Small block or Big Block
 

I have a 69 GMC 3/4 ton long bed. It is currently bone stock. I did a full restoration 5 years ago utilizing the factory build sheet. It came with a small block V8 and 4sp manual trans. It is time to put a new motor in the beast. The old motor still runs strong but leaks oil from every possible place an engine can leak oil. 1qt per month. Even with a pan underneath, I was kicked out of the garage and now being evicted from the driveway by my wife. With 186K mi I got my $ worth from the original motor. I have the opportunity to either replace the old motor with a 330hp small block or a 450hp big block. I am leaning toward the big block because I think it will make the truck more desirable. The old motor still gets the obligatory 12mi per gallon. I am not sure what the new motors will yield MPG but I only drive about 100 mi per week. Any sage advice? This truck is my daily driver, I go everywhere in it.

Re: Small block or Big Block
 

I would be inclined to keep it small block...for many reasons...

Big block will require new engine mounts for a start...plus, it is an A/C truck? Brackets for A/C ? Power steer brackets?

You will be putting a new radiator in it...small block much less expensive...


:chevy::chevy::chevy::gmc2::gmc2::gmc2:

Re: Small block or Big Block
 

Stay with the Mouse motor. Those big Rats are heavy and require a great deal more work.

Re: Small block or Big Block
 

If it was mine, I would keep the original motor but before anything I would do a compression test or a leak-down test, check the valve lift and the vacuum reading. If it all looked decent, I would start fixing oil leaks. -Brian

Re: Small block or Big Block
 

Another vote for a mouse motor.... but I'd be awfully tempted to go with a stroker!

Re: Small block or Big Block
 

I've always loved the idea of the BB; they just appear to be so much more bulletproof and generally awesome; but in my opinion the cam lobes and the crosshatching in the cylinder walls still goes just about as fast on the BB as the SB; and since the SB is so much cheaper and more available (like say from Summit or Jegs) that would be my vote.

There aren't that many gaskets that can leak oil if you think about it.. manifold, heads, oil pan and a few small ones.but yeah rear main seal can be a bummer.

Did you check the threaded block plugs? Try this article..

http://www.superchevy.com/how-to/eng...k-plug-basics/

Freeze plugs are hard too with the motor in..

Re: Small block or Big Block
 

I would stay with SB. Just my opinion... And I have access to a free BB 454 but do not want to add it to my truck!

Bill

Re: Small block or Big Block
 

If you go everywhere in it, unless you tow a lot I'd stay with the small block. As far as the 330 hp goes, that's great if the torque comes in low in the RPM range, but guys often build motors for horsepower when what a truck really needs is that torque down low.

Re: Small block or Big Block
 

Another vote for keeping it simple, small block. Ive had my eyes on the GM 383 truck crate motor. Alot of low end torque.

A couple of more years and seeing a non vortec small block will be harder to find. Just check and see how hard it is to find a complete 327 motor.

Re: Small block or Big Block
 

383 small block. Nice power increase with none of the extra work. FWIW, I am planning a big block swap into my 307 powered truck. But it's an auto. The big block manual trans parts are out there, but they are not commonly found and can be expensive as well as taking awhile to get. Motor mounts are expensive. Power steering pump/bracket/remote reservoir are expensive. Big blocks are expensive.

Figure $10k to do a mild big block swap and $4500 to do a 383.

Re: Small block or Big Block
 

Id have to see a picture of the truck first before I decided what I would like best for your truck =)

Re: Small block or Big Block
 

I was in the same position you are in last summer. My truck is also a long bed with a 4 speed. I wound up staying small block. For my needs the big block wouldn't have really done anything more for me other than initially cost more and cost much more in fuel. A nice 300 hp small block will indeed get the job done...

Re: Small block or Big Block
 

HT383 would probably accomplish your goal just fine. Or the Vortec 350 4 bolt crate engine. Either one is a one piece rear main and roller cam, which takes care of the 2 weak points on the SBC.
It's the ancillary equipment that will nickel and dime you on a BBC conversion. I've had a 454 in one of these trucks, it was fun but they are an expensive engine to build and install.

Re: Small block or Big Block
 

I'll give one vote for the rat motor lol. Yes way more expensive to switch out. Fuel mileage sucks. But they just look so much better under the hoods of these trucks imo. Plus you can't beet the sound of a BB.

Re: Small block or Big Block
 

I had a similar dilemma. I ended up going the big block route (402 out of a 70 C10, with alumn heads cam, 430hp/460tq). My goal was to make a big block style truck, making it look as factory as possible, while being a lot quicker.

