Question<sigh>
Ok, so explain the basics of "compression test." (Shuddering.) Bear in mind I have fairly basic tools, so if this involves anything special, I need to know that too...
I have been considering the rebuild thing at length, but the simple fact is that I lack A) the tools, B) the space, and C) the basic know-how to do it myself. I actually have a friend who could help with the above, but it would be enough of an imposition that I hesitate to ask... Also, '73 is one of the years where the engine MUST come out thru the bottom, so I'd have to find a place for my baby to 'hang out' while I fought with the engine itself... and ok, I admit it, 330 hp sounds soooo attractive... (crate engine from GM Performance. Of course, this is the road to hell, as I see myself getting an Edelbrock intake and carb, and all of my friends laughing at 'Julie's Hot Rod Box')
But back to the point. The number of miles on the current engine is unknown. My gut instinct is that it has been rebuilt in the past, maybe more than once. You know how it is, the van may have 97K miles, or 197K miles, or 297K miles... Anyway, it doesn't quite leak EVERYwhere, but pretty darn close to it. But aside from the possible slight miss thing, it still runs pretty good, and for all I know, might make it another 5 years. The oil consumption is not that bad (actually, my 94 Dodge uses more) so I plan to run it till the bitter end... or until keeping it in the van begins to approach about half of the cost of a new one...
I don't use the van to tow anything more than a small U-Haul. The hitch is only attached to the bumper and sheet metal, and the fuel tank is in the way of putting in anything better unless I want to dump $$$$ to have something fabricated. Doesn't seem worth it. So the current rear end is great for brake stands, but not much else... But 15 mpg would get me half again more than what I am getting now (8 mpg city, 10.5 mpg highway, downhill, wind at back). Is changing out the rear end hard to do?
The van isn't really a restoration... well, not exactly. It's just an ongoing project that expanded into new paint and interior, and by the time I got that done, there were more mechanical things to fiddle with... But it is bright yellow, with excellent pinstipre flames, and turns heads because it is so ugly it's beautiful, if you get my meaning. And still useful. (can load flat sheets of plywood, haul my motorcycle INSIDE, doubles as an improvised RV for tailgateing, you get the idea) And paid for.
And I am babblingon about my baby. Thank you for the suggestions, and I will let you know what happens...
Julie
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Followup To
Question -
I have a 1973 Chevy G10 Van (short body, 350 engine, yeah, it looks like the Mystery Machine) that I dearly love, and plan never to get rid of, but as with any project there are a few issues...
1) I removed the front windows to paint the van and install new weatherstripping, and now they barely roll up and down. I knew the weatherstripping would make them tighter, but they are rediculously hard to move, so I am thinking I don't have the regulators adjusted correctly. I have discovered that this is a skill that has gone the way of the dodo, and it's driving me nuts... can you tell me how to do this, or maybe suggest a website or something with picture that discusses this task?
2) I think my choke is sticking when the van is first started (before it warms up) my evidence is rough idle and black stuff blowing out the exhaust. Can you tell me what I should be looking for the carburator to be doing when I start the van? (Quadrajet type) If I can figure out what it is supposed to be doing, I figure I can fiddle with whatever needs fiddling to make it happen... I know at some point the 'flaps' in the top of the carb are supposed to be closed, then partway open, then the whole way open, but am not sure of the sequence.
3) Even after the van is started and warm, I am suspecting a 'miss' on the right side of the engine. Evidence: black smoke out of that side of the dual exhaust, hesitation during hard accel, idle. I have replaced the carb with a 'new rebuild' (actually, it took a couple to get a good one), replace the plug wires, and plugs (with absolutly anal attention to plug gapping) and it seemed to help the problem some, but not completely. What else can cause this, and what can I do about it?
4) On a cheerful note, this van is an ongoing project, and I have been thinking of replacing the engine with a crate engine, and boy would it be nice to have a trans with overdrive, and maybe something besides a 4:1 rear end would get me better mileage... do you have any thoughts on these subjects?
Thanks for your help, I am not a mechanic, just a national guard truck driver who loves and will never get rid of her van, who is finding the info in Chiltons a little limited on these subjects...
Julie
Answer -
OK, Let me see if I can help here:
On the windows, most likely it is just the fact that the new weatherstrip is much tighter. Get yourself a can of "Spray Silicone" lubricant (NAPA stocks it and so does Home Depot) and spray it into the groove where the glass rides on the weatherstrip. This should help a lot, but you may also have to get inside the doors again and lubricate all the moving parts to the regulators. This is a lot of work, but it pays off in having windows that work like new.
On the choke: The flap in the front of the carburetor top should be closed in cold weather before you start the engine, then it should open a bit immediately when you start it, and slowly open all the way as the engine comes up to normal operating temperature. If it seems to be sticking (which is very common) get a can of spray carburetor cleaner (Gunk is a good brand), at NAPA again, and using the little red straw in the nozzle, soak the axle that the flap turns on, and every moving part that is attached to the flap. You'll have to have someone hold the gas pedal to the floor while you move these parts around to work in the cleaner, as the linkage locks up when no one is pressing on the gas. Keep cleaning and wiggling the parts until everything works really freely, then things should be cured, or at least greatly improved. You'll be able to adjust the choke later, if you are still not getting the flap all the way open with the engine warm.
