block and heads. I called the next day and he said the head is fine. He mention to bring an old push rod to messasure them. The next day I did and guess what. The new push rod is .0030 longer, so he wanted me to use the old ones and see if the engine will run. I spent all day putting it back together since I pulled the engine again. Tomorrow, I'll drop the engine in and see if it will run. I think it will.
Somehow I can't see where 3 thousandths is going to make that much of a difference. But good luck. Hope I'm wrong.
Better news today. I got the engine back in the car and tried to started nothing. So I sprayed around the carb base and guess what it runs. The gasket on the intake manfold and egrplate was leaking. To late to buy one so I made (old school) and used a gasket sealer. That stopped the leak. Finished the timing and set the idle. I don't know if that was the orginal problem or don't, at this point it doesn't matter. I did use the old push rods from the other engine and the values are noisy so I might try putting back the new ones and see if that helps. The new ones are 30 thousandths longer. I just might get this thing back on the road again.
Well another update. The old push rods did not help was doing the samething. Today, PaulS came and spent all day help me figure this out. I had some vaccum hose hook up wrong, fixed another vaccum leak, and found out I had a bad EGR. He brought over his vaccum gauge and I still had almost no vaccum. We double check everything again. The good news the engine does idle put I'm hearing the values. With the new push rods and the old ones. Paul did mention that the values could be to tight and not opening or closeing good. I'm back to square one. I'm going to talk to the machine again about the head maybe it is bad.
It was great you could have Paul come over in person. I only get email help from him. I would love to have the "live" show.
Well, we sorted out the vacuum lines and got all the connections right (or as right as I know how), replaced the bad EGR valve, checked the timing (6 BTDC and Mike assures me the dampener has not slipped), and put my vacuum gauge on the engine. (3 - 6" Hg). When it does idle it seems to be bucking like it is cross firing - checked and rechecked the firing order (153624) checked the float setting according to the rebuild sheet (3/8" with the float "floating" on its spring), the carb finally responded to mixture adjustments, checked for other vacuum leaks (when I pulled a vacuum hose engine rpm increases and smooths somewhat) but the bucking continues. As I left Mike was changing to the shorter pushrods but I hear that it didn't help. This thing has got me fooled. The difference in the pushrods is .030" (the old ones are shorter), it is getting fuel, good spark (DS II), and doesn't seem to have any vacuum leaks. The increase in RPM with the hose pulled makes me think that the float is too high and it is getting too much fuel but according to the specs the float is set correctly for the engine. It actually runs like the valves are too tight but has 150 +/- 4psi compression. The EGR valve diaphram moves with vacuum. This engine (1975) is equipped with the Thermactor AIR pump. Anybody have any ideas?
Oh, by the way Mike - I HURT! My back is killing me - the drive (120+ miles round trip) and me working the little bit that I did was way more than I should have done. I am not blaming you - I did it but I am going to take tomorrow and do nothing but rest so I quit hurting. I wish I could have helped nore man - sorry we didn't get it running. Paul
Sorry, your hurting I didn't think I worked you that hard LOL. Go ahead and take the rest of the day off. Drink some cold ones.
Do you have the original damper on the crank. They are known to slip. If your timing to the marks on a bad one, you will be off.
Yes, I'm using the orginal one. The timing chain is set right. When the car was running I was also moving the distrubtor alot to try to make it run better that didn't help. If the damper slip you could compensate by move the distrubtor.
