farmall Posted May 3, 2015 Share Posted May 3, 2015 Hey guys. My 72 mc with 402 left me stranded tonight. I think my carb MIGHT be the problem or at least one of the problems. I was going to replace the original quadrajet with an edelbrock replacement but wasn't sure what CFM I need. is 600 enough? It is a completely stock and will remain a stock engine as long as I own it. Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted May 3, 2015 Share Posted May 3, 2015 hate to see you just buy a new carb without even knowing what's wrong http://www.cliffshighperformance.com/ is awesome for Quadrajets a 600 should be enough for a stock 402, a 650 might be a better choice, you will need a adapter plate, a Edelbrock is a square bore carb where a Qjet is a spread bore and your manifold is for a spread bore carb Quote Link to comment Share on other sites More sharing options...
MCfan Posted May 3, 2015 Share Posted May 3, 2015 Sounds like you are not going beyond stock performance so why change carbs? If your Q-jet is suspect, get it checked out, repaired or rebuilt. If you anticipate chasing more performance I would strongly suggest the Edlebrock #1806 650 cfm AVS Thunderer Series over the Edlebrock 1406 600 cfm Performer Series which is calibrated for fuel economy. You can easily modify the 1406, of course, but if you plan to take it out of the box, bolt it on and forget about it, I think the 650 AVS is a better choice. It is more versatile in the range of manifold types that works well with. I run a richened 650 AVS on my modified 402 because it is more "streetable" than a 750 Performer series. If you really want to ditch your Q-jet, I suggest you call the Edelbrock support staff at (310) 781-2222 to discuss your engine and driving preferences with them and get their recommendation. Quote Link to comment Share on other sites More sharing options...
farmall Posted May 3, 2015 Author Share Posted May 3, 2015 great advice guys. I was in a hurry to get this fixed last night. I needed a little time to sleep on it. right now both of my cars are having issues: brakes on one and who knows what on my this one. I think I am going to try to get the brakes fixed on other and spend a little more diagnosis time on this one. The engine has a noise that I am afraid is some real trouble. It is also spitting and backfiring and acting like it is running out of gas. I was talking to 3 folks last night and they all said to start off by getting rid of the Qjet. So, while I was broken down at the parts store, I bought a 600 cfm carb before I left O reiley's. They said that it should be fine but I wanted to consult my friends on here before I actually put it on. The car was running great last time I drove it, about 2 weeks ago. I went to move it about a week ago and was having a terrible time, spitting and backfiring. Yesterday, while I was checking the points, I noticed a little black do hickey that was in a vacuum line going from the intake to the heater box. It was broken. I plugged that line and it fired up. It was making a squealing noise that I thought was the belts. While it was running fine, that noise was bothering me. Later, I realized that it might not be belts. I am afraid that I might have an engine failure on my hands. A spun bearing??? Anyway, we were on our way to a cruise in about 20 miles away and about half way there, the car started to feel like it war running out of gas. I made it to the parts store and changed the fuel pump in the parking lot. That didn't help. We started checking vacuum lines. Some were old and I was worried about more vacuum leaks so I started replacing those. That didn't help. It actually continued to get harder to crank. I decided to get a ride back my way from the cruise in to get the trailer. The guy I was riding with said "get rid of that quadrajet". Anyway, I am sure I will be in touch with you all about this. Thanks so much for all of your help. I am not sure what I would do without your help. Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted May 3, 2015 Share Posted May 3, 2015 when's the last time the fuel filter "in" the carb was changed? Qjets have a filter right past where the fuel line goes in the carb REMEMBER!!!!!! always check the easiest stuff first! to eliminate it from solving the issue after the fuel filter I would hook up a dwell meter to check the points and a timing light, if the timing chain is going on it your timing could be bouncing around, the light could show that the squealing noise is what I'm trying to figure out, sometimes what one person calls "sqealing" another may describe as something else any clattering? like a loose rocker arm? Quote Link to comment Share on other sites More sharing options...
mikenewman Posted May 3, 2015 Share Posted May 3, 2015 Jet Performance has a carb that is a direct replacement for the Q jet. When I changed mine over to a four barrel I used one. the one I have has up to 825 cfm. More than I will ever need. Out of the box on the car started up great. only ajusting I did was the fast idle Quote Link to comment Share on other sites More sharing options...
farmall Posted May 3, 2015 Author Share Posted May 3, 2015 I changed the fuel filter this week because it seemed like it might be running out of gas. I also changed the fuel pump last night. I will check the timing and let yall know. Clattering doesn't sound like a good description. More like a squealing belt or a frozen bearing. I am going to remove the belts one at a time to see if it could be water pump, etc. I really hope its not internal. Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted May 3, 2015 Share Posted May 3, 2015 well with it back firing... ignition, cam/valves/timing chain or lean fuel condition Quote Link to comment Share on other sites More sharing options...
farmall Posted May 4, 2015 Author Share Posted May 4, 2015 Well, I had good results today, at least with this car. It seems that my ac compressor and alternator were making some noises from work bearings. I did end up replacing the carburetor with an Edelbrock. The only think I have yet to figure out is how to get the AC fast idle solenoid to mount to the carb. I am guessing that Edelbrock can help with that. Do you all know of a source for a bracket for this? Thanks for all of the help. Quote Link to comment Share on other sites More sharing options...
Leghome Posted May 4, 2015 Share Posted May 4, 2015 Eldebrock does make a solenoid and bracket for that purpose. I have one my son in-law gave but have not gotten around to putting it on. I am still trying to figure out why to power it from. Quote Link to comment Share on other sites More sharing options...
farmall Posted May 4, 2015 Author Share Posted May 4, 2015 glad to hear that. I am also disappointed that my stock air filter assembly will not fit on it. Mine has the light surface rust that I like plus it would cover up some of this shiny carburetor. Do you know if there is some kind of spacer/ gasket that would be tall enough to use my stock setup? Quote Link to comment Share on other sites More sharing options...
GatorDog72 Posted May 5, 2015 Share Posted May 5, 2015 Sent you a pm, farmall Quote Link to comment Share on other sites More sharing options...
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