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

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Petros
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My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

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

Post by Petros »

cam, springs and valve, and other stuff like the rocker arms and shaft should be the same on the 3a and 4a head.

I would test the valve springs for compression strenth, Toyota springs are pretty good, and long lasting but it is easy to do, etiher a machine shop can do it for you, or you can do it yourself if you have a drill press available, even one of those small cheap harbor Freight type bench top drill press works for testing spring strength. with a drill press: put a valve or large bolt in the chuck of the drill press (something large enough so it will fit over the top of a valve spring), put a bath room scale on the drill press work surface, and adjust the height so end of the bolt or valve stops so the spring is compressed to the installed height in the engine (there is a spec in the FSM for this distance). A digital scale works good for this, than put each vale in turn into the drill press and compress it and read the value on the scale. If your set up is accurate you can compare your value to the FSM spec for spring compresson (sometimes called valve seat compression). It is not that critical it be super accurate, as long as it is repeatable, all should be close in value.

I once had three engines worth of toyota valve springs to choose from, so I put them in matching sets, all of the best ones went into the "performance" negine getting the sport camshaft, and the others are just factory spare sets. I labeled the weakest springs as spares to be used if I just needed one spring on an old engine. if any was too weak I threw in the scrap bin.
'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
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My tercel:: 1986
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Re: 3ac to 4ac swap; have motor and questions...

Post by overs10ded »

Thanks Petros! I appreciate the instructions! I have all those items except my scale is analog style but should get me close enough...I am currently trying to figure out how to make a valve spring compressor to dissassemble the heads...

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

Post by Petros »

since you likely can not rent one, making a valve spring compressor is not too bad. Or you can buy them off of ebay pretty cheap.

the valve springs are actually not too hard to get out by pushing on them with your hands (heavy gloves helps), but getting the keepers back on when you assembly it might be rather difficult and likely you will suffer minor injury before you are done. I have seem sloppy mechanics put a socket over the top of the valve spring keeper and give it a whack with a mallot, the keepers often go flying, and you can remove it.
'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)
jimcrazy
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My tercel:: 1985 4wd 1986fwd 1983 4wd

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

Post by jimcrazy »

i borrowed this compressor from a retired toyota tech,worked great
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