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Thread: will 4age head fit on a 4afe bottem end?

  1. #1
    Forum Member 1st year Apprentice
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    Default will 4age head fit on a 4afe bottem end?

    as stated i want to know if a 4afe bottem end will bolt up and run with a 4age head?? since there both 4a series and twin cams is it possible??


    cheers in advance Dai

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    i wrote the Automotive Encyclopaedia roadsailing's Avatar
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    Default Re: will 4age head fit on a 4afe bottem end?

    it probably would work, but i wouldn't bother.

    the 4AFE and 4AGE have vastly different heads, you would be better off just getting a complete 4AGE, as they are quite cheap, cheaper than messing around hybridising things for sure.

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    Default Re: will 4age head fit on a 4afe bottem end?

    ive all ready got one but my mates asking due to his 4afe's head problems and its would be interesting to see if it is possible and what is needed to be done

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    Chookhouse Chooning Automotive Encyclopaedia Hen's Avatar
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    Default Re: will 4age head fit on a 4afe bottem end?

    I am not speaking from experience here, but I would expect that a GE head would bolt to and generally work with a FE bottom end. However the problems that you'd encounter would probably be whether the valves cleared the pistons given the FE pistons and GE valve angle. Also I think there'd be some timing gear from the front of the engine that would need to be swapped.

    Then you'd have to consider swapping manifolds and looms.

    I think it could be done, but I doubt whether it'd be worth the time and money.

    Hen

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    I dont like the term Grease Monkey beige_bandit's Avatar
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    Default Re: will 4age head fit on a 4afe bottem end?

    The key here is 4A. both blocks are 4A
    G is and indication of the head type,F is also indication of head type

    You could put the head off a 4AGE on to a 7A block
    Fundamentally it will work, but there is external mods to be done(nothing heaps major)

    As hen said is it worth time, mucking around and money
    Going from 4AFE to 4AGE using the same motor?

    I say no! just get a complete 4AGE and drop it in
    Im just a little lost but ill be fine!

  6. #6
    Junior Member Domestic Engineer RobertoX's Avatar
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    Default Re: will 4age head fit on a 4afe bottem end?

    ^^ is this entirely correct? Going by what others have said with the "bigport head on smallport block" conversion the blocks are not exactly identical in terms of block to head. Apparently in this case there is a oil drain in the bigport head that needs to be blocked off (or something of this nature) so maybe you should be careful of these sorts of issues also.

    Also I think there'd be some timing gear from the front of the engine that would need to be swapped.
    I could Imagine this being a real pain in the arse too!

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    Junior Member Carport Converter Dale's Avatar
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    Default Re: will 4age head fit on a 4afe bottem end?

    How about the bottom end? Surely a 4afe would have weaker rods and crank to a 4age. Then consider pistons and if you'd have the correct CR once it's all done for a GE head? I think that would just be the start of the issues!

  8. #8
    AE86 Tuning Life Backyard Mechanic Garth AE86's Avatar
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    Default Re: will 4age head fit on a 4afe bottem end?

    when a 7a-fe bottom end goes under a 4age head you have a 7age
    so i guess the 4afe would work, block would be weak as piss but
    Garth - 100% AE86 Addict
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    Default Re: will 4age head fit on a 4afe bottem end?

    its not really the block strength thats the problem (unless you are shoving in massive boost and/or revs), its the rotating assembely.
    the rods are similar to earlier 4age engines, they have a 40mm bigend type crank as opposed to the later 100kw and gze which have 42mm bigends and much stronger rods.
    i know the crank in a 4ac (and i think 4afe) is not a forged steel one like 4age series engines.
    the pistons in the 4afe are also weaker and will drop the compression ratio considerably.
    there is enough piston to valve clearance at tdc, but the crown design was never ment for a high peformance 4age head.

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    Default Re: will 4age head fit on a 4afe bottem end?

    Quote Originally Posted by dan05k
    its not really the block strength thats the problem (unless you are shoving in massive boost and/or revs), its the rotating assembely.
    the rods are similar to earlier 4age engines, they have a 40mm bigend type crank as opposed to the later 100kw and gze which have 42mm bigends and much stronger rods.
    i know the crank in a 4ac (and i think 4afe) is not a forged steel one like 4age series engines.
    the pistons in the 4afe are also weaker and will drop the compression ratio considerably.
    there is enough piston to valve clearance at tdc, but the crown design was never ment for a high peformance 4age head.
    Earlier model FE have what you are saying in regards to the big end, but from memory late model FE's don't ....what all FE's (incl 7A) also don't have are a big end cap and rods in which the cap bolt passes through both the rod and cap which is the secured by a nut, which 4AGE does. They have a tapped thread into the rod itself, this is what lets go first. As far as FIA homogation papers state for the AE101/102, the 4AFE is FORGED!! as is the 7A which I can confirm. Also No FE block has oil squirters, which all 4AGE's have after the 86Kw version. Valves will not hit the pistons, there is heaps of clearence, and the comp of a 4AGE head directly on a 4AFE bottom, work out to be aroubd 7:1, which would still crap for a F/I as it would be a real dog off boost.... Just buy a whole GE and do it properly!

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    Estranged Member Chief Engine Builder mullett's Avatar
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    Default Re: will 4age head fit on a 4afe bottem end?

    Seriously, a whole, good nick 4A-GE will be about $400. I doubt you could get a head and all the other crap for this much if you tried to buy it all seperate...

    So yes, you can do it. And no, it's not worth it.

    RM.

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    Default Re: will 4age head fit on a 4afe bottem end?

    Im with mullet.

    I think it can be done but dont think it is the cost effective option you are chasing.
    There will be alot of fartassing around to do it.

    A sotck 4afe ECU may run the combo but a 4age may have better air flow and use more fuel so things like ECU changes or re-map will need to be considered along with all of the other small things.

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    Default Re: will 4age head fit on a 4afe bottem end?

    yeah, i agree. it is a much better idea to use a whole 4age engine, they are cheap enough to buy.
    thanks for the extra info johnny, didnt realsie there were that many difference between the 4ac and the 4afe.
    i also know for a fact that the 7afe is forged crank, but like you say , the rods are the weak point where the bolts are threaded into the rod.
    having said that i am currently using a 7a block, crank and rods in a 7agte with a big port head a t25 turbo. for now its limited to 10psi boost, but another engine is in planning now, using 4agze rods on a 7afe crank (with the big end journals machined to suit) in a 7afe block that has been decked to bring the compression ratio up to what it should be due to the 4agze rods being shorter.
    then we will see about a bigger turbo...

  14. #14
    Junior Member Backyard Mechanic 3sgte's Avatar
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    Default Re: will 4age head fit on a 4afe bottem end?

    It is quite straightforward to do, assuming that you have a smallport head and a 4AG fuel system to work with.

    The key factor (simplicity side) would be to use the 4AG water pump, headgasket and cooing system bits to preserve the original coolant flow.

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    AGE-16V Automotive Encyclopaedia Dimmy's Avatar
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    Default Re: will 4age head fit on a 4afe bottem end?

    Quote Originally Posted by mullett
    Seriously, a whole, good nick 4A-GE will be about $400. I doubt you could get a head and all the other crap for this much if you tried to buy it all seperate...

    So yes, you can do it. And no, it's not worth it.

    RM.
    i'd agree with that, i would believe that it can be done, as the only major difference is the angled cams. The block wouldn't be as strong so if you're after a turbo/sc setup i wouldnt recommend it. 4AGE's are dirt cheap these days and going from one efi --> another efi is easy
    I have been pruned by old man river!!!!!

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