Bike Carbs 4x32mm

General discussion about our beloved Tercel 4WD cars
PrescottAZ
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My tercel:: 83 4wd, jeep cherokee front springs in rear, cut fenders, mr2 booster, gauge swap for tach, Suzuki Katana 600 Carbs, 330,000 miles and ticking (literally)
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Re: Bike Carbs 4x32mm

Post by PrescottAZ »

Started thinking about it and I have 185/80/13 tires and my speedometer cable slips until I am doing about 20mph and then it jumps up and gets with the program. The clip that connects the cable to my dash is broken and I need to find a new one. I am guesing both of these effect my mileage right? So whatever I read out it should actualy be a bit better than that. I think the tires are 5% and I am not sure how to compensate for the stupid cable problem. Other than buy the clip somewhere and do another tank.
PrescottAZ
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My tercel:: 83 4wd, jeep cherokee front springs in rear, cut fenders, mr2 booster, gauge swap for tach, Suzuki Katana 600 Carbs, 330,000 miles and ticking (literally)
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Re: Bike Carbs 4x32mm

Post by PrescottAZ »

30.8 miles per gallon giving account for 5% difference in tire size and not accounting for the speedometer cable issues. Lots of idleing and reving, hitting redline, driving to PHX and back with about 5000 feet of elevation change. 3 cylinders at 120 psi and one at 80 psi. Not the healthiest motor.

Any thoughts:
I am reading that if it pops and such on the way back down from reving it needs bigger pilot jets. Also, if it is surging and acting unhappy when cold it needs bigger jets. It does all of the above moderately.
But I am seeing that it is also running noticably below the point where the thermostat opens and the fan comes on when maintaining a constant speed. More so than before the carb and I watched it before because I have been losing water here and there. So I watch that guage to see if anything sneaky is going on. Plus the fact that the motor is very happy after 4500 rpm and that makes me belive that it is rich sometimes.

Okay here is what I think needs to happen. Correct me if my logic is bad here. The pilot needs more fuel and the main needs less. I know, I know read the plugs... but mine are old enough that they wont be very helpful and I am not the best at reading plugs.

First I am going to bump the timing up to about 12 and see how it does there. Then I am going to try and move the mixture screw in a bit to make it more rich in the areas that the pilot jet covers. I will wait on mains until I have a better read on what it needs and how it responds to the first two. Or I just say screw it leave it alone cause this motor is a bit over the hill.

Very happy with a 7mpg gain on the first tank. These carbs will pay for themselves soon. I know it would have been cheaper to get the stocker tuned up but that is not nearly as fun and creative.
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Petros
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Re: Bike Carbs 4x32mm

Post by Petros »

surging and/or flat spot is usually a sign of being lean. You will get black smoke and black sooty spark plugs if too rich, and back fires is way too rich.

Not bad for fuel economy. You should find yourself a rebuildable core engine, take your time to rebuilt it with a few more tweaks, and than swap that old tired long block of yours out on a saturday. That will improve your power and ecnomy even more.

I love that carb set up, it looks so hot just sitting there in the engine compartment. Get them sorted out and make a detailed list of the jets it needs, parts, etc. so we will all have the info to copy your great pioneering work on the carb swap.
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PrescottAZ
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My tercel:: 83 4wd, jeep cherokee front springs in rear, cut fenders, mr2 booster, gauge swap for tach, Suzuki Katana 600 Carbs, 330,000 miles and ticking (literally)
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Re: Bike Carbs 4x32mm

Post by PrescottAZ »

Double post sorry.
Last edited by PrescottAZ on Wed Sep 14, 2011 11:24 pm, edited 1 time in total.
PrescottAZ
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My tercel:: 83 4wd, jeep cherokee front springs in rear, cut fenders, mr2 booster, gauge swap for tach, Suzuki Katana 600 Carbs, 330,000 miles and ticking (literally)
Location: Prescott Arizona
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Re: Bike Carbs 4x32mm

Post by PrescottAZ »

