TBI to HEI

[baddawg]

, I've read it somewhere, I think it caused a problem between a few members, but I can't find it again.
I went from a coil and stock distributor (TBI) , to a HEI with the coil built in. As ya'll know the plugs are completely different.
I changed over the POWER and TACH wire, and have them in the proper place, the HEI has its own wire from distributor to built in coil.
That leaves me with the 4 prong plug that went to the old TBI
I have an external fuel pump, so that is not an issue.
I rebuilt my 454 last winter to about 500HP, and I could not get the timing up enough with the old ignition, so I went with a MECHANICAL and VACUUM advance HEI.
I've got no spark at all, I even went as far as plugging in the old TBI, and putting power to the old coil to see if it made any difference.
The Summit tech guys are stumped.
Any thoughts from you guys?
Thanks

Quote

 

[GoToGuy]

What year, make, model ? What other mods? Normally what your doing is a step backwards. There all High Energy Ignition now.

 

[tayto]

the "big cap" HEI only needs 12v to work. make sure whatever 12v you tapped into is HOT while cranking. if it's not it won't spark. I would run a jumper wire from the dist directly to the positive terminal on the battery and see what it does. is this distributor a known good unit? or is it some aftermarket POS? (I am assuming it is since you mentioned Summit tech support)

 

[baddawg]

It's a brand new Accel 59130 HEI.
The truck is a Chevy 1988 C3500 dually, Cheyenne.
Had a Summit 850200 TBI in it, and has run great for years.
Was a 600 cfm EDELBROCK, now a 750 Demon.
More mods??
450 hp heads
9.5 TRW pistons (high dome)
11 231 3 Comp cam, .505.....505
Dual roller chain
Steel forged crank
EDELBROCK Performer Intake
Headman headers

 

[baddawg]

You must be registered for see images attach

 

[baddawg]

As you can see, I've double checked the ignition for a ground.
Even set the old TBI up, plugged it in and put power to the coil, just in case the computer, or the neutral safety switch on the clutch pedal needed to read something

I tapped into the original power wire that ran to the old coil for power

As far as a step backwards, the TBI does not have the ability to give me the timing curve I need with this much HP

 

[baddawg]

I will go straight from battery tomorrow.
I did put a test light on it while cranking, you could see it dim, but very little.

It's late, to many beers for this old man

 

[baddawg]

No spark, direct from battery to hot lead on coil / distributor

I guess I pull the coil out of this brand new Accel distributor, and see if it's junk

 

[evilunclegrimace]

As far as a step backwards, the TBI does not have the ability to give me the timing curve I need with this much HP

Would you explain what this means^

 

[baddawg]

With the TBI, the timing is controlled by the on board computer.
The ECM.
The cam I'm using, wants 30 degrees of advance at 4000 RPM.
Way beyond the scope of the stock 230 HP ECM