As others have stated, it is a hassle. Engine mounts, fan shroud, new trans (700R4), headers, and the accessories and related brackets were the biggest pain in the butt. My radiator stayed the same. I'm still getting the AC hooked back up to the new style compressor.
All said and done, it was really expensive and I may have gone the LS route if I could do it again. Then again, I don't mind looking at the result.
https://i.imgur.com/oodMNEEl.jpg

Re: Small block or Big Block
 

Going with a big block 454 in my 69 from a 350. Little bit of work to make the change over, but in the end I think it'll be worth it. Truck is a flatbed 1 ton.

Re: Small block or Big Block
 

my 68 was a BB when I picked it up in 1981, I did a quick and cheap rebuild, Valve Job, new rings and Bearings. nothing else to the Block. drove it trouble free over 100K. I am sticking with a little different approach but still BB. I like the looks under the hood. in the end it is what do you want, the SB with a 4 Spd will pull anything you want.

Re: Small block or Big Block
 

Cool part about stroking a SBC is you can still badge it as plain ol' 350! :)

To the OP... do you have a functioning PCV system? A lot of oil leaks are caused by excess crankcase pressure from a bad PCV system.

Gary

Re: Small block or Big Block
 

I say go BBC, everywhere I go I see SBC or LS engines. Dare to be different I say.

Re: Small block or Big Block
 

BIG BLOCK unless you like wearing women's panties.....big blocks look mean under the hood and torque, torque. torque, but a small block can be fast, quick, nimble, better mpg and better handling. Apples to oranges. Daily driver-small block. I have one of each, blocks that is-not panties :)

Re: Small block or Big Block
 

Hell yes. I hate seeing a damn ls engine under these hoods. Cheap way out to me. And the big hype over fuel injection. That's crap. My carb motor starts and drives awesome. Just not many people left that knows how to tune them. Sorry on a rant!!!

Big block big power. Can't beet the torque. Stroke a 454 to a 496 and build it right and see a LS motor hang with it. No chance. There's a reason why BBs tear up 700r4s.

(I know I'll catch a lot of crap). But I'm old school. More cubic inch the better

Re: Small block or Big Block
 

I'm with CST10, I had a small block in my 56 and had a BBC available. I see SBC's everywhere, and yes theres a little more to do, but when you open the hood, WALLAH something unique. that's my .02 worth.

If you know of anyone looking for a 327 I know where there's one available.

Re: Small block or Big Block
 

If you want to rebuild the original engine so you can have "numbers matching" that is one thing. If you're going with a completely different engine, BBC is a no brainier.

Re: Small block or Big Block
 

It's all about the wow factor when you raise the hood. I vote Big Block.

POP

Re: Small block or Big Block
 

If you really want something different and don't mind spending a bit more $, go with a Caddy 472/500. They make loads of torque and are all high nickel content so they don't require much block machining. Usually just a hone and go. They also tend to get slightly better MPG than a BBC with a similar cam profile.

Re: Small block or Big Block
 

Big block. The freight train torque is wonderful.

Re: Small block or Big Block
 

Bbc bbc bbc bbc...

Re: Small block or Big Block
 

:sumo:I purchased a square with a BB it's a monster and requires attention need to beef up radiator and other items. I need to put headers on it . I hate when people half a$! Stuff and cut corners. And then I have a 6.0 in my 84 Scottsdale.

Re: Small block or Big Block
 

Thank you all for the responses. The discussion helped me gain clarity. A well built SB would be more than adequate. Heck, getting the my original motor bored and stroked would leave me north of 300HP, provide ample torque, and still have matching stock numbers. On the other hand, dropping in a BB would make the truck unique, more rare, and somewhat exclusive.

Bottom line is the BB worth the $3K upper.

Thanks again for the feedback..

I'll find some photos to post.

Re: Small block or Big Block
 

I don't think I'd go thru all the trouble of going small block to a big block with an sm465 tranny in my truck. I just don't see it being worth the extra cost and effort, especially if you aren't towing a big boat or camper with your truck. I get the cool factor, I removed a healthy small block from my 69 Chevelle just to put a big block in for the cool factor. At the end of the day the only time I got to show it off was at a car show. The other 99% of the time the hood was closed. I'm not all that sure a big block makes it worth a whole bunch more either... Maybe if it was originally a big block truck.

