| Moderated by: Greg Fletcher | ||
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Jim Mckeon Member 
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I have a leak on the #4 port of my original 32 year old exhaust header on my '74 JH. Not uncommon , as I understand. My questions are: Is the engine in any sort of jeopardy of damage, such as a burned valve, if I drive the car until I replace it, and what is the degree of difficulty in replacing it with the newer ones that are available ? Any and all help would be apreciated. Thank you.... |
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Brett Gibson JH5 20497 Member
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Jim, doing the exhaust header is a major PITA, the steering shaft has to come out, and then you need to attempt to reach all the nuts holding it on, and as you can imagine 32 year old nuts trying to get them off without snapping the studs is going to be difficult. Check the club garage under Engine Performance, Greg did a complete write up on this subject, even with photo's, personally I would wait if you can live with the noise to do the job in combination with something else, clutch what have you, and pull the engine doing it all at once. Good luck, Brett. |
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colinw59 Member 
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This is indeed a royal PITA, probably the hardest on a JH. On 15851 I re-installed the restored header with the engine in place. The front header is difficult, the rear is the problem. I had to use a series of extensions and knuckles to locate and tighten the four nuts & washers. If I remember correctly you can't reach these, so it's all done remotely with tools. Don't forget to use Permatex's 'Ultra Copper' on both faces of the header gaskets, which you will of course change. The rack has to be loosened and the steering shaft removed. Make a note of the orientation of the knuckle, if you put it back the wrong way it will foul on the bottom of the left cam cover. Turn the radio up and live with it if you can until something else fails that requires engine removal , if not good luck, Colin. http://jhppg.com/gallery/74-Jensen-Healey-15851 |
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LambandAndy Member 
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Jim, I just did this a couple of months ago with the engine in the car. I had to jack the engine (make sure you have enough slack in wiring, hoses, etc) a good two inches to get the old header out (I think it was an aftermarket). The new header (from JHPS) required less clearance to go back in. I was able to get to the lower studs on 3 & 4 from under the car without too much difficulty, but I did have the advantage of having pulled my cylinder head a few months back and having coated the studs with a liberal coat of anti-seize. 30/60 offset and stubby wrenches would be good to have on hand. Give everything a good soaking in release oil (I like PB Blaster or Kroil) a couple of days before you start. While the engine was jacked up I took the opportunity to replace the engine mounts and I also found that the lower bushing on the steering column was shot so replaced it (I turned one up out of bronze). I had to shim the exhaust side engine mount and the transmission mount (fender washers work fine) to get clearance over the front subframe, but other than that, the new header fitted very nicely. Once I had it back together the car ran so much nicer. No more popping on the down shift and, once I tweaked the carbs back in, it was much smoother and an extra 3 mpg too! Make sure you check out Greg's article (he did it with the transmission removed) and have plenty of vino on hand. Good luck. Andy |
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Ron Earp Member 
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I'd spend the extra 1-2 hours and pull the motor. Then you'll have a much easier time doing all the things that need doing and won't be doing it on your back. I bet you'll save time in the end and you'll be able to do some other maintenance things easily. You can unbolt the driveshaft from the tranny and simply pull it all as one unit. Removing the four bolts that hold the hood on will make life easier, as will removing the four that hold the radiator in and pulling it. Good luck. |
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Jim Mckeon Member
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Thanks guys for the imput. I did check out the club garage article as well. On the "vino scale" I think this job will rate a full case of "two buck Chuck"!! ( that is a Caifornia wine that they sell at Trader Joe's for those of you whom may never have heard the term) |
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