On the warm engine situation: The engine should run just fine with the choke all the way open. If it still seems to be running rich, I hate to tell you but this has to be a carburetor problem. I have found that "rebuilt" carburetors are almost never good. I have learned to either buy brand new ones (Performance Automotive Warehouse or Summit Racing are both good sources) or to rebuild them myself. I don't know what kind of idiots the rebuilders hire, but I've found leaks, wrong jets, misadjusted or missing parts - all kinds of sin on them. Unless you do it yourself, and have an unmolested known good one to start with, you are out of luck with a rebuilt - even from NAPA, which is a quality source for most things. Kits are available, so if you have a carburetor which you KNOW was good at one time, and hasn't been messed with by an idiot, you can do it yourself. It is really very simple, the kits are crystal clear as to procedure - so if you read well (and you certainly write well so I know you do), have a clean well lit place to work and good small hand tools, you can do it yourself and be pretty confident it will come out right. If you don't have a known good core, though, you'd best buy a new one.
One thing to be sure of though is that the engine itself is in good shape. You should do a compression test on it before you spend $300 on a new carburetor. All 8 cylinders should be within a 10% band of compression pressure - if one or more is noticeably low, you've got valve problems and it's time to do a valve job on it.
If you want step by step coaching to do a compression test, post a "follow-up" question and I'll try to help.
As for a total redo of the running gear, I agree that the 4.10 rear end is not what you want unless you are towing a heavy load, but if you could find a 3.70 rear, even with your turbo-hydro 350 transmission, you can get around 15 MPG and relaxed high speed touring with your old 350 engine. I'd think any junkyard that specializes in trucks would have a 3.70 in stock. I don't know where you live, but if you are in Southern California, Gallant's truck salvage in Oceanside is a great place for us truck nuts!
The crate engine sounds delicious, I agree, but I much prefer to rebuild my own engines, and it's a whole lot cheaper!
I'm not really a mechanic either, but I've played with cars all my life (I'm in my 70s) and I've made most of the stupid mistakes on my own stuff, and I'm totally self taught - I've restored quite a few cars, and I'm still at it. I also have a few pet trucks - I have a 66 Ford 3/4 ton I restored for one of my kids, and an ex-Army 65 Ford 4X4 that I use here on the ranch, and a 52 Ford Tow truck (which is chevy powered) that I use to move my old junk around the place. So I understand getting attached to the old stuff - I never sell anything - I just keep fixin' it!
Good luck - let me hear how you make out.
Dick
AnswerOK, the compression test: Since you are a certified car nut, you need to buy the tools of the hobby. You might as well admit it, you're hooked, so make room in your sock drawer for the following:
For the compression test, you need only buy a compression gauge. These are sold at any auto parts store - it is a simple pressure gauge, with a tire valve arranged so that you can pump air into it, but it won't leak out until you press the little tip on the tire valve to let it out. The way this measures compression is that you screw the end of its hose into each spark plug hole, one at a time. Then you crank the engine while you watch the guage. Each time the cylinder you are testing comes up on the compression stroke (every other rotation of the crankshaft), a pulse of air goes into the gauge. After about 5 strokes, the gauge will stabilize at a maximum pressure, and hang there until you release it. Write down each cylinder's maximum pressure and compare all 8. Typical readings will be around 120 PSI (at sea level, lower at higher elevations), so if all 8 run from 108 to 132PSI, your valves, piston rings etc. are in fine shape, and the engine has many, many more miles left in it. The number really isn't important, what matters is that all 8 are within a fairly narrow band. If they are outside of the 10% variation, but still within about 25%, the engine will still run fine, but it's getting tired. If you have one or more cylinders that are way down, you've got problems in that cylinder, probably a burnt exhaust valve, and you need to pull the heads and take them to a machine shop for a "valve job", which will cost anywhere from $80 a head to twice that, depending on how greedy the machinist is. You don't have to pull the engine to do this. You will need a "head set" type gasket set, another $50 or so, and you'll have to rent or borrow a torque wrench for putting the heads back on.
The only other thing you need to know is: Pull ALL the spark plugs first, so that the starter will spin the engine really fast, and block the throttle wide open (put a brick on the gas pedal, for instance) so that the engine can take a deeeep breath when it wants to (that's where the air comes from after all!).
While you're in the mood for buying tools, you also should buy a vacuum gauge (for adjusting carburetors and timing) and a dwell angle meter (for setting your points) and a timing light for setting the ignition timing. You can buy all of these things for around $200 if you avoid the cheap Chinese made junk ("Harbor Freight" junk). When you buy tools, buy the best you can afford - they will last a lifetime, and won't have you chasing your tail for a non-existent problem due to an instrument error.
To the bigger question: The small block chevy is good for around 250,000 miles without repair of any kind. If it is using more than 1 qt of oil for 1000 MI, the rings are probably getting tired, and this is going to show up in the compression test. If the engine is this worn, the bottom end (bearings, timing chain, camshaft etc) are probably near end of life also, so it's time to plan on a major overhaul or a replacement engine.
If you're getting around 9 to 10 MPG on the road, that's rather poor, but with your carburetor problems fixed, that should improve to 10 to 12. With the 4.10 gears, you aren't going to get much better - after all you're basically driving a barn door down the street. Keep it under about 50, and it'll do MUCH better - it is an aerodynamic disaster! I'm assuming this is a half ton van - if it's 3/4 ton, your mileage is about right.
You can disassemble your engine yourself, clean all the bolt on parts, and take the block and heads to a machine shop to have the machining work done, then reassemble the engine yourself. I've done this many times - it ain't rocket science (I've done that too, believe it or not!). All it takes is a desire to learn, a few basic hand tools, and attention to detail. There are many books on rebuilding small block chevys - including mods for higher performance you can do or have done for you. There is a great rush of exultation when you fire that puppy up for the first time and hear it sound like a brand new engine - if you are like me, it is the best feeling you can get without breaking some law!
Welcome to the club!
Dick
