|Topic Review (Newest First)|
|09-10-2019 12:46 AM|
|railroad||Works for me. Glad you got it sorted out. Back to cruising.|
|09-10-2019 12:43 AM|
Well that was the best $140 I've spent. Got the throttle plate today and what a difference it made. Got everything back to normal. Got a good solid 750 idle. Set my idle mix screws with the vacuum gauge and set the fuel levels. It is great when things do what they are supposed to. Vacuum is at 13 at idle.
So like I mentioned, the secondary throttle shaft was wobbly on the old one so that left some air in, but I think the biggest improvement came from the new throttle base. I know from taking a 6 inch scale across the base I could see a slight amount of daylight. I thought at the time that the gasket would take that up but now I'm wondering if it did.
So thanks for all the info, glad I didn't have to go deeper.
|09-07-2019 12:45 PM|
|pbohrs||I'm waiting for a new throttle plate for the Holley to try these suggestions. Not sure how long till it gets here. I don't have many gearhead friends that would have an extra carb laying around, although that would surely eliminate or confirm whether that is the problem.|
|09-06-2019 11:02 PM|
You can check for a vacuum leaking with a squirt bottle filled with water. Set the nozzle to a stream and with the engine running spray water around the intake runners, carb base gasket, etc. If there is a leak you will see and maybe hear the water get sucked in. If it really is that lean you might keep the engine running by putting your hand over the primary side of the carb to restrict the air going into it. You might be able to close the choke a bit to do this. I did this lots back in the day.
|09-06-2019 05:58 PM|
Sounds like it is leaning out. This could be either running out of gas or a vacuum leak.
Do not know if possible, but I would like to bolt on a known good carb and see what happens. If you have any vacuum lines coming off the intake or carb base, this includes capped tubes, put your hand on them. Twist them around and make sure they are solid with no cracks.
Looking more and more like intake gaskets. I hate to go there without trying another carb. Keep me updated, good luck.
I cannot imagine you are pulling enough air around the rear throttle shaft, but you can put some heavy grease around the shaft, where it comes out of the base plate.
|09-06-2019 05:03 PM|
When I start the car it starts right away and runs on high idle until the choke opens, although I can tell it is not a smooth run. Then when I flip the throttle and go off high idle it will slowly try to idle down to about 900, from there it gets stumbly and finally dies. If I squirt ether into the primary side when it is stumbling it will continue to run till it exhausts the shot of ether.
From what I have seen the transistion slots should show only enough to make a square, that's where mine are set.
BTW, thanks for your input on this.
|09-06-2019 02:12 PM|
Those Fel pro gaskets sorta melt. The ones I have seen, leak near the water ports. Before we pull the intake, tell me about not running long enough to adj carb. I do not think WD40 will show anything, but the cost is right. It will not hurt anything.
I thought it would idle. If you have idle speed screw turned in too much the throttle blades un cover the transition slots in the bore. The blades need to be close enough to create a good vacuum to pull idle fuel into the engine. Make sure the secondary throttle blades are closed against the adj screw and move freely after the primaries are open. I assume vacuum secondary. Where plugs pretty consistent, no real clean ones?
Do you feel good about the ignition? I read all kind of inconsistencies with electronic ignitions.
You did not get a load of water in you gas? I guess not you said it ran good once the carb got into the secondary.
Check your float or fuel levels on the carb. The fuel should not trickle out the holes, unless you rock the car, just below the holes.
No vacuum lines on the intake?
|09-06-2019 12:36 PM|
I had thought about the intake manifold. Do you think that WD40 around the runners would pinpoint the problem? I don't know too much about the engine from the original builder so I'm lost as to what was done. I know it has AR heads and an RPM Air Gap intake. I'm going to try a new carb base plate. If that don't help the intake is next.
No vac advance, uses a CD box. Doesn't run long enough to adjust the mix screws. Static adjustment has no effect.
|09-06-2019 11:04 AM|
I would check the intake bolts using the tq pattern for the 302. If you used the Fel pro printo seal intake gaskets, they could have gone bad.
Tough to diagnose not being there.
Do you have vacuum adv on the dist? If so, check the diaphragm.
Do the idle mixture screws still not have any affect on the engine tune?
|09-06-2019 12:24 AM|
Next step, failed again
Took compression readings, all cylinders are at 165-170 (cold). New plugs as long as I had the old ones out.
Rebuilt the Holley, every orfice cleaned and blown out with compressed air, new gaskets, power valve. Didn't make a d##mn difference. I am so sick of smelling like Shell V-power.
I did notice that the secondary throttle shaft is pretty wobbly, not sure it that would be enough to run rough and stall at idle.
Once my checkbook heals a bit there might be a Sniper in the future.
|08-30-2019 06:24 PM|
|pbohrs||Sorry for not replying. Got other things going on here at home with the end of summer coming on. Yes I agree that I might have a vacuum leak. I did replace all of the carburetor plugs, but that didn't help. I'm not sure if this is a clue or not...when I removed the carb from the manifold the base gasket is soaked with fuel on the secondary side.|
|08-30-2019 06:05 PM|
Could be, he has not replied.
