SD_LX_5.0

So i just started up my stang after assembling it from and intake and cylinder head porting job. i got the heads machined, a five angle valve job done, 1.7 comp cams rollers, and a comp mag timing chain. I started it and it was running a little rough but that was what i expected because a vacume line going from the upper intake to the fire wall wasnt connected (it broke), i think some of you might know which one im talking about. anyways when i pluged the hole with my finger the idle smothed out, i wanted to do a walk around of the car so i grabed a near by rag and used it to temp plug the hole walked around the car and made it to the pasenger side; i tried to give the motor a little blip of throttle and it started to bog down so i let off and then continued to even more slowly roll on a small amount of throttle and suddenly the engine seemed to back fire in reverse(meaning out through the throttle body) and a spark/flame shot out as well and the engine there after died. I didnt know what happened but when i scardly tried to restart it with a bypass switch it wouldnt. What happened? can anyone help please? im desperate...

Black Snake

Whats your timing at? Fuel pressure? Sounds like a timing issue or crossed plug wires? Valves adjusted right?

SD_LX_5.0

I dont know what my fuel pressure is at, but i can only assume its what it was at before i pulled the engine apart. same for the timing its set back to the same that it was at before i pulled the car apart. And i had the valve assembly assembled for me at the shop that did the valve job and machining work.
Was it fuel that could have come out or something else?

StangStang

sounds alot like a timing issue, but if thats squared away i would recheck that you install the new 1.7rr correctly. I had a lot of problems installing mine for the first time. Did you preload the lifter correctly? You need to set cam to base lobe and then set the rr to zero lash and make a mark on the pushrod, then tighten to specs and make another mark, than you need to measure the distance between the marks, I dont remember what the distance should be but call up crane cam then will tell you exactly what they told me. If your engine was apart for a long time your lifters probably leaked down, if i remember right you have to achieve 19ftlbs within 1 full rotation (not sure) if you go past that than you have to much preload(need to shim), if you reach 19ftlbs within 1/4 turn you dont have enough(longer pushrods required). Kind of a pain in the a$$ but you may want to go back in and check them out, Marking the pushrod is a betterway of doing it. I did each valve and Some got shimmed and others didnt. If you got a valve job than your valve is probably sitting a bit higher which would require shimming of the roller rockers. Just a guess good luck.
P.S check your compression.

SD_LX_5.0

Ya i almost positive i installed the rockers right i had to shim a few because of the valve job and machining but it was pretty easy to do with out marking the pushrods and now that you mention that i really dont know... i just started it like 5 min ago and it started right you which is better to say than last night after that weird back fire incedent(spelling). Im gonna go fix that vac problem and make sure my headers are tightened all the way because im still getting ticking even though i primed the oil system by turning the pump with a drill... i dont know will the stock valve cover clear te 1.7 rollers with the baffle removed on the passenger's side one? and then run the timming light i guess to check my timing..
does anyone know what that backfire thing was tho...?

Tims 88GT

no no no, you said the vaccum line that goes from the intake to the fire wall is broken. does it go to a lil black box? what year is the car? Because if it goes to the lil black box that is the MAP sensor if that is not hooked up on a sd car you will have problems like you are having. fix that then move on. MAP= Absolote Manifold Pressure SPELLING?