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Discussion Starter #1
Hey guys, new member here... just got done posting a thread in that section as well. I've got '67 camaro with a 327 and a 2 speed powerglide. I've finally got the thing running and timed again after replacing the carb and harmonic balancer (it was a 2 piece one that kept moving the timing mark) and I'm really excited to get this thing on the road. I'm having a few problems though that are probably pretty simple. With all the vacuum ports plugged besides the rear one on the carb going to the pcv the engine finally runs and sounds great! The problem is when I hook up the vacuum advance and trans modulator the car sounds pretty bad but still runs. Before I start changing things I figured I would ask for a little help. The car has run well with this distributor before and nothing has been changed as far as the vacuum advance. I've replaced all the vacuum lines except the portion for the trans that is hardline. I've got the vac advance hooked up to ported vac and the trans hooked up to manifold. For starters, is this right? Ive got an msd 8362 distributor if that makes a difference. I'm thinking my problem might be as simple as just needing to adjust the timing with the vacuum lines hooked up to dial it in again, but I wanted to double check before I start changing things. My last question is about the brake booster, I've read that I can tee it off of a manifold vacuum source but I'm a little confused because the only port near that size is the one I'm using for pcv on the rear of the carb and I've read you aren't supposed to tee the brakes off of the pcv.
Any and all help would be greatly appreciated so thanks in advance.
 

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Modulator leaking? Booster vac should be directly off intake. If you don't have enough ports, get a manifold fitting to make it right. Autozone has these on the help section. Mine has an inverted male fitting to fit a metal tube for booster on one side and 3 smaller nipples for other needs. .

Be sure the booster check valve, "plastic fitting" is not leaking as well as the booster.
Carb should feed your pcv.
 

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Discussion Starter #3
I replaced the modulator with a new one thinking the same thing. I suppose I should have double checked the new one to make sure it doesnt leak but I'm positive its fully seated against the transmission. I will be able to hook up a hand vacuum pump in a few hours to test it for sure though

I don't have enough ports so I guess I'll grab a manifold fitting on my way home. Where on the manifold should this go?
 

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I replaced the modulator with a new one thinking the same thing. I suppose I should have double checked the new one to make sure it doesnt leak but I'm positive its fully seated against the transmission. I will be able to hook up a hand vacuum pump in a few hours to test it for sure though

I don't have enough ports so I guess I'll grab a manifold fitting on my way home. Where on the manifold should this go?
1967 - 1969 Camaro Intake Manifold Vacuum Fitting, Threaded Booster Tube and Three Vacuum Ports
 

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What are your timing settings without vacuum advance? Did you verify TDC with the new balancer? There is some differences in where the timing mark is located on new SBC balancers. Is it in the same location as your old one relative to the keyway slot? Once you are sure you're timed correctly, you may want to try manifold vacuum for your VA.
 

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Discussion Starter #7
I verified TDC when changing the balancer using a piston stop. It's just timed by ear right now, however it's running the best it ever has (without vac lines hooked up). I'm sure it's timed correctly right now, but I'll put a light on it and find out exactly what I've got it set to. I ordered that part for the brake booster line, thanks for the link. I also hooked up my hand vacuum pump to the hard line in the engine bay that goes to the trans modulator and I couldn't get it to hold any vac. I think the piece of vacuum hose between the hardline and the modulator must be leaking. I remember it being very loose and I just didn't have any extra on hand when I replaced the modulator. I'll replace that today and get back to you guys about whether or not that solved the problem, it seems to be the likely culprit to me. Thanks again for help so far, I really appreciate it
 

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This will sound stupid simple but have you inspected the hose for cracks and splits? I've been bitten before thinking its something major only to find a spot of dry rot or mouse nibble.
 

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Discussion Starter #9
Sorry about the delay, I got swamped at work and didn't end up having any time to play with the car. This afternoon I hooked up a hand vacuum pump to every vac line and found the transmission modulator line wouldn't hold much vacuum at all. I replaced every vac line on the car and tested them, the only one with any sort of leak is still the transmission modulator line. I think it might be the modulator itself, however it's basically brand new. If I hook the hand pump up directly to the modulator should it leak any vacuum whatsoever? Right now it leaks very slowly (If I continue to pump at any sort of pace the leak is basically not noticable but when I stop pumping it takes about 30 seconds to lose 10 in hg) Would this leak be indicative of a larger problem in the transmission or is it likely just the modulator or even the gasket between the modulator and transmission? Thanks for the help
 
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