Rebuilding 4a engine.

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overs10ded
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Posts: 93
Joined: Sat May 19, 2012 7:30 pm
My tercel:: 1986
Location: Villa Colon, Costa Rica

Rebuilding 4a engine.

Post by overs10ded »

I have the 4ac in the Tercel and running. But it needs to be overhauled! I plan on doing it around Christmas '16 and feel comfortable that the engine will take care of my wife until then. I have purchased Sterling pistons #12324P- 75mm (.030) oversized along with rings. I am looking at gasket sets and there is a difference between 83-85 then 86-88 engine sets? What is the difference? I don't know what year my engine is either. The valve cover looks identical to the '86 3a that came out of the car. The PCV grommet was different though and I removed the 4ac grommet and used the 3ac grommet along with the 3ac PCV valve. I have also purchased new valve guides-VG874CI for exhaust and an intake guide 022-1318.

While the engines were laying on the ground side by side, I was able to compare intake ports and on the 4ac engine there is a ridge that evidently was designed to contour the airflow. A update from the 3ac head design?

Thanks for any help!

Good times!
Bruce
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Petros
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Joined: Sun Jan 28, 2007 6:31 pm
My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: Rebuilding 4a engine.

Post by Petros »

most gaskets should be identical, I think the later 4ac valve covers were very different and used a different gasket. that may be the only differnace, there might be others that know better.

I think the early 4ac has the same valve cover as the 3ac, so you likely would be safer with the 83-85 set for the 4ac if your valve covers are the same.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
overs10ded
Advanced Member
Posts: 93
Joined: Sat May 19, 2012 7:30 pm
My tercel:: 1986
Location: Villa Colon, Costa Rica

Re: Rebuilding 4a engine.

Post by overs10ded »

After 200 miles and getting close with tuning the weber, I pulled the plugs and found #1 oil fouled, 2 and 3 are nice, #4 has oil but #1 is bad-crusty and gooey! So biding time while I make a stateside trip and pick up parts for my rebuild. Meanwhile the wife can get around fair enough without going to far away from home! Looking like December for the rebuild!
I am sticking with the original cam because I don't have money to get a regrind. While I'm in the states, I'm picking up a dremel I have there to port match the intake and exhaust if it is worth the time and effort.
Is the 3ac and 4ac cams the same grind?

Good times!
Bruce
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Petros
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Posts: 11930
Joined: Sun Jan 28, 2007 6:31 pm
My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: Rebuilding 4a engine.

Post by Petros »

likely needs valve stem seals. Might run a bottle of STP oil additive while you wait to rebuild it. I have found the oil additive "Restore" stopped a badly fouling sparking plug problem.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
overs10ded
Advanced Member
Posts: 93
Joined: Sat May 19, 2012 7:30 pm
My tercel:: 1986
Location: Villa Colon, Costa Rica

Re: Rebuilding 4a engine.

Post by overs10ded »

Hey, an update! I finally found a machinist here and luckily our house is on his way to his shop and he will pick up my stuff when I'm ready! What service! (This is in Costa Rica by the way) He says between $400-500 for bore, hone, balance, and valve job and all other machining incidentals I'm not listing like polishing crank-rod recond, etc. I thought that sounded fair. I do the tear down and assembly.
My first question is how to identify the main bearings that are in the block...I have read that the main bearings are marked somehow? Time to open up the manual! I'll take photos of the engine R&R plus tear down and assembly. I usually like to do things like gasket match and all but really the only thing that has been bugging me is to turn the weber around and have the primary/secondary the oem location. That is all I'm going to try to modify as everything else is pretty OK. Other than the new 2" exhaust that will come...next year! I'm buttoning up installing Poly bushings on the upper/lower trailing arms of my '88 cherokee (pita) then I'll tackle the Tercel!
Good times!
Bruce
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