1972 GMC Sierra Grande

[c10dementia]

I have a 1972 GMC as you can see has a stock 400 with a 400 tranny. All matching numbers engine is good and running, I also have a LS1 6.2 out of a Cadillac Escalade with the 6-speed tranny. My question is if you were in my shoes would you do the ls swap or keep the stock 400 add Fitech EFI and a 700R4... Recommendations please. Thank for your time.

[vics stuff]

It depends on how nice the truck is. The LS engine is a great swap out and have seen several done that way. If the truck is not that cherry then I would opt for the LS conversion.
Vic

[c10dementia]

Thank you for your input Vic. Hope you can see the link that is my truck. If you have IG I'm under c10dementia there you can see what it looks like.

[Mike C]

There is no way you can get the performance from the truck with the big block for the money you can swap the 6.2/6 speed combo. If you want to drive it and drive it a lot and distance too, swap in the LS.

I'm swapping a big block into my C10, specifically an L36 from a '69 Corvette (390 hp motor). I have $6500 in the motor (at least!) and will have $9000 by the time I get a built TH200 4R for it. And it STILL won't be injected.

I did this because of several personal reasons, but if I had that motor and trans I never would have gone down the big block path.

[Coley]

The bigger question here is not which engine combo is arguably 'better'....which has a lot of opinions.

The question is what are you personally trying to achieve?

Do you intend on buzzing around the neighbourhood burning rubber? or are you commuting in the truck? or is this a part time saturday truck?
Do you need good gas mileage and are do you prefer modern convenience, etc?
So are you a 'tire roaster' ? a cruiser? a family guy?....and occasional foot down guy?....adrenaline junky?....very important to figure your own personality and driving habits (90%) into this consideration.

Remember, one thing about the LS engines is that they are real visual 'snoozers' when you pop the hood.....basically as exciting as walking up to an average new car lot and staring under a few hoods.....yawn, lol.
However, they are great (modern) engines....make no mistake.

I wouldn't go to the expense of a drivetrain swap of that nature unless I had very good reason to....because it will be difficult and more expensive than you think and it will have issues.

So....what are you trying to achieve with the truck and your driving lifestyle?

All good
Coley

[1972RedNeck]

BBC all the way. Yes, the LS can make better numbers on the dyno and will get better mileage.

The BBC has more low end grunt and similar top end power for more area under the curve which results in easier tire roasting, more "snap" off the line, and more smiles per gallon.

If you're going to swap an engine for mileage and performance reasons, go diesel.

[jhrusk]

Either way I would recommend staying away from fitech. I had trouble with mine and ended up switching to a Holley sniper. Fitech customer service is lacking. Just trying to save someone some trouble

[morepwr]

I am a sucker for the big block.