The end all for proper Weber vacuum advance???

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ripstock34
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The end all for proper Weber vacuum advance???

Post by ripstock34 »

First time poster here but this forum has given me a ton of info to help me out with my Weber install and trying to maximize fuel economy.

To start I live in the great state of Alaska and just recently purchased an 85 Terc SR5 with the 3A-C. The previous owner had driven it up from California where it spent most or all of it's life so it has all of the wonderful gas sucking california emissions features. At some point the previous owner had snapped off the Thermostatic Vacuum Switching Valve (TVSV) which made cold starts a nightmare and the car was getting around 8 mpg when I got it.

8mpg is totally unacceptable for a daily driver that was purchased to save fuel so after some research I found this site with bounds of info and most members getting around 30 mpg. So I got myself a weber carb 32/36 DGEV and ripped out all of the emissions stuff. I installed it following several of the posts here on this forum and it basically eliminated the TVSV altogether which I figured was the main culprit of the poor fuel economy.

I have now had the Weber on for a few tanks and the gas mileage has improved somewhat but is still unacceptable. Last tank I got around 15mpg and I know the car can do better than that. It is Alaska and we are just coming out of winter so it is still around -10 and 0, the car does have oversized winter tires 205/60/15 but 15 is horrible.

Before I start diving into this deeper I need some clarification on the distributor vacuum advance setup for these weber carbs. There are several posts stating how to do it different ways on different dates and some of them tell you to do it one way and then the pictures show another way.

So my question is what is the proper way to hook up the vacuum advance for max fuel economy with a 3 nipple distributor canister? Is it hook the bottom straight nipple to the "gas filter" on the manifold and plug the other 2 and plug the vacuum advance port on the carb? Is there a better way to do this? Anything would help.

Thanks for all of the great info on this site so far.
Current Yota's
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1977 Chinook Micro RV
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dlb
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Re: The end all for proper Weber vacuum advance???

Post by dlb »

hey hey, ripstock34. i'm very happy to address some of the issues you're having. it sounds like there could be several.

first: vacuum advance routing for the weber. i recently covered this in another post which is here.

https://tercel4wd.com/forums/viewtopic.php?f=4& ... nce#p64885

basically, the lower port goes to ported vacuum on the passenger side of the weber, the upper port w/ no brass restriction goes to the gas filter on the intake manifold, and the upper port w/ the brass restriction gets plugged since you will have most likely removed or disabled the HAC system.

second: your poor economy can be caused by many things. my go-to list of things to check when experiencing lousy fuel economy includes tire pressure, wheel alignment, extra cargo weight, ignition timing, air filter, dizzy rotor, cap, wires, and spark plugs, vacuum leaks, and dragging brakes. best way to check for dragging brakes is to jack up each corner, pump the brakes, and then try spinning each wheel. they should all spin easily. ignition timing in a terc should be 10* BTDC with the vac advance disconnected and plugged—be sure to reconnect them properly after setting the timing though. stock timing is 5* but 10* gives improved performance, fuel economy, and lower exhaust temps.

third: as mentioned above, check for vac leaks. with the weber, this will be much easier but do not overlook it. the intake manifold and carb mounting nuts/bolts can be loose, and the phenolic spacer (which you may or may not have) has been known to crumble away and cause vac leaks on some tercs. the PCV valve (which you should still have connected) can also be a vac leak if it is faulty.

fourth: oversized tires give incorrect speedometer and odometer readings so use a tire calculator like this one

http://www.1010tires.com/tiresizecalculator.asp

to correct for non-stock wheels/tires when calculating your mileage. i just checked and your tires are about 9% larger than stock so 15 mpg + 9% = 16.35 mpg. not a huge difference, but definitely something to take into account if you're serious about tracking mileage. this is also something to keep in mind in regards to speed limits.

although not relevant to your mileage issue, when i had a terc with a weber i initially deleted the charcoal canister but found i could often smell gas around the car. i eventually replaced the charcoal canister and hooked it up to the port labeled EGR (as seen in my other post i linked to) and that cleared up the gas smell. no sense in needlessly dumping gas vapors into the atmosphere.

welcome, and i hope some of that helps. keep us posted as to what you find and how things progress.
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Re: The end all for proper Weber vacuum advance???