Re: Small block or Big Block
 

I would have the original rebuilt for a stock driver. I wish still had mine

Re: Small block or Big Block
 

Build the small-block (or buy a 1-pc rear seal crate engine)and add TPI fuel injection. Plenty of torque and mileage, plus no need to change accessories.

Re: Small block or Big Block
 

Not a bad option either.

If you did a 100% stock restoration by the build sheet, I think it would be fitting to have the original numbers matching engine rebuilt. I would venture to say that this would make it the most "rare" as anyone can swap in a crate SBC or even a BBC. Not everyone can have their original, numbers matching engine.

In short, build what you have or build a BBC. Cost will be a little more for the BBC and either will cost more than a crate SBC - but you didn't cheap out on your restoration, did you? Why would you cheap out on your engine then?

Re: Small block or Big Block
 

Before big block LS it. EFI and OD with some cold a-c

Re: Small block or Big Block
 

When I was still trying to find a truck to buy, I always thought that if I ended up buying a big block I'd keep it, and if I got a small block I'd put an LS in... I ended up buying one with a small block, and now I don't know what I'm planning...

An LY6 with 4L80e attached and all wiring/pedal/sensors etc. for $4k is damn hard to argue with... even if it costs another $2-4k to get installed, tuned and running thats pretty good value for 400hp and a very tough OD transmission... And once its all bolted in place the options for adding pretty significant amounts of power are endless and pretty cost effective...

a ~450hp 383 sbc crate motor and built 2004r/700r4 would cost about the same by the time its installed etc, with basically no power left on the table (without a full rebuild/new internals etc etc), and arguably on the limit of that trans with a 3700-4200lb truck...

But I am inclined to agree that a proper small block looks way more at home in there, and there are plenty of options to custom build a tough small block making plenty of power and bringing plenty of smiles.

The oil marks in my garage suggest I should make some kind of decision soon... and drag week footage has been giving me bad ideas...

Re: Small block or Big Block
 

why get 350ft-lbs for 10mpg when you can get 500ft-lbs for 10mpg

Re: Small block or Big Block
 

I still say BBC, be different.

The tone is deeper, you don't even have to open your hood for folks to know you got one. Tires shredding torque.

It might hit you up for a few more dollars. I built mine as a mild engine by BBC standards. Lays out 475 HP/ 500 TQ all between idle and 5000 RPMs. At 2000 RPMs it's got more than most small blocks at 5000. And I get 12 MPG if I keep my foot out of it. Maybe I'm Ol School, but no replacement for displacement. Tuning is easy with a carb. I say keep them simple.

At shows I get more people looking at that huge motor than the trucks on the side of me without BBC's.

i love SBC's and LS engines too. I have them in a camaro and another truck. I've even got a 250 CI inline 6 silly. Love it too. None compare to the feel of driving that BBC, none compare to the exhaust note of that deep throwing tone.

That's just me, everybody has there own perferances.

Everybody I've known that has installed a BBC engine has never regretted the decision. Actually a few of them won't put anything else in their builds now.

Re: Small block or Big Block
 

Got to say Big Block. That's what I'm putting in and I cant say that its cost me that much more to install it that I reckon it would have to fit a SBC. I did need a set of adjustable mounts so I could slide it into the optimal position.

Attachment 1694159

But I do like the idea of stroking my 454 :metal::metal::metal:

Re: Small block or Big Block
 

I finally got the old motor out and broken down. What a ticking time bomb. The oil pickup came off of the oil pump. Had slight scoring on the crank main and rod bearing journals. 3 cylinders started to scuff also. Everything is still rebuild able. I decided to keep the engine number and frame number match together. I asked myself what would a DIY motor head do back in '69. In other words what would uncle Bob do? So took all the heavy parts down to the best machine shop around and had everything magnafluxed and precision machined. I had the cylinders punched out to 0.040 over and the crank ground and polished. I had the heads redone with all new parts and had them decked. I had a custom grind on the cam that was a bit more aggressive than an RV cam. The motor will lope ever so slightly. My old Carter turned out to be un-rebuild able so I went to the Pomona swap meet and found a rebuild able Holly avenger and an Edelbrock period correct manifold. I am going to port the heads and manifold. Now for the slow and careful re-assembly. MTF

Re: Small block or Big Block
 

Thanks for the update -- always good to hear what the final decision was! Many years ago I had a rebuilt 350 put into my K20. Don't recall the specs but it had too much cam so that got swapped for something milder. Still wish I had spent the extra for a stroker but the budget said otherwise.... :)