Build The Clustertruck Rides Again - Refurbishing a 1975 Chevota

[handcannon]

Most of the older engines we removed that short front bolt and temporarily replace it with a longer one . Holding the rod in the retracted position you can snug the long bolt to hold it there , then install your pump . Remove long bolt , re-install short one and it's done .
Sarge

What you say here may be what I did. I know I was working by myself, so I was questioning my memory after what I wrote in my post. I know I don't have the needed third hand to have held the rod in place and also bolt on the pump. Or do I? I don't know now. It's not fun to get old as your memory is the first thing to go, or at least I think that's my problem.

Don

 

[SuperBuickGuy]

the motor pictured is a 400 (the orange one), but you can see the two bolts on the passenger side, just above the oil rail, on the front of the motor


the upper bolt is the one you remove and put a longer bolt in. Don't lose the short bolt, and don't leave the long bolt in when you fire it up unless you like selling cars to me with a flat pump lobe at bargain prices.

Also, don't be ham-fisted, finger tight will generally be more than enough to keep the pump rod up in place...

 

[RWBeringer4x4]

Well, another frustrating couple of days working on the truck.

It all started when I found out the distributor clamp was not clamped down on my HEI unit. This seemed like as good a reason as any to time the engine. So I pulled out the timing light, and found that the timing mark was way off - showing something like 60 degrees BTDC at idle. Knowing this wasn't right, I found TDC with a piston stop, and drew myself a new timing line. The truck is now set to 20 degrees advanced at idle (no vacuum) and it goes to about 34 with throttle.

Then, I replaced the water neck (again) because the first one I got leaked. It took two attempts cleaning, filing, and a couple extra gaskets to finally get the second one to seal too!

Next, I built some new hard fuel lines from the fuel pump to the carb. This was in an effort to prevent the previous rubber ones from expanding/getting too hot and pushing fuel into my carb as they cooled - part of a longer project dealing with what I THINK to be fuel percolation issues flooding my engine after I shut it down.

The new lines LOOK nice, but now all hell has broken loose.

Here is a list of a bunch of problems that just cropped up that are confusing me to no end:

1. At a cold start, I now have a strange "tap" coming from somewhere (I believe it's in the driver's side bank of cylinders). It goes away once the engine warms up.

2. The truck is now burning oil. The spark plugs I put in a few weeks ago were fouled pretty badly. I'm getting smoke out of the breathers on both valve covers, and out the tail pipe when I rev the engine. I re-checked the compression, it's still showing 139-150psi across all cylinders, so I don't think it's the rings. Valve seals? Thoughts?

3. If I hold the throttle open for an extended period of time, the truck would stall as soon as I let off the throttle. This seemed to go away after some fiddling, so I didn't think anything of it until today -

4. The carb now floods out when the engine is under load. I went to get gas today, and didn't make it out of the neighborhood. The truck idles fine in the driveway, responds properly to throttle, and doesn't flood. However, as soon as I try to DRIVE it anyway (in gear, moving under load) I get gas everywhere. It's backed up into the venturis, it's leaking out the accelerator pump, and soaking through the baseplate gasket and pooling on the manifold.

So, once again, I corrected a bunch of "wrongs" plaguing the Clustertruck, only to find that it ran better when everything was all screwed up!

Anyone have any ideas why the carb would suddenly be flooding? My only thought is something is in the needle and seat - but I'm running 2 fuel filters (one inside the carb, one in-line).

 

[SuperBuickGuy]

I had a Corvette that, when it was fully tuned, would utterly destroy clutches - and it was a constant battle to keep it tuned, point is, it's actually pretty normal.

Have you done a compression check?

tap could be as simple as a collapsed lifter - when its cold, check the lash. It could also be a broken lifter spring - so check that at the same time.

which spark plugs are fouled? or are they all fouled?

it's probably time to rebuild your Quadrajet, both those issues could come from worn, throttle blade bushings.

34* without vacuum hooked up? that means 49* with it hooked up? I have no idea what the motor is, but that's something a very-low compression 350 would run at (like mid-70s truck motor)....