Post by ARCHINSTL »

Welcome to the Club! You won't regret the Weber!
I've had mine on for over 4 years and do NOT regret it. My MPG in mixed driving is virtually the same - 26-29 - which is fine (I cut the car some slack, as it has 188K miles).
My dist hookup is the same as dlb recommends: Manifold vac to front upper canister tube (rear blocked) and carb ported vac to lower canister tube.
My reasoning is that's the way the Federal and Canadian versions were setup from the factory. I've noticed nothing amiss, whether during the initial setup or the 2011 timing change to 10° BTDC (and then resetting the idle mixture).
It's just great to stop monkeying around with the emission stuff (and the EGR stuff) and have a much smoother-running car. The extra space gained around the motor is a plus.

Did you keep the phenolic plate? There is a heater integrated into it. I kept mine, but had to modify the height of the air cleaner filter and the X-bracing of the hood for clearance.

As to the charcoal canister - I deleted mine entirely and have not noticed any gassy odors - however, I DID run a rubber tube from the steel return tube to the gas tank down to the original hole in the chassis where the canister drew its air.
Tom M.
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ripstock34
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Re: The end all for proper Weber vacuum advance???

Post by ripstock34 »

Thanks for the responses. This clears things up quite a bit. It was the link below that was confusing me. If you read through it you will see that the dizzy hook ups change around as the article progresses.

https://tercel4wd.com/forums/viewtopic.php?f=4& ... nce#p64885

So I will hook up the dizzy the way you described dlb and then give the alignment, brakes and timing a once over. If those check out than there must be a decent size vacuum leak coming from somewhere else, and I think that may be the case as the idle is pretty erratic.

I don't know know if you guys had any of these issues but it was kind of a bitch to get the idle on the Weber set right. In fact without turning the mixing screw past the recommended turns I was having a hell of a time getting the car to stop dieseling when trying to turn it off.

Regardless I love the response I get from the Weber and love the removal of all of those vacuum lines even more.

ARCHINSTL by front upper canister do you mean the nipple closest to the passenger side of the car on the top? I tried to keep the phenolic plate but my hood was bowing out when I closed it even with the short filter so I finally removed it completely and routed the PCV to the EGR delete nipple and the other valve cover vacuum port into the air filter like others on this forum have done. Does that phenolic plate effect anything? Better to have it on or off? I just didn't want to alter the hood so removal seemed the easiest route. The charcoal canister attached to the pass side firewall is still in place but I did remove the canister, tubes and connections that sit behind the washer fluid tank. I don't know if everybody has this one or if its part of the CA emissions package.

I'll take some pictures of my engine compartment and post when I get home tonight. It's going to look really similar to the pics on here but it would be nice to get the thumbs up that it all looks OK.

Thanks again and talk to you soon.
Current Yota's
1985 Tercel SR5 4x4
1977 Chinook Micro RV
1985 Toyota 4x4 Chinook w/ 2LT turbo diesel
1987 Toyota Sunrader 4x4
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Re: The end all for proper Weber vacuum advance???

Post by dlb »

that sounds odd about your erratic idle. do check the ignition timing and look for vac leaks because it should purr pretty smoothly with a new weber. i think my idle mixture screw was exactly two turns out.

in regards to tom's comment about the vac can ports being on the front/back, it is important to note that many vac can units have the ports facing in different ways. i don't think i've seen any yet that are identical. some have pointed to the block, some to the firewall, some to the driver fender, etc., so do not use the direction they face as an indication of which port they are. one of the upper ports has a brass restriction in it that you can see if you have it out of the car and that one goes to the HAC unit. best way to tell with it in the car is probably to use a mirror, or take a pic with a small camera that you can get down there.

ripstock, did you remove the old EGR completely and make a block-off plate with a port for PCV intake? if not, i would recommend it. the old EGR valve can be a vac leak even when all the vacuum hoses are disconnected from it since a worn pintle shaft can allow exhaust gases in all the time. i just realized this recently myself.

the phenolic spacer helps prevent the carb body from heating up due to it's contact with the intake and exhaust manifolds. by all accounts, you can remove the phenolic spacer with no problems. i think the only time it might be an issue is in chronically hot climates, which you are definitely not.

the canister that was behind the washer tanks is the EBCV, or electronic feedback carb system, or something like that. you have no need for it since you do not have the stock carb anymore so that's fine that you removed it.
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ripstock34
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Re: The end all for proper Weber vacuum advance???

