Return #5: Spare engine boogaloo

[nyberrg]

As expected my engine build did not last long. It's time to salvage what's possible. More details coming tomorrow but for now I have one question.

Is it possible to use a big port (ae86) head on a 7-rib (smallport, ae92) block? The block has what looks like an external oil return. The internal returns seem to match up too though.

[oldeskewltoy]

As expected my engine build did not last long. It's time to salvage what's possible. More details coming tomorrow but for now I have one question.

Is it possible to use a big port (ae86) head on a 7-rib (smallport, ae92) block? The block has what looks like an external oil return. The internal returns seem to match up too though.

yes you can use a largeport head on a smallport block.

As far as the drain - you could add one to the largeport head(not easy) and then connect them, OR you can cap off the smallport block pipe by using NAPA part# 660-1695 ( a 3/4" coolant cap) and a hose clamp.

[nyberrg]

I'll update this thread and leave the old one. I dissasembled the 7-rib block and found bearings that were not in the best shape. The crank bearings were worn but not discolored in any way. Conrod bearings were worn and brown-ish in some places.

I meassured the crank and the rod journals seem to be out of spec (I found the numbers to be 41.985-42.000 somewhere on the site?) by about 0.05 mm if I read the micrometer correctly. I'll check on this again tonight and meassure my other 42-crank that I ran in the bigport block before the earlier build.

If one is bad I think the other one should be good. It worked earlier at least...

I'll block off the external oil return and just run the bigport returns.

As for oil: My engine was probably on the cusp of proper failure, although I haven't really found any metalshavings or missing pieces from the old bearings and such. Should be safe to use the same oilpump right?

Found some plastigauge to meassure bearing tolerance for when the assembly happens. Aiming to get this together by the 27th as I was planning a trip. But yeah, guess we'll see.

[nyberrg]

In my hunt for bearings I got some from the local Toyota dealer. When they showed up it turned out it was only ONE of each. One crank bearing, one rod bearing. Doing the math of how much a full set would cost me I noped out.

With Flo's being closed for vacation I don't know where to find bearings in the EU, and shipping times are horrendous right now. I managed to find a guy who had a set laying around but I can't make out if they are the right size... Anyone?

https://i.imgur.com/9ZoJfJU.jpg
https://i.imgur.com/DZCJJLF.jpg

[oldeskewltoy]

just a thought.......

you might want to have a professional machine shop check, and set your bearing clearances. They have the equipment needed to set them.

As you mentioned you believe you were out of spec..........

[nyberrg]

Out on deep waters with measurements and honing equipment.



Things look to be in order with the 7-rib block. One crank is good to go. Checked the pistons quickly and they seem to be ok. I will do the proper calculations on tolerances to the cylinders next.

[nyberrg]

As you mentioned you believe you were out of spec..........

Still had one crank that was good to go. There was a distinct difference between the good and the bad.

Checked the main and rod bearing clearances as the Toyota repair manual said and it was good.



Deadline is in eight days

[nyberrg]

I had a bunch of issues with things outside of the engine. But I made my deadline and went on my trip. The new engine performs good so far. Sounds nice and runs great... until it didn't.

One of the rubber flanges I mount my carbs in decided to break the night before causing the engine to run on three cylinder. A temporary fix was implemented using a coolant hose. When I was almost back from the trip the car started running on three cylinders again so I figured it was the fix that had done all it could. Turns out it's another broken flange. The rubber in them seems to be quite ****.

Now I need to find some better quality snowmobile carb flanges

[nyberrg]

It's been a while. Believe it or not, this engine is still going strong.

It was time to get rid of the ol' recirculating ball steering for a proper rack and pinion. I got a hold of a crossmember with rack and steering column from a TA60 Carina. Matched that with the stock control arms, AE86 PS-knuckles, and custom ordered BC coils (AE86-spec with S13 camber plates). Upgraded to RX7 calipers with Mini Cooper discs while I was at it.

Still to be seen how the brakes perform with stock master cylinder and stock rear drum brakes. I can't testdrive it yet cause I lack one vital part, headers. The steering components have shifted place and my old one doesn't fit any more – which brings me to my question.



I'm looking for some info on what would be good specs to aim for. I know a 4-2-1 design is probably better for a street car that doesn't even rev to 8. But I need it to be 4-1 for easier clearance.

