OST-053: Massaging a 20V Blacktop

[oldeskewltoy]

My client asked me to overhaul his Blacktop (for his AE86). It comes to me with a spun #2 rod bearing (atypical, in my exp usually it's #4). The rod is toast, and the crank would need to be turned. "Would", not "will". My client isn't a fan of a turned crank, so we have ordered a new one. And as far as rods go, I have a set of re-worked TRD (20mm pins now) rods, that I'm selling him.





here is the head during disassembly



some grunge, but I've seen worse




Here are the cleaned block, head, valves, and associated parts. Using the back of my car as a pick up......




more to come.....

[kaosboss]

What method did you use to get the head so clean?

[oldeskewltoy]

What method did you use to get the head so clean?

I work with a couple of machine shops, part of the fees in doing head work is a professional cleaning, and checking the casting for its pressure holding ability - make sure there are no porosity issues

Oooh, that's pretty neat.

What are the big advantages of going 20v over the stock 16v head? It seems like a lot of work to import for a mild gain.

There are 2 significant differences. The first is at lower level lifts, the intake side flows much better. At higher lifts, the flow tends to get closer, beginning to equalize. The second major difference is the exhaust size is significantly larger.

With that said... a ported 16V std valve head can be made to do everything, except equal the 20V @ low lifts.


having all the other projects now finished, or waiting on parts, I ficus on the Blacktop head - working the intake side first.


#1 in the right, #2 on the left.




more to come....

[oldeskewltoy]

further progress, this time on the exhaust side......




more to come.......

[Jester_Borris]

Excellent work as alway OST. I’m finally able to revisit my Blacktop project of 7 years ago. This is inspiring - makes me want to get on it.

[oldeskewltoy]

Excellent work as alway OST. I’m finally able to revisit my Blacktop project of 7 years ago. This is inspiring - makes me want to get on it.

any inspiration I can help with is all good!


sometimes... it helps to see from a different POV...... I've added a photo to the above multi-panel





for the sharp of eye who follow my work, the above castings are from OST-034, but they still hold true...... as before, and after exhaust porting on a Blacktop head.


More to come......

[cincybranr]

Subscribed! Awesome!!

[oldeskewltoy]

What is your honest feedback on the TRD conrods for the 20v?

I know i need to rebuild my 20V, not sure if bore walls are STD, if not, big pistons will follow and obviously new conrods (just because).

Not sure what to purchase...

I've had this set of rods for a while... in fact this set's been to Europe and back (sold, and then returned). BUT you don't need to spend BIG money for decent rods. While I have only this anecdotal experience with blacktop rods, this engine's bearings appear to just be old worn out parts - all the bearings were pretty bad. But for the most part OEM rods are plenty strong. As an example of stock rod durability, my smallport is running a 40mm rod journal crank and stock 3 rib 40mm rod journal rods - albeit with new bolts. I'm making 140 ish whp, and I twist it regularly up to 7500+ and it now has over 30k miles on it.

But if you just want better (stronger, and lighter) rods, I usually recommend Molnar Technologies. They run about $450 per set.




Port work continues.... 2 down.... 2 to go




more to come....

[oldeskewltoy]

more to come....

[oldeskewltoy]

3 down... 1 to go....


Time to set up the flowbench, and get some #s........





More to come......

[oldeskewltoy]

Well... it has been forever... (well it feels like it).... and it no longer feels like a massage....

A new crank, a new set of rods(Molnar 42/20).... new custom (dome) pistons (11.5:1).....and MRP oil pan.... and the 20V Poncams are currently not available


We needed a crank, the first one we bought used... found out all the journals were a few ten thousandths (.000_") too thin... it might have worked for a dry sump race build... but for this engine my client (with my advice) bought a new crank.

The TRD rods (Jorge, your machinist has a good eye...) There was a dodgy bushing in one of the rods... to fix it properly would have required making the small end too thin... so the TRD rods got canned, and a set of Molnars were ordered.

JE Piston has a 11.5:1 piston.....



but... that ratio is with an .040" squish, our target is .032-.035, so I asked them to reduce the domes from 6.5cc, down to 4.2cc.





As far as oil supply, we decided a set of Toda pump gears, and an MRP pan





The Poncams....?????????? They've been delayed twice now... Tomei, and Kelford seem to be out of blanks.... and while Cat cams appear to have blanks, I'm not a fan of the Cat cams 20V cam timing.....


The head is ready for re-assembly.........




more to come....

[oldeskewltoy]

nearly a month later....

We sent out his crank, and the Toda oil pump gears to get WPC'ed - http://www.wpctreatment.com/





Now that they are back, bearing clearances are set to .0015" for the main bearings, and .0018" for the rod bearings - in the range specified by the FSM.

