3ac to 4ac swap; have motor and questions...

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overs10ded
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3ac to 4ac swap; have motor and questions...

Post by overs10ded »

I have found a 4a to replace the tired 3ac! Don't know year yet. Missing the distributor! Going to follow Petros suggestions on checking the engine out. I already have the Weber 32/36...I can now A/C delete the car-compressor seized- (need parts?)...I NEED A DISTRIBUTOR! Will the 3ac of my 86 FWD wagon work? Also is the 3a cam and 4a cam the same, so I could send one as a core for upgrade while still driving the 3a ? Petros also advised me of the changing of the intake manifold, the oil pan and pickup, engine mounts, alt bracket, pulleys, maybe water pump...AND pulling # 3 and 4 connecting rod cap to look at the bearings for wear. Thanks for any help with my questions and for the info Petros has already given!

Good times!
Bruce
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dlb
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Re: 3ac to 4ac swap; have motor and questions...

Post by dlb »

this is covered in the FAQ, see #17.

viewtopic.php?f=2&t=7442

yep, the 3a dizzy will work in the 4a. not sure about cams but i think they're pretty similar. i didn't notice any difference in power when i installed a 4a in my first terc so i think both cams are roughly tuned to 'gutlessly economical.'
tercel4wdrules
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Re: 3ac to 4ac swap; have motor and questions...

Post by tercel4wdrules »

I used a 3A one with the 4A-C I installed. The cam should be similar with the exception of the cam in the 4 spd hatch, that one I think used a different profile. You will need the water pump housing from the 3A to swap over as the 4A-C uses a different one.
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overs10ded
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Re: 3ac to 4ac swap; have motor and questions...

Post by overs10ded »

Thanks guys! That is what I wanted to hear!! I appreciate the help and I'll keep tabs on the swap here as best as I can.

Good times!
Bruce
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Re: 3ac to 4ac swap; have motor and questions...

Post by overs10ded »

Missing the fuel pump, but I have a new spare for the 3ac, will it work?? I pulled the #3 rod cap and the crank looks good, the bearing has some light wear showing in line off the oil hole-dirty oil? There was silicon on the pan gasket, or for the pan gasket lol! The timing set looks very good/new! I'll pull the plugs here after pm coffee and see how she was firing. I don't have much of a work space here but I do have a concrete floor-engine is on the floor of my front stoop under the little 3'x6 roof! Rainy season is starting and my roof is only 1/3 done over the patio...but little by little. The engine is under my porch roof on the flywheel and everything is taken off the longblock except the valve cover. I'll take the flywheel off somehow next too.

Also-how do I tell what year it is? 4A 6667743 is the number on the ID

Good times!
Bruce
tercel4wdrules
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Re: 3ac to 4ac swap; have motor and questions...

Post by tercel4wdrules »

Yes, the 3A fuel pump will work, that's what I used on mine. You can get an idea of the year by whether it has a straight valve cover or a wavy valve cover and if it has the TOYOTA lettering on the valve cover. The later 4A engines with the wavy valve cover usually have a black 4A sticker, the earlier ones have a blue 4A sticker on the valve cover. Some even had the VIN etched on a small plate and attached to the block.
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overs10ded
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Re: 3ac to 4ac swap; have motor and questions...

Post by overs10ded »

Thanks tercel4wdrules! This looks pretty identical to my '86 3AC!

Good times!
overs10ded
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Re: 3ac to 4ac swap; have motor and questions...

Post by overs10ded »

Well I pulled the plugs and they look pretty fair! I'm leaving the head on as it seems in fair enough condition and my budget for this swap is about $10! I am looking forward to deleting the A/C system, especially since the compressor seized on my wife a couple weeks ago (on Easter) luckily only a mile from our drive way although she drove 2 miles with it seized but couldn't bring herself to drive farther as smoke was coming out from under the hood. She had called me and I diagnosed over the phone it was seized compressor...that is why she was driving on it, of course she called as soon as something was amiss! Anyhow, that will lighten my load by maybe 50# plus the 120cc extra from the 4a should be a noticable difference! Weber tuning to look forward to also!

Good times!
Bruce
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Re: 3ac to 4ac swap; have motor and questions...

