Carb is rebuilt, all new gaskets. Not sure which Cam is in the motor.... Got it running....sort of. Now have some questions. 1. The bowl float adjustment screws are leaking gas, I have tightened them and it slowed down, but is still wet after it runs for awhile. Do I tighten everything down some more, or should I be looking at different gaskets? 2. I was attempting to check vacuum. I hooked it to the small port in which my vacuum advance is hooked to. It read zero. If I give it gas it jumps up to 10. I unhooked it and hooked it to the spacer and it reads 10. This is the one I should use for adjusting the idle mixture, correct? 3. I started out at 1.5 turns on all 4 corners, it would inly run if I held the throttle open. I backed them all out another half turn to 2 turns and it will idle. HOWEVER, I am only pulling 10 in my gauge? Is it because I need to back the screws out some more? Or the cam? Or something else? I thought this was a pretty stock motor, and was expecting close to 20 inHG. And here I am at 9-10. I know adjusting the idle mix screws will pull it up some. But not 9-10 inHG will it? I don't suspect any leaks...Ive just replace everything. I do have the pcv hooked into the port of the spacer as well. Could this be a problem? 4. I cannot find any marks in my balancer to set timing with. They should have some grooves in it correct? Or were some just painted on?
Advance it a "dab". (When you don't have a timing mark....and don't know how to install a timing tape using a piston stop....a "dab" is what you use!) PUT SOME ADVANCE IN IT....until you find TDC with a tape. That should give you more vacuum. IF not...prolly got a vacuum leak or maybe a snotty camshaft 6sally6!
If you don't have any vacuum leaks and the vacuum gauge is steady, I'd suspect retarded timing. An old instructor I had told me one way to set timing, if you can't find the marks, is to advance the timing to the highest vacuum reading, then retard it about 1" vacuum on the gauge.
I really think that carb is a big truck carb with a governor attached to it . The PCV will work fine where it is located . Ford swapped positions of timing pointers and marks a few times through the years . Why ? It was a better idea . Do your best to get number one on TDC , and use a chalk or something you choose to place a couple of marks on the timing cover and balancer . Try to verify the timing , this way . I bet it’s really slow in timing also . I have an X grind cam in my ‘ 32 , it doesn’t get much snottier than that one and it has 15 ins of vacuum at idle . Same carb , same ignition as you are using .
Make sure fuel pump output pressure isn't excessive. Your vacuum gauge will measure this. 5 to 6 psi. is plenty. More is not better. There is only one float adjustment screw, and a jamnut. I think you're saying fuel is leaking from the bowl screw heads? But anyway make sure pressure is within spec, and float is adjusted correctly. Use a piston stop tool or otherwise find the absolute certain no-shit no question of any kind accurate TDC point for the #1 piston on the compression stroke. Then mark the damper clearly. It "should" be the "0" mark on the timing marks, but TDC is important to verify, because it is the null point for everything ignition timing (and valve timing related). Much wasted time and head scratching can be avoided by this. It is very common for crankshaft damper weights to slip, and the timing marks along with it. It takes some experience to know what the vacuum gauge is indicating. For diagnostic purposes set the ignition timing to factory specs. You can set it later to where you want it, but for test purposes you want to see that the engine is "pulling" what it is designed to. One thing that longtime motor heads know, a worn or loose timing chain set will cause late valve timing. This will also cause a generally low engine vacuum. Advancing the ignition timing well beyond factory specs will tend to compensate for this wear, but for test purposes you want to find out what's what. A high performance camshaft with lots of overlap will also naturally pull less manifold vacuum compared with factory camshaft. So you have to make some allowances for what you're working with, and also take into consideration elevation or altitude. But generally speaking if a stock engine won't pull 19" to 21" steady needle at sea level, there is a serious defect in engine tuning and it will never run like it should. Find out why. Close accurate idle mixture adjustment might get another 1" or so on the vacuum something like that. You want it pretty lean for a crisp smooth idle, that doesn't "load up" the plugs after a few minutes. They will tend to foul quickly too, of course. But if the fuel pump is junk, or the float level is buggered, ignition timing defective, things like that will cause lots of grief and you'll pull your hair out trying to tune it.
Fuel pressure is 4-5psi. Checked it on the bench. Fuel is leaking around the jam nut or screw. Sounds like I really need to get the timing figured out. Might even pull the balancer and get it in the blast cabinet....wish I'd checked it when I had the radiator out. Also going to put a dial on the pushrod/rocker and check lift. This leaves me with a couple more questions before I jump in. 1. The float adjustment has a gasket, jamnut, gasket, and a cap screw. They were snug when I started, the more I tightened them the less they leaked. But still have a hint of fuel. Think I need to try some thicker gaskets? Or try to tighten a bit more? The other thing I just thought of is the original needle had 2 orings and a jam nut. The replacement in the kit had 1 oring with a slotted adjustment nut and cap screw. Everyone said this would work not to worry. Here is a pic of the two valves...ignore the sizes. 2. How much vacuum could I be leaving on the table with timing. Can I gain 1" per degree? This motor should be around 12 degrees. So if I am currently at 6 degrees could I gain another 6"? Just curious as to how the correlate...
