Some questions (pictures soon).

[Blessed66]

Hi everyone.

I've been recently toying with a project (since my 66 is on hold) on my 1984 GMC LWB. This truck is a 5.0 (LE9) with a TH350 (MX1) and approximately 130,xxx miles. It has sat up some and then I sort of inherit it. That's a story for a different day, however.

I will try to add some pictures later, but this is where I'm at (so far). I have checked some of the basics, changed engine oil (some leaks - valve cover gaskets for sure, probably oil pan and/or rear main as well), checked trans fluid (still full and darker red, but not burned surprisingly), and have been removing A/C and emissions equipment (A/C completely empty, not even a hiss, R4 compressor locked, metal shavings everywhere... no emissions hoses stood the test of time, or being parked in rural Texas).

Right now, this truck barely runs - partly due to vacuum leaks I caused () and not having a tune-up done in the last 15 years, probably. But, it still starts and runs decently given all of the "damage" I've done.

I plan on replacing the intake manifold and carb, regardless, to simplify my vacuum situation and help breathe some life back into this truck. Nothing crazy - I'm thinking this 305 probably doesn't need much more than a 500 cfm carb to begin with. Memory serves me right, they don't breathe like their 4" bore brothers.

This is the basic part of my questions, for now...

Given the potential for other issues to pop up (haven't popped diff cover, checked suspension pieces, or even figured out exactly what I want besides a long & low cruising truck), I am going to invest in a set of cheaper headers, intake and carb just to get this truck running somewhat reliably right now.

Is my cfm assumption (~500 cfm) an accurate starting point?
Is there anything specific to the 305/TH350 I should be concerned with?
While I'm sure getting a 4" bore engine would be better for performance options, is there a feasible alternative to building what I have into being decent in terms of power?

More questions (and pictures) to come, I'm sure.

[Blessed66]

A few pics.

[Blessed66]

More. Sooner than I thought I'd post them, but my browser was just being ignorant. I put it in it's place.

[nonstop]

Looks like a good truck! Rather than buying a new carb, you would probably be happier and maybe even money ahead, having the quadrajet rebuilt. Once they are built right, they are great carbs! Cheap rebuild will probably result in some drive ability issues. As for the headers, why? Not to sound condescending, but it's a 305. Accept it is a 305 and take it for what it is. Get it running reliable and put the money elsewhere since you are looking to make it a cruiser.

[Blessed66]

Originally Posted by nonstop

Looks like a good truck! Rather than buying a new carb, you would probably be happier and maybe even money ahead, having the quadrajet rebuilt. Once they are built right, they are great carbs! Cheap rebuild will probably result in some drive ability issues. As for the headers, why? Not to sound condescending, but it's a 305. Accept it is a 305 and take it for what it is. Get it running reliable and put the money elsewhere since you are looking to make it a cruiser.

Thanks! It's in surprisingly good condition, overall.

As far as the carb, I suppose that would be a good option, also. I have better knowledge on Edelbrocks and Holleys, but I'll probably have this one checked out by someone more comfortable with Quadrajets than me, first. Thanks!

Don't worry about condescending, you haven't met my wife. I mention headers because I won't have to plug the manifolds (AIR pipes), won't have to jack with the flapper valve, do believe firmly that a decent set of headers provide benefit to an engine that even a lowly 305 could breathe better by equipping them... and most importantly, because I have a set of cheap FlowTech (older style) headers that came off a SBC Nova that I could probably make work with minimal work.

But, mainly, that last one.

[nonstop]

Well that puts it in a different light, free is a much different story - and coincidentally my favorite four letter F-word! By all means run them, but keep the manifolds in case they start leaking!

[Blessed66]

Originally Posted by nonstop

Well that puts it in a different light, free is a much different story - and coincidentally my favorite four letter F-word! By all means run them, but keep the manifolds in case they start leaking!

Yeah, free is a game-changer. I have, seriously, forgotten some of the things I had laying around from previous cars. For instance, I was baby-sitting my parent's house while they were out of town recently... and found the LT1 (Gen II) bare block I bought years ago from a dude down in College Station. How do I forget that?

