Canuck Posted March 21, 2021 Author Share Posted March 21, 2021 2 hours ago, MC1of80 said: Still needs ported vacuum. Not direct. With the carb rebuilt it probably works much better. The issue may have not been as noticable with the worn carb. 5 and 7 plug wires in correct locations? Yes, I have checked all the plug wires. You are the second person today that asked about the 5 and 7 wires. I’ve never mixed them up but I suppose it is an easy thing to do. As for the ported vacuum there’s nothing I can say further than this is the original carb. I understand where you are coming from though and others have told me that my setup seems odd. 1 Quote Link to comment Share on other sites More sharing options...
1970mcss Posted March 21, 2021 Share Posted March 21, 2021 What is ported vacuum? For future reference. Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted March 21, 2021 Share Posted March 21, 2021 Ported vacuum is a vacuum port that has almost no vacuum at idle and increases in vacuum as the idle goes up as compared to constant strong vacuum port. 5 and 7 is a very easy mix up. The "popping" coming from the carb when racing up the engine concerns me. Sounds like a worn lobe on the camshaft. With a timing light hooked up and the vacuum advanced hooked up also, what is the timing at idle? 1 Quote Link to comment Share on other sites More sharing options...
Dtret Posted March 21, 2021 Share Posted March 21, 2021 Not to sound like a complete a..hole but go back to the very first line of the thread. IMO there is a problem in the rebuild of the carb ( no offense Aaron). Q-jets are tricky to work on, I won’t mess with them but I’ll tear into a Holley like a bag of chips. Go back. What was the reason for the initial rebuild? Was it a carb problem to start with. I don’t know. Keep reading the thread. Switched carbs ran fine. Something don’t sound right with the carb. Possibly a bad part in the kit?? 1 Quote Link to comment Share on other sites More sharing options...
jft69z Posted March 21, 2021 Share Posted March 21, 2021 1 hour ago, 1970mcss said: What is ported vacuum? For future reference. Another quick way to tell which type you are hooking up to is usually full vacuum ports are located 'below' the throttle blades (or the carb baseplate, intake manifold, etc), and ported vacuum would be, you guessed it, 'above' the throttle blades somewhere on the carb. This holds true most of the time, but the sure test is to use a vacuum gauge and see what you actually have at the port. 1 Quote Link to comment Share on other sites More sharing options...
jft69z Posted March 21, 2021 Share Posted March 21, 2021 5 hours ago, Canuck said: This car has been this way all the years I’ve owned it. With that said there was a TCS solenoid when new but don’t know how that affected the vacuum advance. The TCS was gone before I got the car. There is no ported vacuum on this carb that I know of. I haven't fully researched it, but a quick thought seems that the TCS may be a clue to your particular carb and full vacuum possibly being the only option? I think the TCS itself was the controlling factor as to how much vacuum went to the distributor, limiting it in the lower forward gears. Not sure though if they used full vacuum or ported vacuum TO that solenoid, then off to the dist. from there. There was a real good explanation I found on the Corvette forum, however the actual vacuum supply wasn't mentioned. A few other diagrams I found seem to suggest the TCS got it's supply from full manifold vacuum. Only sure way to tell is hook a vacuum gauge up to the carb ports and see how it looks. https://www.corvetteforum.com/forums/c3-tech-performance/3789759-what-is-transmission-temperature-controlled-spark-tcs.html 1 Quote Link to comment Share on other sites More sharing options...
1970mcss Posted March 21, 2021 Share Posted March 21, 2021 2 hours ago, MC1of80 said: Ported vacuum is a vacuum port that has almost no vacuum at idle and increases in vacuum as the idle goes up as compared to constant strong vacuum port. 5 and 7 is a very easy mix up. The "popping" coming from the carb when racing up the engine concerns me. Sounds like a worn lobe on the camshaft. With a timing light hooked up and the vacuum advanced hooked up also, what is the timing at idle? Thanks, that's good to know 1 Quote Link to comment Share on other sites More sharing options...
Canuck Posted March 21, 2021 Author Share Posted March 21, 2021 4 hours ago, MC1of80 said: With a timing light hooked up and the vacuum advanced hooked up also, what is the timing at idle? It is past the timing marks with the vacuum advance hooked up. Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted March 21, 2021 Share Posted March 21, 2021 Do you have a timing light with a dial? Or digital? What is the timing at at idle with it hooked up? 35? 45? 55 degrees or more? Quote Link to comment Share on other sites More sharing options...
