'68 Chrysler 318 / 210 HP Unusual Misfire
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=15996
Printed Date: November-27-2024 at 1:13pm
Topic: '68 Chrysler 318 / 210 HP Unusual Misfire
Posted By: 71Nautique
Subject: '68 Chrysler 318 / 210 HP Unusual Misfire
Date Posted: December-07-2009 at 4:11am
We just got a '68 Barracuda with the 210 HP Chrysler 318 with some problems which have me stumped. It misfires badly below 2,000 rpms, starts to smooth out above that, misfires some around 3,000, but runs just great above that, including wide open (4,600 with 12x15 cup)! I put all new tune up parts on it (plugs, points, condenser, rotor, cap) and the misfire is actually a little worse now, but the topend rpms are higher! I'm having the Carter AFB rebuilt now because it needs it (its leaky), but I don't think that's going to solve the problem.
The engine has decals on the exhaust manifolds with tuning specs including valve lash adjustment recommendations. Does this engine have solid lifters that need to be adjusted periodically? If so, could that cause a strange problem like this?
Also, the engine doesn't warm up like it should even in 60 degree water and air, so I spent $ on a new 145 degree thermostat, but that didn't change anything. The temp gauge looks like it goes to maybe 90 degrees and my infrared temp gun indicates that the front of the cyl heads after an hour of running are only about 110 degrees. The water circulation hoses seem to be in the correct places for this engine.
I will appreciate any advice or insight on these problems.
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Replies:
Posted By: Luchog
Date Posted: December-07-2009 at 8:51am
have you checked the timing?
are you sure that after the tune up you put all the plug wires back on the correct order?
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http://www.correctcraftfan.com/diaries/details.asp?ID=2095" rel="nofollow - 1980 Ski Nautique
Commander 351W
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Posted By: 71Nautique
Date Posted: December-08-2009 at 1:54am
Hi,
Thanks for your reply. We haven't checked the timing yet. I was very careful with the plug wires, but I rechecked them with the Chrysler engine manual we have with my sons looking on. I didn't think it was the wires because the engine runs and sounds so good above 3,000 rpms. My tuneup seems to have made it run even rougher than before in the lower rpms, but much better (perfect) above 3,000. I'm still not certain about whether this engine has solid lifters that need adjusting and if that could cause a problem like this. Still, just my tuneup affected it as described above with no changes to timing or lifters.
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Posted By: Luchog
Date Posted: December-08-2009 at 2:22am
check the timing and that the points are gapped to spec.
You could also pull some plugs and see how they are burning so'll know if any carb tune-up is also needed.
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http://www.correctcraftfan.com/diaries/details.asp?ID=2095" rel="nofollow - 1980 Ski Nautique
Commander 351W
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Posted By: 8122pbrainard
Date Posted: December-08-2009 at 9:12am
Larry,
When you opened up the distributor, did you take a look at the mechanical advance? They can rust up and need some oiling. You may also have a broken spring?
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54 Atom
/diaries/details.asp?ID=2179" rel="nofollow - 77 Tique
64 X55 Dunphy
Keep it original, Pete
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Posted By: 71Nautique
Date Posted: December-09-2009 at 1:11am
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Hi. Thanks for your response. Yes, I completely disassembled and cleaned the mechanical spark advance. It was rusty, but was apparently working to begin with. The springs had a light coat of rust, but were not broken. I'm very familiar with maintaining this part of the distributor as my '71 Ski Nautique has the same thing in the distributor on its Chrysler 318. I'm hoping to get the rebuilt carb back soon and the reconditioned prop and strut and then I hope to run the boat at least one more time this year. If we can't figure this out, it will have to wait for Spring. Please let me know if anyone has any ideas on this problem. Thanks again!
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