4A-FE as a rebuild block

[Nordical25]

I am rebuilding two engines for my Tercels currently.

I will rebuild an early 3A and a late 4A that was originally a 4A-FE.

Is anyone interested to learn here details how to convert late 4A-FE into Tercel 4wd suitable 4AC block? I can make instructions if anyone is interested in that.

Anyhow, I want you all to know that in case of 3A block failure you can buy a 4A-FE/4A-GE and make that work with some modifications.

[SirFoxx]

i mean, if you want to, sure! but theres nothing to convert aside from swapping pistons. if you have a 4a block with the oil pan indent, all you have to do is drill and tap like 3 holes so our pan fits.

[Nordical25]

i mean, if you want to, sure! but theres nothing to convert aside from swapping pistons. if you have a 4a block with the oil pan indent, all you have to do is drill and tap like 3 holes so our pan fits.

I can make highly shortened version unless someone is interested learning further details. It is true that 4A-FE block is kind of similar with 4AC block. And the three custom holes for oil pan is one of main differences indeed. But there are further minor differences too especially if we include all 4A-GE blocks to this thread.

First of all, 4A-FE comes in two generations, 1st and 2nd. Main difference between them is piston pin diameter. 1st generation has 18mm piston pins similarly to 3AC & 4AC meanwhile 2nd generation has 20mm piston pin. It means that you cannot just put new stock 4AC pistons to second gen 4A-FE without having extra set of 18mm connecting rods. Therefore I recommend to choose 1st gen 4A-FE if you don't have an extra set of connecting rods available. 1st gen 4A-FE was used at least in 1988-1992 Corollas. You can still buy aftermarket connecting rods for 18mm piston pin but it is not the cheapest way to go. Or maybe someone here knows suitable 20mm pin pistons for 4AC?

All 4A-FE & 4AC engines have also 43/40mm big end bearings so they are not that different. But later 4A-GE engines have 42/45mm big end bearings and 20mm piston pins. 4A-FE has fully counterweight crankshaft, meanwhile early 4AC, early 4AGE and most of 3AC don't. Therefore, I recommend to weigh 4AC piston + connecting rods against original ones before assembly. Engine may need dynamic balancing if new connecting rod + piston assemblies are much lighter compared to original ones if you want to have a really well balanced engine. All 4A-FE engines have 7 rib blocks, which are reinforced compared to earliest 3 rib 3AC & 4AC, 4AGE.

Procedures for engine assembly and disassembly are found from factory service manual:
http://tercel4wd.com/fsm/1985T4WD.pdf

However, there are minor tolerance differences between 3AC & 4AC engines e.g. oil ring clearances. But they are not very different.

I think that these are the key differences. And some 3AC engines and 4AC engines share even same cylinder head. For example 1985 AE86 4AC has a head with spare part number 11101-15031 meanwhile 1985 3AC cylinder head has spare part number 11101-15031 too. Details:

11101-15031

Head Sub-Assy, Cylinder

CYLINDER

[08.1983 - 08.1985] 4AC..AE86

and

11101-15031

Head Sub-Assy, Cylinder

CYLINDER

[04.1983 - 01.1988] 3A#..AL2#

And here are a couple of useful videos:
https://www.youtube.com/watch?v=uz6l3cmXcy0
https://www.youtube.com/watch?v=Wj7WU5peaII
Good luck!

[Nordical25]

And one last thing, all 4A-FE engines should have similar 6 bolt crankshaft to 3AC and 4AC meanwhile newer 4A-GE's have 8 bolt crankshaft. So 4A-FE crank is pretty identical to 3AC & 4AC. The main difference is that it has more counterweights compared to most 3AC and 4AC and it is heavier due to counterweights.

[SirFoxx]

reuse the 3ac rods, keep the 4afe crank or use the 3ac crank, somehow find a set of 4ac pistons and send it. i dont think anyone here has the budget to balance one of these engines unless youre going to push high power and high rpms. the info is neat and useful to have, but for anyone wanting to convert their tercel to a 4ac is either going to find a 4ac, or may look for other info. getting into the knitty gritty details of every internal difference muddies the waters for the average user, in my opinion.

so far, in the tercel fb page and here, i cant say ive seen anyone convert a 4afe over to a 4ac. i would probably slim down the info you have to keep it more basic in case someone sees this and wants to use it as a guide.

for me, the most useful info ive seen and may be worth sharing to others is, the early 1g 3a's use different bearings than the 2g 3a's.

