I restored this 56 olds holiday 88 from the ground up, and pretty much done. Just have some issue going on with the engine I can quite figure out, hopefully you guys can school me here. New rings and bearings, new lifters. I'm not sure if it's the carb messing with me here. I had to go through a lot of adjustments to get her running and dialed in. I am no expert on these carbs, but I followed the book very closely. The issue is I'm doing a vacuum test, and connected the vacuum gauge to the front p*** side bottom port on the rochester 4 jet carb. I'm only getting 5 in holding, and when I rev the motor. It snaps to 0 like it should, then tops at 10 in. Then immediately drops to 5 and holds. My question is, is this the best spot on the carb to put the gauge? What does this reading say about the engine, and is there something settings on the carb I'm missing? Also does the vacuum advance on the distributor supposed to vent out the bottom. I blew smoke down the line I took off to connect the gauge. That line goes to the vacuum advance diaphragm on the distributor, and smoke shot out of the bottom of that disc. Not sure if it is not sealed like that from the factory, or if it should be air tight? Any help to finally get this long project back on the roawould be greatly appreciated. Mark
The vacuum advance diaphragm should be sealed air tight and hold manifold vacuum. Make sure the connecting hose goes to a source of full manifold vacuum. You can use a port into the manifold itself or connect it to the carb at a fitting that's below the throttle plates. From there, things like initial ignition timing will have a big effect on manifold vacuum at idle. Increasing the timing (up to a point) will also increase manifold vacuum. With a relatively stock cam you should probably see in the neighborhood of 18 to 20 inches of vacuum at idle in neutral at normal operating temperature, ***uming no other vacuum leaks.
The only port on the manifold goes to the heat tube that runs to the bottom of the manifold, and is open to allow heat into the choke. So I don't think I'm getting an actual accurate reading because it's not sealed...Is there a better spot on this old 324 rocket, or does it even matter and that port is just fine for a test? If that's the case I'm still only getting the 5 in from that line. That's I remembered the open tube. I thought it was the manifold leaking when I blew smoke down that line. So I pulled the manifold and realized it was that open tube to the choke. So I pulled the damn manifold for no reason. It was sealed just fine.
The wipers were vacuum and ran through the fuel pump and then to the manifold. Where did that connect? I thought there was a fitting on the manifold behind the carb.
A few pictures of your carb and intake manifold (so we can see both the front, the rear, and both sides) near the carb may help. Its been a very long time since I've looked at a 324 Rocket motor, a jog in my memory might be helpful for me (and others) to be helpful to you.
Yeah there is only 1 port on this rocket manifold, and that's the open ended pipe that goes to the chock on the carb. I tried that line first until I realized it's not sealed anyway. It starts up great cold, but when it warms up it starts dying around 900 rpms. I thought I was supposed to be around 800 to 900 on idle, but it won't survive past 950s and stalls. I'm at 8 btdc on timing. So I felt some sort of large crack or opening at the bottom of that vacuum ***ist on the distributor. Plus when I blew smoke through the line it bellowed out a thick stream of smoke. So it is definitely open on the bottom of that disc. So it should not leak at that point if I blow smoke through it, right? Maybe that is my issue. I have been through the ringer with this carb on set up adjustments. If I was leary about anything on those adjustments. It would be the fast idle setting I believe. The first front one on the linkage. I only have it at 1.5 turns, but it doesn't seem to be doing much of anything.
There is 2 lines on top of my fuel pump for vacuum. The left one(while looking at front of engine in front of car) runs to my wiper motor (top left port). The right line on vacuum pump runs to the back of the carb into a large line that comes up to a T fir 2 large rubber lines that go to brake hydrovac, and reserve vacuum canister. The distributor vacuum line runs to the left front bottom port on the rochester 4jet carb while looking at the front of the car. These are the only vacuum lines on her. I'm not positive but I think I got these line in thier right positions. I can't find a diagram in the book to confirm it for me.