You usually cannot get the engine to idle down with a vacuum leak.
|08-30-2019 03:31 PM|
|dccobra||Sounds like a vacuum leak to me.|
|08-29-2019 01:09 PM|
If the idle mixture screws on either side of the primary metering block have no affect on the engine idle, 1. you may have a vacuum leak
2. the idle circuit has trash or blockage
3. the power valve is bad.
If have not been tweaking on the engine, vacuum lines, or carb, I would say, idle circuit blockage.
If you are capable of adjusting the idle mixture screws, take a set of pliers and pull straight out on the idle mixture screws. This should give you the needle jet and a cork ring on the threads. Do this on both sides. Take your carb cleaner with the extended nozzle and spray in both holes, flooding both sides. Wear eye protection, ok to do with the car on the engine. If you have painted surfaces protect them.
Make sure the needle jet taper is clean and not bent, screw the cork ring toward the taper on the jet, but keep full thread engagement. Push both jets back into the holes.
Gently turn both screws in until they seat. Do not tighten. Back both out 1.5 turns. Start it up, giving time to clear up the carb cleaner and try adjusting idle mixture screws again. You can adj the screws by ear as the engine smooths out and rpm increases.
You have to go back and forth a couple of times. Always lower your curb idle back to you normal idle speed if the rpm exceeds that number.
For the final adj have the air filter on. Some like to have auto trans in gear, be careful with this, do not be blipping the throttle.
Look around for any loose vacuum lines, pcv, ign adv, gauge feeds, loose carb or intake, etc.
Please tell me if you made any changes prior to this issue.
|08-29-2019 12:10 PM|
|RBachman||This is why I'm going EFI. I'm old school and grew up arguing with carbs. I still like them, but not enough to deal with the headaches any longer. I'd take it to a a good engine tuner or go EFI.|
|08-28-2019 11:54 PM|
Yes, I do have good output from the squirters. Here is a brief description of my frustration. I can get the car to idle, but not very well. I have no adjustment on the curb idle, I turn the adjustment several turns 'till it's opening the throttle butterflies where the engine is running at 3000, then back it off to where I'm back down to almost stall. Nothing in between.
The idle mixture screws have no effect at all.
On another note, once I'm off idle and past the stumble and surge it runs great.
|08-28-2019 08:57 PM|
With the air filter off, engine off, key off, shine a good light down into the primary side of the carb, (front under the choke blade) You will need the choke blade fully open. Sounds like you might need 3 hands. Move the accelerator, every so slightly opening it. At any movement you should see 2 streams of gas from the squirter, toward each throttle bore.
Continue moving the throttle and watch to make sure the stream of gas continues.
If this is all good, your problem may be else where.
If you do not know where the squirter nozzle is, it is located under the phillips head screw in the front of the 2 primary butterflies. You will probably see come gas come out when you move the accel linkage.
Another thing that can cause stumble are the idle a/f adjustment screws out of tune.
We will check the squirters and then go there, since you have not been doing any tuning.
|08-28-2019 08:04 PM|
|pbohrs||On the squirter/ accel pump....Nope didn't do anything there yet. Can you explain?|
|08-28-2019 06:28 PM|
Originally Posted by pbohrs View Post
|08-28-2019 12:29 PM|
|railroad||Sounds like accelerator pump. Did you pull the squirter and check valve wt?|
|08-27-2019 11:14 PM|
|pbohrs||Well today I removed the carb and removed the fuel bowl. Shot carb cleaner in every orfice I could see. Now I got a decent idle, but max hesitation in the idle to throttle transition. When I try to accelerate it bogs and then accelerates so fast it almost gives me whiplash.|
|08-27-2019 04:38 PM|
I'm thinking like Bob. It sounds like fuel starvation. Pull the bowl and make sure there's no trash in it. Also check to ensure fuel pick-up tubes are secure and not sucking air (had an Alpha pull that intermittent-loose pick-up tube on me once, almost never got it figured out).
Edited to add that you may want to ensure the fuel tank vent is not clogged.
|08-27-2019 02:41 PM|
Don't overlook the electrics. ie coil.
|08-27-2019 02:17 PM|
|Bob Cowan||CHeck fuel pressure and volume. Take the needle and seat out to check for trash. Check the floats.|
|08-26-2019 11:25 PM|
I was out for a drive yesterday and the 302 was running great. Then...I was on a rural road with a lot of twisties and I noticed that as I accelerated thru some turns I got a surging, but still working fine above 2 grand.
Came to a stop sign and the car died, like it idled down to dead.
Set the idle this afternoon, (carb idle mix and curb idle) thought I had it, but when I took it out it did the same [email protected]##m thing.