On a trip up from PHX I was getting a lot of surging and on one particular hill climb I felt power dropping out and pulled over. I could see bubbles in the fuel filter that runs right over the carbs. Not cool. I richened the mixture screw abit and it drove better. I believe the exhaust manifold was so hot it was causing some boiling in the fuel system and leaning out the mixture even more. Kinda scared me a bit.
The low engine temps I am assuming are due to a missing thermostat. Just a guess but I don't think a thermostat would let the engine temps drop as low as what I see on the highway.
Just moved over to 162.5 mains and noticed the timing was at 6 degrees w/o vacuum advance and bumped the timing to 12 BTDC and now I have much better mid range and it falls flat after 5K.
Any thoughts?
I am going to play with different timing settings and see what I get. I have read here that some are going as high as 15 degrees BTDC w/o vac advance. I dont notice any pinging and I would like my top end back.
I have a 30.8 mpg tank and a 25 mpg tank (4 wheeling)
I am nearing the end of a third tank here and will chime in at the results. 2/3's on previous jetting and 1/3 on the new mains and bumped timing.
Tercel__jon
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Re: Bike Carbs 4x32mm

Post by Tercel__jon »

Thats not bad at all mileage wise. Not what I would like to see...but hey, what can ya do? 25 is about what I see during the winter when Im running around in 4wd.

Ive been experimenting with a vaporizer carb on my tractor. might yield impressive results on a tercel...but Im hesitant to try it on it just yet.
PrescottAZ
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Re: Bike Carbs 4x32mm

Post by PrescottAZ »

So I have been having trouble with above 5k rpms and was poking around and had a blond moment.
I haven't put a REAL choke cable on it yet and have been substituting a zip tie that I hook on it when I start it and then once warm I pull it off. Well I left the zip tie on this whole last tank. Dur. So I pulled it off and low and behold my happy reving motor is back. Except a bit rich. If I blip it up to 6k it goes nicely if I hold the pedal down to keep it there it drops down to 5k until I back the pedal out a bit and then it climbs again.
Rich for sure now.
I will be going to PHX and back on Tuesday and this will tell me more about how I am doing.
I think my pilots are lean and my mains are rich. I think this is where I want to be for now. Lean for good gas mileage and rich for safety at lower altitudes and the potential 7afc4 hybrid someday. Unless the pedal feels a bit like an on off switch. If this setup proves to be good I will start a how to thread.
PrescottAZ
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My tercel:: 83 4wd, jeep cherokee front springs in rear, cut fenders, mr2 booster, gauge swap for tach, Suzuki Katana 600 Carbs, 330,000 miles and ticking (literally)
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Re: Bike Carbs 4x32mm

Post by PrescottAZ »

So I just filled the tank again and I got 33.3 mpg. Best yet and I spent a lot of time climbing steep grade and doing 65-75mph. Not bad. I am using 4th where I used to need 3rd and 5th where I used to down shift to 4th. I am very happy. I also spun the tires on take off a few times by accident and punched it while turning in second and it broke free a bit.

Noticing some rich symptoms.
-When I let off the gas in between shifts the rpms don't drop as fast as normal.
-Power still drops a bit after 4500
-Sometimes I think I smell rich exhaust but it might just be in my head.

A few things to do in the near future. Get new plugs and delete the fuel filter after the fuel pump and replace the fuel line. I might go ahead and adjust the mixture screws back down a bit as well.
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Petros
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Re: Bike Carbs 4x32mm

Post by Petros »

sounds like a good run. You might get a bit more out of it yet. The power dropping off might be the limitations of the head and cam design, their peak hp occurs at only 4800 and the torque peaks at only 2800, it might be pushed up a bit in your case with the carb set up, but that 8 valve head design will be your limitation at higher rpm (that is why all the manufacturers, including Toyota, went to 16 valve design, and even 20 valve in the MR2). So keep this in mind as you continue to refine the jetting.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
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PrescottAZ
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Posts: 115
Joined: Mon Nov 01, 2010 4:03 pm
My tercel:: 83 4wd, jeep cherokee front springs in rear, cut fenders, mr2 booster, gauge swap for tach, Suzuki Katana 600 Carbs, 330,000 miles and ticking (literally)
Location: Prescott Arizona
Contact:

Re: Bike Carbs 4x32mm

Post by PrescottAZ »

