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factman10
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| Joined: | 05-28-2014 |
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I had my '73 off the road for about six months. It started up again with starter fluid but would not run on. I dismantled and cleaned both Strombergs and got it running again fairly well. Now the problem is that as I get up to about 3500 rpm the car hesitates and misfires. Changing up gets me back to smoother running and acceleration again up to 3500 rpm. Is this likely a carb problem, an ignition issue, or timing? I have something called MSD electronic ignition on the car.
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Jensen Healey
Super Moderator
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I'd guess clogged fuel filter. It can't pass enough fuel to run at high rpm.
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Frank Schwartz
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Clogged fuel filter....or....fuel pump going bad???
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factman10
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Many thanks. I will check the filter and replace. However, the car seems to rev up OK in neutral, I only experience the hesitation while driving.
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Tom Bradley
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Possibly something bad in the vacuum system? The amount of vacuum to the carbs and distributor is different under load. Possibly a hose split or something did get not connected up correctly when the carbs were replaced? Also make sure the o-rings between the carbs and the intake manifold are seated correctly. It is easy for one to slip during installation.
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factman10
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Thanks for these suggestions. I did experience difficulty in holding the "O" rings in place, so I will check them again. At the moment I have simply sealed off all the vacuum lines to the carbs and the MSD ignition system has no vacuum connection to the distributer.
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redracer
Member
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If you have SKYPE, most of these problems can be fixxed fairly easily(mine is rockclimber52). A vacuum gauge would be useful as well as a unisyn(I assume you have rebuilt the carbs in the last 6 years?)
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Frank Schwartz
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Re...holding the ruber o rings in place... I usually take a bit of rubber cement and stick them inplace and let the bit of cement dry...hen they stay in place whenn you put the carbs back inplace....works for me...
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factman10
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Good idea Frank. At the moment I am rebuilding a spare set of carbs to replace those currently on the car. I will use your trick when I put them on. I also plan to replace my fuel filter with a transparent body unit so I can observe any sludge.
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factman10
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Hi, I have requested to add you to my contacts. At the moment I am rebuilding another set of replacement carbs and then I plan to check out any fuel blockages. If I still have issues I hope I can call you. Thanks - Brian
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Jensen Healey
Super Moderator
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My clear fuel filter catches small bits of rust on the screen that are hard to see since the screen is brass colored. It tends to weep slightly but seems to work ok. It is satisfying to empty the particles into a pan, but a standard fuel filter might be more efficient.
Kurt
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Tom Bradley
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I am a bit late with this reply, but using glue to hold the O-rings is not a good idea. As the mating surfaces come together, the O-ring is supposed to move as necessary to fill in any gaps. Coating the o-rings with grease makes them sticky enough to adhere to the metal, but also allows them to move as necessary. (I used to work with high-vacuum systems for testing satellite systems and this is what everyone did. The requirements there were rather more severe than in a JH, but I think that adding rigid glue is making the possibility of a small leak all too likely).
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Frank Schwartz
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I beg to differ...holding o rings in place with grease may work for some but it also allows them to slip....just using a dot of rubber cement in three or four places holds until the carbs are bolted up...and the rubber cement is of such tiny amount it will move a bit if necessary.....works for me...
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factman10
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Thanks everyone for the good tips. I just installed my other set of clean and re-gasketed carbs. Also back flushed all fuel lines filters and the pump. (Quite a lot of crud came out). The "O" rings I stuck in place with the help of high temp, non setting silicon gasket cement. All seems well again and I am on the road.
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