Engine alternatives

[Petros]

after only about 10k miles it appears I have another exh. valve failure. I will check tonight, but I get occation puffs of blue smoke, and it is running rough. So either a seal went bad (easy to fix), or I burned and wasted another valve and guide (lots of work to fix).

If so I think this darn 3ac engine is just to fragile (this would be my third burned ex. valve) for the amount of power I am getting out of it. And I keep having to dink around with the carb/emission controls/etc. to keep it running good.

So now I am thinking I should switch to a 4a engine with a better head design, more power etc. But I do not want to go carb but rather switch to EFI if I am going to all that trouble and be done with the old set-up.

My question is what EFI engines will bolt in to the Tercel4wd okay? I notice that on the 3EE engine (with EFI) they moved the distr. to the back of the head (because of the transvers mounting in the newer models). this will not fit in the old Terc without heavily modifying the firewall, heater, etc. Do any of the 3 or 4 series engine have the side mounted distributor (as in the 3ac) but still have EFI? Because everything else I think could be made to fit without too much trouble. Which engines meet this requirment, and which model/year cars do they come in?

[Typrus]

We need this put somewhere in massively bold letters, the question comes up so often...

All "A" family engines will bolt up and bolt in. Will the tranny take them is the question.

[GTSSportCoupe]

Typrus is right as far as the block is concerned. However, the main mechanical bolt in problem is the flywheels on the EFI engine's are too large to fit into the Tercel's bell housing. Most (if not all) of the EFI engine's have 8 bolt flywheels, while the 3ac and 4ac have 6 bolt. This would necessitate a custom flywheel and a strong clutch. Also, all the EFI engines are cross flow heads, so you have to figure out how to route the header around the steering column (probably not a big deal if you are a good welder).

That said, the only EFI A series engine made to fit in the same orientation as the 3AC is the large port 4AGE (85-87) from the AE86 Corolla GTS (RWD). All others are transverse mount (fwd or mrwd). Fortunetely the rwd 4AGE can often be found for $200-300 in ok shape (in my area anyhow). There are pictures on this forum somewhere of a car in Japan that had this swap. The engine looked like it belonged in the car. Personally I think this would be an amazing improvement to the tercel. The large port 4age only makes 100ft/lbs of torque (compared to the 3AC's ~80ft/lbs), so I don't think the torque will wreck your drive train. The 115hp or so would be nice though.

Other engines that can be swapped are the later 4age's and the 4afe's, and maybe a 7afe (taller, might interfere with hood though).

I hate carb'ed engine's and would probably do the 4age swap if my tercel was worth it, but it's just too dang rusty.

[GTSSportCoupe]

Just wanted to add, there are dozens of posts on this same topic, and much to learn. Try a search and see what comes up.

Also, here is the link to the 4age Tercel thread: viewtopic.php?t=1544&highlight=4age+japan

[Mickey_D]

Something to consider is WHY you're burning exhaust valves - the most common culprit is a plugged catalytic converter.

[Typrus]

Improper gap adjustments? Lash that is.
I realize you know what you're doing in a lot of things, but its possible you've overlooked something? Happens to all of us.
I've never heard of someone burning exhaust valves from too high of output. I usually hear about bent things, or even burned pistons before valves....

Maybe a ceramic coating on the face of the valve? Would cut down on exposure? Heck, if you could coat it everywhere but the seating surface, and make it uniform, that valve would be near impervious.

Have you checked the valve seats?

[tercel4wdrules]

Something to consider is WHY you're burning exhaust valves - the most common culprit is a plugged catalytic converter.

How do you check for a plugged catalytic converter? This might be the cause of my poor MPG...

[keith]

If your exhaust valves were new and they are burning up this fast, I would look for a problem, but if you had reground the valve, then I am not surprised to see them burn so quickly. I never grind exhaust valves anymore.

[Petros]

I had a chance to check the engine, the compression is good on all cyl. between 157 and 160 PSI (I am running 11:1 CR). The valves appear to be all okay, so I guess I will not be pulling the engine appart. Valve lash is all still good. Perhaps just have a bad valve seal.

I had burned two valves after my last rebuild when still running the factory 5 BTDC timing. Now I am 10 to 12 BTDC, this should reduce valve temps since more of the fuel is burned before the valve opens. So far, so good. Yes I used reground valves (which I never had trouble before on other cars, if I was to pull the head off again I just might replace the exhaust valves while I am at it).