I am begining to think I am running out of fuel above 5k rpms or I am just too rich. The car loses some power near 5k and feels like it hits a rev limiter at 5200. If I back off the gas pedal a bit to about 75%-80% then it will climb to redline but if I mash it at redline it sputters and drops back to 5200.
New filter, plugs and wires helped a bit. Moved it from problems starting at 4500 to about 4800.
I plan to move the float setting up a bit so the jet has a deeper pool of fuel to begin with. This may help when it can't keep up with demand just by having a bit more supply. I think this may show if it is a supply problem or an overly rich problem. If it is a suplly problem it will rev up more temporarily and fall back once the fuel bowl is emptied. If it is just too rich it will act the same.
I think I am going to drive it this way for a while and later go to 155-157.5 mains and shim the needle valve to keep the mid range power I have now.
The only reason I went to the 162.5 mains this last time is that is what they had on hand for a full set.
I should have been more patient and ordered 155's as planned.
Also I may get an electric fuel pump if I can find a decent deal on one since the 7afe head won't have a fuel pump attachment point. The 5afc head does but then I would have to get a 5afc head and a 7afe bottom end and merge the two. Too much of a headache for a fuel pump and possibly raised compression. I'd rather go electric now and have the head shaved on the 7afe if I want more compression... If? Kinda doubt I want more power than the 1.8 can dish out.
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Petros
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Re: Bike Carbs 4x32mm

Post by Petros »

that sure sounds like it is acting like it is running out of fuel. There are lots of aftermarket high volume electric fuel pumps to choose from, go to any hot rod shop and take a look.
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tercel4wdrules
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Re: Bike Carbs 4x32mm

Post by tercel4wdrules »

PrescottAZ wrote: Also I may get an electric fuel pump if I can find a decent deal on one since the 7afe head won't have a fuel pump attachment point. The 5afc head does but then I would have to get a 5afc head and a 7afe bottom end and merge the two. Too much of a headache for a fuel pump and possibly raised compression. I'd rather go electric now and have the head shaved on the 7afe if I want more compression... If? Kinda doubt I want more power than the 1.8 can dish out.
I remember you put a JDM 5A-F engine with a Weber in your previous Tercel if memory serves correctly. Now, you want to take the carbureted 4A-F cylinder head and put it on the 7A-FE block? Effectively you will have a 7A-F 8). I wonder how much HP and torque it will produce, the 4A-F in stock form makes 90 HP, with the 1.8L block it will be a bit more. I would calculate the compression ratio with the 7A-FE pistons before milling the head down.
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PrescottAZ
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My tercel:: 83 4wd, jeep cherokee front springs in rear, cut fenders, mr2 booster, gauge swap for tach, Suzuki Katana 600 Carbs, 330,000 miles and ticking (literally)
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Re: Bike Carbs 4x32mm

Post by PrescottAZ »

True I did the 5af motor swap w/ a webber.
I think I will take my current carb set and apply them to a 7af (if I can find one at a good price) and instead of swaping heads I will just refresh all that is a stock 7af and put new intake manifold on there, my carbs and an electric fuel pump.

I have a lot of work ahead of me though first before I dive into a 7af.

Need to do front brakes, wheel bearings, ball joints, tie rod ends, shocks... So that the front is tight before I jam some power through it
Also need to do a rear axle swap (w new rear bearings and brakes) to get the low gears in it as they are already in the front from the PO. Want new larger wheels and tires 205 75 15? ish.

My point earlier was if I want to follow my fuel problem more I may go after an electric pump so that it is one less thing to buy when/if I go 7af.

Wish I had more money...
Don't we all.
PrescottAZ
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Posts: 115
Joined: Mon Nov 01, 2010 4:03 pm
My tercel:: 83 4wd, jeep cherokee front springs in rear, cut fenders, mr2 booster, gauge swap for tach, Suzuki Katana 600 Carbs, 330,000 miles and ticking (literally)
Location: Prescott Arizona
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Re: Bike Carbs 4x32mm

Post by PrescottAZ »

Did some more poking around. Mapquested a route in town and I ran 60 miles and my odometer only showed 40... Mileage figures are way off I am guesing. In town the odometer only kicks in after 15 mph so short start and stop and I show no mileage.
Still getting 29-33mpg on average w broken cable. So I might be doing better by 2mpg. I did a few carb tweaks and I am seeing some of my top end back. Was too rich.
Will report in on my mileage after a tank. PHX and back tomorow. 230 ish miles.
I might be ready for a how to thread soon for you guys.
J
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Petros
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Re: Bike Carbs 4x32mm

Post by Petros »

is that 29-33 of mixed driving? Than that is great milage. even if only hwy that is not too shabby at all. Probably the most accurate way is to track a trip with a GPS, than you would have both accurate MPH and miles, and can figure the MPG between fill-ups.
'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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