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Old 02-22-2011, 04:18 PM
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Sbc 327 (Estimated HP)

Hello, I'm planning on building a sbc 327(Large Journal) and I have a set up in mind, I was wondering how much HP I could possibly push with this set up. I don't want to hear people say anything about my choice of engine either. The 327's are getting harder to find, plus make plenty of power.

-327 Block (.30 over)
-461 Double Hump Head(2.02,1.60) Mild port&polish
-Comp Cams Thumpr' Cam 279TH7
-Speed Pro Hypereutectic flat top pistons
-1.6 Ratio Roller rockers
-High Volume Oil pump
-"Noisy" Gear Drive"
-Stock Rods(ARP Bolts)
-Performer RPM Intake
-650 Holley Double Pumper

Any suggestions, comments, estimates?

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Old 02-22-2011, 07:15 PM
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what's the compression ratio? or at least what cc heads?

not sure, but i've heard the "noisy" gear drive is basically a pre worn out set. AKA it won't last long and may offset the timing. Again, no personal experience with that, just what I've heard. (but if you want the whine of a blower Throw one on it!)
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Old 02-22-2011, 07:21 PM
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Quote:
Originally Posted by QParker
not sure, but i've heard the "noisy" gear drive is basically a pre worn out set. AKA it won't last long and may offset the timing. Again, no personal experience with that, just what I've heard. (but if you want the whine of a blower Throw one on it!)
Never heard that before. I had one before three years and it worked fine. I couldn't stand it for those three years either. It was so loud that I wanted to wear ear plugs while working under the hood with the engine running.

Later I bolted a supercharger on that same engine and I don't think they really sounded that much alike. The supercharger had a very distinct whine and sounded much better than the gear drive.
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Old 02-22-2011, 07:22 PM
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Yep, we need to know the compression ratio to be able to even guess.

The noisy gear drive is your worst choice in a camshaft drive. A good true-roller chain and gear set would be much better.
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Old 02-22-2011, 07:31 PM
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You will need at least 11-1 comp to get close to 400hp maybe more.
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Old 02-22-2011, 08:22 PM
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Probably around 10:1 Compression I would think. I'm not positive on this.
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Old 02-22-2011, 08:28 PM
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Quote:
Originally Posted by PaulsChevy64SWB
Probably around 10:1 Compression I would think. I'm not positive on this.
The website you linked to for the pistons says 9.14:1 and using a compression ratio calculator I just found online I came up with 9.25:1. I did make assumptions on head gasket volume and piston height though.

Do you want power out of your engine or do you want a cool sound? There are better cams for making power than the Thumprs. They're specifically designed for the rough idling, racy cam sound. I'm not saying you won't make a lot of power but other cams that don't focus on sound will probably perform better.
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Old 02-22-2011, 08:32 PM
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If the heads are still 64cc and haven't been ground bigger in the chamber to deshroud the valves, using a flat top piston in a undecked block you will only get about 9.1-1 compression in a 327. (in fact the link you posted shows 9.15-1).

The Comp Cams Thumpr is not the best choice here, I'd guess you will get about 325-340hp at best. Not enough compression ratio and not enough cam to spin it to a high enough RPM to see real good power from this small inch(by todays standards)engine.

Last edited by ericnova72; 02-22-2011 at 08:43 PM. Reason: spelling
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Old 02-22-2011, 08:41 PM
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So do you think a set of domed pistons(.200 or so) would be better with these 64cc heads? I was going mostly for sound, but I may end up going with a Comp Cams Magnum 280H
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Old 02-22-2011, 08:45 PM
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What are you putting this in??

What does it weigh??

What transmission/torque converter stall??

What rear gear and tire diameter??

Street, strip, offroad, street rod??
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Old 02-22-2011, 08:52 PM
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Most likely an 1989 s10(short bed, single cab)
Probably around 4500 pounds dry weight
TH400 Tranny 1800-2200 Stall
4:10 Gears (Haven't decided on whether I should mini tub it or not)
Street and Strip
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Old 02-22-2011, 08:59 PM
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The domed pistons would be a big help, would get you into the 10.25-1 compression range or a little higher.

S-10 short bed will be a lot closer to 3200lbs, 4500lbs would be a 4 door 4x4 S-10 Blazer weight.

The 280H Magnum wouldn't be too bad here with the added compression...but do you have anything against using a small solid lifter cam?? It would really wake things up in the 4500-7000rpm area without giving up anything down low.
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Old 02-22-2011, 09:03 PM
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I can't even find a set of cheap domed pistons for a 327. The pin height is different on a 327 engine than a 350 right?

I wasn't sure on the weight, I googled it real quick and of course that's what came up. I had a hard time believing it was 4500.

I've heard once you use a solid, all your reliability goes down the drain.
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Old 02-22-2011, 09:21 PM
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Yes, pin height is different than the 350, because the stroke is different, but rod length is shared by both.

Have you looked at Keith Black for pistons?? More expensive than Speed-Pro though.

Not true about the solids, they are more reliable today than they ever have been. To really make a 327 shine I consider them to be manditory, you've got to rev it to get power(make your own decision here, I never build a small block smaller than 383 any more as I don't think it is a good return on investment vs power made...so I'm a bit gung-ho, always build the biggest that will fit into a 350 or bigger block...406 = ).

Solids are no less reliable than hydraulics, you will just have to check the lash every 3000-5000 miles or so. If good pushrods, rockers, and springs are used they will rarely be out of adjustment more than a thousandth or two. Lash figures are tighter on modern solids so they don't beat the valvetrain up like the old days.
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Old 02-22-2011, 10:35 PM
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Quote:
Originally Posted by PaulsChevy64SWB
I've heard once you use a solid, all your reliability goes down the drain.
I agree with ericnova here. Solids are the way to go. I used a Comp 282S in in a 350 and it was great. I checked the valves a couple times a year and in two years I had to adjust the valves on maybe four cylinders. I also used the 280H in that engine when I first built it. It too worked very well for me.
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