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| starting an old GT | Rate Topic |
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| Posted: 06-25-2007 06:06 pm |
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1st Post |
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jonbenya Member
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I've got an old Jensen GT that hasn't run in about 20 years or so, the previous owner suspected that he had bent the valves. As it turns out the cams were never lined up properly after some work was done. I have the engine turning freely for the first time in 20 years, carbs rebuilt, alternator, starter, plugs etc. replaced; and I'm even getting spark...... but no combustion. With the carbs off I can get a little puff by shooting ether down the manifold, but it won't fire up. I've even gone so far as to put a little gas down into the chamber via the spark plug points. any idea what the problem may be?
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| Posted: 06-25-2007 06:42 pm |
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2nd Post |
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Jensen Healey Super Moderator 
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The carbs, fuel lines, pump, filter, and gas tank are all suspect. Probably full of varnish and gum.
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| Posted: 06-25-2007 07:19 pm |
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3rd Post |
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jonbenya Member
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that would be my suspicion to, but the carbs have been rebuilt and run beautifully on my 74 healy. the pump and filter are new and working properly, and the gas tank may be gummed up. I am currently using an external tank to try and at least get it to fire. all of the components are in working order as they have all been tested on my 74 healy, which is why I am having a hard time tracking down the source of the issue.
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| Posted: 06-25-2007 07:24 pm |
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4th Post |
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jonbenya Member
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All I want is to try and find a way to get the engine to fire up and idle and then I plan on rebuilding the whole thing. I'd like to ideally get it moving well enough that I can take it to Jensen East this weekend even if I have to trailer it to VA and then just drive it on the field. If need be I'll swap the motor with the Healey and do it that way but I really like the idea of keeping it's block in it if possible. Sadly I'm beginning to wonder if that's even possible. I would have thought that with some ether directly into the manifold it would at least fire up, but I'm not even seeing that....
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| Posted: 06-26-2007 01:59 am |
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5th Post |
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Judson Manning Member 
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Getting an LBC to fire after 20yrs is a HUGE boost to one's ego and provides unlimited motivation to getting the car back on the road! If the carbs are in good shape and you have fire, the problem is in one of two places: Either the timing is bad or there is insufficient compression (also a sign of wrong timing). Double check your timing and verify the plugs are firing in proper order while turning the engine by hand. You can check the valves w/o a leak-down rig with a 24" length of tubing and your mouth. Set the engine to TDC, pull plug #1, make a fairly tight connection with your tubing, and blow. If the chamber won't hold any pressure, the valves are either timed wrong or bent. Repeat with 3, 4 & 2 for each 180^ turn of the crank. We're pulling for you!
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| Posted: 06-26-2007 02:55 am |
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6th Post |
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Jensen Healey Super Moderator
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The plug wires in the wrong place got me once. Since the distributor is facing the rear the wires are connected 1-3-4-2 counter-clockwise if you're looking at the top of the cap. Of course the engine turns clockwise when viewed from the front. If the valve timing and compression are good and fuel is in the cylinders the spark may be weak. Check the white with slate wire from the solenoid to the coil. It gives full 12 volts during starting. Kurt
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| Posted: 06-28-2007 05:27 am |
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7th Post |
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jonbenya Member
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Absolutely a compression issue. I am holding very little compression right now so there's no way I'll be up and running in time, however I'm going to see if I can swap the engine tomorrow with one that should run. I'll let you guys know if it works out, thanks so much for the advice! I'm going to check the boards to try and find the best way to lift the engine.
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| Posted: 06-28-2007 01:26 pm |
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8th Post |
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Mitch Ware Member 
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Easier than lifting the engine, is lifting the car off of the engine (easier, that is, if you have a hoist that can lift that much) Just disconnect a few items and undo the four nuts/bolts that hold the subframe to the car. http://www2.kjware.net:8079/mitch/Install%20Engine%20005.JPG Mitch Ware #19670
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| Posted: 06-28-2007 03:37 pm |
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9th Post |
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jonbenya Member
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excellent idea, does anybody have more detail on how to do this exactly? What concerns me is getting the block out from underneath the body once it's lifted.
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| Posted: 06-28-2007 04:55 pm |
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10th Post |
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Jensen Healey Super Moderator
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You roll it out with the suspension attached after removing the driveshaft. The 4 attachment points are rubber isolated. Make sure you have new bushings in hand if you do it this way. The main issue with removing the engine the usual way is getting to the exhaust manifold nuts with the engine in place. I cut the exhaust pipe behind the wye and removed as a unit. If the engine and transmission are removed as a unit they are very long and the car must be very high off the floor to get them in or out. The transmission bolts are hard to reach in situ but do-able. Do not lift from the intake manifold. Remove it and use the manifold bolts and a chain. Good luck! Kurt
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