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Port matching Edelbrock Exhausts |
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jpnjim
AMC Addicted Joined: Nov/25/2007 Location: New England Status: Offline Points: 2752 |
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Posted: Mar/29/2018 at 10:32am |
I'll try to post some pics from my phone after starting this thread,
but how much has everyone been opening up the exhaust ports on their Edelbrock heads to match their headers? The factory literature says the exhaust port is "CNC-profiled to match Fel-Pro #1434 exhaust gaskets", but it really is pretty small compared to the header gaskets I have here, especially the roof of the port, and also the dog leg. I understand the value of leaving a bit of a lip from the exhaust port to the header (helps with anti-reversion), but going from the Eddy heads to Doug's d103's (1.75") is much more than a small step up in size. Just knocking down the edges would probably not change much, and I don't know how far I can, or should change the roof line just to port match. Any input on this would be appreciated Thanks! |
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71 P-code 4spd Javelin/AMX
some Jeeps and some Fords |
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jpnjim
AMC Addicted Joined: Nov/25/2007 Location: New England Status: Offline Points: 2752 |
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^this is the Edelbrock 60119 head with the gasket that came with Doug's D103's attached. Difference is greatest at the top of the port, and ends of dogleg. Outside two ports are very similar to this
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71 P-code 4spd Javelin/AMX
some Jeeps and some Fords |
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jpnjim
AMC Addicted Joined: Nov/25/2007 Location: New England Status: Offline Points: 2752 |
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Here is the same gasket on the flange of the D103's. There is one small spot that I would clean up on the headers, but for the most part these match the gasket almost perfectly. Unless someone says otherwise, I would want to leave somewhat of a lip on the heads (head slightly smaller than the gasket opening), but would open up the top and dog leg of the heads so maybe 3/4's of the difference in size was gone. ^Are the ports thick enough on the roof for that? Is it worth doing? This will be about a 9:1cr 401 with a straight pattern 225-230 net cam, around 520 lift on 108* lobe centers, R4B & the D103 1.75" headers. Tigher lobe center cams appreciate a free flowing exhaust, so I don't want to leave food on the table so to speak by not opening up the port match a bit. Edited by jpnjim - Mar/29/2018 at 10:53am |
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71 P-code 4spd Javelin/AMX
some Jeeps and some Fords |
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jcisworthy
AMC Addicted Joined: Jul/23/2009 Location: North Carolina Status: Offline Points: 2805 |
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You should be able to match to that gasket without any problems.
The heads I got were much higher at the bottom compared to the header gaskets I have and if I were to match it there would have been about .080" on the bottom for gasket sealing.
I left the bottom and matched from sidways and up. With a valve job and porting the ports went low 190's without a pipe. Out of the box the exhausts flowed in the 160 range I think. |
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Specializing in dyno services, engine building, and cylinder head porting
rbjracing.com Phone Number 518-915-3203 |
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jcisworthy
AMC Addicted Joined: Jul/23/2009 Location: North Carolina Status: Offline Points: 2805 |
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Specializing in dyno services, engine building, and cylinder head porting
rbjracing.com Phone Number 518-915-3203 |
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amx2bfast
AMC Apprentice Joined: Aug/07/2013 Location: middlesex nc Status: Offline Points: 217 |
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a few years ago when they just came out, I had KP port them for me. I do not recall all that was done bit the exhaust ports look similar to the pics. I think the upper runners were increased a little bit. I have found them easier to seal because the header does not need to be modified as much.
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1975 gremlin
1973 javelin 1976 pacer wagon |
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jpnjim
AMC Addicted Joined: Nov/25/2007 Location: New England Status: Offline Points: 2752 |
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Thanks John! I was hoping you'd chime in I'm a little surprised how much more centered/higher your ports were to start, though I guess it could just be the bolt locations that shifted a bit at some point. I don't need to get too crazy with this build, but why bother using long tube headers and aluminum heads, if I'm going to leave power on the table leaving the small exhaust ports as is. I just wanted to be sure there was enough material up top to opening it up. |
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71 P-code 4spd Javelin/AMX
some Jeeps and some Fords |
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jpnjim
AMC Addicted Joined: Nov/25/2007 Location: New England Status: Offline Points: 2752 |
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Header seal is a good point (my current set up leaks now!) but since the non-dog leg side and bottom of these heads are already the same size, or bigger than the gasket I might as well open the ceiling up, where a couple more horses may be hiding. |
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71 P-code 4spd Javelin/AMX
some Jeeps and some Fords |
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gremlinsteve
AMC Addicted Joined: Dec/16/2008 Location: houston Status: Offline Points: 884 |
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I say go for it
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Ken_Parkman
AMC Addicted Joined: Jun/04/2009 Location: Ontario Status: Offline Points: 1814 |
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The Edelbrock exhaust has a quite small csa around the bend. In any case there is a massive expansion into the header so matching the flange without doing much more extensive porting is not necessary, and actually probably not a good idea. I'd not bother port matching.
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