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Author Topic: Building dz302 engine  (Read 5709 times)
drSwan
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« on: June 25, 2009, 12:30:39 PM »

Im thinking about building my own dz302 out of a 327 block. I have a hard time finding the exact specs of it.
Is there any way to find all specs in one place instead of scouting for bits and pieces all over the internet?

TIA/ Andreas
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1968RSZ28
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« Reply #1 on: June 25, 2009, 01:58:39 PM »

Andreas -

If you want your engine to have 4 bolt mains (without the additional machining cost) like a DZ 302 you should use a 350 block.  A 327 block will work fine for a MO or MP 302.

You can find all the engine specs for a DZ 302 in the 1969 Chevrolet Chassis Overhaul Manual.

Paul
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drSwan
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« Reply #2 on: June 25, 2009, 02:03:59 PM »

Hmm that gives me a bit more meat on the bones so to speak.
Ill have to order that overhaul manual. Ill do it while ordering some other books I need. I live in Sweden so I need to import all that stuff.
Thank you very much.

/Andreas
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hotrod68
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« Reply #3 on: June 25, 2009, 11:04:38 PM »

Is your 327 a small or large-journal block? Be aware that in 1968 the bearing sizes were made larger, and a '67 and back 327 crank won't work in a '68-'69 block. You can tell easily, because the '67 and back engines had a canister oil filter instead of a spin-on filter, and there was a breather tube in the back of the block beside the distributor. The specs on a 302 are simple: 4" bore x 3" stroke. All small-blocks used 5.7" rods except for the 400. The difference in 302, 327 and 350 pistons is the pin height. You just order 302 pistons.
Oddlly enough, if your 327 is a small-journal, and you have access to a 283, you can use the 327 block and rods, 283 crank (which is a 3" stroke), and the 302 pistons. As a plus, 283 cranks were forged steel instead of cast iron, as were 327 cranks up to 1968, when they went to iron.
If it's a '68-'69 327, you'll need a 3" stroke large-journal crank and 302 pistons. Everything else is the same as far as the specs.
Hope this helps!
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HotRod'68  1968 SS350 coupe undergoing frame-off resto/rod. 386/350/4.11s
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1968RSZ28
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« Reply #4 on: June 26, 2009, 03:56:09 PM »

If it's a '68-'69 327, you'll need a 3" stroke large-journal crank and 302 pistons. Everything else is the same as far as the specs.

Nope; '69 302s had 4 bolt main caps, '68-'69 327s had 2 bolt main caps.

Paul
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drSwan
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« Reply #5 on: June 26, 2009, 05:16:30 PM »

Well the engine in my car is a small journal '67 327 but I dont want to use that engine. Its the original engine so...
Perhaps a 4 bolt 350 block is the way to go since the bore is the same. What about camshaft, heads and valve train?

/Andreas
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hotrod68
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« Reply #6 on: June 26, 2009, 10:07:11 PM »

I was referring to the rotating assembly, Paul. No 327s ever had 4-bolt caps, and the '69s were the only 302s with 4-bolt caps. You're absolutely right. Guess I should have been more clear. My bad.
As for the cam, the "Off Road" GM 140 cam is hard to beat both in performance and sheer great sound if you want to use a GM cam. The heads must have 2.02" intake and 1.60" exhaust valves and the alternator bolt holes if you do a DZ 302, but these original heads are now very hard to find. Edelbrock Victor heads are very close in appearance to GM heads, and they have far superior ports.
As far as the valvetrain, I'd go with Lunati or Comp Cams--any good aftermarket stuff--Chevy Hi-Perf parts are outrageously expensive over the counter and all you're buying is the Bowtie. They're no better than high-quality aftermarket valvetrain parts.
My 2 cents. Good luck!



 
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HotRod'68  1968 SS350 coupe undergoing frame-off resto/rod. 386/350/4.11s
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JohnZ
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« Reply #7 on: June 27, 2009, 06:25:40 PM »

-Chevy Hi-Perf parts are outrageously expensive over the counter and all you're buying is the Bowtie. They're no better than high-quality aftermarket valvetrain parts.
My 2 cents. Good luck!
 

All of the OEM factory cams are available as blueprint versions from Federal-Mogul/Speed-Pro and Sealed Power at very reasonable prices, and all of them use the standard GM #3911068 valve springs (or F-M/Speed-Pro #VS-677, which is the exact same spring for lots less money).
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pdq67
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« Reply #8 on: November 26, 2009, 09:57:33 PM »

Fwiw, the 302 is different each year so beware if it mean's anything to you?

The '67 used 1/8" tall, 1/2 round dome's like the earlier 283's used and press in pins. SJ here.  And don't forget about the road draft tube.

The '68 used a domed piston like the 350/360/370hp/350, but still pressed pins and finally in '69, they went floating pins. Both MJ here.

As for heads, probably the big valve -462's, -291's and -186's will do, but I forget what numbers went on what year engines.

And the old -346/30-30 "Big Duntov" solid lifter cam is it!  I say "Big Duntov" vs the old 097 solid cam, the "Little Duntov"!!

Then a stock true high-rise aluminum dual plane intake OR a great old Holley 300-36 and a 780 cfm, 3310-1 Holley carb.

pdq67

PS., and if anybody think's the old -097 solid cam is out to lunch, GM ran it in the high output 283's and 340/360hp/327's back then!
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Buddy
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« Reply #9 on: November 27, 2009, 11:09:31 AM »

67's had the 462 heads, not sure on the others

Buddy Cool
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JohnZ
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« Reply #10 on: November 27, 2009, 11:12:34 AM »

67's had the 462 heads, not sure on the others

Buddy Cool

The 291 heads replaced the 462's in Corvettes in March-April of '67; don't know if the same change occurred in Z/28's.
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