It's the kids, I tell ya.

[Blessed66]

Recognize this? Yeah, me neither. I do love that these diagrams don't really add up, sometimes. Here's the issue; I've ripped out much of the emissions and am currently working on rerouting the lines needed to stop my vacuum issues. Curently, I cannot get this truck to even run. Help! I know I have some work to do on my own, but I could sure use a hand in double-checking this set-up. Pictures coming in hot!



I've replaced the PCV Grommet (47062 Dorman/Help!) and the Valve was still ok, so I capped off the line running to the canister (It's gone). The exposed AIR tubes and check valves are an exhaust leak, basically, but they shouldn't be keeping this truck from running, right? It's not like a blown manifold gasket keeps your truck from running.



I did go back and cap the exposed EGR vacuum line on the valve and it tried to start for a moment, but wouldn't continue running. I ran a fresh line from what I believe is a ported vacuum on the carb to the ignition advance (you can see port in previous photo on L side). It made no difference - the only change was when I capped the EGR valve. Exposed AIR Valve, again. It did run like this for a bit a day or two ago. Sounded pretty terrible, honestly. I used to love open headers, too. Bet I won't anymore.



I do not like this thing. I gotta get under the truck and find the other bolt holding it on so I can fully rip it off the truck. I had a really odd knocking noise when it was running with all of this hooked up. I had read that this pump can sound like knock when it fails. I may be wrong (probably) because the knock was never constant with the engine running over idle. Sounded like a loose bracket somewhere.



Do I need to cap these Ported Vacuum switches? I doubted it because if there's no signal line going to the switch for distribution, it makes sense that there would be no vacuum leak if nothing was hooked up, right? I know these things do wonderfully to distribute vacuum without having dozens of ports on the carb itself, but I really only want vacuum to my P/B Booster, Transmission, Ignition and PCV system. Cruise would be nice, but I don't really care if I have it or not.



This is a heck of a mess. I put a cap on the back of the diaphram next to the EGR. Memory serves it's a vaccum brake for the secondaries. Keep the opening of them smooth. No change to the no-start condition. There is a small line going to the back of the carb from the diaphram so it should still be getting vacuum, but I couldn't tell if the nipple coming off the "top" was open or an adjustment (blind nipple) of some sort so I capped it just to be safe.

Thoughts? Suggestions? The odd part about this was the truck did start up and run with a majority of these ports unplugged. But now, it won't? Kinda irritated, of course, but maybe someone can steer me in the right direction.

Oh, and the front left wheel (for sure, haven't checked the right wheel) is frozen. No wonder I almost killed myself pushing the truck. I'll get to that after I get it started up and atelast not running so dang badly. I know a carb rebuild is likely in the future, and I may have found a guy nearby to do it who I trust, but I know this truck was running about a week ago. Ran bad, but it ran. I need to get it back to that baseline first.

[Dannyboy1966]

First off nice looking ride, I have the exact same truck, only mine is blue, has a 350, and SM465 manual. I may sound like a hick from the sticks but have a few suggestions for ya. First Carb rebuild, my Rochester Quad needed it when i got it. second; un screw one of those air valves out and go to a hardware store with it and find a copper or steel pipe plug in the plumbing area, Get you two of them and plug those holes up for now. third; Does it still have the factory Catalytic Converter on it?? If so, get rid of it as long as it's not required by your state. It can plug up and cause your engine to die, I had a boss that had the same problem with his converter on a 79 Ford. Last; The only things you need hooked up to vacuum is Distributor advance, brake booster, PCV valve, your cruise control if it works, and a vacuum line to your heater control which should be connected to a round ball shaped thing (a vacuum reserve bottle). Best of luck, it should be a rocking mobile when you get done. Mine is, except mine is getting hot right now, but thats life.

[Blessed66]

Thanks, man. The attention usually goes to the 66 sitting in front of it, but this truck was actually a more enjoyable ride. May be remembering the past through rose-colored glasses, as I was a youngin' when my grandfather used to take me places in this truck. Always loved it, and the smell of this truck always reminds me of him.

