Tennesseestorm

Hi guys, I am new here and while I dont have a Corvette, I do have a 1972 Chevrolet and in desperate need of some help. I have a 1972 Chevrolet Kingswood Estate (Caprice) wagon with a factory 402 big block engine, which I think was also an engine available in the Corvette that year? I am thinking maybe the Vette had the 454 as an option instead, but should have the same carburator?

I had to get a new camshaft and lifters installed in my wagon. It was done about 6 months ago, but the car never did really run smoothly after it. My dad let a guy he knows that was supposed to be a good Chevy mechanic do the work. Well, after the work was done, I never had time to fool with it until recently.

I got to looking today to check the vacuum lines and it seems like the moron that did the work ran hoses different than they were before and even completely left one part off that I had no clue as to what it is. He had routed some wires wrong and I discovered that one complete electrical plug is not plugged up. I had luckily taken some pictures BEFORE he did the work and found out that he completely left a part off that the plug is supposed to go into as you see in the photo. I cant even find it, nor do I even know what it is. Can anyone tell me what it is and if its something I can buy somewhere and where I can find a vacuum hose diagram for this car?

Also, in the other photo there is a long metal vacuum line (circled in red) that is completely gone now and the hose is not plugged up to anything. Before that, there were also two other lines plugged or not plugged to anything. (circled in yellow).

Does anyone have any clue as to where these go? OR does anyone know where I can find a vacuum hose diagram to see where these hoses go? I think these things are the culprit to my poorly running engine.

Thanks in advance!

Again, these photos were before the engine work was completed....

Here is the part that is missing and I have nowhere to plug that wiring harness into... (someone told me this was the TCS solenoid)?




other question photo...


more photos...









Thanks for any tips/advice!

markdtn

Corvette never had 402 as an option. 396 was available half a year, then 427, then 454.

You really should get a GM shop manual for your car or buy a correct vacuum diagram sticker from a vendor.

Eddie 70

The missing metal line you have circled in red is for the vacuum advance. I am guessing he connected the advance to the carb at another port instead of using the metal tube. Completely acceptable if it is to the correct port.

The TCS solenoid even though it is electrically connected in the pic, it is not connected to any vacuum source so it is not in use any way. Most of us have done away with this too.

Hopefully someone else can chime in with some more help for you.

Alan 71

Hi TS,
Perhaps you should take a look at Dr. Rebuild's site. Look for Spark Control Hose Kits. There's a schematic for a 72 454 engine that seems very similar to your 402. Perhaps you'll see some answers there.
I agree that the GM Chassis Service Manual is probably a good idea for you.
Regards,
Alan

69elky

Looks like you have a rare wagon and your best bet with your Chevelle would be Team Chevelle,you can get the same level of support that is here on the forum,dealers etc:go to their website and join teamchevelle.com P.S.you may also be interested in another group American Chevelle Enthusiasts Society/ACES deadicated to 64 thru 72 Chevelles,have a good meet in Goodletsville,Tn the first weekend of June.

Tennesseestorm

Thanks for all of the replies. I will check all of that out.

69elky, thanks for that info... my car is actually the big Caprice not a Chevelle, which was bigger than the Chevelle/Malibu, but maybe still some good info there. Thanks again!

chevygod

Hi 'Storm,

Looks the same as my 72 Monte Carlo 350. Same stuff, slightly different location. If you still need help, here goes:

Pic 1, is TCS solonoid, electrically controls vac advance vacuum to control spark by hooking into the trans to know when you are in high gear. Vac hose from advance ("S" shaped in pic) would be sectioned and would go onto port covered by hose. Remainder after cut hooks to metal tube on right/pass side of your carb. The metal tube has a short hose connecting to vac port at drivers/right front corner of carb. This is for spark port or throttled vacuum (part time). You can leave this bypassing that TCS solonoid like in the pic. That's how my Monte is.

Pic 2, shows previously mentioned metal tube (red outline). Yellow outlined port on pass side of carb without cap is manifold (full time) vacuum for air cleaner. Cap this. It is just for the thermally controlled snorkle on the aircleaner. The other yellow outlined port at front of carb with cap is vacuum to run the A.I.R. valve (for air injection pump). I also capped this.

Pic 3 shows your spark port vacuum tee'd into the vacuum advance hose and the vapor canister contol hose. I set this exactly as you have it shown here and in the first pic, bypassing the solonoid.

For a long while, the solonoid stayed bolted on the car unhooked, simpler to store it there than in a box.

