It's not going to run well with the throttle blades completely closed! That should have been clarified to read; "If you don't want to take the carb off and look, you can back the idle speed down until the blades close....then give them a little bit of opening as a starting point." THEN you can start your adjustments over again. Sorry! I don't want to address too many carb issues in this thread but, Seating your idle mix screws all the way in does indeed close off fuel flow through that circuit. Might be running from the fuel spilling into the engine from the float mishap. Might not have your float/needle and seat assembly assembled correctly or clean. Not sure if it affects the float mechanism but I have a rule about not overturning a Q-jet carb that's assembled. It can't possibly help it stay in position, and it MIGHT make something hang up funny.
I'm guessing this is it. Another thing I forgot to mention when adjusting the float don't just go by what you are measuring (1/4" or w/e) in my case the float I had available would sit slightly lower in the fuel then I think it should have which was causing it to keep too much gas in the carb. After some trial and error I eventually found the sweet spot and have kept it there ever since. I don't remember the exact float setting I have at the moment but I assure you it is not the factory setting or one that has been recommended to me. I probably should just replace my float but I just want to leave well enough alone knowwhatamean? ALSO It would not surprise me at all if you actually do have a vacuum leak at the throttle shaft though it probably is not enough to cause your idling issue. I rebushed my throttle shafts on an old worn out baseplate I had around using .015" teflon sheet. It has been as effective as the traditional bronze bushings used although it will probably not be as long lasting a repair (the sheet cost me 5 bucks btw)
lets start over, did the car run and drive good before starting down this road of messing w it??? did you have a problem w the power brakes not working acting goofy etc? or were they ok??
Ok lol. Car drove fine, but idle was always very rich on the wideband O2, and was sometimes a little rough. This all started as an attempt to get my vacuum up to increase brake performance. Idle mixture screws had almost no effect when tuning. Inspection showed that the transfer circuits were overexposed, but I fixed that. Still the mixture screw change vacuum px by no more than 1" hg. Car will barely lope with them in all the way. Checked for vacuum leaks and replaced carb base gasket which was leaking. Airhorn gasket gets soaking wet when car runs. That is where I am at.
Making progress: Pulled the air horn off. All of the internal nooks and crannies were full of fuel. The float level was 5/16 as best as I could measure. The needle didn't have any debris blocking it, BUT the float needle pull clip that attaches the needle to the float arm was missing. I am not sure that could cause flooding of the bowl since it helps open the needle, but it is a missing part. Edit: Ken said that the clip is supposed to be missing. Apologies Ken! I have a stock fuel pump so I am not running some high pressure system that is forcing the needle open. It would seem logical that the overflowing fuel could cause a drip that could explain the unresponsive mixture screws. I also checked for air horn warping with a straight edge. There is a tiny bit front to back in the middle of the horn, it it looks to be less than a mm.
More news: I got the timing doped out for sure. Thanks to Jim, the timing does not advance until over 820 rpm. Ken from Everyday Performance has been a great resource. He guided me through some checks and the carb is doing what it needs to. Looks like the low vacuum is related to an internal issue of some sort. Time for a leak down test! I am guessing a manifold leak or worn rings.
or an alternative to all that could be, if it idles, if it drives, if it has power brakes, throw the vaccum gauge away, put a chain and lock around bumper and hood, and start driving it, IMO.
man I cannot tell you how many times this very same personality trait has gotten me into trouble with this car LOL! speaking of tinkering..... This weekend I will be partially plugging off ( 3/4" steel expansion plugs with some small holes drilled into them) the exhaust crossover in my heads and doing "Doc's dual plane intake mod". Also will be replacing the front brake shoes and possibly getting around to replacing some ac parts that were messed up in my engine fire last year.
Well here are the results: Compression: 1 140 2 135 3 120 4 130 5 125 6 130 7 130 8 130 Leak down: 1 40% 2 45% 3 33% 4 47% 5 34% 6 35% 7 80% 8 50% Well compression isnt great, but at least they are consistently low. The 7 and 8 leak down results are pretty crappy. They said it sounded like the rings on 7. Guess it really is time to pull it...
You didn't mention WHERE the leakage is going. Leakage past either valve, or into the cooling system is unacceptable in my garage. I've never seen a cylinder that didn't leak past the rings, that's where the leakdown percentage comes into play. I have seen propaganda for special, magic piston rings with "0 percent" leakdown, but I don't believe them. What does that equipment show on a known-good engine? While unlikely, you could have a defective compression gauge and an extremely-sensitive leakdown tester. If testing a known-good engine with the same equipment shows remarkably-better results, yes, your engine is toast. While you've probably already got your answer, I'd be interested in the results of a cylinder-balance test as well. Shorting one cylinder's spark and then watching either RPM drop (OK) or manifold vacuum reduction (better) will tell you if the cylinders are performing evenly at idle.
I had a shop here do the tests. They do some restoration and circle track stuff so I mostly trust them. They said they didnt hear air coming from the exhaust or intake. I will do the balance test. I guess I could chuck some air into that cylinder to see if they.missed something, but I don't have the equipment for that at the moment.
Just did the balance test. All chaged rpm 30-40 rpm... vacuum change was hard to read, but all around 1".
Did some more investigation today. I pulled the plugs, and they all had oil in the threads. I know one side had some signs of a leaky valve cover, but the other was clean. The straps and porcelain looked pretty good, with a nice strap band, and minimal to no deposits or coking. I do suspect done leaky valve guides and seals. I tried to do my own compression testing, but the tester I rented was broke! It had a massive leak In the rubber hose. I pulled my drivers valve cover to take a look at things. Everything looked stock and in decent shape. I wanted to look at the casting numbers, since it dawned on me that my 70 SF block, which is black with some red showing through, has BLUE heads and front accessories. I never thought about it having the crap blue 75-76 heads, and it just dawned on me last night. Thankfully, the casting numbers do match 70 heads, so somewhere along this car's journey someone got a little creative with the engine paint. I also checked timing chain play. It looks to have about 6-8 degrees of play. It is tought to measure without a degree wheel, but I used a breaker bar to turn the engine and found the arc length that the bar moved through without affecting the distributor. Some quick math will give you the degree sweep if you have arc length and radius. Anyways, so that is worn too.
Might as well buy one. It's an indispensable tool--like a vacuum gauge, timing light, and beer. Turn the crankshaft in the normal direction of rotation, until the timing mark on the damper exactly aligns with "0" on the timing pointer. Reverse direction of crankshaft rotation, turning SLOWLY until you see the distributor rotor move--and read the degrees directly from the timing pointer. (Works with most engines that have degree marks for 10 or more degrees advance, stamped or cast onto the timing pointer.)
ive read all the threads, i would suggest putting it back together and driving it, 30-40 rpm drop per cylinder, cant find any kind of vacum leak, carb is clean and apperars to be functioning properly, timing ok, advance ok, about all that leaves is either a over cammed car, or a car theres nothing wrong with = IMO,
Yeah I hear you and agree. It is not heavily cammed, stock if anything. I am chalking this up to a tired old motor. Now this is just me learning and going through the troubleshooting wickets for the first time. I really want to pull this thing for the sake of a fun project now soon. Would be a great learning experience, while also taking care of the leaky pan and worn rings/valves. I am still entertaining the 470 idea
