Re: Port Matching Exh ports on 340/360 heads
[Re: domingo]
#1246166
06/06/12 12:55 PM
06/06/12 12:55 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
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Master
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Romeo MI
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Quote:
suggestions on how to make the short turn better?
Do I risk hitting any water jackets? Places to watch out for thin spots? How much can I poen them up all around? 0.060"?
Behind the short turn is water.... just make that a bigger radius... the top has a pretty sharp edge that needs a better radius... basically your trying to make a straight run out of it(but you cant)
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Re: Port Matching Exh ports on 340/360 heads
[Re: domingo]
#1246168
06/06/12 01:09 PM
06/06/12 01:09 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
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Quote:
Thanks!
and how can larger can I make the ports all around? How much is safe?
Dont know a number but dont go stupid on the bottom short turn or the top where the spring is on the top
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Re: Port Matching Exh ports on 340/360 heads
[Re: MR_P_BODY]
#1246169
06/06/12 02:03 PM
06/06/12 02:03 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
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DO NOT port match the bottom 1/3 of the runner. It may even decrease flow.
Any port matching will be worthless unless you open up the valve bowl. That's the choke point.
On the exhaust side you want to leave the port a little smaller than the gasket and then make the header or exhaust manifold slightly larger than the gasket to give you a step to reduce reversion. But don't touch the bottom of the port window!
Look up articles about porting LA heads on the internet. There is a wealth of information out there, some of it true.
R.
Last edited by dogdays; 06/06/12 02:06 PM.
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Re: Port Matching Exh ports on 340/360 heads
[Re: domingo]
#1246174
06/06/12 06:56 PM
06/06/12 06:56 PM
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Joined: Jul 2006
Posts: 4,595 On the south side of Nowhere
S/ST 3040
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Don't enlarge the exhaust port at the exit, at all. The later the head casting, the better.......... (894, 915, 587, 974, 596, 051, 308)
Short turn is non-exsistant on early heads. The best you can do is "roll" as big of a radius on it as possible off the seat. Don't cut EGR bumps out of the floor but, if they are drilled, plug them. (late heads)
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Re: Port Matching Exh ports on 340/360 heads
[Re: S/ST 3040]
#1246175
06/07/12 02:45 PM
06/07/12 02:45 PM
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Joined: Aug 2004
Posts: 2,128 sweden
sshemi
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sweden
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Quote:
Don't enlarge the exhaust port at the exit, at all. The later the head casting, the better.......... (894, 915, 587, 974, 596, 051, 308)
Short turn is non-exsistant on early heads. The best you can do is "roll" as big of a radius on it as possible off the seat. Don't cut EGR bumps out of the floor but, if they are drilled, plug them. (late heads)
why wouldnt he want to make the port bigger at the exit???
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Re: Port Matching Exh ports on 340/360 heads
[Re: sshemi]
#1246176
06/07/12 10:42 PM
06/07/12 10:42 PM
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Joined: Oct 2008
Posts: 235 Glendale, AZ
Dave W
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enthusiast
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Posts: 235
Glendale, AZ
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What head porter is best known for obtaining the most power potential out of a factory set of small block heads? This video is very impressive! Does anyone know the details on this paticular combination? 644 hp with modified stock heads, intake, carb, exhaust manifolds while running the factory air cleaner assembly...that is AWESOME! http://www.youtube.com/watch?v=I1gswAFxcBc
Last edited by Dave W; 06/08/12 07:33 AM.
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Re: Port Matching Exh ports on 340/360 heads
[Re: Dave W]
#1246178
06/08/12 08:44 AM
06/08/12 08:44 AM
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Joined: Sep 2004
Posts: 2,094 oberlin, Ohio
Rapid340
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oberlin, Ohio
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Thanks for the compliment, I ported the heads and intake, Scott Koffel did the valve job and final blend to the seat. The motor is apart at the moment and as a matter of fact I am making a slight change to the intake short turn.
On the exhaust gasket match, the 308 exhaust has a really nice short turn and port shape in general. I would do a clean-up on the runner. Raise it to the gasket and widen it just to clean up. After cleaning up the short turn dont make it any lower just to match a gasket(I would not go all the way to the gasket shown on the width, especially the shared wall of the two center ports, but I dont think you would hit water).
Last edited by Rapid340; 06/08/12 10:04 AM.
1971 Factory Appearing Duster 340 11.000 @ 122 mph
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Re: Port Matching Exh ports on 340/360 heads
[Re: Rapid340]
#1246179
06/08/12 09:28 AM
06/08/12 09:28 AM
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Joined: Oct 2008
Posts: 235 Glendale, AZ
Dave W
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enthusiast
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Glendale, AZ
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Thanks for the feedback. Are you running a 800cfm thermoquad and is that the current set-up in your Duster?
Last edited by Dave W; 06/08/12 09:39 AM.
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Re: Port Matching Exh ports on 340/360 heads
[Re: Dave W]
#1246184
06/08/12 10:54 PM
06/08/12 10:54 PM
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Joined: Sep 2004
Posts: 2,094 oberlin, Ohio
Rapid340
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oberlin, Ohio
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Dont want to take over this guys post, I will PM you.
1971 Factory Appearing Duster 340 11.000 @ 122 mph
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Re: Port Matching Exh ports on 340/360 heads
[Re: Rapid340]
#1246186
06/09/12 11:30 PM
06/09/12 11:30 PM
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Joined: Jan 2003
Posts: 9,672 Lima, Peru
domingo
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Lima, Peru
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Quote:
Dont want to take over this guys post, I will PM you.
please post all details you want here! your build is impressive!!!
Id like to know too.
I have to build some stock looking small blocks and I would defintely want to buildonelike yours!
I have a 71 340 I will hgave to build for a cuda.
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Re: Port Matching Exh ports on 340/360 heads
[Re: cheapstreetdustr]
#1246189
06/10/12 07:47 PM
06/10/12 07:47 PM
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Joined: Sep 2004
Posts: 2,094 oberlin, Ohio
Rapid340
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oberlin, Ohio
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Domingo, thanks for the compliment and interest but I dont want to give out my build details and to be honest most of the work is porting heads, intake, exhaust, plus cam timing, carb mods ect). PM me if you want some basics, or if you like I would be willing to build one for you if you could come up with reasonable shipping arrangements.
Tom, we made hotel reservations but on friday when checking main bearing clearances I found I needed to order a different set of bearings so I lost this weekend and wont quite be able to make it in time (and I am not willing thrash and come out without a little bit of shakedown). Will really miss being there with you guys.
Cheap, a 360 block is acceptable.
1971 Factory Appearing Duster 340 11.000 @ 122 mph
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Re: Port Matching Exh ports on 340/360 heads
[Re: F1Scamp]
#1246191
06/11/12 01:47 PM
06/11/12 01:47 PM
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Joined: Sep 2004
Posts: 2,094 oberlin, Ohio
Rapid340
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Joined: Sep 2004
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oberlin, Ohio
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Quote:
Jeff you should still come up, hang out, watch some racing, party,and show me what the hell I am doing wrong with this tq....
Brian you cant be refering to my old carb (the one you set the SB record with). I think you at least have a clue on how to tune it.
On a more serious note, if I do make the trip I will be happy to help.
Domingo, PM with the octane you will be running and I will reply with a solid 11 sec recipe.
1971 Factory Appearing Duster 340 11.000 @ 122 mph
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