Well guys, I finally have to swallow my pride and post my blunder to the message board cause I need help. If anybody here has read my profile, I'm a computer systems engineer during the day, so please, keep that in mind when flaming me for my retardation. I in no way consider myself a good mechanic

Alright, so on to the problem. I have a 350 in my '67 SS that's been nice and strong since I bought the car. It's needed a little tuning here and there--stuff I can handle. Well, recently, I started getting a tick from one of my valves on the driver side, and it was annoying the crap out of me, so I figured I'd just go in there and regap 'em. Got my gapper out, found some specs on the internet, and it looks like my 350 should have a gap of .024 on the intake valves and .030 on the exhaust (which is probably wrong), so I gapped em up. It took me a little while, and most of the rockers were on there pretty damn tight, so I had to loosen em up to get the gapper in there, but I finally finished. So, I bolted on my valve covers and figured it's time to take this thing for a test run. Well, the car ran fantastic! Seemed to have a lot more pick up and some more ***** to it, so I'm thinking that the rockers being so tight was actually causing my some compression loss due to valves that always remained slightly open. Well, after 10 minutes of my test run, I figure I'll give it some gas... I get to about 5k RPM and I get a nice boom out of my carb and stall. I coast off the road, figure I'll try to start it again, and I get nothing. So I pop the valve covers off, tighten up the rockers a little bit (since that's the only thing I changed), and try to fire the car up again... nothing. Occasionally I get a backfire up through the carb, but I never actually start. I've tried retarding the timing back a little... nothing but a backfire now and then. It's almost like I'm not getting spark anymore, but that shouldn't be related to the rockers being loosened up, right?

I need some help here! I got a beautiful '67, that could be eating up mustangs, just rotting away in front of my house at the moment.

 

67 SS 350's came with a hydraulic cam, so unless someone installed a solid cam, you shouldn't be lashing the valves. They should run a preload.

The dead engine problem might not have anything to do with you messing with the valves. So just do the basic troubleshooting routine, air, fuel, properly timed spark. It's possible that while you were messing with the valve covers you might have knocked a wire to the coil loose and it fell off during your test drive.

 

I'm not sure if it's a hydraulic or mechanical cam in the engine as it's not the original engine and I have no idea what year the engine actually is. I can roll the lifters between my fingers no problem, which from what I understand means that I probably do not have a hydraulic cam.

But yes, the engine is behaving like I'm not getting spark. It could just be 100% coincidental that my distributor stopped working or something or that I knocked something loose while playing around in there.

 

What kind of carb are you running? im going to assume everything is stock.

if its a holley carb you may have blow the power valve with the 5000 rpms backfire.

if its a Q-jet they usually dont get hurt.

How hard did you try to start it? did you hold you foot to the floor to see if it was flooded? how about is it getting enough fuel, did you try pumping the gas several times before cranking?

sounds like maybe your valves floated and caused the backfire, about the only thing it could have damaged that would cause it to ack the way you say would be movement of the distributer or maybe you bent a pushrod when it backfired and its keeping an exaust vavle closed or an intake closed.

I would agree, go over all the tipical items, make sure it is getting gas through the carb and down the intake, pull a plug out and have a look, let it lay agains something metal and see if you see spark, if you have fuel and spark and it still backfires when trying to start, ...
(PS DO THIS WITH THE IGNITION WIRE DISCONNECTED!! this is the wire on the distributer cap that is closest to the brake booster, should be a thick orange or red wire)
pull the #1 spark plug out (its the on farthest to the front on the drivers side), then get somebody to turn the motor over while you hold your thumb on the hole, hold really tight, when it blows your thumb off the hole you are at top dead center, now take your distributer cap off and see where the rotor is pointing, make sure its pointing at the #1 spark plug wire, if its not then you need to check some things out or move the distributer (DONT PULL IT UP OUT TO MOVE IT) try moving it by loosening it up and rotating it like you do when timing the motor.
Once you have it pointed at #1 spark plug wire, then put the cap back on, the plug back in, and the dist power wire back on. try starting it again, if it starts then you can time the motor and readjust the valves like you did before (if you gained power and it didnt make any noise you probably had it just right where its supposed to be).
if it doesn start you need to pull all your plugs and make sure they are all good and not soaked with gas or fouled out or burned off, holding valves open can burn spark plugs up.
if all this turns out to be fine and it still doesnt start, then there is something major to look at, like maybe you broke your timing chain or it jumped severly!
A good backfire could break your chain, heck, you might want to check that first. take the cap off the distributer and take the power wire off too, crank the motor over and see if the distributer turns. if it does do the spark and timing check.
If when you check the rotor position in the distributer and find it off enough that you cant adjust the distributer far enough to accomodate it, then you may want to pull your timing cover off and check to see if you did jump a tooth on the timing chain, and put a new one in while ur in there, i bet you get more power from a new chain anyhow since an old chain will allow the cam to move and push your power curve around.

