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Erik_K
Erik_K
3/18/21 11:33 p.m.

I recently rebuilt my Chevy 350 engine putting new headgasketa and replacing headbolts with head studs. After putting it back together it will not start unless I have wide open throttle and when it does start it will not stay running on it's own. It also seems to be misfiring slightly. I have all of the valves adjust to a preset of a half turn from zero lash. My distributor is set in correct and is not 180 off. And I recently just resealed my entire intake so there should be no vacume leaks from the intake manifold. One thing i did change is deleting the fuel pump and putting in an electric mini fuel pump. I'm not really sure why my engine won't run correctly maybe I missed something small but any help would be much appreciated!

Mr_Asa
Mr_Asa UltraDork
3/18/21 11:55 p.m.

Cam timing one tooth off?  How sure are you that you have that correct?

ShawnG
ShawnG UltimaDork
3/19/21 12:07 a.m.

How did you find "zero lash"?

It's very easy to collapse the lifter completely and think it's zero lash.

Usually I spin the pushrod with my fingers and feel when it starts to tighten up a little, then add the half turn.

Erik_K
Erik_K New Reader
3/19/21 12:15 a.m.

In reply to ShawnG :

I did the up and down movement and spinning the rods, turning the engine 90 degrees repeating for multiple rotations so I believe that is not the problem

Erik_K
Erik_K New Reader
3/19/21 12:28 a.m.

In reply to Mr_Asa :

I'm not sure how would that get messed up?

 

Mr_Asa
Mr_Asa UltraDork
3/19/21 12:34 a.m.

In reply to Erik_K :

I'm assuming that when you say you rebuilt the engine that you tore it completely down, but looking at your post again it appears you might've just stuck to the top end?

If you didn't remove the cam, disregard what I said.

SkinnyG (Forum Supporter)
SkinnyG (Forum Supporter) UberDork
3/19/21 12:40 a.m.

Distributor out a tooth and disastrously out of time?

Fuel pressure too high, over-powering the needle-and-seat, and flooding the engine out? (it shouldn't fire at WOT unless it's flooded)

Erik_K
Erik_K New Reader
3/19/21 12:49 a.m.

In reply to SkinnyG (Forum Supporter) :

It is very possible I might have to high of fuel pressure. I removed the old mechanical one and installed a Edelbrock electric fuel pump.

Mr_Asa
Mr_Asa UltraDork
3/19/21 12:51 a.m.
Erik_K said:

In reply to SkinnyG (Forum Supporter) :

It is very possible I might have to high of fuel pressure. I removed the old mechanical one and installed a Edelbrock electric fuel pump.

Do you have, or can you look up, what the pressure is of that pump?

Apexcarver
Apexcarver UltimaDork
3/19/21 6:18 a.m.

Have provision for a vacuum gauge to be attached?   worth checking. 

Physically verify that your timing marks are correct. (rod down spark plug hole to find TDC). I know a few people sent on a wild goose chase from this. 

 

pres589 (djronnebaum)
pres589 (djronnebaum) UltimaDork
3/19/21 6:52 a.m.

Have you checked the plugs?  I would assume the carb is faulted, like a stuck needle & seat, and the engine is flooding unless you give it WOT.  Fuel pressure would be interesting since you changed the pump.

P3PPY
P3PPY Dork
3/19/21 7:13 a.m.

Not a helpful post but my first thought is that "I guess it's a race engine now"

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) GRM+ Memberand MegaDork
3/19/21 9:17 a.m.

Most of the bases are covered here.

1) I'm assuming you just did head gasket repair, so everything you took off went back on?  Carb? Intake? EGR?  If so, I suspect a vacuum leak somewhere, especially if it's a pre-87.  It's not that they're known for vacuum leaks, it's that many times poeple just don't get them torqued properly, they use cheap gaskets, or they use silicone on the intake ports which can very quickly cause failures.  If you re-used the carb's base gasket, it is also highly suspect.

2) Don't trust your balancer to give you an accurate timing.  Old balancers can slip on the rubber, so the outer ring with the timing marks could be incorrect.  Verify TDC by pulling the #1 plug and using a BBQ skewer, welding rod, or stiff wire in the hole.

3) I can almost guarantee your fuel pump is giving too much pressure.  Depending on the carb (likely Qjet if it's stock) they can be highly sensitive to fuel pressure.  A Qjet with a perfect needle, float, and seat can usually take 5psi max.