[Nordical25]

I have already all parts for both engines so I will have hopefully two rebuilt engines before May 2025, we will see. I want to do 4A-FE to 4AC conversion because 3A and 4A engines are getting quite hard to find. But we have still some decent mileage 4A-FE engines left. Unfortunately all European cars with 3A and 4A engines are now at least 36 years old from year 1988, meanwhile newest 4A-FE engines are about 24 years old from year 2000. I have read also via project section that some forum members haven't found succesfully a 4A engine anymore from Europe.

I have read via Facebook group that MrWrench has used 4A-F or 4A-FE 1st. gen bottom end for 4AC conversion but this build will be hopefully first 2nd gen 4A-FE to 4AC build that I know. And I can definitely slim down the info if you think that this topic includes too much info. I like always to read some extra info before I do this scale projects. But you could suggest via message how I could slim down unnecessary parts. I understand if this amount of info is a bit too much for average builder.

And thanks for the crankshaft main bearing tip. I have to check my 3A bearings before I install them.

[SirFoxx]

I have already all parts for both engines so I will have hopefully two rebuilt engines before May 2025, we will see. I want to do 4A-FE to 4AC conversion because 3A and 4A engines are getting quite hard to find. But we have still some decent mileage 4A-FE engines left. Unfortunately all European cars with 3A and 4A engines are now at least 36 years old from year 1988, meanwhile newest 4A-FE engines are about 24 years old from year 2000. I have read also via project section that some forum members haven't found succesfully a 4A engine anymore from Europe.

I have read via Facebook group that MrWrench has used 4A-F or 4A-FE 1st. gen bottom end for 4AC conversion but this build will be hopefully first 2nd gen 4A-FE to 4AC build that I know. And I can definitely slim down the info if you think that this topic includes too much info. I like always to read some extra info before I do this scale projects. But you could suggest via message how I could slim down unnecessary parts. I understand if this amount of info is a bit too much for average builder.

And thanks for the crankshaft main bearing tip. I have to check my 3A bearings before I install them.

The easiest way to tell is that the early 3a's have both the rod and i think main bearing tangs on the opposite side vs the later 3a's. here in the states the early 3a's are 80-82.

[Nordical25]

The easiest way to tell is that the early 3a's have both the rod and i think main bearing tangs on the opposite side vs the later 3a's. here in the states the early 3a's are 80-82.

I just checked my main bearings. I have a bare block waiting for con rods + pistons from machine shop. Unfortunately main bearings matches your description well. Someone has opened this engine before for sure, because now my crankshaft main bearings have only lower halves. They look good so I am not sure if I want to replace them. They were also within tolerance when I inspected them with Plastigage. Thank you again for the tip.

I don't get how in the world I could own an early 3A? They were not even sold in Finland, because Finnish first gen Tercels had always 1.3 litre 2A engine. This must be imported as used to Finland probably from Japan in the 1980's or 1990's.

[SirFoxx]

The easiest way to tell is that the early 3a's have both the rod and i think main bearing tangs on the opposite side vs the later 3a's. here in the states the early 3a's are 80-82.

I just checked my main bearings. I have a bare block waiting for con rods + pistons from machine shop. Unfortunately main bearings matches your description well. Someone has opened this engine before for sure, because now my crankshaft main bearings have only lower halves. They look good so I am not sure if I want to replace them. They were also within tolerance when I inspected them with Plastigage. Thank you again for the tip.

I don't get how in the world I could own an early 3A? They were not even sold in Finland, because Finnish first gen Tercels had always 1.3 litre 2A engine. This must be imported as used to Finland probably from Japan in the 1980's or 1990's.

that is pretty strange. interestingly the 4afe im working on has the block cut for both style of bearings. I've never seen that before.

[Nordical25]

It is strange indeed. I did also googling and every bearing set for early 1980-1982 3A looks different than my current bearings. But maybe the answer is included in my picture. I wonder if someone has not known this early bearing thing and has used two sets of late model bearings. I mean all bearing halves have oil holes but there is no route for oil in crankshaft cap. And two thrust washers were installed wrong way. Wrong way installed thrust washers does not sound Toyota assembly line either.