Additionally we now have a deck (.004" piston above), so the somewhat common .8mm head gasket is getting too thin with our deck - .028", so we have decided to get the Cometic .040"(1mm) gasket. This will allow a slightly more generous .036" squish (versus a .032" squish).


As to our new internals - mass savings of 20 grams... Blacktop stuff is pretty well optimized.




Now that all the machine work specifics have been finalized, this block is getting the Eastwood black coating I first used in OST-050.... so more time between postings....


more to come...

[oldeskewltoy]

so...... while waiting for the block coating.....


and since the oil pump was going to be opened up for the Toda pump gears.... a little work to "improve" on the OEM unit....





more to come.....

[oldeskewltoy]

and the 20V Poncams are currently not available



The Poncams....?????????? They've been delayed twice now... Tomei, and Kelford seem to be out of blanks.... and while Cat cams appear to have blanks, I'm not a fan of the Cat cams 20V cam timing.....

Thank you Barry!

Kelford finally got 20V cam blanks, and so my client ordered a set of MRP/Kelford custom cams for 20V.






Here is the cam card for the Tomei 20V Poncams...




Note the differences...??


meanwhile.......

The block has another week before it can go back to the shop for assembly




more to come.......

[oldeskewltoy]

Note the differences...??


meanwhile.......

The block has another week before it can go back to the shop for assembly




more to come.......

No one saw the differences??? Even something as vague as yeah.. a few more degrees, and a bit more lift..??? Oh well...


short block is now assembled...








and the head is now ready for assembly...





more to come....

[oldeskewltoy]

assembling the head.... special tools....






intake side first... 11 of 12 installed in this view....




more to come....

[oldeskewltoy]

assembling the head.... special tools....

speaking about special tools... my mini micrometer gets to be retired as this dial drop gauge make the job far easier, and much quicker!




more to come....

[oldeskewltoy]

Well... FSM is wrong....

The actual shim availability is no where near as extensive as the FSM would have you believe......




more to come....

[oldeskewltoy]

Well... as I expand to include more 20V head work, I'll need to expand my shim bank.



Here are about 3 heads worth of shims





Up until recently I kept all the 20V shims in a tiny ziplock bag... but with more use, it just doesn't pay to measure all the shims each time, so I bought another shim storage compartment




So with 3 heads worth of shims, the first thing I noticed is the tolerances for the shims isn't very tight. I have 18 shims that fit into the .0748 drawer, but the shims in there vary widely from .0740" - .0750". I have a feeling that as I collect shims, I'll need a bigger shim box - likely including shim drawers to the .0005".

So of the 3 heads worth of shims, I didn't get any of the first 4 sizes, or any of the last 5 - so I've placed an order to fill out my bank a bit more.....



More to come.....

[Rogue-AE95]

For all the 16v heads you've done, I can imagine that the 16v bank is more than double the size of the 20v bank there

[oldeskewltoy]

For all the 16v heads you've done, I can imagine that the 16v bank is more than double the size of the 20v bank there

actually I have more than double of my total of 20V shims in 3.00mm 16V shims alone

Dan, do you have the dimensions (preferably in mm) of the (lash cap) shims ?
If I'm not mistaken I think they are 7mm OD, 5mm ID, but I'm interested in the depth of the "skirt"

8.02-8.04mm OD, 5.02-5.04mm ID, shim skirt depth was between .245mm and .265mm (just about .010") on 5 samples


more to come.....

[oldeskewltoy]

20V shim tolerances are pretty bad. I've now had new, as well as old shims, and in some cases the shims vary by as much as .001" (up to as much as +, or - .0005" either way). I have purchased shims now from a supplier here in the USA, as well as directly from Japan.




with that kind of error, and a still small, growing - but still small shim bank, to set tolerances to within .001" was going to be a challenge... but I did manage to set all the intake with nothing tighter than .010", and nothing as loose as .011", and setting the exhaust side with nothing tighter than .017", and nothing as loose as .018"......

I'll wait.....


I did need a bit of "help" to do it......

[oldeskewltoy]

I'll wait.....

.0105" / .0175" within .005" so .26mm / .44mm

I never realized how BIG the valve clearance where on the 20v !

If I may ask, why did you choose the Toyota specs (.015" to .020") over the Kelford specs (.30mm so .012") on the exhaust side ?
Or maybe it's a typo on the Kelford spec card ?

You found what I was alluding too.......thank you. Toyota has a minimum spec, it is based on a great deal of engineering, and KNOWING the materials that they build the engines with. There is a LOT of heat, and therefore expansion on the 20V exhaust valve. Besides Toyota's spec, I've been told by a Uk 4AG engine builder that as well. The Uk engine builder advised me in the past to avoid over ambitious (tight) valve clearances on the 20V valves, especially on the exhaust side.


Here is a small example of the heat involved. These came out of the same 20V engine.....