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Differences between a 307, 327, 350?

23K views 9 replies 5 participants last post by  poncho62 
#1 ·
I'm a Ford guy that Ended up With a 1968 Chevy C20 Pickup, Currently it has a 307 Chevy (Origional engine) and it needs a rebuild bad, The trucks been a daily driver since it first rolled off the lot back in April of 68... The Truck was a gift from my grandfather (origional owner, purchased new) and I've been trying to restore it for a year and 2 months now.

I know the Bore and Strokes on the 307 are Different from the 327 and 350's, and as far as I know the only differences between the 327 and 350's was the Crank and 327's were only offered in 2 bolt mains...

Well my Major question is, Will the flywheel and clutch from a 307 Chevy (NP435 4spd Manual) Bolt up to a 327 or 350? Or will I need a new Fly wheel?... As far as I know the block I'm going to get is Internally balanced, and my uncle's (Chevy Fanatics) all say everything should interchange...

If I have to I can use the 2 BBL Mainifold and carb from the 307 Right?
(Carb Was recently rebuilt)

And my Truck came with the HD Radiator, and its specs are the same as the 350's specs except mine was only 1.5 - 2 inches smaller, I was told that this will handle the 327 / 350 Just fine... True?

How good are the 327's , I've heard amazing stories about them but the thought of only 2 bolt mains and about 300 HP / 360 TQ (Projected) sounds a little scary...

I'm on a LOW budget, so any tips you guys can give me on this conquest? any help at all is GREATLY appreciated...


Mike
 
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#2 ·
Your rado will be fine if its not all chewed up on the inside.

You can use the same flywheel, but I would get a new one after all those years of use.

327's did have a 4 bolt main on some blocks. You just have to watch out for big and small journals, if you're using a crank that's not OE for the block.

You can use your intake and carb, they'll bolt right up. However the heads may not feed a 350 very well.

K
 
#3 ·
Somebody correct me if I'm mistaken.

The stroke was the same between your 307, and the 327.
You should be able to use the crank and rods out of your 307, in a 350 block, to make your 327. Provided, of course, that its a large journal engine.
If the flywheel isn't cracked, you could have it surfaced, slide a new ring gear onto it, and use it too.
According to my Chevrolet interchange manual, the 307 was not a good engine, because it lacked tin and chrome in the block alloy, so it was ore prone to cylinder wear, and heat related cracking.
If your block is alright, you could save it, drop in a short crank, and build a 283.

If it happens to be a small journal engine, I think you can still use the flywheel, heads and such, but I think I'd agree with killer, on the flow issues, if you are planning a healthy buildup.
 
#4 ·
Haha yeah you guys are right the cranks are the same from 307 / 327 (Just checked Haynes Manual) I'm not planning on using my 307 heads, and sice the 307 is origional and has all the matching casting #'s I'm going to do a standard rebuild over 3 years on it....

Im looking into buying a 327 or 350, preferrably 4 bolt mains but I'll settle for 2 if its a 327... as far as I know the Fly wheel's in perfect condition, but it needs a new clutch (Which I'm going to pickup in a couple mins)

Thanks for the help on my Cooling Situation and Everything else...

The other thing I want to know, The 327 and 350 should line up perfectly with my Stock 307 Exhaust correct? and I can use my 307's Point Distributor correct?

My uncles going to give me an old Edelbrock Performer SP2P Intake, and Holley Vac. Secondary 750 4 Barrel to go with it, I think that would over carb the 327 though, Your thoughts on that matter as well will be greatly appreciated.. :-D

Mike

You guys are life savers, I got my answers in less then 15 mins...
 
#6 ·
Yep, Dual plane. It was manufactured back in the late 60's early 70's, in its time it was the "Best" on the market (Or so they say) They canceled production because they kept making newer stuff that improved slightly to greatly on the design... The Power band on it is 1500 - 5500 RPM (As far as I know)

Thanks, again! You have no Idea on how much I appreciate the reassurance :-D


Mike
 
#9 ·
As long as it had reg. 2.45 mains other wise I think it would be hard to find a 400 size crank (3.75 stroke) in small journal since 400 cranks are at 2.65 already and the aftermarket stroker ones come turneddown to 2.45. The bore size is the same though so with the right crank I guess you could do that.


Chris
 
#10 ·
killerformula said:
327's did have a 4 bolt main on some blocks. You just have to watch out for big and small journals, if you're using a crank that's not OE for the block.

K

Nope.............no 327 4 bolt mains. Not from the factory anyways....

68 and 69 had large journals, before that where the small.............
 
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