Rebuild opportunity....

[Jims86]

Sounds good. Ive gotten a lot of my TPI info from a Camaro forum I peak in once and awhile when I have motor Q's. I guess Im not really comparing Apples to Apples if the 400 is going in a 1/2T truck.

Good news is that I got the casting #330817. Shows to be the 2 bolt w/4 freeze plugs as opposed to the 4 bolt w/3 freeze plugs. The 2 bolts seem to be the preferred block of the two.

Ok, I just found a project that is similar. 2 more things stand out about the L98 heads and TPI. 1) Doesn't seem like a biggy, and thats having the chambers Machined to match the larger bore, and 2)there is some concern about the rear coolant crossover on the lower TPI manifold, and I dont remember which Plenums had them open...there are 3 factory TPI plenums, one with external EGR, used on the Aluminum L98 in the Vette, the standard plenum for the Iron heads, and then there is the early Non Centerbolt plenum used in 85 and 86.
I dont remember any of them having the rear passage, and I dont know how detrimental it would be not to have it. It may not be a big deal, due to the heavier cooling system in the truck.
Here is the link:http://www.eecis.udel.edu/~dzug/92z28/406project.html
And Im not sure what your smog laws are,or what your budget is, but keep in mind that you are not stuck with the factory TPI Manifold, look at Edelbock p/n29135 for example.
There are some things in there about Cam and crank clearance, and block cracking issues you may be concerned about.
All in all, If you go with this engine, you may consider taking it to a machine shop and have it gone over...
It is doable, but after reading up a little on the 400, I think I would aire on the side of caution, and just freshen up the 350, and install the 383 cam.
Thats just me.

 

[8T6K5]

Ok, I just found a project that is similar. Here is the link:http://www.eecis.udel.edu/~dzug/92z28/406project.html

Read that article and the links provided several times earlier tonight.

From that I gather, the problems that are associated with the 400 block are mainly found in high HP builds. Im basically looking to end up with very mild, but torquey motor with some balls to pass on the highway without hesitation.

I hear ya' on the 383. I like to be a little different and to me a 400 says so.

Going way back here....

383 = OJ Simpson - LaDanian Tomlinson

400 = Jim Brown - Jerome Betis

All great backs, would love to have any of them in my backfield.

 

[Jims86]

Read that article and the links provided several times earlier tonight.

From that I gather, the problems that are associated with the 400 block are mainly found in high HP builds. Im basically looking to end up with very mild, but torquey motor with some balls to pass on the highway without hesitation.

I hear ya' on the 383. I like to be a little different and to me a 400 says so.

Going way back here....

383 = OJ Simpson - LaDanian Tomlinson

400 = Jim Brown - Jerome Betis

All great backs, would love to have any of them in my backfield.

Since you already have the TPI, I am kinda gunnin for you to keep it. I had mine all Ca smog certified, and running..albeit not as good as I wanted, so I stepped back to TBI.
Dealing with some issues on my current setup have brought attention to some of the causes of the issues I was having With TPI, but its too late now.
I have the TBI running Great, and its more tinker friendly...especially when swapping out injectors.
Another reason I would like to stick with it, is that it looks likemyou may go and do some wheeling every now and then, and the last thing you want is to have a carb that is going to bog out at high angles.
If i Knew then, what I know now, I would probably still have TPI.
BTW, been looking into it more, and that is the only site that mentions the rear coolant passage...all others press the obviouse steam ports, which are a cake walk with some gaskets and a drill press.