Engine Heat Riser Tubes with holes --Compression Loss? (Pics)
#1
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Greetings to all Cats. I am still restoring my old 77 XJ6, and was about to install the rebuilt carbs when I noticed that those 6 small heat riser tubes (is there a better name?) which come up from each of the 6 cylinders......well, the main horizontal tube has some small rust holes in it. Pics:
![](https://cimg6.ibsrv.net/gimg/www.jaguarforums.com-vbulletin/1600x1200/sta70346_bd3cda748fbf19803586d539aeb11f1cf4f737fa.jpg)
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In the pic below, you can see where a prior owner had cut the pipe going to the "air pump" and just crimped it. My question is: Do these 6 small pipes run down to the 6 engine cylinders to pick up gas fumes/emmissions from the combustion process? So, if the pipes have small rust holes, then the engine will be losing compression, right?
Even this crimp was "jerry-rigged".....would have been better to solder a metal cap to the end of it, as this crimp could also be leaking:
![](https://cimg7.ibsrv.net/gimg/www.jaguarforums.com-vbulletin/2000x1504/sta70343_d99197e6210795ce5ec0594208567b362b4deedd.jpg)
So, I sanded the pipe down, and used some ole JB Weld on the holes:
![](https://cimg9.ibsrv.net/gimg/www.jaguarforums.com-vbulletin/2000x1504/sta70357_3305eaf035b6d2a2e43afe007deef750fede450c.jpg)
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Any replies would be appreciated......whether cylinder compression is lost through this tube or not.
Thanks.
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#3
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DD.......Thanks for that bit of information. With the small pipes being fitted down beside the spark plugs, it seemed that it was going straight down to the cylinders. Way better that they go down to the exhaust ports, I suppose before the exhaust manifold.
So, those rusty pipes were only leaking a bit of healthy carbon dioxide and unspent gas fumes, and no compression loss. Good news. On with the carb install...............
So, those rusty pipes were only leaking a bit of healthy carbon dioxide and unspent gas fumes, and no compression loss. Good news. On with the carb install...............
#4
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Since it is useless anyway, why not remove it and plug the resulting holes in the head?
I plugged mine with these:
https://www.ebay.com/itm/10PCS-304-S...MAAOSwHHFY~ZQi
I plugged mine with these:
https://www.ebay.com/itm/10PCS-304-S...MAAOSwHHFY~ZQi
Last edited by Nanonevol; 05-19-2018 at 06:29 PM.
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Roger Mabry (05-19-2018)
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Solved, so long as you keep it and not choose sell it to a buyr ina "nanny" state.
I figured out a loop hole in the registration of two past critters to "ditch" the pump and it's plumbing. In another, I "dummied" the rotten pipes well enough to pass...
Carl
I figured out a loop hole in the registration of two past critters to "ditch" the pump and it's plumbing. In another, I "dummied" the rotten pipes well enough to pass...
Carl
Last edited by JagCad; 05-21-2018 at 11:04 AM. Reason: repair typo
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