 

[RWBeringer4x4]

I had a Corvette that, when it was fully tuned, would utterly destroy clutches - and it was a constant battle to keep it tuned, point is, it's actually pretty normal.

Have you done a compression check?

tap could be as simple as a collapsed lifter - when its cold, check the lash. It could also be a broken lifter spring - so check that at the same time.

which spark plugs are fouled? or are they all fouled?

it's probably time to rebuild your Quadrajet, both those issues could come from worn, throttle blade bushings.

34* without vacuum hooked up? that means 49* with it hooked up? I have no idea what the motor is, but that's something a very-low compression 350 would run at (like mid-70s truck motor)....

@SuperBuickGuy -

1. Yep, I have done a compression check, twice - 139-150 across all eight cylinders

2. I'm hoping that's all the tap is! I can also "feel" something through the valve cover, a knocking, on the driver's side cylinder bank. it doesn't seem to knock at the same time as the "tapping" noise but I'm wondering if I have something contacting the underside of the valve cover...

3. They are all fouled. They've only been in there a couple weeks, but given how much I've been fooling with the timing and such, I don't know that this really diagnoses anything definitively.

4. I already rebuilt the quadrajet. Only about 500 miles on the rebuild, but this definitely seems like a needle/seat or float issue. The welch plugs are already epoxied. Throttle bodies seemed ok (very limited play, if any).

5. 34 degrees without vacuum. It's a 1965 283.

 

[SuperBuickGuy]

1 - that's excellent
2 - look at the underside of the valve cover - there should be a witness mark where it's hitting (if it is)
3 - PCV valve is allowing that blow-by back into the motor
4 - the needle/seat of a Quadrajet is hateful - I'm running about 30% getting it set right the first time - that said, you could have dirt in it
5 - yikes, that seems high; but I've never delved that far into a 283 to remember its timing specs.

 

[71FJnick]

You're symptoms sound similar to what I've been chasing on mine.
I only have theories so far.

1) manifold vs ported vac advance
When you set the timing did you change or modify the port for the advance?
It might be worth putting a vac gage on the port to check
Manifold =16-22 @idle, that's how @SuperBuickGuy got a total of 36 deg advance since if the vac was connected to manifold vac the you'd max it out at idle
Ported=0 at idle an climbs as you open the throttle then goes away again at WOT

My theory would be that your engine may want less initial timing and use manifold vac to increase timing at idle then allow off idle to transfer to less timing
Or
Your setup wants a lot of initial timing (like 22) then ported vac advance to allow it to pull in more off idle

There's lots of discussion on the topic but really whatever works best for the engine, works best for the engine. It might be worth looking into that since all you did was set initial timing

 

[71FJnick]

Just read your other thread, didn't realize you have fuel leaking out.

Is it possible some gunk got washed in your fuel line and is causing your float to stick?

 

[SuperBuickGuy]

to complete the thought - I say Quadrajet needle valves are hateful because they're so sensitive to too much fuel pressure. Where the AFB and the Holley carbs push up on the needle to let fuel into the fuel bowl, quadrajets go the opposite direction - thus, when you get too much pressure it holds the valve off the seat. I think it's this because of two things you said 1) WOT, which is highest fuel pressure, tends to cause this the worst; and 2) you just made the fuel flow better with a new line and filter. the right way is to put an adjustable regulator on the line (3-5 psi) and turn it down to 3 psi; the other way is crimp the line a bit to restrict flow...

 

[RWBeringer4x4]

1 - that's excellent
2 - look at the underside of the valve cover - there should be a witness mark where it's hitting (if it is)
3 - PCV valve is allowing that blow-by back into the motor
4 - the needle/seat of a Quadrajet is hateful - I'm running about 30% getting it set right the first time - that said, you could have dirt in it
5 - yikes, that seems high; but I've never delved that far into a 283 to remember its timing specs.