Post by jimcrazy »

did my 4a swap this morning,runs well not a lot difference from the 3a until shes comes up to 3500-4500 rpm then she comes alive. I live on a gravel road, in 2wd 2nd gear bring it up to 3200-3500 then floor it will spin the front wheels lol.
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overs10ded
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Re: 3ac to 4ac swap; have motor and questions...

Post by overs10ded »

Very cool! Mine is FWD (2wd) 5spd and runs pretty good however it is now smoking a quart per 250 miles-no leaks! But still running great! No smoke at idle but w/revs she smokes! More revs-more smoke! So my wife found the engine while trying to track down a new window mech for the drivers door, which is worn out with 'needle teeth'...the guy says he will reweld, creating new teeth, then file and fit, for $20! I'll give him a try! He wanted $400 for the engine but I had a Mitsubishi 4x4 trans and transfercase I traded. I have A/C but will be deleting the system.

Thanks for your pictures!

Good times!
Bruce
overs10ded
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Re: 3ac to 4ac swap; have motor and questions...

Post by overs10ded »

I took the wife to the airport in this car (hers) this morning (my ol' Cherokee diesel isn't together) and the 3a is still running strong! Just smoking a lot! Seems to be taper IMHO. But the wrist pin noise at cold start-up isn't getting any better and I swear there is a knock that isn't the fuel pump. Anyway I believe I still have some time, but don't want to trash the 3a either pushing it too much. I did hit 90mph on the way home though-pushing it-for the "test"! She sounds good with revs too, (love the weber howl) - just the smoke trail :/...350 miles on the last quart! Using the trip odometer for oil economy instead of fuel economy now lol!

I have a question on the intakes of the two engines...are they identical? They look very close!

Good times!
Bruce
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Re: 3ac to 4ac swap; have motor and questions...

Post by Petros »

the gasket face of the 4a head and the 3a head is identical. so the the 3a induction system, and integral exhaust manifold, will bolt right up to the 4a head so it will work in the Tercel.

I do not recall if you have to remove several of the manifold studs, the Tercel intake has two bolts, rather than the typical stud and nut. But that is an easy swap, double nut the stud and it will come right out.
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overs10ded
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Re: 3ac to 4ac swap; have motor and questions...

Post by overs10ded »

Thanks Petros! Greatly appreciate your experience and wisdom!

Good times!
Bruce
overs10ded
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Re: 3ac to 4ac swap; have motor and questions...

Post by overs10ded »

OK! Well after the timing belt broke on the 3ac I decided to swap the used 4ac in and see how it worked. Everything went smooth and I was able to get my local machinist to cut a bunch off the flywheel-the entire back lip that runs outside the starter teeth-plus recut the face too, for $40! I had a new spare fuel pump, I also used the oil pump from the 3a that was new 35,000 ago and still looked it compared to the wrung out 4a pump that was coked up pretty bad-the engine has seen some heat! Also installed a mechanical oil pressure gauge so I could testify that I indeed have oil pressure. I deleted my A/C system firewall forward and cut the alt/ac bracket in half to only support the alt, and lost about 4# along with all the A/C stuff; compressor, fan, evaporator, dryer, it adds up! Sooo I did it all with minimal tools and a come-along off a cross beam I have on my patio. Worked pretty well and able to do it alone to boot! Fired the new engine up and now have about 40 miles on it dialing it in. Great oil pressure! Without a compression tester, I have to say one cylinder sounds pretty weak. But there's still some life left, no knocks, no bubbles in the radiator, and mediocre smoke!

I have had an issue with dialing in the timing. I stabbed the dist at TDC#1 and all but the timing was too retarded and would only run at the anchor limit, with no mid or top end. So I andvanced a tooth and then too much timing. At the opposite stop on the dist anchor with detonation. So I'm toying with relieving some of the material on the distributor housing to allow more range to get those few extra degrees retard from where it is now. I was pretty careful with the timing belt and rotated the engine several revolutions and rechecked and everything seemed fine but I've had mysterious cam timing changes before with engine assy. =/ Anybody?? I'll post some pictures when I get that figured out!

Good times!
Bruce
overs10ded
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Re: 3ac to 4ac swap; have motor and questions...

Post by overs10ded »

Yep! The cam timing is "there" and the "optimal" ignition timing is between two teeth where one is too far advanced, the other too retarded. So I'm going to massage the hold down anchor slot end to allow more CCW rotation on the dist. housing to retard my timing-get more rotation. Getting close!!

Good times!
Bruce
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