Souping up a 3A Engine

[booksandbones]

I am being given a 1984 4WD Tercel basic wagon with 5 (6) speed trans. I am in California so my engine modifications options are extremely limited (due to smog laws); however, I would like to get a little more horsepower out of the 3A engine. I read a link somewhere about putting in a Schneider cam and springs and putting in a 4C head-gasket to help with the cooling. It also mentioned installing a Weber. I'm not sure that CARB will allow a Weber for passing the smog test and there would probably be a reduction in fuel mileage.

I cannot find the link and wondered if anyone out there might know of it or of any other ways of giving the 3A a little more juice. I don't need a lot of power, just enough for the car to get out of it's own way. I plan to use the vehicle mostly for getting out into some of the more distant canyons in the desert so we can do some serious hiking. The main criteria here is reliability, good mileage, and enough HP that I can get on the freeway without being run over by a semi when accelerating out of the on-ramp.

Thank you for any help you can extend to me on this.

regards,
Christopher

[Mattel]

Hi Chris,
Sadly there is no easy way to gain more power easily with these engines. They are just slow cars sadly. I have run both weber and a reconditioned Stock carb and the stock carb is more drivable and doesn't bog down and have flat spots like the weber and also there was very little difference in power.
Best thing is to keep your car well tuned. All the things you mention are incremental. The biggest gain is from advancing the timing but this does bring on the chance of head gasket failure. Do a search in the box at the top of the page to see the results.
Have you replaced the transmission oil yet - don't forget the rear diff.
Also wide wheels and heavy roof racks or equipment can soak up a lot of power gains so keep that in mind.
I would just get used to flooring it and keep it high revs but make sure you keep up with the oil changes. Be happy you don't have the automatic box!

[booksandbones]

Hi Mattel,

I saw a wonderful sticker on the back window of a similar model that said "Slower than it Looks". It seems to be appropriate for this beast.
I have not received the car yet as it is in northern California, about 700 miles away. I will most likely have it brought down on an Auto Transport truck because I do not want to drive the car that kind of distance without spending some time checking it out and servicing it BEFORE the trip. I cannot be away that long as I am now a full time caretaker for my wife as she has aphasia. Since the car is free, and the transport costs are not too onerous, it makes the most sense.
When it arrives,I have plans to upgrade the front brakes (see the Bearded Wrencher), change all the fluids, (especially the trans) and give it a complete tune-up before going anywhere with it.
I may put 14" rims and tires on it (nothing too aggressive) and possibly a very mild lift. The car comes with the stock roof rack which is very low profile and I do not plan to change that. I would like to get good fuel economy with this so I do not want to alter the aerodynamics too much.
Fortunately, the body is in good condition with only a couple of mild rust spots; it's a California car, so no salted roads here. The vehicle has 229,000 miles on it and it has been well maintained. The friend who is giving it to me says that they have not driven it more than 80 km (50 miles) a year for the last five years and they have all the receipts for work done. they said that it starts very easily, even in the cold winters. They are in Mount Shasta area, which is about 1100 meters (3600 feet) and they can get a lot of snow there.
I noticed on you profile that you are using all synthetic oils. Any recommendations on brands and weight? And how often are you changing these?
There was a post about the 3A saying that the exhaust valves tend to wear out, so when it arrives, I will see what the compression is like and change them out if they are worn. Any thoughts on the head-gasket or giving it a different cam if I have it apart?
Everything I have read agrees with what you said about the stock carb so I would prefer to keep it as is.
I cannot figure out how to add an attachment to this; when I do, I will send you some photos. Hope you are well and thank you again for all of your words of wisdom.
Warm regards,
Christopher

[SirFoxx]

Hi Mattel,
There was a post about the 3A saying that the exhaust valves tend to wear out, so when it arrives, I will see what the compression is like and change them out if they are worn. Any thoughts on the head-gasket or giving it a different cam if I have it apart?
Everything I have read agrees with what you said about the stock carb so I would prefer to keep it as is.
I cannot figure out how to add an attachment to this; when I do, I will send you some photos. Hope you are well and thank you again for all of your words of wisdom.
Warm regards,
Christopher

You can get more power with a cam regrind and double valve springs. Several members, especially on the facebook page, run regrinds with good results. they wont make the car a rocket ship, but anything helps. If you wanted to go one step further, you could gasket match the intake and head. you'd be surprised how poor the castings are.

the exhaust valves only fail if you maintain the factory 5* timing. Up it to 10-12 and you shouldnt ever have an issue with burning exhaust valves.

