390 Compression, HP and Torque Est please

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Aug 17, 2004 | 06:38 PM

Azguy54

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390 Compression, HP and Torque Est please

Ok guys, got the bottom end together so here goes:

Deck Clearance: .030 (as measured)
Head Gasket Bore: 4.300 avg. (Victor Seal) Not round so est. of avg bore
" " thickness: .041
Piston Volume: 10.8 ccs
Cyl Bore: 4.080 (.030 over)
C8AE-H Heads 68.1 to 71.1 (From Steve's book)
Valves: 2.09 / 1.65

Cam: Comp Cams XE262H-10
Specs: Gross Lift, Int. .513 / Exh. .519
Duration @ .006 Tappet Lift, Int. 262 / Exh. 275

Valve Timing OPEN CLOSE
@ .006 Int: 25 BTDC 57 ABDC
Exh: 72 BBDC 23 ATDC

Duration @ .050 Int. 218 Ext. 224
Lobe Lift Int. .2980 Ext. .3010
Lobe Seperation 110.0

Performer RPM
Edelbrock 600 CFM
Hedmen Elite Headers

Hope that's all you need. Thanks guys, this site has been huge in helping me decide things on this build. Got a ways to go but it sure has been a blast as well as a great learning experience. My son loves coming over and working on this truck and that is a big big plus too. Hell, who knows, someday we may even drive the thing, ha ha.

Aug 17, 2004 | 07:17 PM

rusty70f100

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From: Iowa

I'll get back to you with the desktop dyno estimate since I'm at college now, but I can tell you something right now. If you're gonna run those stock heads with the performer RPM manifold, you'll have to port the heads to match, otherwise it wont flow good and it WILL hurt performance. See the thread "Porting Revisited" for more instructions.

Aug 17, 2004 | 08:15 PM

polcat

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From: Corpus Christi, Texas

I am running the same heads and intake Azguy54 I had to port out the intake side to get it to match. I am running a larger cam, but I can tell you a larger carb will also help if your looking for a lot of HP. Sounds like you got a good setup good luck!!

Aug 17, 2004 | 08:34 PM

Azguy54

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I took the intake gaskets and it looks as though the bottom of the head ports is slightly above the gasket. To check it out I made a template of the intake and there isn't a lot of "porting" to be done it seems. Maybe just "chamfering" the areas to match? I thought there would be a LOT more difference but there really isn't. am I missing something here?

As for the carb, we were looking at the 750 but we'll see how it runs this way first. If it seems to "starve" then we can take a look at the bigger carb. We were only using thsi carb because it came with the truck but was mounted on an old Edelbrock Streetmaster that has a hole in the water jacket just above the thermostat housing.

Aug 17, 2004 | 09:08 PM

polcat

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From: Corpus Christi, Texas

I ran a holley 600cfm on mine for a while it seemed to run good , yeah your right about the heads that will all you need I went a head and ported the hole head on the intake side but went to far on the exhaust side so I am making some more changes on my heads by installing the bigger valves. Mine is mostly set up for very little street and more race I am running a Comp 292H cam it has a very radical idle would not suggest it for a everyday driver.

Aug 17, 2004 | 09:28 PM

Azguy54

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My son will be driving mostly street with this one. Not looking to knock socks off but run "nice". Hence the mild build. I did several sets of small block heads back in the day when I was young and foolish. Concentrated on the exhaust ports more so then the intakes due to messing with the atomization of the fuel/air mixture. I take it that the same would hold true here?

Aug 18, 2004 | 09:18 AM

RapidRuss

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From: Smith Mountain Lake, VA

Well this is what the DD is telling me? I used 70ccs for the heads for an average..

CR- 9.83
Cam @ .006"
335HP @ 4500RPM
459LBS of torque @ 2500RPM

this is just a guesstamate...because there are know previsions for stock heads with large valve's

Some one who has a flow chart for the heads with the larger Valve's and the flow chart for the RPM intake, will come much closer...

Russ