4.1L to 350 Swap

[Wdschell]

Hey guys new to this forum but have had my truck a while. I decided to do an engine swap for a v8 from my L6. I'm running into a problem with brackets , it seems I have the short water pump. The block cast number is 3970010, but the heads don't have a hole in them for the alternator mount on the passenger side. I picked the motor up on Craigslist for 300 bucks looked in pretty good shape. I assume I am not the first person to have this problem, but can't find any information on how I might get the alternator mounted.

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[CSFJ]

What heads are they?

 

[1987 GMC Jimmy]

As far as I know, those are either 896 or 520 heads. They are generally known as 283 SBC "Power Pak" heads. As far as specs go, I believe they're a 1.72 intake, 1.5 exhaust, and 60cc combustion chamber. They also didn't come with accessory holes from the factory. In my opinion, running those heads would be a mistake. I don't think it'd be worth trying to tap for accessory holes. It would also require some port and polish work to even match good 305 head specs (unworked 601/416 factory castings are the ones I have in mind). If it hasn't been upgraded to bigger valves already, you're going to have a pretty high compression ratio on that 350, and it won't make enough power to justify switching from the 250. If it were me, I'd find a good non-Vortec factory casting so you can keep your intake. I'd suggest camel hump heads that have been worked and have accessory holes if you can find them. Aftermarket cast iron or aluminum heads are also a good option and would likely be cheaper than finding a pair of camel hump cores and fixing them up/an already fixed up camel hump pair. These heads are much more appropriate for someone building an older 283 or 305. It's a pretty motor, and it'll treat you right with a good top end setup.

 

[Wdschell]

The casting number on the head is 3795896. That's what I was afraid of. It can't ever be an easy swap can it?

 

[gpmorgan]

I ran a 355 several years with the no bolt hole camel hump heads. I used a 92 chevy alternator and made brackets for the back and top of the alternator . I used a factory bracket off of the waterpump for the front lower bracket.

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[Wdschell]

Thats what I was thinking about doing before I found out about the heads. I had to do something similar when I rebuilt my 6 and got rid of the all-in-one head/intake thing.

Is it possible that my block is a 327? They guy I got it from said it was out of his 65 chevelle and he thought it was the factory 327. Obviously the block casting number indicates otherwise...

 

[gpmorgan]

Yes. I have that same block number. 4 bolt main 350. I raced with a guy that ran those heads and his car was pretty strong. If you don't know what's been done to them. I would give them a try. You can always do a head swap with the motor installed if they don't work out. Oh yeah. You need a long waterpump.

 

[Wdschell]

Ya, I have no idea what it is, only that it was recently rebuilt and still running when the guy pulled it. Have not even pulled the pan to see if it is 2 or 4 bolt.

 

[gpmorgan]

That cast # should be 4 bolt.

 

[Wdschell]

Alright, I will just put everything together and give it a try.

Can I reuse the same flywheel that was on my L6? I have the muncie 465 transmission and from what I have read that should bolt up given that its a chevy engine.