[Petros]

the 3a is not really suitable to getting more power out of it. I tried for years, and just kept blowing head gaskets because the head design sucks. the 8 tiny valves really limit its output, and the crappy water jacket design does not allow for even cooling in the head, more power causes it to warp under high out loading, and than the head gasket is compromised. Follow my instructions on installing the head gasket, and altering the coolant flow in the head, to improve the head gasket installation, in a thread in the repair guides section.

Also, as stated, the factory carb, if you can keep it running good and in tune, is I think better than the weber. I have owned tercels with both, and driven them across the country, and the stock carb has better drivablity, better economy, and is generally more reliable, also better at extreme temperatures, easier starts in very cold and very hot conditions. the weber will make for a much more simple fuel system, and easier access to the jets for fine tuning, but it will not get approved in California.

Here is what I recommend: get a 4ac engine from the same year collora, externally they look identical and should pass the visual inspection, and might actually be an acceptable substitute since they are almost identical engines, one is 1500cc the other 1600. Rebuild it, install new exhaust valves, the intakes can be reused, balance the crank and connecting rods, go with an overbored engine and larger pistons.

Have about 5 or 6 lbs (or more) removed the stock flywheel. the stock flywheel is way too heavy. it will not give you more power but will greatly improve the throttle response and acceleration since you are not having to spin up that 22 lb flywheel. the corolla with the bigger engine only has a 16lb flywheel, which is heavy from a performance standpoint. do not be afraid to take too much weight off it, the more you can get off the outer edge the better, than have it and the clutch balanced too. the balancing will not make more power, the factory balance is not bad (compared to how US makers balance their engines), but it will make it run smoother and have better high rpm response.

To get good reliable power, you can go max overbore of 0.040" and pistons (but if you drive it long enough to wear it out, you will have to replace the short block, or you can 0.020" over bore giving you one for oversize if you need it).

Get the Delta Cams street regrind, it is way cheaper than the Schnider cam, and better suited for a daily driver. I know someone that used a Schinder and it was too much cam for this engine, the power band was way too high, where the tiny intake valves could hardly supply the power. He removed it after a few months and eventually installed the Delta regrind. I am not sure what Schinder was thinking to make a racing cam for such an obsolete engine design, perhaps they assumed a builder would install oversized valves, port it out, etc. Delta Cams in in Tacoma WA and will swap out your usable cam for their regrind for only like $40 (check prices, it has been a while since I bought the one I am running). You ship them yours, or you buy the regrind, and sent them back your core, and they will refund the core charge.

You can clean up the ports in the head quite a lot if you have the tools to do so, but the small valves are really the limiting factor, opening up the ports and smoothing them out might help a bit, I did it on mine.

Make sure all of your ignition components are good, some have considered after market electronic ignition, but in the USA the stock system is already solid state and works well, not much to be gained with a costly aftermarket system. Unless yours is no good and you want to up grade the whole thing. but that may not pass your annual inspection either. Make sure the fuel system is operating properly (carb and all the vac operated components), especially look for vacuum leaks in the many vac lines. it will never run well if there are one or more vac leaks in the system.

You can install a 2" or larger exhaust system from the manifold back, you have to keep your catalytic converter but I think there are approved aftermarket cats for California, you will not be able to buy a new factory cat, toyota does not sell them. there are a few header type manifolds out there for these cars, but the factory one is not a bad design and you will not get much benefit from the aftermarket headers. You might consider cleaning up the inside of the exhaust manifold, just like porting an engine, but it is cast iron and would take a bit of effort but should help with power output a bit. One benefit of doing this is that from the outside a visual inspection at an emission check, you could not tell the difference, it will look factory on the outside.

Always set your spark ignition at 10 deg BTDC, it is more efficient and better for the engine, and a bit more power. just remember to set it back to the factor 5 deg BTDC before each snog test. Be sure to set it back or you risk causing heat damage to the exhaust valves, the retarded timing ends up causing higher exhaust temps, and will heat damage the exhaust valves, I have seen the valve heads break off and trash an engine, this is because they are strength compromised from running in the high exhaust gas temps causes by the poor spark timing, fuel is still burning when the valve opens. This is also why you should allays replace the exhaust valves any time you take the head off, they do not cost much and it is just not worth the risk of having a valve disintegrate while the engine is running (it happened to my engine when I stupidly reused the exhasut valves after a rebuild, and I have seen on many stock engines too). it will not do the environment any good to junk otherwise good cars because of this foolish and short sighted emissions requirement.