PM me if you need any other info about 1972 passenger car stuff.

Best regards,
Tom

Tennesseestorm

Thanks Tom. Tomorrow if it dont rain me out, I am going to post some photos of the cars lines in their current state. Maybe even later tonight. They are different than that now since the guy that did the work left off that long metal line and left off that "TCS solenoid". Strange, they are both gone and nowhere to be found. He did the work right here in my own driveway, but I have looked and looked and cant find them. Even currently, the engine still looks nasty. I specifically stated I wanted the engine cleaned up and painted and when I got home and saw the car "completed", it was not painted and my dad had already paid the man for the work, because he did not know I wanted that painted/cleaned. I guess all of that will wait until later.

Thanks again for all of that info... hopefully I will get all of this sorted out soon with all of the info I am getting here.

Current photos coming soon!

Tennesseestorm

OK... I went ahead and went out this evening and shot these... this is the engine in its current state. Nasty... he didnt even paint the valve covers. My main concern now though is getting it running good. You can seen the TCS connecter dangling and he had that hose thats not hooked to anything in the photo to the air cleaner. Thanks again!

chevygod

Hi 'Storm,

OK, pic 2 shows the vac advance hose going from the advance can to the port for the air cleaner. You need a longer hose that connects the advance can port to the "tee" at the front of the carb. Once you have removed the hose from the port it is on, cap that port, unless you need the thermo control on the air cleaner.

Pic 3 shows the tee with an unconnected hose on the passenger side end. That is where your hose from the vac advance needs to go.

Pics 2 & 3 also show an uncapped vac port, right above the fuel inlet in the pic. That is for A.I.R. control vacuum. Cap that.

You are currently getting manifold vacuum to the distributor, which is full advance at idle. When you tip in the throttle, it goes mostly to zero, so not much advance. You also have that vac port leaking at the front of the carb, and a vac leak at throttle tip in from the spark port vac port by the tee. This will all contribute to the car not running as you expect. Re-rout and -hook everything up, and give it whirl. Also, check your timing after you have everything correctly hooked up as the "mechanic" may have tuned it to adjust for the above mistakes.

Learn about your car, buy what manuals you can, and get to where you can fix it yourself. You'll have a great feeling about what you have accomplished, won't have to fix others mistakes, and have a better idea that it is done right, or at least why it is wrong!

Good luck,
Tom

69elky

Sorry,thought it was a Chevelle,reread and its a Caprice

Tennesseestorm

Thanks for all of the replies. I THINK I have it right now, but here are some updated photos I took a little while ago of how they are going (vac lines) now. We found that long metal vac line that he had lost and put it back the way it was originally, but not sure if its right or not. That outlet on the side of the carb is still without a hose, I guess I should just plug it? The one on the lower front is now going to that area on the lower front and the outlet on the upper front is now connected to a vac line on the air cleaner. Not sure if this is right or not....

Sorry, the engine dont look that great, even after I painted the valve covers. I just want to get it running good now. Its running alot smoother, but at idle, it still has a splutter and the engine will shake a little.

Also, on part of our driveway thats a steep grade the car will still not pull itself up from a dead stop on the hill. I have to get a run and go. Maybe its normal for a 5000 pound car with a 245 hp engine, but I know my 73 Pontiac with a 455 will easily accelerate up the hill. I still think something is wrong and we have set the timing time and time again.

First of all, I found these bolts down in the grill area that the moron that did the work left off from somewhere...















and of course the part that is missing (TCS solenoid) that this plug is supposed to plug into....

chevygod

Hello Storm,

on a 72 V8, the vac port above the filter on the pass front side of the carb is for the Air Injection Reaction system (AIR). Cap that. The port on the passenger side above the choke mechanism is for the thermo air cleaner. This ducts warmed air into the air cleaner for cold starts and can also be capped. I have capped both of these on my 72 Monte 350 V8.

Looks like the vac advance is correct now. To check your operation of your system, disconnect the hose going to the distributor at the "tee" and hook it directly to the carb spark port. This bypasses the vac valve on the charcoal cannister. Does it run better now? If so, you vapor cannister vac valve is leaking. I have a vac hose going from the driverside front spark port directly to the distributor without connecting to the vapor recovery system.

Low power in my non-Corvette cars was usually carb base- or vac hose-vacuum leaks, or bad dwell or timing. That motor should be able to drag that car up any driveway incline from a stop with 2 dead cylinders if everything is tuned right. Good luck on your project, hope you get it beat!