@SuperBuickGuy - no PCV valves, just breathers. I've been debating whether or not to install one. Haven't had a chance to pull the valve covers yet, but I'll definitely be looking for a mark when I do. As for timing - without vacuum advance at idle, it's at 20 even. The advance is being fed by full manifold vacuum (not ported) so it really sits at about 30. However, as the throttle plates open, manifold vacuum drops so the advance should actually be weaning OFF as I move up in engine RPM's...so probably full advance is still somewhere around 34. The factory recommended setting for a 283 is 4 degrees BTDC. This one won't even idle below about 8-10 BTDC. It seems to be happiest between 16-20 at idle, which also correlates to about 34 mechanic advance at open throttle, which is right where it should be. I'd need to full with the weights and springs to open up the idle/throttle gap more.

You're symptoms sound similar to what I've been chasing on mine.
I only have theories so far.

1) manifold vs ported vac advance
When you set the timing did you change or modify the port for the advance?
It might be worth putting a vac gage on the port to check
Manifold =16-22 @idle, that's how @SuperBuickGuy got a total of 36 deg advance since if the vac was connected to manifold vac the you'd max it out at idle
Ported=0 at idle an climbs as you open the throttle then goes away again at WOT

My theory would be that your engine may want less initial timing and use manifold vac to increase timing at idle then allow off idle to transfer to less timing
Or
Your setup wants a lot of initial timing (like 22) then ported vac advance to allow it to pull in more off idle

There's lots of discussion on the topic but really whatever works best for the engine, works best for the engine. It might be worth looking into that since all you did was set initial timing

I'm definitely on full manifold (not ported) vacuum. The engine pulls about 15 PSI manifold vacuum at idle. I should be getting 34-36 at WOT.

Just read your other thread, didn't realize you have fuel leaking out.

Is it possible some gunk got washed in your fuel line and is causing your float to stick?

I think this is very likely. That fuel filter right before the intake is not "new" and it had some particulates in it. Even though it's hooked up in the right direction, those particles are inexplicably gone...and they went somewhere...

Whats weird is that the engine runs FINE when sitting in my driveway at idle. It's only when it's loaded up and I'm driving around that it floods out - and I mean FLOOD - gas out of ever oriface. The only thing I can figure is that the float is sticking, and it just is more apparent when the vehicle is bouncing around...

to complete the thought - I say Quadrajet needle valves are hateful because they're so sensitive to too much fuel pressure. Where the AFB and the Holley carbs push up on the needle to let fuel into the fuel bowl, quadrajets go the opposite direction - thus, when you get too much pressure it holds the valve off the seat. I think it's this because of two things you said 1) WOT, which is highest fuel pressure, tends to cause this the worst; and 2) you just made the fuel flow better with a new line and filter. the right way is to put an adjustable regulator on the line (3-5 psi) and turn it down to 3 psi; the other way is crimp the line a bit to restrict flow...

I do have a new pump and lines. I've read a ton about quadrajets being SUPER sensitive to high fuel pressure. That said, my fuel pump is a stock, mechanical pump that was rated for about 6.5psi. That was the lowest output pump I could get, and 6.5 should be low enough.

It's not really at WOT that it's flooding, it's at cruise - maybe 2000rpm, low throttle.

Given that the fuel filter wasn't NEW, and the particles are not gone, I think I'm going to start working under the assumption the float is sticking, or there's crap on the needle/seat - as much as I dread buying more carb gaskets and tearing the Q-jet down - I'm planning on replacing it with a full rebuild in a few months as it is...

 

[SuperBuickGuy]

6.5 shouldn't be too much, however, these are just guesses based upon my experience, since I cannot see MD from Seattle, and are subject to full refund if they don't work

or the float has sunk - what material is the float?

PCV valves will lean out the mixture - sometimes that's a good thing; others, such as on a race motor, it's a terrible thing

Do you still have a filter in the filter holder on the carb?

your vacuum advance should be on the ported port - if you put it at full vacuum 100% of the time, you have a mechanical start retard. On high compression motors, having the timing back 15*(ish) degrees (since you can buy adjustible and different advance vacuum pots) can really help the starter live. On a street motor, you want advance when you just get onto the throttle - thus putting the advance to the ported side - on street motors, you know you have it wrong when the vehicle stumbles at tip in then pulls hard once it's past that point.

 

[RWBeringer4x4]

6.5 shouldn't be too much, however, these are just guesses based upon my experience, since I cannot see MD from Seattle, and are subject to full refund if they don't work

or the float has sunk - what material is the float?

