350 crank in 327 help

hello, I have a 327 from a 1968 camaro in my 1980 camaro. I just pulled the motor out and I am planning on rebuilding it. I have an edelbrock rpm airgap manifold, holley 600,and a 4 speed saginaw. i have a 350 crankshaft and I was wondering if I put it in the 327 and NOT change anything else (rods, pistons, heads..) would it increase my compression and still clear the valves? I have been googling this question but no good answers to whether it will clear if you dont change the rods and pistons...
I appreciate your help very much
Thank you!

 

Pistons will be above the deck. Will not work. Also is the 327 large or small journal (bearing diameter)?? All 350's are large and the 327's are either one.

 

350 and 327s share the same 4.000" bore... 350's had a 3.48" stroke, while the 327's had a 3.25" stroke. The blocks are basically the same, it's the rotating assembly that makes the difference. With proper pistons, you could use your 350 crank and have a 350. There's no replacement for displacement!

 

No can do. As 47chevycoupe stated, the extra stroke length will put the pistons about 0.23 inch higher, or way above the deck. 327 stroke = 3.250, 350 = 3.480. Your 68 327 should be a large journal, but it might be small journal. I think 68 was the first year for large journal, assuming the engine really is a 68 casting and assembly date.

If your block is a large journal, then you can use a 350 crank if you put new pistons. The compression height is what is different between the 327 and 350. Rod length is the same. 327 and 350 have the same 4.000 bore as orig built.

If you just want more cubes, then it might be easier to just get a 350 and sell the 327. Even better, get a 383 or 400 for more cubes yet.

 

If it has rebuilders pistons it is already below the deck,have you checked to see how much?

 

i have not taken it apart yet.. i dont really want more cubes,just a higher compression.

 

I think you need some pistons if you want more compression.

 

There are a couple of approaches to this. As someone alluded to, in most stock or "rebuilder" engines, the piston sits quite a ways down in the bore at TDC. Cheap rebuilder pistons are nearly all like this. One cure is to deck the block to zero, or close to it.

Another cure is to use a piston with a dome. Yet another is to use flattop pistons, but ones with only two valve reliefs, not four (most cheap pistons have four). The price difference is sometimes only about $50.

Yet another possibility is to use different cylinder heads with smaller combustion chambers.

The answer as to which method or methods is best- depends on your budget, what you expect the engine to do, and how much you want to raise the compression.

 

im just looking for close to 400hp? i have the "small" camel hump heads. I do not want to spend a ton of money, really just a re-ring and bearing kit along with a cam. I just figured "hey I got this bigger crank, wonder if all the stock parts will clear if I put it in.."

 

The pistons will only be half that .23 as when you increase stroke you are going down as well as up the additional stroke. Example a added 1/4 stroke only moves the piston up 1/8 more as well as 1/8 lower at the bottom of the stroke = 1/4 more stroke, I hope this helps you understand. You are right the pistons will be out of the hole and will not work.

 

Ahh, ok. maybe i'll just keep the stock crank, I hear they are forged anyhow.

Thanks for the help!

 

Motorhead...if the casting number on your block ends in 660 or 678 then it is a large journal and you can just put any 350 crank in...but like others have said..you will need 350 pistons. All that being said you will gain 23 cubic inches or 28 cubic inches (355) if you bore it to .030...that will give you a hp boost right there...I think 350 pistons are cheaper than 327 pistons too since they are in more demand..

 

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If you want 400hp then it will not be cheap. And you will need to burn high octane fuel.

The cheap way to go would be to re-surface the heads and bore the block .030. Both of these will raise the compression and add power. If you calculate a 9:1 or 10:1 ratio with the parts you use, you can get by on pump gas, anything more then I'm thinking 95 octane or more as compression goes up.

 

Some places charge the same for a 327 or 350 piston set...

 

Dont guess, there is a simple way to tell and be 100% certain. The whole length of the crank that has NOT been machined, there will be a " parting line ". If this parting line is a fine line, maybe a 1/16" to 1/8" , kind of jagged edged, then it is a cast crank. If the parting line is wide, anywhere from 1/2" to 3/4" wide, and somewhat smooth, then you positively have a forged crank, good luck, TR

 

As stated, you're going to have to make some more changes. This engine is in one of our 55's, it's a 327 with a 350 crank with a .040 bore (approx. 358ci). With .202 fuelie heads, a solid lifter cam, and a vintage Paxton blower it makes approx. 500hp/500ft lbs.
-Dean