Best,
Tom

CCrane65

Ok, here is some input form another '72 BBC owner. On my 454, the vapor canister vacuum line goes to the base of the carburetor near the large PCV hose and NO T for vacuum advance. I would not feed fuel vapor to the distributor since there are sparks in there.

If you are going to continue to bypass the TCS then use the port on the passenger side under the choke pulloff and run directly to the vacuum advance can on the dirstributor. This is manifold vacuum and is available all the time. If you use ported vacuum there is no vacuum at idle.

Plug any unused ports on the carburetor as they will be a vacuum leak.

If you should decide to connect the TCS vacuum hoses PM me and I will tell you how. I have all my hoses in place and plugged so it's an easy swap if I decide to.

Also, my '72 big block does not feed any warm air from the carburetor to the air cleaner but maybe the full size vehicles are different. You should check the manuals yourself. Besides, that does not make any sense. A vacuum port would take air not feed it.

Feel free to contact me with any ????. I have done quite a bit of research in this area.

cc

PS, whenever you change vacuum advance from ported to manifold or vice versa you will have to re-time the engine to account for the difference in advance.

Tennesseestorm

Thanks for the replies. I will go out there in a bit and take another look at it. I bought caps, so I can plug off what I need to.

One other question... there is small vac hose on the lower front side of the air cleaner... where does it plug into? I was thinking i went into that vacuum port on the upper passenger side. Not sure now.

Tennesseestorm

Thanks. I will look into that. Where is the carb spark port? I am kinda dumb on this stuff. lol.

The car is definitely wrong then, because its LOW on power - I just want to get it on the road - I have worked on it for so long and have so much money invested in it. Like I said, my 73 Pontiac Grand Ville is like a Ferrari compared to this wagon.

If I dont get it right soon (if its something else), I will probably end up selling it off.

Thanks again.

chevygod

Storm,

answers for 2 posts here.

last post: The carb spark port supplies vacuum that is only available when the throttle is opening. Usually vacuum advance is hooked here, therfore spark port. When throttle is more open this vacuum dies off, but mechanical advance comes in then. When the throttle is cracked open, manifold vacuum (full time vacuum) drops momentarily, which could allow advance to drop if it is hooked to mainfold vacuum ports.

Second to the last post: That is the vac hose for the hot air stove pipe valve on the air cleaner. This vac hose would connect to the vac port above the choke mech on the passenger side of the carb, and it is the control vacuum for the air cleaner hot air valve that allows warmed air to be pulled up the stove pipe on the exhaust manifold and into the air cleaner. You can plug this port if you don't need hot air for cold engine starts.

CCrane72 mentioned the vapor cannister lines. The big line tee's off at the PCV over the valve cover. This line is connected to the big port under the front of the carb and goes to the big port on the vapor cannister (the other big line goes to the fuel tank). The control vacuum is tee'd from the spark port vacuum line and controls the fulltime vacuum from the PCV line. Big one is full time suck, the small one turns it on and off. From what you have posted yours looks correct.

Low power and you had a cam installed? Are you sure the cam is timed correctly? In any case see if giving it a little more initial advance of the distributor helps the power. If your outer ring on the dampener (with the timing mark on it) has slipped, your timing will look right but will be off.

Good luck,
Tom

Tennesseestorm

Thanks. Well, I went out and capped that upper outlet on the top and went ahead and put the air cleaner hose on that port on the choke mechanism.

Its still not running so great... its sputtering at the exhaust (tailpipe) and the engine is not smooth... it lopes side to side some, even when I rev up the engine some and hold it at a certain RPM it will shake alittle.

I guess I need to invest or borrow a timing light to see if the cam is timed correctly. Yeah, that mechanic put a new cam in it (and lifters) as the old cam had worn off lobes.

Its so reminiscent of my old '69 Caprice sedan (396 car) because it had a miss (and a knock) when I bought it and it had a wiped out cam too. A new cam took care of the problem though. Its enough to turn you against BB Chevys. lol.

CCrane65

The 402 big block is just a bored out 396 so it should be very reminiscent of your old 396. In fact, Chevrolet bored out the 396 to 402 in 1970 but didn't dare mess with the SS 396 name plate for fear of losing their faithful following. However, in the large cars they called it the TurboJet 400.

cc

Tennesseestorm

Yeah, even the fender emblems on my car are the "400" emblems, but it has the 402.... even the sticker under the hood says its a 402, but exterior wise, if someone didnt know, they would think it was a small block 400. Not sure why they did this.