Your 4AFE find sounds interesting. My 4AFE is in machine shop so I cannot check it currently. But there are many versions of 4afe for sure. According to Wikipedia there is even 3rd generation 4AFE sold in Asia during late 90's and early 2000's. So there is still a lot of details to explore. European 4afe's have for example three different types of ignition: 1. Denso distributor, which looks similar to 3AC distributor 2. Bosch distributor, which has no coil in distributor and has red cap 3. Ignition without distributor on latest 4A-FE's.

[Petros]

That is good information.

there are several differences between the 3a and 4a head (and a number of 4a variations). but they are interchangeable, I suspect they discontinued the 3a head and now just have the 4a listed as the replacement for the 3a engine. it uses the same size valves, rocker assembly, and same intake/exhaust port configuration. but the water jacket circulation is different and improved on the 4ac head. And it appeas some imported 4ac head had bosses over the intake port that appear to be to machine in fuel injector mounting points, that I have never seen used on any 4ac engine. There is also a "wavy" valve cover confituration, that looks different and needs a different valve cover gasket.

I recently blew my high mile 4ac engine in my '84 T4wd (not rebuildable, crank case blew out the side). No wrecking yards I could find within 150 miles even had a 4ac or 3ac engine (or the cars they came in) in stock. I was surprised because they used to be quite common, but I suspect are now so old they just send those cars to the crusher without inventorying them.

it has not occurred to me to use a 4afe short block, I have rebuilt them and they are almost the same as the 4ac, including the six bolt flywheel mount. Those should still be around, and they are almost identical to the 4ac short block. I guess I did not want any surprises when I am trying to get it together and all bolted up. the later 4afe looks like it is not compatible, unless you want to get some 4a pistons and risk having a machine shop bore out a 20mm wrist pin bore. the heavier crank and larger connecting rod ends seems like an unnecessary overkill for the 3a/4a installation since they are such low hp output.

I have located a rebuild-able 3a from another FB forum member and plan on rebuilding it to put back in my daily driver. I am a bit disappointment I could not find the slightly larger bore 4ac short block. I think my 4ac head is still okay, but I have not gotten it apart yet to know exactly what let loose inside the engine, and what can be salvaged.

I have also done some 4age conversions, and that short block has a lot of differences, and frankly not worth the extra cost. beside the 4afe is far more common and cheap. I would not use a 4age short block to turn into a frankinstein 4ac, a good 4age is getting hard to find, and you would have to either swap out the crank or have a custom Tercel 8 bolt flywheel machined up.

this is good information, I think it might be more useful perhaps if it was rearranged into individual bullet points (with one topic each) to make it easier to quickly reference if one was to print out this information to look at while they are rebuilding their engine.

[Nordical25]

I am glad that you like the information. And we could later reorganize the information somehow. For example, which parts and pieces are suitable for 4AC build or for 3AC build.

Information like this will get more important during coming years when spare parts are harder to find. I did find from a website a 4age comparison. It shows the differences between 4AGE blocks, but as you say, the crank is different in most cases. Someone sold here in Finland recently 4AGE blocks but I did not buy them because I knew that some of the 4AGE blocks have bigger crankshaft bearings. And 8 bolt crankshaft is an issue too as some have documented already in this forum several times in 4AGE build section.

The next build pieces going to machine shop are 2nd gen 4AFE crankshaft + two 4A heads. A late and an early model. I took pictures of both so you can compare them. And one picture includes my recently rebuilt 3A head too. And yes, valve covers and gaskets cannot be mixed between early 4A and late 4A heads. But most 3A heads and early 4A heads have same valve covers.

You could definitely look up for a low mileage 4AF or 4AFE. My recently purchased 2nd gen 4AFE had really nice cylinders compared to my early 3A. The machine shop will measure soon my 4AFE cylinders and pistons and I will hear soon how good is my 4AFE block actually. If it is nice enough, I will buy another one too as a replacement block for my temporarily seized and already freed 4A spare engine. And getting 1st gen 4AFE is much better choice. I will hopefully soon prove that 2nd gen 4AFE to 4AC is doable but it may do some additional harm to your wallet.

There could be still suitable pistons for 20mm wrist pins but someone would need to test them. Some 7AFE pistons and some latest 4AGE 20V pistons could fit to 4ac build but not all of them. One would need to verify if those pistons have room for valves by comparing them against original pistons.