L29 Coil near plug questions

[8T7K5]

As soon as my engine is back from the machine shop I'm planning on tackling the 0411 swap and coil near plug on my 99 big block. I've got a set of L21 valve covers and without having the engine to mock it up, it looks like (from pictures) the bottom of the resonator is going to interfere with the coils on the passenger side valve cover. Has anybody done cnp on an L29 and if so were there any clearance issues? I'd rather not mount the coils remotely, I'm trying to keep it as clean looking as possible.

 

[yevgenievich]

It will not work directly because of the way intake is set up. One or the other has to move

 

[8T7K5]

It will not work directly because of the way intake is set up. One or the other has to move

That's what i was afraid of. I wonder if a cold air intake would work since it comes straight off of the throttle body.

 

[yevgenievich]

That's what i was afraid of. I wonder if a cold air intake would work since it comes straight off of the throttle body.

Possibly if coil brackets moved around the intake. Where two coils one one side and two coils on other side.

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[8T7K5]

These are the L21 valve covers, I don't see any way to make it work short of moving the coils.

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Possibly if coil brackets moved around the intake. Where two coils one one side and two coils on other side.

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[454cid]

Hold on.... the L21 uses the same intake manifold and places a larger (DBW) throttle body in the same spot as the L29. It has to fit, unless the linkage hits a coil maybe.

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That K&N looks like it moves the MAF in the way.

 

[yevgenievich]

It actually does look like possibly clearing if maf is farther in stock location

 

[JeremyNH]

I put in cnc on my L31 a few months back and had to stack the coils on the drivers side forward. I put in a marine intake at the same time with the egr mounted outboard of the AC compressor so the valve to manifold tube goes where the coil was intended to mount. Even if not for that the coil wouldn't have cleared the compressor pressure switch harness so would have had to move anyway. Regardless I used some 1.5" steel spacers from my local True Value and longer bolts to stack the coils for #1 and #3 cylinders at the #3 location. Easy enough and it looked designed that way when I finished. Not the same motor as yours but stacking the coils using spacers should be platform independent and it does work well should you need to do it.

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[TexasAggie]

What is the advantage of converting to this type of ignition?

 

[JeremyNH]

What is the advantage of converting to this type of ignition?

Mostly reliability and maintenance of performance since there are no longer mechanical contacts to corrode. There are theoretically benefits to efficiency and power since the spark is more precisely controlled but at the low RPMs typical of truck motors it's marginal.