1970 C20 dilemma

[GMC69]

So here is my problem. 1970 C20 with a 396 big block and recently put a built 700r4 behind it. Runs good, might need a rear main seal soon.

A few weeks ago I picked up a 2001 4.8l vortec with a reman 4l60e, plus wiring harness and PCM, some 6.0 manifolds and a transmission cooler for 300$.

Engine supposed to have 208,000 kms, so about 130,000 miles
transmission has maybe 3,000 kms, so about 1,800 miles.

I opened up the motor cause I don't the history, even though the guy I bought it from said it was from his grandfathers truck and was going to install it in his 1950 chev pickup, then decided to go diesel.

The heads look nice and clean inside and cylinders still have some crosshatch left. Checked a couple main bearings and rod bearings and they look new. Hard to believe there is that much mileage on it.

The plan is to replace the oil pump, re-gasket the whole thing, new timing chain and possibly gears, new balancer, replace the valve springs with LS6 springs in case I decide to swap the cam later on. Clean up the exterior, long tube headers and a tune.
With the info I can find, I should be able to get it to about 330hp at the crank, compared to my daily driver 2014 Silverado which is 355hp. Not to mention my 1970 weighs about 1,500lbs less than my 2014 which is about 70ish horsepower feel due to weight difference.

So do I drop the LS/4l60e combo in my truck or keep the 396/700r4 setup and install a stand alone efi system. Pretty sure my 396 is one of the low HP versions. Just looking up casting numbers now to confirm, plus I don't know what was done to this engine before I bought the truck.

[GMC69]

Current engine

[GMC69]

LS before tear down. Would all be repainted to match the vehicle.

[palallin]

The truck is an original big block? No question: keep it.

[Smith & Sons]

Depends on what your preference is,old school- the BBC hands down.New high tech ,high HP & good MPG economy-the LS conversion.Are you good with electrical & computers?

[1972BlueC20]

I wish I had a factory 396 with a 700R4 in my C20. I'd keep the big block. If you don't. PM me lol

[GMC69]

The truck was originally a 350, but you wouldn't know unless you looked at the RPO codes in the glove box. It's a summer toy so not a daily driver. The last few daily drivers I have had, I alway get into tuning the computer on them.
I could always keep this LS combo for some other project vehicle that comes by later on too, and just get a stand alone EFI for the 396 like FItech or one of the others out there.

When I start adding up all the extra things I need with the LS, I'm looking about the same dollars as getting an EFI system for the 396.

Once you factor in the time required for either option, keeping the 396 and adding the EFI is quicker.

Plus I guess there is something with opening the hood and seeing a big block under it.

This is a tough call, lol.

[old Chevy guy]

Me personally , I'd keep the 396. Getting away from high tech computer nonsense is why I spent a few years fixing an old truck instead of buying a new one. You already have the overdrive so it will cruise on the highway what more do you need. If horsepower was an issue put some mods on the 396. Even a low horse 396 must tow that 70 around pretty good now I'll bet. Just one mans opinion. Nice looking truck what ever you decide.

[GMC69]

Now that I'm making a pats list, I am leaning more towards keeping the 396 and maybe leaving it alone. Take the money I would spend on the swap or EFI conversion and get the air bags done on the truck. I think air bags would give me more than EFI on the 396 for the money spent.
Decisions, decisions, lol.

[GMC69]

UPDATE-----

So I decided that keeping the 396 was best, plus driving it around after coming out from winter helped that decision.
I've already sold the engine and trans, should be picked up this week.
My problem now is deciding what bags to go with. The D2600 that come in the kit I'm looking at from Travis at AZ Pro Performance, or swap the bags for some SS-7s.

I made a post in the suspension section for some input.

http://67-72chevytrucks.com/vboard/s...d.php?t=705323

[Ed F]

You've already got the 2014, why would you want to do that this one. For me part of the enjoyment of owning the older trucks is...well...having it like an older truck. I love my 2013 but I don't want my C10's to act or drive like the 2013. If your not convinced you can send that BBC my way so you don't have to stub your toe on it.

[GMC69]

I've been moving the truck out of the garage the last few days cause it's parked under the lift and I'm working in the mustang. Every time I fire it up, I think of why would I get rid of the 396.