Since it sounds like the only change you made was the fuel pump, look there first.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) GRM+ Memberand MegaDork
3/19/21 9:19 a.m.

What was the surface prep?  How did you clean the block and deck surfaces before re-assembly?  And how bad was the old leak on the head gasket.  Possible you have head warping/damage?

Erik_K
Erik_K New Reader
3/19/21 9:22 a.m.

The fuel pump I have installed is running about 7 psi of fuel pressure Wich I believe may be a little high. I'm running a Holley four barrel double pumper so it is a pretty large carb. I will also later check if the engine is actually at top dead centre. 

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) GRM+ Memberand MegaDork
3/19/21 9:24 a.m.
SkinnyG (Forum Supporter) said:

Distributor out a tooth and disastrously out of time?

Fuel pressure too high, over-powering the needle-and-seat, and flooding the engine out? (it shouldn't fire at WOT unless it's flooded)

Only if it's really old.  Starting in 74 they were all HEI which doesn't matter if it's off by a tooth... or all the teeth.  HEI can be installed in any orientation and just pick which plug on the cap is closest to #1 to start your plugs.

.... which brings up a good thing to check.... making sure you didn't get the firing order off.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) GRM+ Memberand MegaDork
3/19/21 9:25 a.m.
Erik_K said:

The fuel pump I have installed is running about 7 psi of fuel pressure Wich I believe may be a little high. I'm running a Holley four barrel double pumper so it is a pretty large carb. I will also later check if the engine is actually at top dead centre. 

Is the carb the same as what you took off, or did you add the Holley as part of this project?

Erik_K
Erik_K New Reader
3/19/21 9:37 a.m.

In reply to Curtis73 (Forum Supporter) :

It is the carb that was already on it when I started

Erik_K
Erik_K New Reader
3/19/21 9:37 a.m.

In reply to Mr_Asa :

The pump puts off 7 psi

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) GRM+ Memberand MegaDork
3/19/21 10:18 a.m.

7 psi is on the edge for most Holley's depending on which bowls/float you have on it.

Is it possible to put the mechanical pump back on for a test?  Or would that involve a lot of un-doing plumbing that you did to add the electric pump?

Streetwiseguy
Streetwiseguy MegaDork
3/19/21 10:39 a.m.

It's probably flooding.  Did you turn the carb upside down? Can be bad news on an old dirty carb. Find a piece of rubber hose in the fuel system and pinch it off.  Start the engine.  Does it go from flooded to running well to running out of fuel?

Is there fuel dribbling out of the venturis at idle? Shouldn't be. Is there fuel coming out of the secondary at idle at all? Shouldn't be.  Is the secondary throttle plate closed properly?  Should be.

pres589 (djronnebaum)
pres589 (djronnebaum) UltimaDork
3/19/21 10:42 a.m.

I think when I had too much electric fuel pump on my Capri after I got rid of the mechanical pump I could see fuel dribble out of the discharge boosters when the pump was powered.  I think I had picked up a 7psi pump on the recommendation of the guy behind the counter at the parts store who was much more used to dealing with domestic V8's.  I replaced it with a ~3.5psi pump and the issue went away.  Fumbling with the needle and seat and floats didn't matter, it was just too much pressure, but that was with a smaller carb.  Still might be what's happening to your setup.  Perhaps could be fixed with an adjustable regulator but I have no direct experience with them.  And that's again only if the pressure is too great.

Erik_K
Erik_K New Reader
3/19/21 10:55 a.m.

The carburator was recently rebuilt and it is very clean on the inside so I'm not to worried about problems there. I have a fuel pressure regulator so when I get the time I will throw that on and see if turning down the psi will make a difference one thing I did notice was after running the vehicle for a little bit feeling the manifolds one cylinder was still cold, one was warm, and the rest where hot, making me think two are not firing correctly. Could this also be a result of over fueling?

ShawnG
ShawnG UltimaDork
3/19/21 11:16 a.m.

Double check your firing order.

pres589 (djronnebaum)
pres589 (djronnebaum) UltimaDork
3/19/21 1:59 p.m.

"one hole was cold, one was warm, all others were hot after running" sounds like ignition and not fuel.  The only way that would make sense is if one of the intake runners was completely blocked and the other mostly blocked.

This sounds like ignition now, like firing order or a bad component. 

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