4A-FE/GE Franken Motor, With Carbs!

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Kozuto_98
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4A-FE/GE Franken Motor, With Carbs!

Post by Kozuto_98 »

Here's the follow up to the 2nd gen 4A-FE swap project I've been planning out.

I've gone through some iterations and changes in my plans through the months, but I've finally reached my final plan on what I'll be doing with this project. For those who might be unfamiliar, my earlier plans are in a sperate thread. Initially I wanted to do an ITB setup with a 2nd gen 4A-FE from a
1997 Corolla running on wasted spark coil packs on Speeduino 0.4.4b. Then later a curveball came into my plan when I was offered a silvertop head from my friend Addie. She later found upon inspection of the head that there was a crack in the head, which would have most likely led to coolant and
oil mixing. And this brings me to the final plan that I've been drawing up, which has been motivated by my recent 3A-C rebuild and it's subsequent oil leak issues.

So here's my full rundown on what I'll be doing.

Bottom end
2nd gen 4A-FE block, crank, rods, and bearings.
For pistons I'm currently looking at smallport pistons from a 1988 MR2 as they should have the correct wrist pin size I need (20mm).
Being reused from my 3A-C will be the oil pump, rear main housing and seal, oil pan, oil pickup, balancer, and water pump assembly.

One thing I should bring up is the difference in the oil pan shapes for the 3A-C and later 4A blocks.
While early 4A and 3A-C oil pans have straight lines back, in my case since I have a later 4A block I have a small indent on one side.
Originally I was going to try to graft the seal surface of the 4A pan to my 3A-C pan, but I think instead I'll make a custom adapter plate to save
cutting both oil pans.

3A-C oil pan gasket
3ac pan seal.jpg

4A-FE oil pan gasket
4afe pan seal.jpg

Top end
For a top end setting, my plan entails a 1988 4A-GE MR2 head (3rd gen/smallport/redtop).

For induction I'll be using a set of bike carbs. Currently my options are either a set of CB750 carbs I currently have, but need a full rebuild and clean,
or for a few bucks a set of CBR600 carbs. Depending on what I go with I'll either be cutting an intake manifold to suit the CB750 carbs, or going with
the bike carb manifold offered by DanST. https://danstengineering.co.uk/Toyota-1 ... orolla-MR2

I'll still be making a custom exhaust header to clear both the starter and steering column. I'm still deciding on a full route to take for the header
back to the muffler right now, but in due time I'll cobble something together. I'd love to see what folks with twin cam setups in their Tercels have
done for a full exhaust route so I can build some ideas.

Ignition
Here's where things get a little interesting.
There's a few ways you can get spark with a bike carb 4A-GE. MSD, Programmables, ect. But for me I wanted to keep a carbed setup as simple
as I could, so I started looking into vac/mechanical advance options for the 4A-GE.

One option I cam across was grafting the 4A-GE distributor into a Toyota 4Y distributor (yes, the forklift motor).
https://youtu.be/FHSFny0yHAM

This is what got the bells ringing in my head for getting spark. Later I did some reading on using the 3A-C & 4A-C distributor on a GE head, and at
first glance some folks were saying it wouldn't work. I was going to take the word of mouth on it, until I came across this video showing a carbed
4A-GE running on a 4A-C distributor.
https://youtu.be/r9gcEyzFdyc

I will point out that in the 4A-C distributor video, the person was using an MSD on top of it. But I can't see why the 3A-C distributor wouldn't work.
What using this distributor entails is taking off the drive gear, and putting on the 4A-GE drive gear. From what I could find using the original gear
likely doesn't fit the other drive gear, and would spin the distributor backwards.

I wasn't sure at first if the 3A-C distributor used an external circuitry like an ignitor, but after consulting the Tercel fsm I found that it's a self contained system, hence why the fsm refers to it as "IIA", or integrated ignition assembly. So in theory, I should be able to put the 4A-GE gear on
this distributor, plug it in, and have spark with a vac advance. The power lead for the distributor will for sure need to be extended due to the different placement, and maybe some mixed and matched leads to keep the plug wires somewhat cleaned up.

If anyone knows what the other covered connector on the 3A-C distributor is for I'd love to know. My best guess was maybe a feedback signal for
misfire reporting of some sort?

This is the plug I mentioned.
3ac dizzy.png

That's my final plan for now. The reason I went carbs over EFI is for simplicity. I can always leave room to go full EFI later on if I so desire.
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1987 Tercel Wagon SR5 4WD
1998 Honda Accord Coupe V6 J35 swap
1997 Acura CL (Sold for 4A-GE money)
RIP 2016 Civic (wrist pin recall)
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NWMO
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Re: 4A-FE/GE Franken Motor, With Carbs!

Post by NWMO »

Koz,

The mentioned connector is most often refered to as a “test” plug or port. I assume it could be usegul for diagnostics, but more often folks w/o factory tachs are hoping to pull signal from the plug.

