Intial start up & timing 5.7gsipefs /6.2 long block s

Lubak572

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What is the intial startup/ timing procedure for twin 5.7gsipefs that were upgraded to new gm 6.2 long blocks? I used all old stuff off original motors intake, tbi, distributor, etc.. I had mefi bob reflash ecms for the bigger 6.2 long blocks. Can't get motors to start/run. I set distributor to tdc #1 compression stroke will not start. Per the manual I am trying to get it to start/run and get warmed up then put it into base timing mode with my laptop running rinda diacom, and set it to 8* BTDC with timing light. Can't get that far. Am I supposed to put it into base timing mode upon intial startup right off that bat?
 

alldodge

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Are you getting spark?
Does the fuel pump prime with key ON?

Crack the fuel line going to the TB with a rag around it and when key is turned ON see if gas comes out
 

Lubak572

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Getting fuel and spark. No dtc s on laptop. Got starboard motor to run ,but had to give 3/4 throttle. Was running rough. Does it need to be in base timing mode for intial startup? I thought it should run and warmed up before hand. These are standard rotation/ standard Chevy SBC firing order. I just don't get it.
 

alldodge

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Does it need to be in base timing mode for intial startup?

No, should fire up and then rotate the distributor to get it running better, then place in base timing mode

It it will not smooth out, then its firing order or other issues

Who rebuilt the motors?
 

Lubak572

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Motors were brand new gm 6.2 long blocks. I took off everything from old motors cleaned up and reinstalled on new long blocks. Had mefi bob reprogram ecms for bigger 6.2 motors. Everything worked before one motor ingested water. Decided to replace and upgrade both motors. New cap, rotors, plugs, coils, wires plus new exhaust went with hardin marine seaward series. Batteries charged up, even put switches on parallel start. Cranks over fine just won't start.
 

alldodge

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Its getting spark and fuel then it should fire. If it was way out of time it would still backfire. Look for the tach to show at least 300 rpm when cranking, this will tell you if the ECM is seeing the distributor.

Maybe start with the motor that will run rough and get it running good first. Getting it going may give an idea what is going on with the other.
 

cptbill

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Here's a stupide question for you, is the dist. tuning and is the motor building oil pressure?
 

Saline Marina

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Make sure that you understand which TDC is correct. In other words the piston reaches the TDC position 2x during the entire 4 cycle process. Another way to think about it is because the cam is a 1:2 underdrive from the crank then the crank has to hit its TDC position 2x as the camshaft and distributor make 1 full revolution.

The only bulletproof way to check is to pull the rocker cover for the #1 side and observe rocker arms as the piston approaches apex. Both rocker arms will be "quiet" and not moving on each side of the correct TDC as the cycle is transitioning from compression to power. On the "incorrect TDC" the valves will be in motion as the cycle is transitioning from exhaust to intake.

A quick way to check without pulling the rocker cover is to place the #1 spark plug wire 180 degrees away from its current position on the distributor cap and then working your way around in the same firing order. Likely there will be issues with plug wire length, crossing, and routing, but it will tell you quickly if what I suggest is in play. You could also pull the distributor base and advance the crank 1 full revolution and then replace the distributor base aligned with the traditional #1 post location. Several possibilities.
 

Lubak572

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Tried port motor today. While cranking with my laptop hooked up to motor with rinda only saw about 150 rpm cranking. Batteries stated 12 volts have been on charger whole time, but they are old. I did put new Ebay starters on both motors. They sound fine cranking over.
 

Lubak572

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Guess I will try new batteries. I had battery switch even set to parallel ( emergency start). I sure hope it isn't just the batteries. Maybe these cheaper starters.....?? Seem to crank fine.
 

alldodge

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The 150 is a bit slow, connect the laptop to the starboard motor and see if it cranks at the same speed

Are the new starters Permanent magnet type or regular?

Are you sure your getting spark?
 

QBhoy

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Don’t know much about the efi to be fair. But me thinking along simple lines...is the auxiliaries you swapped over from old engine all compatible? Is there an ecu that is now miss matched
 

Lubak572

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Both turn over the same....weird. Guess I will have to wait until March now, as boat will be going into storage. I will get new batteries in the spring. To be continued
 
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