392 Trail Rig Build

[Fishwagon]

Hello folks,

I have torn down a non-ic 392 I acquired to start a build for my trail-queen Scout traveler.

Any comments would be appreciated. This vehicle will never see cruising speeds.

Some info on the rig first:

1. 14bolt rear/Dana 60 front, both detroit locked, 5.13 gears turning 40" tires

2. Transfercase is a klune underdrive followed by a Dana 300 (stock gear ratios in Dana 300). Dana 300 upgraded with 32 spline outputs. Dana 300 to be replaced by atlas in future.

3. Rebuilt 727 tranny, with B&M shift-kit from iho, Jeep output shaft/tailhousing

4. Current engine is a tired 304

ok, onto the engine to replace the 304:


1. Zero deck block w/ silvolite pistons - anything available to try to get say 9.5 or 10.0 compression? I'm not concerned with running premium fuel as it's only a trail rig. Even if it's possible, is it worth it? I have flat top pistons.

2. Smooth out oil passages

3. Clean up exhaust side of heads - still researching this. Keeping 392 heads....not putting 345's on....my research shows 392 heads breathe better (not saying much when it comes to IH heads I know, but I'll take it), bbc valve springs, 3 angle valve job, mill heads just enough to ensure flatness.

4. Balance rotating assembly

5. Stan's headers

6. Researching any intake manifold cleanup that can be done to enhance torque. Remachine intake if needed to correct as a result of block decking

7. Upgraded ignition

8. Eventually replace carb with FI

question:

1. Camshaft - looking at IHOnly's isky grinds, and am torn between the isky-190125-26 and isky 190170. Thoughts?

This is my first IH engine build, so still reading all threads I can get a hold of, but figured I'd post up also. Will be calling for parts once block goes to shop and it passes crack check and I see what bore I'm going to wind up with.

Comments?

Thanks....and have a great day everyone...

Rich

 

[Robert Kenney]

You're on the right track on what you have posted.
One real important detail to get right is the cam bearings. Make darn sure you get the oil holes lined up spot on and the rear bearing set to the correct depth. To far back and it will not supply proper oil flow to the lifter galleries.
The cam and compression will go hand in hand. Bigger cam requires more compression. The smaller cam you listed will work well @ stock - 9-1. If you plan to port the heads properly the larger one will work but I'd go 9.5-1 on the compression.

9.5 is tougher to achieve as the stock replacement pistons have a large decompression cut out that is worth about 10cc's.
I don't recommend whacking .050 off of your heads to get the cr up. It will weaken the mating gasket faces.
"0" deck the block or have the crank offset ground to increase the stroke to zero deck.
Take .020 off of the heads and you'll be around 9.2 +/- .1

 

[Fishwagon]

Thank you Robert, I appreciate your response.

I am with you, I do not like taking material off heads, if anything, just enough to ensure flatness, but other than that, I usually leave that alone.

As this is a trail rig, I don't intend to go to extremes to get more power.

I'll be calling you/iho once block/crank/heads are checked, so I know where my starting point is, so I can get parts together and talk about the heads.

Appreciate your time,

Rich