I will likely be pulling the carb to either tackle it myself or have a friend take a look. I'm not too experience with QJets, and unfortunately, I've suffered expanding my knowledge becuase I bought into the QJet hate early on. I know zip about them other than everyone else's exaggerated horror stories about them.

The air valves won't be an issue, as I found a set of old SBC headers I had lying around. They aren't pretty yet (I bought sandpaper and good rattle can paint today with the headers in mind), but they will do the job.

No catalytic converter, actually. So, that's good.

That's kinda what I was thinking, really. The power booster line is plugged into the back. I ran a new 5/32" line from what I believe to be a ported vacuum line to the vacuum advance. Cruise is still all hooked up, don't know if it works or not. PCV is hooked up. I believe the heater controls are messed up. I had just the supply and return hoses (intake nipple to firewall, radiator nipple to firewall) for my heater system and bypassed the core due to an extremely bad leak. There was no control valve.

The problem that's bothering me is that this truck was running and now it isn't. I'm searching for any exposed vacuum I might have made while ripping out emissions stuff.

I'll begin the headers and changing the VC gasket tomorrow, depending on my motivation and temperature. This old(er) guy hates sweating buckets.

[TrybalRage]

Originally Posted by Blessed66

Do I need to cap these Ported Vacuum switches?

No. I currently have mine bypassed so the vacuum always opens the manifold flapper as soon as the truck starts.

Originally Posted by Blessed66

This is a heck of a mess. I put a cap on the back of the diaphram next to the EGR. Memory serves it's a vaccum brake for the secondaries. Keep the opening of them smooth. No change to the no-start condition. There is a small line going to the back of the carb from the diaphram so it should still be getting vacuum, but I couldn't tell if the nipple coming off the "top" was open or an adjustment (blind nipple) of some sort so I capped it just to be safe.

That diaphragm also opens the choke slightly in a cold start situation, so it should be operational. Speaking of the choke, why is yours stuck wide open like that? Should be closed until the engine warms up.

When I first got my truck, the PO had the timing so screwed that the idle screws were completely backed out and the engine was racing. Fixing the timing meant screwing that back in until it could stay running. Something else to consider.

[Blessed66]

Originally Posted by rich weyand

Mine's capped off. There was no such thing before 1968 emissions laws kicked in. I have manifold vacuum connected to TH350 and brake booster (off the back side of the manifold) and vacuum advance and PCV valve (off the front side of the carb). That's it. Mine's a '78, so I don't have vacuum-operated heater controls, but hooking those up is OK, too.

That's what I was thinking. I'd bet the TH350 has a vacuum modulator. Easy enough to check, just haven't yet until I get the engine sorted out. Thanks for that!

Originally Posted by rich weyand

BTW, don't lose the PCV valve. Blow-by from the rings will condense in your crankcase and turn into sludge in your oil. The PCV valve allows the engine to pull those vapors out of the crankcase. The difference when you pull a high-mileage engine apart between with-PCV and without is unbelievable. One is pretty clean and the other is all garped up with sludge.

You don't see PCV valves on race engines, because they pull them and rebuild/replace them so often. Street engine, different matter.

Around these parts, people will tell you it's because of Pennzoil. Some myths die very hard. I don't underestimate the importance of the PCV - and I'll likely replace the breather cap on the passenger side valve cover with a PCV valve and T the lines into each other when I replace the VC gaskets. Thanks!

Originally Posted by TrybalRage

No. I currently have mine bypassed so the vacuum always opens the manifold flapper as soon as the truck starts.

Cool beans. Kinda what I was thinkin. Thanks!

Originally Posted by TrybalRage

That diaphragm also opens the choke slightly in a cold start situation, so it should be operational. Speaking of the choke, why is yours stuck wide open like that? Should be closed until the engine warms up.

When I first got my truck, the PO had the timing so screwed that the idle screws were completely backed out and the engine was racing. Fixing the timing meant screwing that back in until it could stay running. Something else to consider.