Post by ripstock34 »

Here are some pics under my hood. It would be great to get some pointers as to everything being hooked up right or not. If I can get the thumbs up here I can start tackling some of the other issues and try to get to the root of this mpg issue


Image

Under the hood

Image

The Base of carb w/o phenolic spacer

Image

PCV side with "other" valve cover vac hooked to air filter

Image

EGR side of carb

Image

Up close shot of EGR delete

Image

Image

These last 2 shots are the way i modified the throttle without doing any fab work. I basically moved the nuts that hold the cable down as far over as they could go on the bracket and then used washers to line the stock throttle plate out to match the cable. I was a little worried about this set up at first but seams to be doing fine.

My car also didn't have the metal line that others have running to the dizzy, so I just have lines running all the way to the dizzy can.

Well thats it. Hope it's all right but I would appreciate any input if you see any changes to be made.
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Re: The end all for proper Weber vacuum advance???

Post by dlb »

that mostly looks great, ripstock. i have only two questions. 1) it looks like you used red RTV sealant between the weber and the adapter. is this the case, and did you also do this between the adapter and the intake manifold? 2) i see you completely removed the EGR valve. is the large metal tube that used to attach to the valve blocked off? it's difficult to see in the pics, and would be a significant exhaust leak.

like i mentioned in my last post, checked the timing and the intake manifold nuts and bolts and rule those out as causes for you poor idle. both would also cause poor mileage. then check the other things i listed in my first post. good luck.
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Re: The end all for proper Weber vacuum advance???

Post by ARCHINSTL »

ripstock -
Your installation looks great - as do your photos!
I see you followed the splatterdog protocol! I did as well, save using the phenolic plate for the PCV OE mount.

As dlb mentions - and it's hard to see - an uncapped/plugged steel EGR tube will lead to an obvious exhaust manifold leak; this is easy to remedy. Just get a bolt sized 20x1.50mm - and also use some shallow washers when installing in the manifold threaded hole. This is an ordinary bolt - nothing special. This also provides a tad more room.

As to the upper capped port on the dist - I was not aware that the location of the HAC nipple (constricted one) could vary. In any event, route the manifold tube to the unconstricted top tube.

As mentioned, I had to Dremel away part of the hood's X-member for clearance, as well as later cutting down the filter element - see
https://tercel4wd.com/forums/viewtopic.php? ... 225#p43225

I also modified the attachment of the crankcase tube to the filter box - the plastic fitting was a POS: See the last photo here: https://tercel4wd.com/forums/viewtopic.php? ... an+#p33319

Your mod of the OE throttle bellcrank to fit the Weber is clever, and simpler than mine. I thought about doing it your way back in '08, but I'd swear the stud was not long enough to move the Aisan bellcrank out far enough. I might add that in the pix, the cable is not quite running true into the groove; you might want to smear some grease in the groove for smoother running and to lessen abrasion on the cable.
Tom M.
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Re: The end all for proper Weber vacuum advance???

Post by Petros »

I would bend the cable bracket toward the front of the car, this will allow better cable alignment and give the cable pinch nuts better purchase.

You should try and see if you can find some regular all season tires to test out, aggressive tread will drop the fuel economy significantly.

If you find no other issues you may have to experiment with re-jetting the carb. You can buy jet kits for the weber and experiment with different jets. I seem to remember there was a thread on this forum where it was discussed what is the best weber jets for the 3a engine.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
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Re: The end all for proper Weber vacuum advance???

Post by ripstock34 »

I've been part of several different forums in the past but this one takes the cake. I can't believe the amount of info embedded in this site (just reading about Larry McGraths engine swap). If you guys were part of all of the other forums out there they would surely be better. Thanks for all of the input on this problem so far.

So it is not red RTV sealant on the carb, I just put a little grease on the gaskets to make a better seal. The old EGR pipe is plugged with a rubber cap although it's hard to see in the pic. I was thinking about cutting it off but I don't like the idea of not being able to go back (even though I'm sure I never will). However if a 20 1.5 bolt will fit in the threaded hole it leaves behind I may just do that.

