Burnt valve 350...fix or swap to 383, 454, 6bt?

[Warkmeister]

hey guys, I just gotta say first off, you all are a fantastic group of individuals. I’ve asked a few questions already to get my 81 CCLB project up to speed, and they’ve all been met with a high degree of human decency that lacks at other sites...you all know where I mean.

To the question!

I know my 350 has burnt valves on both banks, lub sounds dollar bill test and true dual exhaust told me so. I like to think about long term goals and fix short term issues accordingly. I can drive it, but it needs fixed and I need more power. Here are my options as I see them:
1. $500 or less gets me fixed heads, used aftermarket or performance GM heads.
2. $500 or less also gets me an 86 c2500 with 454 of unknown condition, but is mated to an sm465 just like my current motor. I know the owner and have already agreed on price of $400, all I need to do is pay him and drag it home. Truck has 96k on it, ran when parked, and has been sitting for 15-20yrs.
3. $500 or more gets me a new crank and more, and starts me on the path of building a stroker 383, obviously more costs after that to finish the build.
4. ?$ gets me a 12v Cummins and I get to learn the work associated with that swap.

I’ve never swapped a motor, this is my first sbc and squarebody, and I’m pretty mechanically inclined, albeit inexperienced in these areas. I’ll dive in to almost anything in order to learn.
My goals are to have a fun driver that can haul ass (-ish....1tons only go so fast), the kids, and trailers/rvs when called upon. Not a daily driver, but something that is always at the ready for just about anything. I want to stay manual too. I’d love to crest the 400hp/tq mark in either option. 400lbft is nice in our Tundra as a benchmark, but it’s getting sold.

 

[Craig 85]

I assume Sanger is in the bi-annual smog area. With that said, if you go the 454 route, you need to decide what smog year you want to go with 81 or 86.

454's break down from 1981 to 12/31/84 and 1/1/85 to the end of 1986 production. My truck is an '85, but falls under the 1984 smog specs due to its build date. The '86 is a dual smog pump motor, but runs factory stainless exhaust headers (photo). Finding parts used for only 1 1/2 years could be problematic. So take everything related to the engine and that has a vacuum line hooked up to it.

If you stick with 81 smog specs, I don't know if all the small block parts are compatible to a big block of the same year. most brackets are different. I know I had to do a 9 hour road trip to buy discontinued smog parts from a guy in Dinuba that parted out a motor home.

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[Warkmeister]

Considering your reply, I forgot to mention, this was a factory diesel, so no smog! Very thorough though, and valuable info. Thanks.
My plan with the bbc would be no smog stuff, so just an intake initially, then mild cam, headers, and oval heads or other good flowing units, nothing crazy.
Knowing that, would you still vote 454?

 

[DoubleDingo]

You need to make sure there isn't any back fees on that vehicle. If it's been sitting non-op, you're golden. Non non-op, you'll be paying a huge amount in back fees.

 

[yevgenievich]

454 sounds like an easily economical swap without too much of complications and would archieve desired goals(might have to add heads/cam to really archieve desired goals)

 

[Warkmeister]

You need to make sure there isn't any back fees on that vehicle. If it's been sitting non-op, you're golden. Non non-op, you'll be paying a huge amount in back fees.

The 86 parts truck would never be registered again, unless I’m misunderstanding you, so no worries there. Back fees only apply if not renewed within 7 years. After 7, it’s s new title. At least that’s how it’s worked in the past with the motorcycles I’ve restored. I’d pull the big block and scrap the rest. If it all works out, $400 for a running 454 with tranny plus a pile of parts is more than worth it.

Thanks again for the advice and info youve all offered.

 

[Rusty Nail]

Repairing heads is both easy AND fun, there is no good reason to not do that.
A $400 complete BB "parts truck" that MAY run with a little tinkering and a battery?
Again, no good reason to not do that.

400HP is a very lofty goal i think after you get these "smaller" goals knocked out, they may build hella confidence while you try to save some cash! Cuz you're gonna need it brother!

 

[Craig 85]

FYI the '86 454 has a 7.9 compression ratio with peanut port heads.

 

[4WDKC]

I know you are focusing on the engine right now but keep in mind your trans also, reason is the truck likely has 410 gears and no overdrive is going to be high rpm slow speed. If you want to see what its like look up the gears in your tundra and the trans to find if a gear other than D is 1:1 then make a drive like that. Back to the engine honestly I wouldnt spend a dollar on smog heads when there are much better options that could be used. Look for good used heads before repairing, $400 is hard to beat for a big block truck, that said maybe get it running to make sure the engine doesnt need rebuilt.

 

[DoubleDingo]

The 86 parts truck would never be registered again, unless I’m misunderstanding you, so no worries there. Back fees only apply if not renewed within 7 years. After 7, it’s s new title. At least that’s how it’s worked in the past with the motorcycles I’ve restored. I’d pull the big block and scrap the rest. If it all works out, $400 for a running 454 with tranny plus a pile of parts is more than worth it.

Thanks again for the advice and info youve all offered.

If it's being scrapped then it shouldn't be an issue. I've never heard of the 7 year rule as you mentioned, but if that's how it works that's cool. I guess it's a common law type of thing like living with a girlfriend for 7 years you're now married to her...lol... But yeah, getting a good engine and trans and miscellaneous parts for $400 and no title troubles, sounds like a good deal to me.

 

[K10eddie]

I would 100% get the bbc truck. Swap the 454 into your current truck, sell the sm465 for decent coin (unless you wanted to keep it) and part the 454 truck out for spare parts and stuff to sell.

Personally while the 454 is out, I would swap to closed chamber heads, refresh the valvetrain, gaskets and send it. Unless you wanted to put a new cam in it, then do that too.

 

[ali_c20]

454... I helped swapping a 78 350 with a 72 chevelle 454 on friends truck. The result is big smiles evertime you floor it. And a every year at least one set of new rear tires.

 

[DirtyDYT]

I say go big block, that’s what I’m doing. My first swap will be a previously mildly upgraded ‘85 454 into a 350/TH350 ‘79 C10 long bed. My goals are similar-dive in and learn as you go while building a truck that can really scoot when you want it to.

I’d happily pay $400 for that configuration of parts truck. I’ll be lucky to find a used SM465 for under $200 around here. A local guy buys them all to rebuild and resell for $1000-$1500. I paid $750 for just my 454 to swap!

 

[78C10BigTen]

454... I helped swapping a 78 350 with a 72 chevelle 454 on friends truck. The result is big smiles evertime you floor it. And a every year at least one set of new rear tires.

How much of a hassle was that swap?

 

[ali_c20]

The truck is a 4wd, the biggest change was the exhaust, we made a new system with more diameter. The old exhaust was too small for a big block and position of the manifolds is different.
New hoses for the cooling system and a new hi torque starter because the flexplate on the big block was different and the old starter had seen better days.
I guess 1 day of work with beer and looking at our work included.
And 1 day for the exhaust system.