Well no, manifold vacuum will always increase as the ignition timing is advanced (up to a point). But again you want to check the vacuum at factory ignition timing specs, and they are usually something like 6° or 8°. Yes, you can grab a chunk and give the distributor a big ole twist and that will improve vacuum greatly. "Late ignition timing" is one of the possibilities for a low, but steady vacuum indication on the gauge. But then, "late valve timing" is too. All things being equal if you have to advance the ignition timing well in excess of stock settings to achieve normal manifold vacuum that indicates a worn timing chain (slop) or late valve timing. This is one reason to degree a cam at installation, so there are no surprises. First though, you need to make sure it is timed correctly. Make sure TDC on the crank balancer really is TDC. Then, using a timing light, set the base ignition timing (engine barely idling slow at say 500 RPM w/ vacuum advance port disconnected and plugged) set the timing to factory spec listed in the shop manual. I bet it's probably no more than 8 degrees. You can set it higher later if you like. For test purposes though, now observe what manifold vacuum is achieved. The gauge will tell you what is wrong, if you know how to interpret it. But if it's an unknown camshaft, it might be difficult. It's a matter of what a particular engine "should" pull as opposed to what it is pulling.
It's 10° before top dead center.... And hook up the distributor vacuum line to manifold vacuum... That should get you a couple more inches on the vacuum reading....
I always set my timing in an engine with a cam , by setting 35-37 * total at around 2000 rpm . Let the static timing fall where it may
Right, that's one technique for setting ignition timing at the optimum point. I don't believe he is at that point in tuning yet. If he doesn't know what camshaft is installed, that makes it more difficult to know what it should pull for vacuum. Whatever it is capable of, is what you want. For engine diagnostics or test purposes, for an accurate meaningful vacuum test we want to set it up to stock specs. A stock or stockish engine, every shop manual ever published will indicate it should pull 19" to 21" steady on the gauge, but it has to be able to to that at factory timing. A lot of OEM factory engines only had 3 or 6 degrees timing, and a ported connection to the distributor, and adding in a lot of extra initial timing before the test will skew the results. I guess in this case, it's 10 degrees. But the idea in testing is to see if there is a basic engine tuning defect, not to "cheat" to see if we can get it in the green.
Update .... Didn't have much time today, but I did manage to pull the float needle screw and nut. Cleaned everything up and reassembled with some lithium grease. So far, so good, no leaks. Now, while I had the engine warm I thought Id play with it some. Adjusted the idle mix screws on the primaries, and advanced the timing. It was pulling about 13 inHG and started to knock. Backed it off to 12 and had to back the fast idle off some. Definitely a noticable chop, I think this thing has a "snotty" cam. Compression test was even across all cylinders. And the valve train is all tight. I should be able to spend some time on it tomorrow and I am going to set the timing on the crank to 6 degrees, and use a test light to bring the the distributor to it, and then check the vacuum. Question: I thought I would pull the PCV hose and plug it just to see if it had any affect. As soon as I popped the PCV valve out of the valve cover the engine died. Didn't even really stumble...just died. Tried it again, same thing...why is this?
I know it’s a 302, but y blocks are famous for slipping the damper, and you’ve got to find TDC as they said above. I’d plug the PCV hose for now. The wrong one can be a massive air leak (happens on yblocks all the time because we can’t find the right one). There should also be a manifold vacuum port on the carb, as well as the ported vacuum you found in 2. in your first post.
There are only three ports on the carb... One above the bowl capped in blue.... And two on the base... Both of the small ones have 0 vacuum until you get in the throttle....
Right, for a vacuum test have to connect gauge to a carburetor port that is sourced below throttle plates, or on the manifold itself. Not sure on the background for this engine reading the initial post. Did it ever run before you got it? You're doing all the right stuff, some people are pros at sniffing out problems first time everytime, but sometimes it can be tough depending on what the previous owner did. Or didn't. Good compression #'s are encouraging anyway. I suppose with a degree wheel or at least a dial indicator you could kinda reverse engineer the cam a little bit. At least verify TDC on the balancer, and also maybe see if the camshaft centerline falls where it should e.g. ya want the valve timing to be on time on target. A timing chain set and camshaft that wasn't installed correctly will cause grief too. With a performance camshaft, a lower # power valve is necessary than factory. Keep that in mind. This is actually where the "idle vacuum divide by 2" advice makes sense, though it still might open too early. Give your engine what it wants. Spool the engine up to cruise RPM and beyond with vacuum disconnected and plugged and see what kind of mechanical timing curve the distributor might have. Also you may well want a manifold distributor connection, it will idle smoother and run cooler for street driving, 20 or 30 degrees ignition advance at idle won't hurt anything.
Well... pretty much a wasted evening. Pulled the balancer cleaned it up...nothing...nothing at all. Put a piston stop in and found TDC. Marked the balancer off. Unhooked the PCV and plugged the port. Left the valve cover hole open. Tried to start it, it would start, surge, knock and die. Was also shooting fuel out around the accelerator pump area...not sure how or where. Surging to probably 30-40 degrees with timing light. Backed timing down to 6 degrees. Hooked pcv back up Took idle mix screws all back to 2 turns. Fired up, pulling 7 in at 6 degrees. Advanced to 12 degrees an am pulling 13 inches. Lift on pushrod is around 0.210" and about 0.340" on the valve itself. Doesn't seem to aggressive. I now however think I have a constant knock...not sure if it's the open headers echoing or what, will try again tomorrow. I hope I didn't foul it up... I do not understand why the pcv circuit is having such an effect on the engine. You would think with it plugged it would be fine. The PO was running 2 breathers and I don't think he even had that port blocked off...
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