Good point on the choke. I had noticed that and I know the electrical connector on the factory harness looks busted. I'll slap a spade terminal on it and see what I get. I'm sure that would make it run poorly, but not so sure that would make it no-start. Then again, my battery is being a pain and not wanting to stay charged. Maybe my choke is staying on and draining it? Is that a thing? I don't have near as many tools as I'd like - but it looks like a multimeter might be a good start.

Timing wise, I don't think this truck has been touched much since my grandpa got it in 84. It ran ok prior to my emissions-stripping, and I have a few things I need to quit procrastinating about and just do.

There's some work to be done, for sure, but it'll be a solid truck.

[rich weyand]

Move the vacuum advance to manifold vacuum. Ported vacuum is more emissions nonsense. See first three posts here.

http://www.hotrodders.com/forum/dist...1-a-59033.html

[Blessed66]

Originally Posted by rich weyand

Move the vacuum advance to manifold vacuum. Ported vacuum is more emissions nonsense. See first three posts here.

http://www.hotrodders.com/forum/dist...1-a-59033.html

I'm still reading, but what I've seen so far is impressive. That is a very handy amount of information. Thank you for this! Would it be fair to say that ported vacuum - in any form, on this truck anyways - is useless, then?

I can't think of anything that you'd find on these trucks, besides the advance before reading those posts, that would need it now. That might make my vacuum routing much, much easier.

[rich weyand]

Originally Posted by Blessed66

I'm still reading, but what I've seen so far is impressive. That is a very handy amount of information. Thank you for this! Would it be fair to say that ported vacuum - in any form, on this truck anyways - is useless, then?

I can't think of anything that you'd find on these trucks, besides the advance before reading those posts, that would need it now. That might make my vacuum routing much, much easier.

Mine's capped off. There was no such thing before 1968 emissions laws kicked in. I have manifold vacuum connected to TH350 and brake booster (off the back side of the manifold) and vacuum advance and PCV valve (off the front side of the carb). That's it. Mine's a '78, so I don't have vacuum-operated heater controls, but hooking those up is OK, too.

BTW, don't lose the PCV valve. Blow-by from the rings will condense in your crankcase and turn into sludge in your oil. The PCV valve allows the engine to pull those vapors out of the crankcase. The difference when you pull a high-mileage engine apart between with-PCV and without is unbelievable. One is pretty clean and the other is all garped up with sludge.

You don't see PCV valves on race engines, because they pull them and rebuild/replace them so often. Street engine, different matter.

[rich weyand]

Well, you already have a properly connected PCV valve on the driver's side, and a breather on the passenger side. You can reverse those if you want, but one side should be a PCV valve and the other a breather, so you get air flow through the engine.

Note the size of the PCV valve fitting and the associated carb fitting. Your carb fitting already points to the driver's side, so I would leave it where it is. Just make sure the valve rattles when you shake it up and down. That's normal, and proves it isn't stuck.

[Blessed66]

After proctrastinating a little, I decided to get out and get the caliper changed. I'm wanting to get this thing rolling and the jackstands had sunk about 1/2" into the old asphalt in out driveway. Not good.

I could've sworn this was a heavy duty brakes truck. Turns out I gambled and lost. My rotors are the light duty 1" rotors. I swore that most of these trucks used the HD brakes, but it's not a big deal. Swapped the caliper for the right one, got it in place. Wheel spins freely now.

But, I must have missed a step somewhere. Had the Mrs. pump the brakes to start bleeding the system and... the caliper still hasn't moved. Got the new copper washers, no leaks, plenty of fluid in the M/C. Huh. I cracked the bleeder screw and I'm getting nothing. It's not a total loss, as we've been using the Armada to pull it around at low speeds and the drums are pretty solid so it can atleast be moved, but that just bugs me.

So, all in all, I yanked the caliper today, slapped on the new one and got it off of jackstands... so far. I disconnected the wire going to my electric choke and, while it's staying open still, the battery charger actually green-lighted me this morning (indicating full charge) which is great, will go to check if she runs or not. I hooked up my advance to manifold vacuum (thanks again, rich!) and added some fresh fuel...

We'll see in a bit.