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Kozuto_98
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Re: 4A-FE/GE Franken Motor, With Carbs!

Post by Kozuto_98 »

NWMO wrote: Fri May 07, 2021 4:31 am The mentioned connector is most often refered to as a “test” plug or port. I assume it could be usegul for diagnostics, but more often folks w/o factory tachs are hoping to pull signal from the plug.
Interesting. The black wire from the other 2 pin connector is where the tach lead comes from for models that came with a tach, so I'd assume folks wanting to use an aftermarket or swapped cluster could use this. I might try tapping into the other connector with a sunpro tach I kept around to see what happens.

dizzy diagram.png
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1987 Tercel Wagon SR5 4WD
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1997 Acura CL (Sold for 4A-GE money)
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Re: 4A-FE/GE Franken Motor, With Carbs!

Post by AugustusFerdinand »

I used an oil pan adapter on my 7AGE build, but it was necessary to clear the extra stroke (and I still needed to do some hammering). The clearance shouldn't be needed on the 4AFE bottom end, so you could honestly get away by welding in a trapezoidal piece of sheet metal to the 3AC's pan where it would match up with the 4AFE's block and be just fine.
1983 Toyota Tercel SR5 - 7AGE swap in progress
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Kozuto_98
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Re: 4A-FE/GE Franken Motor, With Carbs!

Post by Kozuto_98 »

That thought had crossed my mind, but I'm a little hesitant to weld or cut my 3A-C pan just yet. I got a lot of sheet steel from furnace tanks and I was
thinking of making an adapter out of that. I forget if the 7A has these, but did you use a windage tray?
1987 Tercel Wagon SR5 4WD
1998 Honda Accord Coupe V6 J35 swap
1997 Acura CL (Sold for 4A-GE money)
RIP 2016 Civic (wrist pin recall)
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Re: 4A-FE/GE Franken Motor, With Carbs!

Post by AugustusFerdinand »

The 7A does have one, but I did not use it. I didn't pay it much mind, but I think a cursory look said it wasn't going to fit inside the 3A's pan.
1983 Toyota Tercel SR5 - 7AGE swap in progress
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Re: 4A-FE/GE Franken Motor, With Carbs!

Post by Kozuto_98 »

Got the 4A-FE pistons off the rods. Thought I'd do another small info dump incase anyone is curious/going to to do something similar.
The wrist pins were on the whole assembly really tight and I eventually caved and took them to a shop to be removed.

As I've said before, 2nd gen 4A-FE rods are nearly identical to smallport and silvertop rods, but do not share the same part number.
I suspect the integrated oil squirter in 4A-FE rods is the reason for the part number difference. These rods could be nice to use in blocks that don't have
oil squirters. I think only 20v blocks and gze blocks have them.
20210514_023045_HDR.jpg

One thing I should point out for using 4A-FE rods with 4A-GE pistons is the difference in the wrist pin fitment.
these rods use a press fit pin which requires lots of heat and a press to be put in, and do not require a small end bearing. 4A-GE pins on the other hand
use floating style pins, which requires a bearing and circlips.
20210514_022948_HDR.jpg

Right now I cannot verify if the pin bearings will press directly into these rods right now, but I'm going to assume no.
Thankfully these bearings are still being sold, which includes Toyota's genuine parts site.
https://parts.toyota.com/showAssembly.a ... lYear=1988
The part number is 13201A in the diagram.

Once I have these bearings in hand I'll follow up to this a bit.
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1987 Tercel Wagon SR5 4WD
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Re: 4A-FE/GE Franken Motor, With Carbs!

Post by AugustusFerdinand »

The wrist pin is the same situation with the 7AGE build. Bearings are only necessary if the rods are set up for floating pins, since the 4AFE (and 7AFE) rods use press fit pins you just press the pins into the rods like normal, no bearing necessary.

Getting the pins in place does not require a press and can be done by hand, just requires a quick set of movements, a torch, and some dry ice.
  1. Place ring clips in one side of piston (same side on all pistons as the rods and pistons are directional)
  2. Place piston in soft jawed vice, just enough pressure to hold it in place.
  3. Put pins on dry ice, they will scream, leave on ice until they stop screaming as this indicates they've hit the same temp as the ice.
  4. Heat rod end to ~400F (light straw color)
  5. When heated, quickly put rod into piston with rod against the clip side, push pin all the way into rod until it hits pin, pull rod back to center.
  6. While still warm I like to squirt assembly lube into the pin oil holes on the bottom side of the pistons, it'll get sucked into the pin surface via capillary action.
The bearings won't fit the 4AFE rods, in order for them to do so you'll have to have the rods machined to fit the bearings therefore converting the rods themselves to floating pin (unnecessary).
1983 Toyota Tercel SR5 - 7AGE swap in progress
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Re: 4A-FE/GE Franken Motor, With Carbs!

Post by Kozuto_98 »

Awesome! Thanks for clearing that up.

