It's a edelbrock double roller chain, It's been a long few weeks I guess i could have figured out that you can pull the wires from the cap...
it is a bigger cam... Today I will pull the wires to see, also i plan on adding new plugs. The condeser is new with the dizzy
Big cams - 280 degrees advertised duration or so - in big engines that are running right will idle around 10"-12" vacuum. Really big cams an inch or two lower. The same 280* cam in a smaller engine will also idle a touch lower, maybe 1"-2". Fwiw, big = 455 or so, smaller = 265 - 283 or so. That's with a reasonable idle. My 462" Buick idled at 600 rpm with both a dual quad and single quad setup. As you run the rpm up to 1000-1200 (no load) or so the vacuum should settle in at 17"-19" for a healthy engine. So 15" with a hot cam sounds ok. Keep in mind al***ude will take the vacuum lower at idle. To the tune of 1" per 1000' of al***ude. Running the highway vacuum levels will be about the same regardless of reasonable al***udes. My experience going from 350' al***ude to 6000' or so. If you run the engine up to 1200-1500 rpm - no load - and the vacuum stays at 15" that may mean you have a retarded cam. 12" was the figure noted with my friends 302 Ford powered 46 Ford sedan when the engine was spun up 1200-1500 rpm. We're at 3300' and idle read 8"-10" indicating the cam was retarded. Like you, he and another pal had run through everything else. When they opened up the engine, sure enough the previous owners "mechanic" - he had the car built - had the cam retarded. A new timing chain was also installed. The cam is a mild one, perhaps 265*-270* advertised duration or so This could be your problem, but I'm leaning more toward a mis-adjusted valve or two. It could also have a broken valve spring - kinda common with the 400-M series of Ford engines. Had three of them on both a Norris cam and Crower cam. One spring broke at diferent times, but a set of Crower springs cured the problem. Ford seems to have let a bunch of bad heat-treat valve springs out from what I heard and experienced. I'm ***uming a hydraulic flat tappet cam. Getting back to the mis-adjusted valves bit, sometimes they'll run ok and others they'll make a soft popping noise. Depends on whether it's an exhaust or intake valve that's out of adjustment. A lot of guys run the valves and spin the pushrod until they can't spin it due to play is taken out and then friction resistance tells them the valve train is at the point where they can add the additional 1/2 or 1 full turn for proper adjustment. Problem doing it that way is that you can still spin the pushrod after play is out and you may end up with an overly tight adjustment. What works best for me is to make sure the lifter is on the base circle - several different ways to do it - and move the pushrod up and down while turning the adjuster screw tighter. When all play is out, adjust the one turn tighter or whatever it is that you run. Since the valve train is lubed - from just running or from the builder before the initial fire-up - you can spin the pushrod long after all play is out. I'd be inclined to do the plug wire removal bit as Tommy noted and then run the valves. If that pans out ok, then you can dig a little deeper, but I wouldn't get into tearing the engine apart unless it's indicated by doing the basic stuff first. ~~~~~~~~~~~~~~~~~~ Incidentally, Champion spark plug used to sell an inexpensive diagnostic tool that looked like a ball point pen, but had a neon light on it and operated off induction from a single plug wire or the coil wire. Handy gadget, I have a couple and they're great for checking spark at each cylinder. ~~~~~~~~~~~~~~~~~~~~~ One other one I thought of, if your engine is a GM and you have #5 and #7 cylinder plug wires running next to each other you can be inducing a voltage from one to the other. Got good plug wires? With #5 and #7 well separated? One good way to tell if the plug wires are bad is to run the engine in a dark environment and see if sparks and arcs are dancing around. That'll indicate bad plug wires. Good wires don't show anything in the dark. Make sure too that you can see all of the plug wires. My FE 390 in my 59 Ranchero started losing gas mileage on a long trip in 72. Opened the hood in a dark area, didn't see anything. Pulled the air filter lid and I could see sparks dancing from air cleaner to carburetor. Spooky it was. What was happening was, the plug wires were lying against the bottom of the air filter housing - stock Ford - and going to ground. The air filter on that engine overhung the front mounted distributor a bit. A set of new plug wires cured that problem.
Man, that sounds pretty low, even for a big cam. I am running a large roller cam and I'm pulling 10 inches in neutral and 7 inches in gear. Have you checked your initial and total timing?
I am going to replace the plugs 1st thing with R44TS Then I'll check that out. Ran the valves last night per David Vizard's method in his Small blcok Chevy book, wait for #6 to rock and adjust #1 no slop, which I checked by moving the pushrod up and down, and then 1/2 turn. I'll check 5 and 7 to see if they are arcing. my dial back light shows 12 initial with 24 in the dist for a total of 36. The symptoms I have happend with both old and new plug wires. Could be fouled plugs... or?
put new plugs in and she started and was popping burping out of the carb, advacned the dizzy and it stopped. She still misses at low RPM.. Vacuum went up to 7 Hg, she bogs when gas is pushed. Tried to pull a plug wire fromt the dizzy and pulled the mallory cap sideways, and broke the spring loaded part where the rotor takes power form the coil... But did notice that the hose for the PCV was kinked closed so that answers the oil in dizzy thing. Could that also have affected soenthing else?
Yeah, a PCV system is basically a controlled vacuum leak that's compensated for by setting the idle mixture richer than it would be without the PCV. If it get's kinked closed, clogged, etc... you're instantly running way too rich at idle. I had this problem with my early econoline once. It would run terribly and sometimes actually stall out when the hose collapsed. I'd fire it back up and it would run fine for a few miles till the hose collapsed again.
Ok, maybe the oil in the cap caused the initial miss & rough idle. Then when you put in the new dual point dizzy maybe you got it off by a tooth or two.
Cracked #7 intake valve spring. The spring cracked, is still there in 2 pieces but the retainer and pushrod and rocker are OK. Valve looks good too. I checked my cam specs and found the right ones to order.
But still, FIVE inches of vacuum? Really? I don't know how big your cam is, but I bet it's not big enough to idle that low. I think you have something wrong more than just one cracked intake spring. My 406" SBC has a BIG solid roller (268/270@.050, .632/.632) with an 825 Race Demon, and it idles at 7.5".
The vacuum is what it is, I got it up to 7 by advancing the timing, and adjusting the idle speed. I'll replace the springs and see where that takes me.
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