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Discussion Starter #1
Help! I'm seeking some other opinions as to what's up with my car. here's the stats. 1970 4v closed chamber Cleveland. motor is fresh(less than 100 miles since complete overhaul). here's the scenario. when i first start the motor the rpm's shoot up to about 1700 then without touching anything after about 15 seconds the idle drops down to where it stalls. I turned the curb idle screw in a little and it's the same thing. i checked for vacuum leaks at the manifold to head area and the carb base plate, no leaks present. i closed off the pcv hose with some hose pliers and the car died immediately. i covered the air horn and it dies almost immediately. I just replaced the power valve and re-jetted the carb. it's a 600 holley. I pulled the #1 plug out and it is very sooty. like its way to rich but i ran the air/fuel mixture screws in and turned them out 1 1/2 turns. same thing happens. it's got a healthy cam but i have no power accessories that require vacuum except the headlight system. but for this scenario i have plugged off the nipple that the h/light hose connects to. I'm stumped. i,ve got the fuel pressure regulated to 6.5 psi and 10 deg initial timing. what the hell am i missing?
 

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sounds like rockers are too tight, did you set them up again after the break in, hyd. lifters are weird that way. It happened to mine, wouldnt idle worth a $hit, did a running rocker tighten/loosen, and it ran ALOT better. Do one side at a time, and get the rpm down low enough so it idles,and a few rockers at a time then shut it down (could cause fire and lots of smoke). Just a sugestion.

Rick
 

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Discussion Starter #3
Thanks for the suggestion, I just finished installing the .030 pedastal shims on all rockers after reading your reply to my post. when I assembled the motor I checked lifter preload with a dial indicator. It was at the max of .060", so I felt that your reply may have had some validity. Unfortunately the f&*$ing piece of s^#@ is still acting up. I've encountered this type of problem on a customers car at the shop I work at, but I never got to finish finding out the cause due to the customer not wanting to pay for the time. I also used modeling clay on the piston tops to check for piston to valve interferrence. it does not misfire or pop or anything like that. I used Victor gaskets on the cylinder heads and sprayed them with permatex hi-tack sealer, I'm wondering if anyone else feels that they need to be retorqued? Or any other suggestions? AAAHHHAHAHAHGHGHGHGHGHGHGH.
 

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Sounds like a bad power valve, but you replace it already. See if you can get a hold of another carb to try out. It seems like you have eliminated vacuum leaks as a problem.

Some Holleys had "backward" idle mixture screw adjustment. Turn out to lean and turn in to richen. Also a Holly should be in adjustment with only 3/4 turn on the screws. Anything more than that and you usually have vacuum leak problems.
 

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Discussion Starter #5
Thanks for the reply and advice. since my last post i have done just that, acquired another carb. the carb was the only variable left in the equation whose integrity was suspect. I borrowed a 650 double pumper with 4 corner idle circuit from my brother. Thanks again to the forum and it's members.
 

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Discussion Starter #7
Success! the 650 worked just fine. stable idle & decent vacuum for this cam(about 16.5 in.). now all that is left is to dial in the advance curve. Thanks again for all who read and responded. Somtimes0 it takes another persons perspective to point you in the right direction!
 
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