I might have a bad catalytic converter too since it has some 220k miles on it (I would like to know how you test for that too, is there a simple test? I've never heard of one). But I am planning on replacing the whole exhaust system later this year with a 2" system anyway (that should lower the exhaust temps too). Unless I go for one of those 4age engines (not likely at this point, though I do want to get rid of that OEM carb!), then I will save my money for a custom exhaust system for the 4age, and a new flywheel.

Would a 4age head fit on the 3ac block? Is there any mods required? This might solve the flywheel problem, and save some weight.

Here is what is happening. heavy bluish-white smoke at idle when warm. No smoking running above 2000 rpms or under load, no smoke at start-up, only when I come to a stop with the engine warm and let it idle (at a stop light). It seems to be worse at hard stop, or steep down hill (front of car downhill at stop). Smoke stops as soon as drive away from stop. It does not seem to be using much oil, and otherwise runs good exept for a rough idle right at cold start-up (could be something else). All of the spark plugs look good and all the same (not any with stains or fouled), and as noted above, compression is all good. And there is also an occational smell of gas I can not locate (seems something around carb is dripping on to heat sheild, I can see the stain, but can not find the leak!), not likely related either. I am also losing water somewhere, have not found it but I suspect the o-rings on the pump by-pass tube. Could a bad head gasket cause smoke at idle and the water loss? It does not seem likely without other symtoms.

I can not think of what might make it do this but perhaps a mis-installed exhaust valve stem seal. Though it is a bother, they are cheap and not too bad to replace without pulling the head. Unless anyone has any other ideas to check first I will likely replace them this weekend. Any ideas or suggestions?

[Typrus]

Your cat is toast. I can basically tell you that right off.
A vacuum test will check for a plugged one, but not a bad one as far as I know.
I dunno if just a bad seal would make for "heavy" smoke. But your idea of heavy and mine might be very different.
Could it be that you put the rings in wrong? With the gaps kind of lined up, rather than 180 off? That'd create a little bit of blowby.

What Octane you run for 11:1? What'd it take to get there? 10:1 was my goal, but higher would be nice if I can reach it safely.

Where'd you get those flattops and do you have any pics??

[GTSSportCoupe]

Your cat is toast. I can basically tell you that right off.
A vacuum test will check for a plugged one, but not a bad one as far as I know.
I dunno if just a bad seal would make for "heavy" smoke. But your idea of heavy and mine might be very different.
Could it be that you put the rings in wrong? With the gaps kind of lined up, rather than 180 off? That'd create a little bit of blowby.

What Octane you run for 11:1? What'd it take to get there? 10:1 was my goal, but higher would be nice if I can reach it safely.

Where'd you get those flattops and do you have any pics??

Remember that Petros is an engineer. I'd expect that he has a good idea of what he is doing, or at least good attention to detail. I wouldn't discredit him so quickly.

You ever seen an 80's dodge minivan with bad oil seals? Those things can put out so much smoke you can't see the road behind them! My vote is bad oil seal(s) in his engine. Messed up rings would have caused smoke from the minute he put the engine together I would think?

[76RA24]

I did some asking on other boards and it appers that the 4age head will fit on a 3ac/4ac block.

I might attempt this with my 81 in hte summer...

pete

[Typrus]

It should fit. Why? I know people have put 3AC heads on 4AC blocks, and I know people have put 4AC heads on 4AGE blocks. I'd call that good evidence.

I didn't mean to discredit. Everyone makes mistakes. Hell, I didn't even know about lining the rings up like that until a few weeks ago. (shrug)

I base my cat statement off of the fact that every one I've seen with over 200k miles on a stock cat is suffering from a collapsing cat superstructure. Makes for lots of rattlies. That, and its hard to push adequate oil past a good cat to get any respectable amount of smoke.

Don't bring up the Dodge's. They were probably a military operation to make a better beach raid craft equipped with smoke cover that never worked out. So they sold it to the public >.< lol. I've had to wash my car after following one. (shrug) I suppose. I just wouldn't think that much oil could get by a tight valve and guide.

My idea of a lot is not being able to see anything through the smoke. A lot of peoples idea of a lot is any amount visible from the drivers seat.

[Paul]

Unbolt the cat and look at the inlet side. You will be able to see if its noticably clogged. If your Terc is off-road or for use on other planets, beat the innards out with a long chisel or piece of rebar. A sudden increase in power and mileage would confirm a clogged cat.

The mysterious gas odor smells familiar. Try checking for a ruptured AAP diaphragm by temporarily disconnecting and plugging the vacuum line to it.

[Typrus]

Could be unrelated, but I figured I'd mention it- is there oil on your firewall right behind the fuel pump?