- What diameter is good for the primary tubes?
- My exhaust is 2,5" all the way back. Should the collector just be the same size or is there any benefit for it to be smaller or bigger?
- What is a good target length for the primary tubes?
- In what pattern should the primary tubes meet at the collector?




I'm thinking I want something like this header built for a 20V AE86, but closer to equal length.

[jondee86]

You can talk to Martelius and see if they can do something suitable. According
to MRP (who sell these in NZ)... "For ease of shipping and installation, this header
comes in 3 pieces and is just slipped together, then bolted in place". That might
help if the header has to straddle the steering column.



Currently the Martelius Group A header is supplied in stainless construction...

4-2-1 type exhaust manifold for race and street use. Fits both 16- and 20 valve
cylinder heads. Pipe diameters 38-44,5-50,8mm. Material Aisi409 stainless.
Designed for engines with power up to 180hp. Includes extension pipe with
flange to fit oem uncatted exhaust system. Includes flange fitting for oem
Toyota lamda sensor and thread fitting for M18 x1,5mm lamda sensor.

Cheers... jondee86

[nyberrg]

I surely can't afford custom fabrication from a company. My friend will help me build a set of headers. The rusted one I have uses a pipe diameter of 38 mm, if that's good enough for Martelius, I'm sure that's the right diameter for me too. The header will use 38 mm primaries into a 2,5" collector.

If anyone has info on how long the primaries should be to make more usable torque I would appreciate that info too. In the end it will probably be what it'll be because of limited space and a limit on how extravagant the design can be. However, it doesn't hurt to have a target length to aim for.

Thanks for the info Jondee86!

[davew7]

Here is the exhaust spec's that maybe helpful.

Pipemax : This output is for a stock BT in low overlap VVT position.

Pipemax is about as close as you are going to get to that type of fancy maths estimating real world results.
Cylinder Ignition Interval = 180 degrees 8000 RPM Hertz frequency = 66.7 Hz
Target EGT= 1338.7 degrees F at end of 4 second 600 RPM/Sec Dyno accel. test
96.838 CID Exhaust System operating RPM Range from 6000 to 8500 RPM
--- Single Primary Pipe Specs --- ( Low to Mid-Range RPM Torque and HP )
Diameter= 1.326 to 1.451 Total Length= 19.8 to 21.7 inches long
--- Single Primary Pipe Specs --- ( Mid-Range TQ to Higher RPM Horsepower )
Diameter= 1.388 to 1.513 Total Length= 19.8 to 21.7 inches long
--- Conventional Straight Tube Collector Specs ---
( TQ ) Diameter= 2.343 to 2.593 Best Length= 12.8 and also 25.6 inches
( HP ) Diameter= 2.593 to 3.093 Best Length= 12.8 and also 6.4 inches
H-Pipe= 12.8 X-Pipe= 51.3 distance behind end of Primary Tube ends
-- Total Exhaust System Tuned Lengths (Primary ends to TailPipe end) --
Best HP/TQ Tuned Collector Lengths= 12.8 , 25.6 , 51.3 , 102.6 inches long
Worst HP/TQ Loss Collector Lengths= 19.2 , 38.5 , 76.9 , 153.8 inches long
Note=> measured from where the Primary Pipes end inside the Collector to
the point the Collector or tailpipe exits into the atmosphere.
Note-> all Pipe Diameters are OD and based-off .0625 inch Pipe thickness
---- Primary Pipe's Harmonics ----
1st Harmonic = 90.7 inches long ... typically never used
2nd Harmonic = 33.8 inches long ... longest recommended
3rd Harmonic = 19.8 inches long ... highly recommended , best Torque Curve
4th Harmonic = 13.5 inches long ... shortest recommended
5th Harmonic = 9.9 inches long ... typically never used
6th Harmonic = 7.6 inches long ... typically never used
7th Harmonic = 6.0 inches long ... typically never used
8th Harmonic = 4.8 inches long ... typically never used
---- Collector's Harmonics (includes Intermediate, Muffler , TailPipe) ----
1st Harmonic = 102.6 inches long ... longest with Mufflers and TailPipes
2nd Harmonic = 51.3 inches long ... longest recommended with Mufflers
3rd Harmonic = 25.6 inches long ... more bottom-end Torque
4th Harmonic = 12.8 inches long ... highly recommended , best Torque Curve
5th Harmonic = 6.4 inches long ... reduced Torque , more top-end HP sometimes
6th Harmonic = 3.2 inches long ... reduced Torque , not recommended