PCV valves will lean out the mixture - sometimes that's a good thing; others, such as on a race motor, it's a terrible thing

Do you still have a filter in the filter holder on the carb?

your vacuum advance should be on the ported port - if you put it at full vacuum 100% of the time, you have a mechanical start retard. On high compression motors, having the timing back 15*(ish) degrees (since you can buy adjustible and different advance vacuum pots) can really help the starter live. On a street motor, you want advance when you just get onto the throttle - thus putting the advance to the ported side - on street motors, you know you have it wrong when the vehicle stumbles at tip in then pulls hard once it's past that point.

I appreciate all the follow-ups! I honestly can't remember what material the float is - I know the rebuild kit came with a nitrophyl one, and the carb had a brass one in it when I took it apart. Can't remember which one I put back in...Float might have sunk, but again - I'd be surprised if it only lasted 3 years...

To be honest, I only comprehended about half of what you said about ported vs. manifold vacuum. I've seen people with opinions that go both ways. You're saying putting too much initial timing will hurt the starter? Not sure what "tip in" is but my truck generally only tends to stumble OFF throttle (like, if I've been running down a road then pull up to a red light, it ocasionally tries to stutter or stall.

And yeah - I have a filter in the carb as well. That's why I'm kind of surprised particles might have made it through to clog the needle and seat - that would mean they made it past 2 fuel filters...

 

[SuperBuickGuy]

you want the advance from the vacuum to happen when you open the throttle blades - the only reason you wouldn't want it that way is if you're running a high-compression motor. High compression motors, if the spark happens too soon will (in best case) stop the starter, and in worst case literally blow the starter off the motor sometimes taking the block with it (really ask me how I know, it wasn't my motor this happened too - I just had to fix the aftermath).

The reason I pointed that (manifold vacuum) out was to help you understand why you would hook the vacuum canister up to manifold vacuum. Most race cars don't use vacuum advance at all, rather they either control it mechanically with the weights (and kill starters), run without any advance, or control it electronically like I'm doing with my FJ40 build. vacuum advance is more a fuel economy, part throttle benefit.

If it is the neoprene one, it's possible that alcohol has already killed it (depending on the formulation)... but I only mentioned it for completeness, your symptoms don't seem to be a sunk float.

 

[RWBeringer4x4]

you want the advance from the vacuum to happen when you open the throttle blades - the only reason you wouldn't want it that way is if you're running a high-compression motor. High compression motors, if the spark happens too soon will (in best case) stop the starter, and in worst case literally blow the starter off the motor sometimes taking the block with it (really ask me how I know, it wasn't my motor this happened too - I just had to fix the aftermath).

The reason I pointed that (manifold vacuum) out was to help you understand why you would hook the vacuum canister up to manifold vacuum. Most race cars don't use vacuum advance at all, rather they either control it mechanically with the weights (and kill starters), run without any advance, or control it electronically like I'm doing with my FJ40 build. vacuum advance is more a fuel economy, part throttle benefit.

If it is the neoprene one, it's possible that alcohol has already killed it (depending on the formulation)... but I only mentioned it for completeness, your symptoms don't seem to be a sunk float.

I'll have to look again - I was kind of surprised because I THINK the vacuum port I'm hooked to should be ported. However, I have a VERY early (1967) Buick Quadrajet. I have read that some of the earliest renditions did not have ported vacuum...so it could be that I have it connected to the correct port, but it isn't "ported" if that makes sense. I know generally speaking the ported vacuum on the quadrajet is just above the driver's side idle mixture screw.

It's all sort of a crapshoot, because the 283 never really got a Quadrajet "from the factory" anyway - so setting one up is a bit of a guessing game. I can only confirm that I get 20 degrees advance mechanically, and it goes to 30 when I hook up the vacuum advance at idle, which, to me, sounds like the port is pulling vacuum at idle, and therefore isn't ported.

What I can also tell you is that the engine really did not want to run below about 12 degrees of mechanical advance. "Factory" is 4 degrees BTDC but it was trying really hard to die that low...