Sounds like the distributor runs on ported vacuum. To test engine manifold vacuum you need to get a connection from the T at the back of the carb.
I haven't tried that yet but I will try as soon as this temp silicone fix drys on the bottom of the distributor vac ***ist. So you think I'm getting a false reading by going to the distributor port from the carb? Now I'm questioning where I have all my vac lines installed...
Check that last statement. The right line from fp vac goes to wiper motor. The left line is going to the back of the carb where the T line is going to the brakes.
Good eye I didn't catch that. Should go manifold to fuel pump, fuel pump to wiper control, from there to the wiper motor then vented to air.
I hope this helps, but this is a crude drawing of how I have my vac lines installed. Maybe someone can catch if I ran something wrong.
The line to the distributor is a ported vacuum that only comes on when the throttle is opened. It will show a little vacuum if the idle speed is too high. Constant manifold vacuum can be had at the inlet line to the top (vacuum) chamber of the fuel pump or to the vacuum line to the power brakes. Idle speed on a stock engine should be in the 500 to 600 RPM range. Some are as low as 450 RPM with the car in gear.
So is there supposed to be a hole at the bottom of the vac ***ist disk/diaphragm on the distributor? I blew smoke down that line looking for leaks in the system and it poured out smoke out the bottom of the diaphragm. I'm not sure if that's normal. Another guy on here said no it should be sealed. I just want to get a confirmation on that one if I could. I think my wipers are not hooked up right. I normally rebuild army trucks and halftracks. So the wiper motors I think are slightly different then this set up. Could you look back at that picture I drew, or the photos on here and tell me what I'm doing wrong here? I think I need to run from vac pump to switch. Then switch to one of the ports on the motor. Not sure which one middle or long 90 ° pipe on far left of wiper motor. Then I still have one of those wiper motor lines not connected if I do that. Where does the other line go? Thank you Mark
Ok I don't know what's going on now. I checked the vacuum at the brake booster T at the rear of the carb, and now I'm getting 15 in vac. Although that's better it just stays there the whole time. It doesn't go down to zero and bounce back when I rev it. Just 15 the whole time no matter what. Staying around 1200 on idle and still cutting off when it heats up after 10 min........I'm not getting any change in idle when I mess with the idle mixture needles. So it would seem the carb may not be working right. I cleaned out twice and adjusted everything per manual. Is it possible the carb is sabotaging me here?
OK, you need to look at manifold vacuum, which you've finally found. The port that goes to the fuel pump, is manifold. So are the ones for the brakes. I am confused about where the large line on the p***enger side is going. You wrote that it goes to the vacuum canister for the brakes? On my 55, the canister, is right under the brake cylinder, on the driver's side. Are you sure it's a vacuum canister you're hooked up to? Are you sure it's tight, doesn't leak? Can you find a check valve in there somewhere? It looks as if someone cobbled up something, very far from stock, and it might be missing a check valve, or have the vacuum going to the wrong place. Rubber hoses , if not made for using on vacuum, could present a problem, as well. If not now, later. I try to hardline vacuum lines, with absolute minimum rubber. As for changing vacuum while adjusting idle, I find if it's close, it really doesn't change much. Timing will make a bigger difference in vacuum.
The wiper motor should only have one vacuum line going to it, coming from the wiper switch. Fix that and disconnect the vacuum canister from the system, plug the line, and then see what your vacuum readings are. Also the distributor vacuum chamber should not leak, if it does, the diaphragm has a hole in it and will not work the advance correctly.
