3AC or 4AC

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Jonymoto
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My tercel:: 1983, DLX 4wd wagon with 4.1 manual gearbox, tow bar). Manual steering. 313,000 kms. Tercel 4WD SR5, 1987, 500,000kms. Other car - 2003 Rav4, AWD, 2l manual, Peugeot 407 Diesel (93,000 miles) in Ireland for use when on holiday there.
Location: Melbourne, Australia

3AC or 4AC

Post by Jonymoto »

This weekend I adjusted the valves on my 3AC engine. As I didn't have a new valve cover gasket, I borrowed one from a fully reconditioned engine that I bought earlier last year. It was advertised as a Tercel engine and it definitely looks like one. But the valve cover is different from my 3AC's cover, see attached photo. Note that one side of the cover is wavy. I suspect that this cover is from a 4AC engine. My question is could the whole engine be a 4AC not a 3AC? How do I tell without removing the cylinder head and measuring the bore diameter?
20161205_212410_3_resized_1.jpg
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When you lose, don't lose the lesson - The Dalai Lama
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Jonymoto
Top Notch Member
Posts: 296
Joined: Wed May 06, 2015 9:39 pm
My tercel:: 1983, DLX 4wd wagon with 4.1 manual gearbox, tow bar). Manual steering. 313,000 kms. Tercel 4WD SR5, 1987, 500,000kms. Other car - 2003 Rav4, AWD, 2l manual, Peugeot 407 Diesel (93,000 miles) in Ireland for use when on holiday there.
Location: Melbourne, Australia

Re: 3AC or 4AC

Post by Jonymoto »

The block is stamped 3A, maybe the cover is was a later version.
When you lose, don't lose the lesson - The Dalai Lama
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Petros
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My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: 3AC or 4AC

Post by Petros »

it is possible it was a "crate engine" imported from Japan, than it might be a 3a with a different head. Or it could be a 4a as noted (not all of the 4a had the "wavy" valve cover either). if there are no external markings you can do a "displacement test" that determines displacement without having to pull the head off. you use a graduated cylinder, with the engine at TDC, valves closed spark plug off, carefully measure how much fluid (like oil, water, solvent, anything handy) will fill up the chamber to the top of the spark plug (it helps to tilt the engine over so the spark plug is the high point of the combustion chamber). than suck or blow it all out, and set the piston at bottom dead center, and do it again. from that you can determine the total displacement (multiply the difference in the two measures by 4) and you can determine the compression ratio (divide one by the other).

You want to do this fairly carefully, so it is accurate. But you do not need to pull the head to determine the displacement.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
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Mattel
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My tercel:: 1988 Corolla 4wd Wagon (AKA Corolla All-trac) 5speed, AC, Power Sunroof, Windows, Mirrors, Steering, Locking, Diff Lock, 14" Corolla SX Alloys with Silica Hankook Tyres, 4afe, King Springs, Upgraded Headlights, Full Synth oils, 210,000kms
Location: Melbourne, Australia

Re: 3AC or 4AC

Post by Mattel »

Could be a 3a scv engine? they had a slightly different head and the one in my first Tercel was a JDM replacement 3a SCV and actually felt revvier than the normal 3a
Previous: 83 Tercel SR5 4wd, 84 Tercel SR5 4wd
88 Corolla 4wd Wagon 5speed, All power options, Fact Sunroof, Diff Lock, 14" SX Alloys, Hankook Tyres, 4afe, King Springs, Upgraded Headlights, Full Synth oils, Tow Bar, 210,000kms
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Jonymoto
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Posts: 296
Joined: Wed May 06, 2015 9:39 pm
My tercel:: 1983, DLX 4wd wagon with 4.1 manual gearbox, tow bar). Manual steering. 313,000 kms. Tercel 4WD SR5, 1987, 500,000kms. Other car - 2003 Rav4, AWD, 2l manual, Peugeot 407 Diesel (93,000 miles) in Ireland for use when on holiday there.
Location: Melbourne, Australia

Re: 3AC or 4AC

Post by Jonymoto »

Matt - I did a search on the 3A SCV and it looks like you are right. But I can't find what the difference is between the 3A and 3A SCV apart from the head being different. Do you know? I take it it is still 1.5L and 52KW rating.
When you lose, don't lose the lesson - The Dalai Lama
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Mattel
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Joined: Tue Aug 17, 2004 12:11 am
My tercel:: 1988 Corolla 4wd Wagon (AKA Corolla All-trac) 5speed, AC, Power Sunroof, Windows, Mirrors, Steering, Locking, Diff Lock, 14" Corolla SX Alloys with Silica Hankook Tyres, 4afe, King Springs, Upgraded Headlights, Full Synth oils, 210,000kms
Location: Melbourne, Australia

Re: 3AC or 4AC

Post by Mattel »

No i'm not sure. The 3a scv engine was lower km by about 150,000 to my 3ac car that replaced it which probably made it seem a lot faster. I think the SCV was a later model with a Swirl Control Valve? whatever that was!
Previous: 83 Tercel SR5 4wd, 84 Tercel SR5 4wd
88 Corolla 4wd Wagon 5speed, All power options, Fact Sunroof, Diff Lock, 14" SX Alloys, Hankook Tyres, 4afe, King Springs, Upgraded Headlights, Full Synth oils, Tow Bar, 210,000kms
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