Air and Exhaust Question?

[swingerboy]

Hey guys

I have myself a 73 Dart. The car has a 318 engine with a 650CFM carb and a Performer intake manifold from Edelbrock. Currently, the car has a 9x2 air cleaner on it. Is this too small for the engine? Ive been having a high idle problem recently and for some reason a guy at school told me that it could be too small of an air filter. With the high idle issue, the idle screw doesnt seem to work! Its a new carb too. My neighbor who hotrods all the time came over and confirmed, the idle didnt seem to change when the screw is turned and yes its the right screw. Everywhere I go, people say it idles too high. What could this be? And please keep in mind my dart doesnt have a tach either. Lastly, with the intake and fuel setup I have, Im planning on getting Summit headers and exhaust for around $350 total. Will I need a bigger cam along with this? Or is it ok if I let it go for now? Honestly, im only 18 and lack the skills to do a full cam swap which is why im asking haha.

Thanks all for the help in teaching us youth on classics!
rayer:

 

[jefflock]

Just try and adjust the carb without the air cleaner in place. This should tell you if the carb or the air cleaner is the problem.
As far as idling to high have you checked for a vacumn leak?

 

[rumblefish360]

Good idea Jeff! Spray some WD-40 around the crab base and the along the intake to head mating surfaces. If the idle goes up, that is where the leak is. Also check the vacuum hoses.

If you find no leaks and the engine, Try removing the air cleaner. with it removed, readjust the idle. If you get good results, use a 14x3 air cleaner. This is a good size to step up to.

You do not need a bigger cam to use headers. You can use the stock cam with headers.
The Summit header and exhaust system is a good deal.

 

[67Dart273]

High idle as you describe, with a stock cam (IE the cam is not screwing with the carb metering)

is most likely one or a combo of
1--Vacuum leak. Use a combo of stuff to find. Use a length of fuel hose to your ear and probe around the base of the carb. Use a water spray bottle to "spritz" a fine mist of spray here and there at the carb base, which will change the idle if you find the leak. Don't forget to examine carefully any/ all vacuum hoses such as the PCV valve and brake booster if used. Plug them off, inspect, etc

2--Interference with the carb/ mount. Could be a combo of wrong base gasket interfering with throttle blades, linkage hitting the manifold casting and not allowing full return or even something bent/ etc with the carb linkage itself, AND..............

the throttle cable or kickdown linkage may not be properly adjusted in order to allow the throttle to fully close


So far as your "buildup," I'm REALLY happy with a mid--70's smog engine I bought off Craigslist in my 67.

70'ss turned out to be low miles smoggy engine, 200 bucks

Installed approximate equivalent of a 340 "stick" cam. Do NOT go "too big" on the cam when you get one

Cheap Hedman headers, which I won't buy again. Poor fit, no excuse

Torquelflite, as I can't row a clutch/ 4 speed anymore. I found a reverse pattern, manual valve body, "so it's still fun," LOL

3.7x rear gear and fairly tall tires gives me about 3200 at 70

600 -ish cfm carb worked great, but in my case went with Edelbrock injection I bought used. The threads:

http://www.forabodiesonly.com/mopar/showthread.php?t=205959&highlight=pro-jection

http://www.forabodiesonly.com/mopar/showthread.php?p=1969670768#post1969670768

And no, you certainly don't need a new cam to run headers, but the headers might be overkill without it. If you already have dual exhaust, I'd put a cam in first. If not, go ahead with headers first.

 

[swingerboy]

Something I remembered...The man who sold me the car told me that the car would need a throttle cable soon and a trans kickdown! Maybe i should get on that lol. Thanks guys alot! I appreciate it! I will do a full run through this weekend!