1200 Idle on a stock engine is way too high and that's the reason the idle mix needle aren't working right. Too much air around the throttle blades and it's actually idling on the transition circuit. The vacuum not dropping from 15 when rev'd up sorta sounds like there is a vac reservoir somewhere in the brake line and you are seeing a measurement in front of the check valve. You need to be directly into the manifold, even if that means removing fittings and hooking up direct until this gets cleared up
The large line that goes to the p*** side goes to a large vac*** resovior stuffed tightly under the fender. It did not have a check valve on it, or within the line anywhere. I'm not familiar with this system, so I'm not sure if it was changed or pulled from for parts before I got her. As for the cobbled up rubber line job, we'll I have to take ownership of that one. I replaced everything the way it was installed. So I'm not sure what is incorrect, but I'm pretty sure all my lines are good besides the wiper motor. Now I'm pretty sure I screwed those lines up..haha. the wiper motor has 2 lines on it, and I only have 1 line going to it from the dashboard switch. With the vacuum, it's not small changes I'm worried about. The problem I'm seeing is that when I rev the engine the gauge does not drop to 0 then snap back to 15 like it should. It just stays at 15 the whole time no matter what the engine is doing. So I find that to be odd, and I'm not sure why. Would that have something to do with no check valve installed in that line?
You need to find the check valve in the brake booster line. Usually located right by the carb. You want to take your reading from the carb side of the check valve. The other side of the valve will read the cannister vacuum . Leave me a private message with your email address and I will give you some help.
I temporarily plugged the hole in the distributor diaphragm with silicone until I can get a replacement. I'm not sure if it really did anything because the engine still shuts off after warming up for 10 minutes. The wipers are still not working but I'm still not sure if I ran the lines right. Top right line from fuel pump vac to dashboard switch. Dashboard switch to middle port on wiper motor. Then I still have the left port on the wiper motor open with nothing going to it. So that can't be right
If the diaphragm in the vacuum advance is leaking, using silicone on the outside of the canister isn't going to fix it, even temporarily. It would also be good to know if both the vacuum and mechanical advance in the distributor are working properly. As already mentioned above, it sounds like you've tried connecting the vacuum advance to the brake booster vacuum line downstream of the vacuum check valve. That's why it's recommended to find a manifold vacuum source to the intake manifold if possible, or at the carburetor itself. It's usually best to have only the booster connected to its own, dedicated vacuum source. What type of choke setup do you have? Is it adjusted properly, and fully opening when the engine warms up?
Hook the vacuum line to the side of the wiper vacuum motor. Disconnect the lines going to the top of the fuel pump. Start the motor and put your finger over the disconnected fuel pump ports. Find the one that ****s, and that one goes to the wiper switch. The other port goes to the suction port under the carb. The center port of the wiper motor is a vent, nothing goes to it.
Yeah it didn't have a check valve on it when I saved her from the grave yard. So I never installed another one. I looked for one on line for this car, but can't find the exact valve or even what the original looks like. Do you have any suggestions on a valve that will work?
Thank you for that, I figured out the lines now. Unfortunately they are still not working, so since I never rebuilt the wiper motor. I think the motor or switch us toast. Is there a way to test the wiper motor? Is there a good rebuild kit out there for these, or am I stuck sending it in somewhere for $300? Still having trouble with the car shutting down after 15 minutes when warmed up. Then she doesn't want to start again until it cools down all the way...
Not trying to **** into this, Too many voices can cause as many problems as no voices, because you don't know who to listen to. If the motor dies every time it gets warm, and won't start up until it cools off, I would probably check to see if the coil has battery voltage on the + post after the motor dies. Is the choke plate on the carb opening up fully when the motor gets warmed up, just before it dies? I suspect your going to find you have more then one problem and they are ganging up on you. Your 4th motor picture shows a steel line coming off the base of the carb under the choke thermostat. Does that small diameter steel line to to the carb choke pull off canister? The radiator hose is blocking the view on where that steel tube is going. I suspect that small diameter steel tube is a great place to connect your vacuum gauge.
Good advice to check coil voltage after the engine dies. If there is voltage to the coil you could have a bad coil that fails when hot. Also could be the condenser, and no easy reliable way to test. Just replace it as they are cheap. To test the wiper motor just run a hose from the intake manifold directly to the wiper motor. Make sure you have good vacuum at the hose before hooking to the wiper motor.
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