Compatible with GM 12363392?

[Duke W.]

Re: Compatible with GM 12363392?

But the LS-6 was designed to operate on 91 RON unleaded fuel, which is about equivalent to current 87 PON fuel in terms of detonation resistance.

I think 9.4 is perfectly acceptable with aluminum heads and the OE camshaft, and 91 PON fuel should allow for a fairly aggressive centrifugal spark advance curve - more aggressive than OE. It may even tolerate mid-grade.

Duke

[Justin S.]

Re: Compatible with GM 12363392?

Should I use bolts or studs with these heads?

[Joe L.]

Re: Compatible with GM 12363392?

Should I use bolts or studs with these heads?

Justin------


Either is OK. However, if you use bolts make sure they're of the correct length for use with these heads. Also, you MUST use either bolts or studs in conjunction with hardened washers.

[Justin S.]

Re: Compatible with GM 12363392?

Do the valve reliefs need to be cut due to the 2.19/1.88 valves on these heads?

[Joe L.]

Re: Compatible with GM 12363392?

Do the valve reliefs need to be cut due to the 2.19/1.88 valves on these heads?

Justin------


No, not with the KB203 pistons.

[Justin S.]

Re: Compatible with GM 12363392?

The ring installation instructions that came with the pistons are different than the ones that came with the rings. Which ones should I follow?

[Joe L.]

Re: Compatible with GM 12363392?

The ring installation instructions that came with the pistons are different than the ones that came with the rings. Which ones should I follow?

Justin------


How are the instructions different?

[Justin S.]

Re: Compatible with GM 12363392?

KB says that the dimple on the second ring faces down. Sealed power (rings) says that the dimple faces up. This ring is beveled too

[Joe L.]

Re: Compatible with GM 12363392?

KB says that the dimple on the second ring faces down. Sealed power (rings) says that the dimple faces up. This ring is beveled too

Justin------


In all cases I am familiar with, the dot or dimple faces UP. I would contact KB technical service to see why they specify it to face down.

[Justin S.]

Re: Compatible with GM 12363392?

If anyone is considering these heads,
Because of the washers needed for the head bolts, it subsequently raises the exhaust manifold, creating a misalignment of the bolt holes. I was able to make it work by reaming the holes on the manifolds to 1/2" diameter. The front and rear cylinder holes are nearly this diameter to begin with.
(Obviously this has been a long project)

Justin

[Justin S.]

Re: Compatible with GM 12363392?

Joe,
Which spark plug would you recommend with these heads?

[Joe L.]

Re: Compatible with GM 12363392?

Joe,
Which spark plug would you recommend with these heads?

Justin------


I've forgotten what I determined to be a good plug for these heads. I'm in Italy right now so I don't have ac cess to my records.

[Joe R.]

Re: Compatible with GM 12363392?

Hi Justin,

I would suggest starting a new thread titled something like “What spark plugs should I use for my L-xx engine?.” I think you will get a lot more useful replies that way. I think Duke recommends a slightly hotter spark plug than what GM recommended back in the day. But I can’t remember the specifics.

Joe

[Justin S.]

Re: Compatible with GM 12363392?

Joe,
This clearly isn't a rush job. Is there a problem with recycling the thread I started?

Justin

[Joe L.]

Re: Compatible with GM 12363392?

Hi Justin,

I would suggest starting a new thread titled something like “What spark plugs should I use for my L-xx engine?.” I think you will get a lot more useful replies that way. I think Duke recommends a slightly hotter spark plug than what GM recommended back in the day. But I can’t remember the specifics.

Joe

Joe-------


The 12363392 heads do not use the exact same plugs as were used on original engines/heads. These are a GM Performance Parts aluminum head and are SERVICE-only. They were never used on any PRODUCTION engine and were never specified as SERVICE for any PRODUCTION engine although they have been used on some SERVICE-only engine assemblies. They are ROUGHLY similar to L1969-71 BB, rectangular port aluminum heads.