As for the throttle cable, I is definitely not lined up perfectly but it being such a small bend I was thinking it wouldn't effect anything too much. I will be slapping a little grease in there and maybe try to bend it a little. ARCHINSTL it's funny looking at the pictures of your throttle set-up it looks like spacing out the throttle plate as I did would have never worked for you. There looks to be a lot more space between your bracket and throttle controls on your carb. These card must just have little subtleties everywhere. But I really like the bracket set up you have going on.

Petros, if you do find the jetting that works best for these cars (looking at fuel economy) I would love to hear it. That is another one of those topics in here that is so lengthy it gets confusing as to which way is right. I will look at a couple things this week and at lease try to figure out my erratic idle. I will keep posted on changes in fuel economy and hopefully have it up to normal soon, but if there is anymore advise on other common vacuum leak areas let me know.

Talk to you all soon
Current Yota's
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1977 Chinook Micro RV
1985 Toyota 4x4 Chinook w/ 2LT turbo diesel
1987 Toyota Sunrader 4x4
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Re: The end all for proper Weber vacuum advance???

Post by Petros »

I do not have a weber, so I have not messed with one. You will have to just read the threads on jetting the weber, there might also be some forums specific to the weber as well, there were several cars that came stock with them in the "BS" era ("Before Smog").

I find the factory carb works well, it is reliable and fairly simple despite the mass of vac lines necessary for emissions equipment. I decided to do the 4age engine swap with EFI before I got a weber installed. The 3a head is just obsolete and not suited for tweaking to get much more power out of this other wise good engine design.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
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Re: The end all for proper Weber vacuum advance???

Post by dlb »

yes, this is a dedicated forum. in my mind, this forum has become one of the reasons that these cars are so sweet.

ripstock, what altitude do you live at? from my own experiences and from what i've read both on this forum and others, the stock jets seem to work fine for most people of a wide variety of altitudes. it seems to be the first thing a lot of people look at when a weber acts up but i personally think that the other basic elements (all the things i have previously mentioned) should be investigated first.

however, for information's sake, there is an easy way to test for correct jetting. i did a quick search on google but can't find it so here it is as best as i can remember.

1) with the engine off, turn the idle mixture screw all the way in (not tight, just snug).
2) carefully turn the screw exactly 2 turns out.
3) start the car.
4) turn the screw in and out until you find the 'best lean idle,' keeping track of how many turns out you wind up at. you're probably aware but best lean idle is basically where the engine seems to idle happiest—no misses, surges, etc.
5) if the final resting place of your idle mixture screw is between 1.5 and 2 turns out, your jets should be fine. if it's less than 1.5, you need smaller jets. if it's above 2, you need bigger jets.

again, that's from memory so i could be a little off but that's the basic idea behind it.

here is an online weber troubleshooting guide. i find it pretty useless since it's just like 'look elsewhere, your new weber is fine,' and it may have come with your kit but it's something to reference anyway:

http://www.webercarbsdirect.com/v/vspfi ... 0Guide.pdf
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Re: The end all for proper Weber vacuum advance???

Post by Petros »

one other thing to check: the cam timing is set properly. sometimes it can be a tooth or two off and still run but be gutless and get poor economy. You just a have to pull the upper timing cover off (some 10mm bolts), you also have to remove the water pump pulley to remove the cover. put the front pulley mark on TDC and than check the cam sprocket lines up with the marks as shown in the FSM. If it is off, you will also have to reset the spark timing after you correct the timing belt (which may require moving the distributor gear up a tooth as well).

Good luck.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
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Re: The end all for proper Weber vacuum advance???

Post by Petros »

deleted, wrong thread!
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
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ripstock34
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Re: The end all for proper Weber vacuum advance???

Post by ripstock34 »

So, I've advanced the timing and readjusted the carb. I haven't run a tank to recheck my mpg but it seems to run pretty good. However, the idle is still fairly erratc, it seems to have trouble kicking down once it warms up and for the life of me I cannot get the thing to stop dieseling. When it's really warm it can sit there and diesel for 20 straight minutes after the key is pulled out. I've taken to popping the clutch after I shut it off to kill it. Anybody else have this issue with the Weber's?
Current Yota's
1985 Tercel SR5 4x4
1977 Chinook Micro RV
1985 Toyota 4x4 Chinook w/ 2LT turbo diesel
1987 Toyota Sunrader 4x4
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