Really, I'm about ready to retire this one, and go to a good rebuild (thinking Sean Murphy Inductions) with the wells/throttle plates professionally done, the air horn decked for flatness, proper, known jetting, and a working choke. There's a lot wrong with the old Buick setup I've been ignoring but it's getting to the point it might need to get put in the "backup-parts" bin.

 

[SuperBuickGuy]

your trials are similar to what made me go to holley for race cars, and afbs for everything else. of course, holleys and afbs then made me go efi - which made me go back to holley on my race cars...

as for Buick-specific carbs, despite my screenname, I dunno. I have several quadrajets hanging on my wall; but I'd be hard-pressed, without looking up the numbers, to tell you which is cadillac, which is buick, and which is heaven knows.

 

[RWBeringer4x4]

your trials are similar to what made me go to holley for race cars, and afbs for everything else. of course, holleys and afbs then made me go efi - which made me go back to holley on my race cars...

as for Buick-specific carbs, despite my screenname, I dunno. I have several quadrajets hanging on my wall; but I'd be hard-pressed, without looking up the numbers, to tell you which is cadillac, which is buick, and which is heaven knows.

Yeah, if I remember correctly I traced my engine back to a Chevy C10 or C20 283, running an aftermarket SP2P 350 manifold, and the carburetor from an early Buick Wildcat with A/T. A total hodgepodge!

 

[DPV7070]

Really, I'm about ready to retire this one, and go to a good rebuild (thinking Sean Murphy Inductions) with the wells/throttle plates professionally done, the air horn decked for flatness, proper, known jetting, and a working choke. There's a lot wrong with the old Buick setup I've been ignoring but it's getting to the point it might need to get put in the "backup-parts" bin.

I had SMI build me a Stage 1 Quadrajet and I cannot emphasize how much I endorse his work. I drove up to Huntington Beach to drop it off and he took time to talk with me face to face. It was complete in about 2 days, looked brand new, and even better it ran like a dream---absolutely NO bogging, stumbling, etc.

He walked me through how to fine tune it, but I never even touched the adjustments and it ran perfectly. This guy is well versed in the black arts of QJ's. The carb is still running on someone's 40 up north somewhere.

 

[RWBeringer4x4]

I had SMI build me a Stage 1 Quadrajet and I cannot emphasize how much I endorse his work. I drove up to Huntington Beach to drop it off and he took time to talk with me face to face. It was complete in about 2 days, looked brand new, and even better it ran like a dream---absolutely NO bogging, stumbling, etc.

He walked me through how to fine tune it, but I never even touched the adjustments and it ran perfectly. This guy is well versed in the black arts of QJ's. The carb is still running on someone's 40 up north somewhere.

Glad to hear someone who has some actual experience with him! He seems to be very well regarded on the Chevy forums I stalk when it comes to engine stuff. Most of the advice I get here is "Just buy a 2F."

I wish I lived closer! I spoke with one of his guys today (James) and he gave me the rundown on how it would work. He said they've definitely built Qjets for bone-stock 283's in the past and they've turned out well. They apparently heavily limit the secondaries' movement - keeps velocity through the primaries up, and doesn't completely douse the 283 in gasoline by opening up the secondaries wide when it simply can't handle the extra gas/CFM well.

I've rebuilt Q-jets, they aren't super difficult but I know this Buick one I'm running is probably an 800CFM monster, has a broken fast idle cam (rare, Buick, plastic cam), a warped air horn, and probably leaky (albeit not serious) throttle shafts. If I'm going to go through another rebuild, I'd might as well start fresh with a known "good" carb, set up for my engine, instead of jerry-rigging this thing along any further.

Unfortunately, lead time is about 6 weeks from SMI and 8 weeks when it comes to my bank account, so sounds like the Clustertruck's gonna be sitting for a couple months - which I'm sure is shocking to no-one.

 

[brian]

these v8s sound like a pain in the butt.

 

[RWBeringer4x4]

these v8s sound like a pain in the butt.

You won't hear me arguing that! However, in defense of V8's - mine's an amalgamation of about 3 different eras of engine which could be part of the problem. 283 block/heads, aftermarket 350 manifold with a Buick carb that's about 2X too big for the engine...My truck has been aptly named.