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2012-05-30 02:51:31 |
Duplex manifold
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Peter
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Kind Sirs - could anyone weigh in with advise on how to go about removing/closing off the tube and periferals leading from the rear exhaust manifold over to the intake? If one fashions a metal plate and sandwiches it between the gas return tube and where it affixes to the exhaust or the intake, will that do the trick? Will this modification affect the tune of the car and should any other adjustments be made to improve its driveablity after this modification. Also, I have read and observed that there's a hot water hose going into the intake manifold to heat up the air as it enters the engine, if memory serves. Why have I always been lead to believe that colder air is better for combustion due to density? '68 2+2 |
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2012-05-30 08:00:36 |
Duplex manifold
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Dick Maury
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Jaguar has a cast aluminum piece that fits on the later cars, no use fabricating one. However, if you remove and blank off this piece with a flat plate, you will have to remove the secondary butterflies or you will have severe driveability problems. The Jaguar piece will work as it is not a plate but a pass through. Dick Maury, Rebuild Department, Coventry West, JCNA President |
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2012-05-30 13:56:50 |
Duplex manifold
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Peter
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Would you happen to know where one can be found? I have searched online for this cast alluminum piece and have found nothing. |
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2012-05-30 14:48:10 |
Duplex manifold
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Preston Garner
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I fabricated mine from aluminum stock, and removed the secondary butterfly plates. I put headers on the motor. The "Jaguar" emblem is a key chain that I glued to the plate. 1960 Mark IX 1968 E-type |
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2012-05-30 14:53:07 |
Re.: Duplex manifold
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Preston Garner
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Edited on 2012-05-30 14:57:53 Sorry, the photo did not upload. 1960 Mark IX 1968 E-type |
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2012-05-30 15:07:20 |
Re.: Duplex manifold
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Dick Maury
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Here is a shot of the factory piece. If you use flat stock, the secondary butterflies must be removed. You should also consider replacing the rear exhaust manifold with the earlier style as the flat boss where the crossover bolted on will still be there. You can call 800-331-2193 ext.210 if you want any of these pieces. Dick Maury, Rebuild Department, Coventry West, JCNA President |
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2012-05-30 15:26:42 |
Re.: Duplex manifold
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Preston Garner
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Dick, That is pretty cool. What is it called, part number, etc. I may want to buy one in future, as a just in case. 1960 Mark IX 1968 E-type |
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2012-05-30 16:42:41 |
Re.: Duplex manifold
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Dick Maury
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Not sure of the part number as this is used. Last one I have also. But then, who knows what the future holds. Dick Maury, Rebuild Department, Coventry West, JCNA President |
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2012-05-30 20:07:27 |
Re.: Duplex manifold
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David Barnes
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I removed the secondary butterflies from my '68 FHC several years ago but left everything else ( cross over pipe, rear exhaust manifold etc) intact. I am delighted with the improved throttle response with only the secondary butterflies deleted. Is there additional advantage by removing the crossover pipe and changing over to the Series II '69 configuration with the blank off piece and one piece rear exhaust manifold ? David Barnes |
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2012-05-30 20:41:41 |
Re.: Duplex manifold
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Michael Frank
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The easiest thing to do is to simply disconnect the secondary linkage and wire them open. Cool air is "better" if you can control the fuel charge to match air density. Cars, especially older cars, heat the intake charge to a relatively constant temperature by circulating coolant through the intake manifold. This is in part because carburetors can't be precisely regulated to temperature. The second benefit is that the fuel vaporizes. Vaporization not only gives smoother operation, it requires a great deal of energy. The energy comes from the hot coolant, and has a measurable impact on cooling system efficiency. The point is that some heat helps. |
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2012-06-02 13:12:10 |
Re.: Duplex manifold
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Josiah Bartlett
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I have a 1969 E-Type that does not have the crossover to the Exhaust. Was this an "improvement"? I am considering eliminating the secondary butterfly maninfold either by removing it, wireing them open, or just removing the butterfly plates themselves. Obviously removing the secondary manifold affect the intake port length. Is this shortening a good thing or not? Will eliminating the additional intake heating that the car gets from this secondary manifold hurt the performance? |
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2012-06-02 13:31:34 |
Re.: Duplex manifold
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George Camp
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That was version two of the Ex/Em engine--see the Judging guide for the S2 cars! JCRC SE Member JCNA Publications JCNA Authenticity help lineJCNA RD SEVp JCNA |
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2013-02-25 21:00:51 |
Re.: Duplex manifold
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John Lynch
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Dick Maury, stated 2012-05-30 15:07:20 "Jaguar has a cast aluminum piece that fits on the later cars, no use fabricating one. However, if you remove and blank off this piece with a flat plate, you will have to remove the secondary butterflies or you will have severe driveability problems. The Jaguar piece will work as it is not a plate but a pass through." Is this part in photo still available to buy? -- if so where? Is there a similiar shaped piece to cover exhaust manifold opening after removing the cross-over? Alternative is to replace the rear exhaust manifold. Jaguar e-type 1968 series 1 1/2 coupe |
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2013-02-25 22:58:23 |
Re.: Duplex manifold
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Dick Maury
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Why don't you give me a call. 800-331-2193 ext.210 if you are interested in the part? Dick Maury, Rebuild Department, Coventry West, JCNA President |
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2013-02-26 00:12:16 |
Re.: Duplex manifold
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John Lynch
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Edited on 2013-02-26 2:48:28 Edited on 2013-02-26 2:43:15 Edited on 2013-02-26 1:25:44 Edited on 2013-02-26 1:24:19 Dick, what part is fitted for the rear exhaust manifold when the crossover is removed? Why does your plate have a bulge per photo? -- why is it not flat? Jaguar e-type 1968 series 1 1/2 coupe |
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 cover plate for removal of duplex manifold on inlet manifold |
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2013-02-26 06:44:33 |
Re.: Duplex manifold
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Peter Crespin
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As Dick said and Mike Frank's pictures shows - the system routes mixture over the engine and back, to bypass the closed secondaries. The bulge plate does not stop this like a flat plate would, it merely short-circuits the route across the engine but you still need flow as long as you have the secondaries. You swap the exhaust manifold just because it looks odd - there is nothing that needs to be blanked off. A flat alloy plate would mean the engine would be strangled until the secondaries opened so to use one yu have to jam the secondaries open. Removing them requires dismantling the intake system and means the spindles can now slide sideways and come a bit loose. Assuming your secondaries still have a return spring around the spindles you can get most of the benefit by just disconnecting the linkage at the little retaining washers and turning the link forward to jam the secondaries fully open against the manifold. No wire, no nothing, takes five minutes, max. Car accelerates much better and I probably won't bother fitting triple SUs to a Federal S2 from now on. Pete Crespin, Gaithersburg, MD 66 D-type, 69 E-type OTS, 60 MkIX 2x70 FHC |
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