88 K5 Chevy 350 brought to TDC but back fires out Throttle Body?

[88Chevyk5]

Hey everyone,
Just picked myself up a fairly clean 88 Chevy K5 square body with a 350 TBI. Motor wouldn't run. I brought it to top dead center and the distributor was about 180* out. I brought it back within range to where it should start but now it back fires out of the throttle body while cranking and wont start. I have fuel coming out of the injectors when cranking. I have good spark when cranking and a new cap and rotor. I would look into sensors and such but the fact that it back fires out of the throttle body even though the distributor is within range where it should run makes me think it's something else. Any suggestions on what it may be?

I've been looking around to see if I can find someone with the same problem online but I couldn't find anything pertaining to my situation.

Thanks for any help!

 

[rich weyand]

No run + backfire out the throttle body is usually distributor stabbed 180 out.

Are you sure you have spark on the compression stroke?

 

[GTME94]

Correct, there are 2 TDC, one is TDC compression/firing the other is TDC exhaust. You have to know where the cam/valves are to know which is which.

 

[MadOgre]

Yes X3 if it wont fire there then spin it 180 and try again

 

[88Chevyk5]

What my father and I did was take the valve cover off and turn the motor over with a bar through the exhaust stroke and just past the intake stroke so the rocker arm on the intake valve was just loose (tdc?). Then I took the distributor out and pointed the rotor towards the number 1 spark plug. I then adjusted the cap so number one on the cap was about where the rotor was pointing. Does this sound right? I'll double check everything tonight and if you guys still think I should go 180* I will do that tonight as well. Sorry for the late reply! I've been doing a lot of training trying to get ready for USMC boot camp!

 

[MadOgre]

What my father and I did was take the valve cover off and turn the motor over with a bar through the exhaust stroke and just past the intake stroke so the rocker arm on the intake valve was just loose (tdc?). Then I took the distributor out and pointed the rotor towards the number 1 spark plug. I then adjusted the cap so number one on the cap was about where the rotor was pointing. Does this sound right? I'll double check everything tonight and if you guys still think I should go 180* I will do that tonight as well. Sorry for the late reply! I've been doing a lot of training trying to get ready for USMC boot camp!

How much did you have rotate the distributor to get the cap and rotor to line up?

 

[MadOgre]

If your sure your at TDC on the compression stroke and the rotor is pointing at the #1 plug then you should be good to go.

Just make sure your plug wires are routed properly in firing sequence/order

 

[88Chevyk5]

I probably had to rotate the distributor about 90 to 100* it wasn't exactly 180 away. I did the tdc by the valves because I've been reading the plates on the balancer can slip over time. I'll bring it to tdc one more time tonight to make sure I'm at tdc and I will go over the plugs to make sure they have the correct order again. I'll report back soon! Thanks guys!

 

[MadOgre]

the #1 plug boot on the cap should be front left at 10 oclock postion when viewd from the drivers seat

 

[88Chevyk5]

Okay rechecked wires on the cap and made sure we were at tdc. Rotor is pointing right at the number 1 spark plug wire as it should. Could the distributor be bad even though I'm getting spark?

 

[88Chevyk5]

I just realized when the intake valve rocker is loose at tdc the timing mark on the balancer is on the opposite side of the plate. It's not quite a full 180* but it's close so I'm going to try spinning the distributor completely around. I may have been looking at the wrong valve under the cover? I was judging by the second valve in from the front.

 

[highdesertrange]

with number 1 spark plug out, turn it over by hand watch the intake valve open then close. then stick something in the plug hole(wire, tie wrap, etc) and feel for the piston to come up to tdc. works every time. check mark on balancer at this point and don't drop your piston feeler into the cyl. now go ahead and position you distributor. highdesertranger

 

[rich weyand]

You need to make sure the #1 piston is TDC, AND use the valves to make sure you are at the right TDC. One easy way is that the keyway on the crankshaft is at 1:30 by the clock as viewed from the front of the engine when it is at TDC. That is, the keyway on chevy V8s lines up with the #1 piston throw. Since the firing positions on the pistons are 90 crankshaft degrees apart, they fire with the keyway at 1:30 (1 & 6), 4:30 (8 & 5), 7:30 (4 & 7), and 10:30 (3 & 2).

 

[88Chevyk5]

Okay reversed the distributor and now it is backfiring out the exhaust.

 

[rich weyand]

That's better. Sounds like too retarded. Distributor should move counterclockwise as viewed from the top. Not a lot; I think you're close.