One other thing you might want to mess with, but I have not done it so I can not give you any guidance. someone found that the older 20R engine in the same year trucks uses the same type carburetor as the Tercel, but it is larger. It has larger barrels and larger throttle plates. it looks very similar, and it may give you more power to switch to this larger carburetor, it will have to be rejetted to be optimized for the smaller 4a engine, and likely some of the vac routing will be different and you will need to study both systems and get them routed appropriately. This can be troublesome and may take some creative tinkering, even on the various year Tercels with the same engine and same carb, they changed where various vac lines plug in, or used vac manifolds that were different. I have a different year carb in my daily driver, and there is one vac line that has no where to plug it in on the carb, but it does have one on the original carb (that was worn out at about 400k miles, and not rebuildable). I got to find another place where it gets the same vacuum from and add a tee or some other means of getting this hooked up properly. I do not know if you want to get into it this far, but it seems a viable way to get a bigger carb and still get it past the emissions inspections. if you go this route, share what you discover with us here.

This will give you a higher HP output, and be a great improvement in performance, but it will still output only perhaps 90 hp +/- or so. so it will not be a hot rod, but you will be better off when pulling out in to heavy traffic, trying to pass, or climb big hills. all of these mods are fairly simple bolt on improvements. the next step would be to install higher performance 16 valve EFI 4age engine, a big job and costly, but you get a modern engine design. even stock that engine will double your power output. I do not know if California allows that kind of swap, when I lived there years ago it was allowed as long as you used a state approved engine and all of the emission systems components that came from the original car. it is a cleaner more efficient engine, but stupid laws may not recognize such improvements, they just ban any modifications over the factory configuration.

Good luck.

[xirdneh]

Quick and fairly easy way to boost engine power is to change the main primary jet on stock carb.
Stock is usually 101 or 103. Put a 106 in there and you will notice an increase in power and a 5 mpg decrease in mpg.

[Esaus]

Where are jets avaibable? I googled and found a site and they just wrote JB weld a jet to make it smaller and drill it out or use a larger drill to enlargen it. It was a carb shop site that wrote that under the jets category.

[SirFoxx]

Where are jets avaibable? I googled and found a site and they just wrote JB weld a jet to make it smaller and drill it out or use a larger drill to enlargen it. It was a carb shop site that wrote that under the jets category.

i dont think anyone carries aisin jets. and dont use jb weld, use solder. i would get a set of carb jet drills and just drill it out a tad bit bigger. going from 103-106 is a very tiny increment, so be careful.

[dlb]

xirdneh might have spare jets in the size you want kicking around he could sell you. either send him a PM here or look him up on facebook, he is on the 4wd tercel group and his name is robert walker.

[Esaus]

I live in sweden so theres the issue of international postage =) but ill keep that in mind. I will look into carb jet drills if i can find any. I want to go up a little in jet size so a small drill would do. is 106 in increments of inches or something? If it is .106 inches is 2.69mm so a 2.7mm drill would be fine. IIt is not in inches! I measured the 103 i had in my carb and its slightly closer to 1mm. It was alittle loose but most likely its 1.03mm. Im not sure however cant find info on this. can get a handdrill set with a bunch of small drills included.

[dlb]

The jets are tiny. They would fit in a regular envelope. Probably only be a few dollars to mail. But you're right, there are a few options for achieving what you're looking to do.

[Paul]

Awhile back I was doing some Aisan carb research, and I read that Hitachi jets will work and have the same numbering system.
https://board.marlincrawler.com/index.p ... c=100917.0
I have not tried them, but for the price... maybe worth trying one.
https://jetsrus.com/a_jets_by_carbureto ... n_4H7.html

[Nordical25]

I wonder how they got 90hp out of Japan top spec. 3A-SU? I think that it had dual carbs, maybe bigger cam etc. So 90hp should be possible without Turbo. And a Supercharged Turbo 3A could produce even more. But I don't know if that is worth the trouble. 4A-GE swap or 4A swap could be even easier. I recommend 4A. That is a bit of extra power if you find one for a reasonable price. Or you could try to overbore 3A from 77,5mm to 81mm first. Then bigger carb etc.

[Esaus]

I have put up a advert for buying a 4A engine on marketplace in sweden. I think its hard to find since most old toyotas are shipped to africa and such. I was lucky to find 3 tercels for parts and they were up for parting to africa as i went there. Hopefully ill be able to find some random car left. I dont want to part out a in good condition car just for the engine. Even if i find a car they might want too much money for it to be worth buying it for the engine. People are relizing they are rare over here.

Even the wrecking yards have no old corollas or engines for them. I have a hard time finding even the most common items at times.

[Esaus]

Im currently renovating the carb for my 87 corolla ae82 with the 4A engine. The carb for it is slighlty different than the one i have for my tercel a 86. Im guessing it has slighly bigger jets and a different main venturi design over the tercel one. I think if i find a corolla carb like that one somewhere it might be more efficient and give a slight tune over the original one. The venturi design has several small holes that should provide better atomization over the large hole the original one has aswell.