Canuck Posted March 21, 2021 Author Share Posted March 21, 2021 3 hours ago, Dtret said: Not to sound like a complete a..hole but go back to the very first line of the thread. IMO there is a problem in the rebuild of the carb ( no offense Aaron). Q-jets are tricky to work on, I won’t mess with them but I’ll tear into a Holley like a bag of chips. Go back. What was the reason for the initial rebuild? Was it a carb problem to start with. I don’t know. Keep reading the thread. Switched carbs ran fine. Something don’t sound right with the carb. Possibly a bad part in the kit?? No offence taken. The carb was working fine before the build but was pretty dirty. I wanted to clean it up and put new gaskets in as well as the rest of the rebuild kit parts. Note that Ive gotten it to start nicely, the choke works right and it runs smoothly. My current issue is with the secondaries which could very well be a problem with the carb rebuild. When I tried the 71 carb I just started it up and ran it. I did not drive the car with the 71 carb or test the secondaries since my concern at that time was just getting it to run. Quote Link to comment Share on other sites More sharing options...
Canuck Posted March 21, 2021 Author Share Posted March 21, 2021 1 minute ago, MC1of80 said: Do you have a timing light with a dial? Or digital? What is the timing at at idle with it hooked up? 35? 45? 55 degrees or more? No, just a timing light. Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted March 21, 2021 Share Posted March 21, 2021 Disconnect the vacuum advance and drive the car. See if that makes a difference. I bet it does at idle when you rev it up. Most likely won't "pop" out of the secondaries. Quote Link to comment Share on other sites More sharing options...
Canuck Posted March 21, 2021 Author Share Posted March 21, 2021 2 minutes ago, MC1of80 said: Disconnect the vacuum advance and drive the car. See if that makes a difference. I bet it does at idle when you rev it up. Most likely won't "pop" out of the secondaries. I’ve tried that. The secondaries still pop without the vacuum advance hooked up. Quote Link to comment Share on other sites More sharing options...
Canuck Posted March 21, 2021 Author Share Posted March 21, 2021 There’s a retired mechanic near me that’s rebuilt lots of these over the years and seems quite knowledgeable. He’s the person who helped me get it running better a couple weeks back and got my choke adjusted. With my continued secondaries issue he’s offered to pull it apart and take a look. 1 Quote Link to comment Share on other sites More sharing options...
stangeba Posted March 23, 2021 Share Posted March 23, 2021 Just found this, may be of help. 1 Quote Link to comment Share on other sites More sharing options...
stangeba Posted March 23, 2021 Share Posted March 23, 2021 This is #1 1 Quote Link to comment Share on other sites More sharing options...
Canuck Posted March 26, 2021 Author Share Posted March 26, 2021 Update. I had an experienced fellow near me pull the carb apart to inspect/rebuild. He said I did a good job but the float was slightly high. He adjusted that and reassembled for me. I picked it up last night, put it on, made some minor idle adjustments and took it for a drive. The cold start is better which may be the result of the float adjustment. Runs great until I really get on it hard just like before. He says the “reversion” that’s happening in my engine is spitting the fuel back out the secondaries and is likely a valve issue. He lent me his compression tester and I will check compression on the weekend. The car runs and drives OK but just can’t get that extra bit of horsepower. Overall it appears the issue that started this post has been addressed and in the meantime I may have discovered something possibly more serious. I thank everyone here for their tips and advice which pointed me in the right direction. 1 Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted March 26, 2021 Share Posted March 26, 2021 Glad to hear it's better. I would still disconnect the vacuum advance and try it before doing a compression check. You could be that far advanced. Plus, it's easier. Lolol Quote Link to comment Share on other sites More sharing options...
Dtret Posted March 27, 2021 Share Posted March 27, 2021 It’s possible that you were dumping enough raw fuel into the cylinder that you washed the rings. I hope not Quote Link to comment Share on other sites More sharing options...
wallaby Posted March 28, 2021 Share Posted March 28, 2021 I had an issue with a broken valve spring once....It was a bugger to figure out. Quote Link to comment Share on other sites More sharing options...
Canuck Posted March 29, 2021 Author Share Posted March 29, 2021 4 hours ago, wallaby said: I had an issue with a broken valve spring once....It was a bugger to figure out. Yeah and you were 900 miles from home too. I remember. You and Tim changed the spring in the hotel parking lot. Quote Link to comment Share on other sites More sharing options...
Dtret Posted March 29, 2021 Share Posted March 29, 2021 6 hours ago, Canuck said: Yeah and you were 900 miles from home too. I remember. You and Tim changed the spring in the hotel parking lot. Was that ugly shirt day? 😂 2 Quote Link to comment Share on other sites More sharing options...
stangeba Posted March 30, 2021 Share Posted March 30, 2021 I found some info from 1993 when I had my original 1971 350 Quadrajet rebuilt, re bushed and the color restored, all for $179.00 + shipping. I will start a new subject so I can include all the scans on one topic page. 30 March 2021 bas Quote Link to comment Share on other sites More sharing options...
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