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Discussion Starter · #1 ·
I got the engine installed and started and ran it for about 30 minutes. The engine was running very poorly, much to rich, in fact the tail pipe and all the plugs are black with soot. Rechecked the timing, working on the carb again. I checked the compression and six of the cylinders read 150lbs (1,2,3,4,7,
one is 160lb (#6) but one is only 130lb (#5). Maybe the rings are not seated yet or the cylinder was washed with gas and hurt the wall. I then used a leak down tester and the leak is past the rings, the valves are not leaking. Usually I run an engine 500 miles or so before I check the compression to give everything time to seat but with the way it was running I thought it would not hurt.

Now the question, should I pull the head and check the cylinder wall for the low one or just get the carb right and run it some more to see if the rings seat in that one cylinder.
 

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I think i would run it for a while and give it a chance. First thing to do is to sort the fuel prob.It will always run poor if the plugs are black.
 

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Fix the timing and get the carb adjusted, changed the oil and filter now and then just start driving it. Best thing for it. Change the oil again in 500 miles and check it then.
 

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Keep running it then after 250 or 300 miles if the compression hasn't evened out, then pull the head and check the cyl walls...


FE
 

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Is the choke opening?

Can you see fuel running down the carb, maybe bad needle/seat or float level?

Something isnt right, I wouldnt chase compression yet, they'll run on very little, you are flooding the motor somehow
 

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Discussion Starter · #6 ·
I went and picked up my spare carb which was just rebuilt and plan to try it when I can get home from work before dark. These 12-16 hour days are killing me. I will try a wet commpression check before I reinstall the plugs and make up my mind from there. I would think if the wet check is just a bad that I have a broke ring or land.
I just don't want to go over the road with the motorhome if that is the case. If the wet check shows an increase close to the other cyl. then I hope it is just a cyl. not yet seated. Thanks for the assistance and does everyone think I am on the right track???
 

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Install the new carb get it properly adjusted then do a wet check.
Yes you're chasing it just fine!



FE
 

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Can you beg, borrow or steal a known carb and ignition system from a bud with a similar 460 for a day? Knowing that you can eliminate one or the other as a cause of the problems is muy importante...

Check the choke for proper operation. Check to make sure the PV isn't dumping raw gas in the manifold at idle -- can be a problem when you use an aggressive cam with a stock-ish carb. A PV for a typical car is set to open at a low vacuum which you now have most of the time. Go to a lower numerical to keep it from dumping.

Check your static timing. If the engine is retarded or not putting full voltage to the coil ... and eventually, the plugs ... it will feel flat and load up like a [email protected]#4er, and the more you drive it the worse it gets.

Wet check your low cylinder, too. There is a trick to get it to reseal but I wouldn't do it unless it looked like you were staring at a teardown.

Make sure you're not working against a vacuum leak, it will throw off your best tuning efforts. It's easy to chase with a little starting fluid.

Make sure the plugs aren't wet with oil. 385 series have ports that seal uncomfortably close to a lot of hot oil splash, and if the gasket shifted and you're sucking it in, wetting the plug permanantly.

No prescriptions, just things that happened to me back in the dayyyyyy.

BOB
 

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Discussion Starter · #9 ·
Well completed the wet check and it was good, 175 wet again the others dry were 150-160 so I think that will be good. Now I have to change the oil and both oil filters in my dual oil filter system. I then plan to install by backup carb which has been rebuilt with all new gaskets and a new PV (6.5) which is more than low enough. I also will use ASF52C plugs to break in the engine which is one step hotter than stock to get thru the breakin period. Then switch back to ASF42PF which is the normal heat range and platinum at about 500 miles or one fuel tank full in that it is in a M/H with a 100 gallon tank. At that point the PV will be changed to a dual PV and I think it is a 10.5/5.0 PV. Timing will be at 10-12btdc. The cam is a Comp Cam 34-334-4 which is and 487 intake lift and a 493 exh lift for a good low end to mid range torque for pushing 18000lbs + a 8000lb trailer at times. THANKS for the inputs and advice. I felt a lot better with everyone saying to go for it....
 
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