Question out of curiosity, do 7A-FE rods have the same integrated oil squirter?
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Re: 4A-FE/GE Franken Motor, With Carbs!

Post by AugustusFerdinand »

Nope. And I'm kinda jealous they don't.
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Re: 4A-FE/GE Franken Motor, With Carbs!

Post by Petros »

curious they put the extra oil squirters on those rods, and not on the other similar engines. normal wrist pin and piston skirt lubrication comes from the oil spraying off off the main journals as the crank spins.

years ago when I worked at Nissan, all of the production car rods had this feature, but we would block them off when we built a racing engine. we took the factory rods and converted the small end to fully floating wrist pins, with a bushing, and delrin plastic end "buttons" to locate the fully floating wrist pins (the clips would rarely, but occasionally do fail, and cause serious damage when the wrist pin started gouging out the cylinder walls). we also installed stronger bolts, and balanced and shot peened the factory forged rods to make them suitable for a racing engine. I asked why we blocked off the oil squirter and my boss said the racing engine gets plenty of lucubration by the oil spray off the large engine at the high rpms it runs at all day. on turbo charged engines it provides a means of directly cooling the underside of the piston. but I do not think the 4afe ever had a turbo option available. so it is still a mystery that only toyota knows, it may not have even been necessary.

I was also curious about the "fully floating" wrist pins, why factory used pressed in, non floating wrist pins. Pressed in place has fewer parts and is more reliable than having small clips and a small end bushing. the busing to rod clearance was very critical, it works out well for a racing engine to have 0.0008" clearance in the small end bushing. when fully floating it was free to rotate, so it allowed us to use a lighter wrist pin, since the stress was allowed to be alternated to different parts of the wrist pin as it rotated. I was able to determine an average wrist pin rotation rate of about 50 rpm in the racing engine, based on failure rates in a racing engine vs. a static testing jig that I designed. we used that information to redesign the wrist pins out of stronger material. a vendor who provided the racing piston blanks also provided the "racing" wrist pins, which were rather poorly made (poor alloy and poor quality control made them unreliable in a racing engine). my testing revealed that the factory Nissan wrist pins were way stronger and better made. But the normal, simple, but heavy, press in place wrist pin is simple and reliable for a street car that you expect to run for 200k miles or more (unlike a racing engine).

though I have several times ran across engines that had the press in place wrist pins work loose, and do damage to the cylinder walls. I do not know what would cause that to occur, but when it does, it usually means the engine block becomes scrap metal, it gouges out a large groove too deep to repair. When I have seen this kind of damage, it made me want to convert to fully floating wrist pins, but there are no off the shelf 3ac/4ac pistons with floating wrist pins available, so you would be on your own to fabricate your own from scratch. Likely, even if they did, they would be very costly, no thanks.
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Re: 4A-FE/GE Franken Motor, With Carbs!

Post by Kozuto_98 »

Questions for those using a 4age head.

What alternator bracket and belt are you using?
I would like to try and retain the alternator I have and just move it. There's a few aftermarket options, but if I use a stock bracket for mounting on the intake side what belt part number would I need?
1987 Tercel Wagon SR5 4WD
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Re: 4A-FE/GE Franken Motor, With Carbs!

Post by AugustusFerdinand »

Kozuto_98 wrote: Tue May 18, 2021 4:41 am Questions for those using a 4age head.

What alternator bracket and belt are you using?
I would like to try and retain the alternator I have and just move it. There's a few aftermarket options, but if I use a stock bracket for mounting on the intake side what belt part number would I need?
Haven't gotten that far yet, but had mentally planned to just make a bracket and use couplers/rod ends to adjust tension on whichever side works best for my 7AGE swap, but I'm also bumping up to a higher output alternator from a Suburban so that's also a variable in the alternator choices.
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Re: 4A-FE/GE Franken Motor, With Carbs!

Post by Kozuto_98 »

Cool cool. I might consider the chev alternator upgrade whenever I swap over to EFI with this build. My alternator is borderline anemic when I have lights, radio, and accessories going. I'll have to keep up on your build to help get some ideas for a bracket.

In other news, I'm going to a junk yard to get a 4A-GE head. I'm mainly after a smallport head, but I can live with a bigport. Depends on condition, and I know the guy running the show has more bigports than smallports.
1987 Tercel Wagon SR5 4WD
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Re: 4A-FE/GE Franken Motor, With Carbs!

Post by AugustusFerdinand »

Kozuto_98 wrote: Thu May 20, 2021 6:12 am Cool cool. I might consider the chev alternator upgrade whenever I swap over to EFI with this build. My alternator is borderline anemic when I have lights, radio, and accessories going. I'll have to keep up on your build to help get some ideas for a bracket.

In other news, I'm going to a junk yard to get a 4A-GE head. I'm mainly after a smallport head, but I can live with a bigport. Depends on condition, and I know the guy running the show has more bigports than smallports.
Where is this magical 4AGE junkyard?
1983 Toyota Tercel SR5 - 7AGE swap in progress
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