Goodluck!

PS, a good place to ask this question is at www.nastyz28.com there is a LOAD of info there and VERY knowledgeable people, the more input the better when dealing with a problem like this.
just go to the message board, you can create a name and password and even make it the same one as this one so people are familiar with your name.

 

Sadly, the engine isn't stock in the car, its got a 750 Holley doublepumper. I'm pretty sure the timing chain is still okay because when I crank the starter I can watch all the valves open and shut. It's more than likely the distributor, that thing was already on its way out when I bought the car, so I might've just done it all the way in.

 

Alright, so I just did a little more debugging and here is what I have now. I figured it was probably a distributor problem, so I removed the cap and rotor and took a look in there. The first problem I noticed was the vacuum advance spring. One of the springs had actually rusted, broke, and was loose in the distributor body. So, I took that out, cleaned out the cap and rotor a little, and put it all back together. I tried to fire up the car; every now and then I get a pop through the carburetor. So, now, I figured I'd just test for spark. I got my timing light out, plugged it into plug #1, and turned the starter. Well, I got zero lights for a few seconds then the light lit up once, followed by a deafening BANG from the driver-side pipe.

So here is where I am currently: I've got an HEI distributor with a broken vacuum advance spring, and I'm apparently not getting any spark. Now my question is what should I replace first to try to get this thing sparking again? Coil, rotor, cap? I obviously need to replace that timing advance spring.

 

check the wires running to the ignition control module, sometimes they break inside and when the distributer moves they make contact and then break up, this would cause intermittent spark patterns.
also make sure the cap and rotor are in good condition, scrape all the buildup off the terminals.
check your coil wires, usually these just burn out and stop working all togather.
or if you can make it to a junk yard, heck , just buy a used distributer whole and drop it in and see. much easier and cheaper than popping new parts at it.

 

Have checked to see if the distributer is actually turning? Last time mine quit with a boom like that was when it stripped the gears off the end of the distributor!

 

Man did you call it! Check these out:

http://home.tampabay.rr.com/stalemeat/distributor/

The distributor was DEFINITELY not turning. Popped in a freshly built HEI that a buddy gave me, for which he is the man , put a new power valve in the carb, and the thing fired up. Needless to say, I still need to do a few more things to get the motor running top shape again. New plugs, a few gaskets, and I absolutely need to drop the oil pan and get those pieces of gear out of my engine. Thanks for all the help!

 

Yea, thats what i meant by the timing chain may be broken or skipped a tooth, when things like that happen you either strip dist gears, break timing chains, jump teeth, snap cams, or bend valves.
If you were running nitrous i would have said check for a hole in the piston

Glad to hear you found it!

 

Since the dist. wasn't turning, is there a possibility it did any damage to the camshafts' gears? Or the oil pump? You might want to keep an eye on your oil pressure for drops. If it stripped out the dist. it might have or lead to taking the pump and cam with it???

 

Yeah, me too! "Those pieces" have been in my pan since the summer of 1990, and I don't know when that roller rocker failed and lost all those needle bearings.

 

just a thought worst case sanerio 5krpms advance spring broke timing went nuts predetonated backfired throght the carb blew the powervalve in it holleys are notorius for this and possibly blew a hole in one of the pistons

 

Alright, I've got an update... finally. First off, here is the rest of my distributor and a depressing picture of my car:

http://web.tampabay.rr.com/stalemeat/oilpan/

Now here is what I found out with some diagnostics. I did a compression test on all the cylinders, on cylinders 1, 3, 5, 7, and 8 I got readings between 146-149psi, now on cylinders 2, 4, and 6 I got readings of like 155-160. I don't know if this is a big difference, but I figured I'd post it.

Also, on the right hand side of the motor, I pulled a good amount of black liquid out with the plugs. Smelled like gasoline, so it could've been a mix of gas and oil. I also get a good amount of white smoke from the pipes on both sides of the motor, more on the right side of the motor.

When driving the car, it dogs quite a bit. The ride is real jerky and I get a sort of resisting noise from the exhaust. It almost feels like my '96 Camaro ran when I had a clogged up cat converter. Under load the engine fires up through the carburetor. Also, the car has almost no power and my power brakes are barely functioning so I don't think I'm getting much vacuum. I think something might be screwy with my carburetor as I can adjust the screws on both sides and I don't really get much difference in the sound of the engine. Not like it used to change before I blew it all up.

Just for reference, the 350's running a Holley dual-feed 750 through a Weiand intake manifold, and I've got my timing up to about 14 degrees before TDC, which is normal. Could it possibly be that my Holley just sucks? Next time I'm buying Edelbrock!

 

Sounds like your timing might be retarded a bit. That's what happens when your timing chain skips a couple teeth. It could've happened when you stripped the gear off the distributor.

The only other thing I could think of is that maybe you blew out something other then the power valve in the carb?