sqeeek

Basically, my engine was rebuilt by an aged man in the 1990’s and I don’t know how it’s put together, but it’s not stock. There are so many things that could be wrong that I’m just going to try to accurately describe what’s going on and if anyone can either tell me it’s fine or point me in the right direction I’d really appreciate it. Something just doesn’t seem right.

Engine is a ‘70 455, not the W-33 unless I’m mistaken but one step under that. Points, cap, rotor, wires, plugs, even alternator are brand new and all seem okay. Using an old school non-adjustable sears timing light and some ancient dwell/rpm meter.

1. Turning distributor clockwise makes timing mark move towards the 12*BTDC mark and makes the car idle faster and have more vacuum.

2. Connecting the vacuum advance to manifold makes the timing mark move towards the 12*BTDC mark (away from the ‘after’ side) and drastically increases idle speed. Manifold vacuum increases to 19-20 psi.

3. With timing set to 8*BTDC@1100rpm, with no vacuum advance, engine seems to knock and manifold vacuum sits at 16psi or so. The farther I go upwards from 8*BTDC on the crank, the faster it idles and the ‘smoother’ it sounds.

4. With timing set at 12*BTDC@1000rpm or so according to the crank and vacuum advance plugged in, engine idles at about 1350-1400rpm (I should clarify, idle adjustment screw is completely out). It also sounds like it’s low compression and I can smell (and hear) unburnt fuel in the exhaust.

5. Driving with vacuum advance plugged into manifold, acceleration is weaker in low RPM but throttle response is better. Going down a hill in 1’st, there is no ‘popping’ in the exhaust (glasspacks). However, vacuum advance plugged into carb, throttle response sucks but picks up faster when it hits the primaries and has that glasspack-going-down-a-hill popping noise. And you can't smell a cloud of gasoline afterwards.

I’m about to go throw octane boost in there and see if that gets rid of the knock. I’m trying to not rely on the knocking noise as a way to set the timing because the valves also make noise occasionally and there’s a nice leak in the manifold, so it might be just fine. Carb also might have warped base, making throttle flaps not close completely, so idle is screwed anyway.

Long -> short – Can anyone tell me if that’s what should be happening? I’m a beginner and haven’t ‘been there done that’ yet but it seems like something is backwards…

JPMDaddy

Perhaps one of the 'old men' on this site can help you out

oldcutlass

I'm not old, just older.


Any vacuum leaks need to be repaired if you want the engine to run properly. If there are tapping or knocking noises within the engine it means something is worn and also needs to be repaired. Pinging is something different and means timing is too far advanced. You need to be running 93 octane.


Make sure your dwell is at 30* (point gap) using the ancient dwell/rpm meter.

Set your timing next to 12* BTDC with vacuum disconnected and plugged and with the rpm set @ 1100rpm using the old school timing light hooked to the #1 spark plug.

Once this is set, then plug you vacuum advance to ported vacuum (no vacuum at idle). Then set your carb idle to 650 rpm, with car in drive. After this is set put car in park.

Plug in your vacuum gauge to manifold vacuum and adjust your a/f mixture screws so that they are about equal turns between the two until you have the highest amount of vacuum on the gauge.


You don't need octane boost yet.

hookem horns

Sounds like you may have carb issues that could cause vacuum leaks and make the engine run lean. I would make the basic adjustments like Eirc suggested and then check/fix the carb before any more timing adjustments.

sqeeek

I had 89 in it, so I was going to stick some octane boost to jump the whole tank up a bit. Ended up just topping off with Premium, turns out my tank leaks so it was lower than I thought anyway. *facepalm*

Knocking - I guess it sounds more like valves to me, which might just be clogged channels in the lifters? Had the valve covers off and it was a bit dirty in there, also noticed I have the old non-adjustable lifters. Shouldn't be making too much noise though, I checked for lash and there was nothing too loose when the valves were open. So why does it stop making ungodly noises when I advance the timing? [edit: duh, faster idle, faster oil pump, more oil pressure, more oil in valve guides] That's what I can't figure out. Wish I knew exactly what 'ping' sounded like, heard it on different motors but on this one there's so much damn 'pinging' under the hood from valves, fuel pump, alternator, fan clutch, exhaust leaks, loose junk everywhere...

But anyway, set the timing to 12*@1100rpm without the vacuum advance plugged in, dwell is at 30*. Thing stumbles around a bit. If I take it to 8*@1100rpm (other common option in CSM) it stumbles around like a drunk german. Starting to think it's more of a carb issue. I'll do a compression test too, just to eliminate that whole can of worms.

Vacuum seems to be okay at 17 on the gauge, runs like crap if I make a leak, obviously. Still could be a smaller leak somewhere. I've been through the carb a dozen times to get it this far and it looks alright.

Last question - if I were to determine that the timing mark on the crank had nothing to do with what the engine was actually running, could I just set it by ear/vacuum gauge? I think that's what's bothering me - I generally know what I'm hearing, but I don't really know what a 455 should sound like. I just need to get joe the mechanic to say 'yup, that sounds right' and I'll be okay with it, just because of the vast difference in [exhaust] sound that even a bit of timing adjustment makes.

Sorry if this is a bit incoherent, doing work paperwork. Thanks for your help.

sqeeek

Set the idle a bit better, checked everything again and revved it up and down to check for pinging, I think I've got it close now. I think most of the noise I'm hearing is in fact the manifold, I thought it was just a leaky gasket on cylinder 8 but it sounds like the whole thing is having issues. I'll see what I can do about the leaks tomorrow and hopefully it'll sound a little better. Still not convinced that my damper line is where it should be. Actually not convinced that anything is where it should be. At least it runs.

Might put something other than a glasspack on it at some point. Wasn't my idea... makes it sound like a boat inside. Then maybe I can hear what's really going on over the scream of four hundred and fifty-five cubic demons.

I need to befriend an old guy that knows what the heck he's doing.

70cutty

Not old guy just older, or a guy that knows what he is doing. The noise could be your exhaust manifold gasket leaking.

sqeeek

Haha alright, I'll see if any of my neighborhood mechanic friends will give me a hand. I usually try not to bother them because I know how annoying it can get.

Replacing gasket tomorrow, I know for sure it's leaking so I'm hoping that's the noise that's worrying me.