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Old 09-12-2017, 08:12 PM   #1
KahunaEdd
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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.
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Old 09-12-2017, 08:20 PM   #2
AussieinNC
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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...


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Old 09-12-2017, 08:32 PM   #3
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Re: Small block or Big Block

Stay with the Mouse motor. Those big Rats are heavy and require a great deal more work.
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Old 09-12-2017, 08:39 PM   #4
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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
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Old 09-12-2017, 08:45 PM   #5
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Re: Small block or Big Block

Another vote for a mouse motor.... but I'd be awfully tempted to go with a stroker!
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Old 09-12-2017, 09:02 PM   #6
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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..
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Old 09-12-2017, 09:06 PM   #7
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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!

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Old 09-12-2017, 09:18 PM   #8
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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.
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Old 09-12-2017, 09:27 PM   #9
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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.
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Old 09-12-2017, 09:30 PM   #10
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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.
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Old 09-13-2017, 01:40 AM   #11
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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 =)
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Old 09-13-2017, 06:30 AM   #12
Ken B
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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...
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Old 09-13-2017, 08:53 AM   #13
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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.
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Old 09-13-2017, 09:06 AM   #14
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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.
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Old 09-13-2017, 09:28 AM   #15
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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.
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Old 09-13-2017, 12:56 PM   #16
kwmech
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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.
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Old 09-13-2017, 01:16 PM   #17
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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.
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Old 09-13-2017, 02:29 PM   #18
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Re: Small block or Big Block

Quote:
Originally Posted by Stocker View Post
Another vote for a mouse motor.... but I'd be awfully tempted to go with a stroker!
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
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Old 09-13-2017, 09:34 PM   #19
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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.
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Old 09-13-2017, 09:56 PM   #20
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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
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Old 09-13-2017, 11:28 PM   #21
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Re: Small block or Big Block

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Originally Posted by CST10 View Post
I say go BBC, everywhere I go I see SBC or LS engines. Dare to be different I say.
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
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Old 09-13-2017, 11:46 PM   #22
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Re: Small block or Big Block

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Originally Posted by CST10 View Post
I say go BBC, everywhere I go I see SBC or LS engines. Dare to be different I say.
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.
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Old 09-14-2017, 09:16 AM   #23
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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.
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Old 09-14-2017, 10:55 AM   #24
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Re: Small block or Big Block

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

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Old 09-14-2017, 11:06 AM   #25
clay68c10
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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.
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