454 in a 715

[tweeder8011]

so i finally got a 715 and looked it over good and figured out what direction i wanted to take as far as a restoration goes. i decided i wanted it to look military with a modern twist. ive taken a 454 out of a 89 chevy pickup and bolted it to the factory tranny and moved the firewall back about 3 inches the best i can tell. its tight but everything is going to work well except for the factory fan but that an easy fix with an electric unit. my question is, has anyone done this conversion before? my motor is in and its setting on the factory mounts but they need a little work to get it bolted up so does anyone know where to find motor mounts or do i need to fab some? i think this is going to be a very cool truck when up and running but until then any guidance in any issues that anyones knows i might have will be great! this is the first time ive done a 6 cylinder to a v8 swap but not the first time to put together a project.

[randyscycle]

I have a fuel injected 396 in mine right now with a TH400 trans. I did however make my own motor mounts as the original frame mounts had been torched off.

The rear of the right cylinder head is about 3/4" away from the firewall and with a short water pump, I could barely (and I mean barely) fit a mechanical fan with the radiator bolted to the stock core support. Later I recessed the radiator into the core support and it allowed more room, than I decided to just go with a Taurus electric fan and an aluminum CJ V8 conversion radiator.

It cools fine even in the 90 degree Summer weather we get here.

As far as motor mounts, you can just use a steel plate on the block and then drill the three necessary holes to use a stock GM mount to it in pretty much any position you wish.

Here is a pic from a couple years ago when I installed it:

[kwai]

Why would you need to move the firewall? The 454 will fit on the stock engine mounts using the spicer plate with no firewall modifications at all.

[Kaiserjeeps]

Kevin here locally in Or has a 454 in his truck. He might have a comment.

[brute4c]

I have seen a couple 454's in hese trucks withot touching the firewall...Joe/Ia has one that has been in his for a decade or more now...

[Barrman]

396/NV4500 for me with no firewall mods and a mechanical fan. They fit fine, sound awesome and run down the road great. Pretty darn good on the trails too.

[FlatlinesUp]

guess it all depends on what you're going to do with it and how much work you're willing to put into it.

A firewall move and engine setback will make the truck handle better and work better off road if that's it's function in life, as well as help w/some driveline length issues (possibly, depends on driveline used) but if you're planning on an everyday truck ie street/tow/light trail, there's no need for a setback IMHO

[jeepcj]

Mine has a 427 tall deck with an Allison trans and fits fine with no fire wall mods

[tweeder8011]

Thais for all the advice so far but what I ran into when I started the swapwas that some one had done a v8 conversion on the truck before I got it and had sectioned the firewall and moved back once before. What i found with the 454 was when I bolted to the factortranny my distributor wouldn't fit, the heads were pressed into the wall and smashed the valve covers, there was no room at all for exhaust on passenger side and I couldn't route the factory fuel lines for the throttle body on the back of the motor and there was no room for the radiator and fan that I had. I've already sectioned the firewall behind the motor and rebuilt it to make the room needed to fit everything and there's still. It much room for a mechanical fan but I'm not to that point yet. My motor mouth are lining up within a inch and half or so so I guessing I need to fab up some plates to get it bolted down?

[Barrman]

That is a bit too far back. I can take a full size Snap-On 9/16" combination wrench and tighten the distributor tie down without hitting the firewall on my truck. Stock firewall by the way.