4AF head prep and porting

[PrettyCoolWagon]

I ask for your assistance.... since I currently do NOT have any spare "F" heads, I need to "practice" somewhere.

And since toymods.org is the brightest Toyota Think Tank I know of....

here is my 1st idea for porting the crappy port.




at least with the above, there is very minimal chance of breaking through to either oil, or water galley. I chose NOT to remove more material from the thinnest part of the wall, but to remove the large arc, for far more port wall, and a much smaller arc - 2 arcs actually, the port floor and roof......

Like it? Hate it? Why?

edit... this head will get flow bench time to attempt to equalize exhaust flow

I like it - even if it is a head that disgusts all 4A series modders, at least you're porting skills & ways of getting around problems is improving.

I think you've done a really good job of reducing the top & floor webs, you could also use a tiny bit of JB weld resin as a lead up before the remaining bump that can still be seen in the picture ...& after it as well.

You'd have to do this one side of the remaining bump at a time by tipping & securing the whole head in such a way that gravity is making the resin settle & cure into the depressions made by the remaining bump.

I know the first thing people will think of is restriction but that's why I said "a tiny bit of resin"

We're not restricting it any more than the restriction that's already there.. we're just just filling in 2 small areas of 'dead air...

If the the lead into & away from a restriction is nice & gradual it can actually increase velocity (speed)

If you try this & you're still concerned about restriction, you might consider also shaving a small amount off the opposite side to match the newly created shape, but I wouldn't do it with out accurate tools for measuring your wall thickness first..

Think I'm crazy??

Check this out...

http://www.mototuneusa.com/homework.htm

Sure... it's for motor bikes & he's talking about intake not exhaust which I admit is a little different, but most of the principles of flow, volume & velocity still apply.
Worth considering at the very least...

[oldeskewltoy]

well, now that the flowbench is just about ready, I felt it was time to set the standard.... so to speak.

The above is my attempt to allow a bit more flow to compensate for an awkward corner. I've removed quite a bit of material, and smoother the port walls on the valve side(blind side/important side)so that the amount of the intrusion of the oil return is minimized. I've also tailored the splitter some as well

[oldeskewltoy]

It has been too long since my last update. I'm currently working on actuating the valves while on the flowbench. I had a friend make me an actuator for the G head, but alas, the G head and F head use different sized cam journals

tool for 16V G head



the problem is that tool will not fit in the "F" cam journal since the F journal is smaller.........


Here is my first idea.... the toggle clamp is fastened to the neighboring journal - this should allow enough clearence for operation



This one doesn't quite have enough reach to it, but I believe I can find* a toggle clamp to accomplish the job......

* - by "find", i mean I'll look, but since this is a cheap crappy Harbor freight tool, I may just modify this one to work as I need it - by taking 2 of these clamps, and extending the arm part of the clamp by about 1 inch, and then moving the entire clamp to be better situated over the neighboring journal

[PrettyCoolWagon]

Sounds like you know what you need to do Old Skewl..

Keep goin..

Be interested to see how the AE95 sedan goes once it's hooked up with all the new mod's

Spewing I missed out on one of those at a local wreckers ..there's not many around at all.

Keep up the good work

[oldeskewltoy]

well, I finally was able to get my friends lathe up and running.... so I was finally able to back cut the 4AF valves.....







One things for sure... 4AF valves are utter crap... look (below) at how irregular the exhaust valves can be.... The valve on the right fits the seat and now has a back cut, but you can see the valve on the right is NOT uniform in shape by evidence of the irregular shaped back cut





Now that the valves are ready.... #1 cylinder(exhaust side) is set for testing

[PrettyCoolWagon]

irregular back cut on that right valve.

Was it in a 4 jaw or 3 jaw chuck? (4 jaw gives more control over centering)

Nice set of grinding wheels you've got hanging up in the background there OldSkewl

..when faced with an irregular or out of round shape in a lathe, I remove material with a very fine file resting against the job as it spins.
That way the file just follows the contour of the job & removes material in an even fashion.

It takes a steady hand, a lot like die grinding & porting. I use a fine file, so if I slip it does minimal damage. More importantly a fine file removes material in a safe & gradual manner.
(haven't ported yet but I've done years of lathe, die grinding & hand engraving work)
attached a pic - a bit off topic - that piece on the left is an antique & the one on the left is my replica.
Fancy engraving aside, the guy I contracted to do the castings fkd them up ...I had to do heaps lathe work on them & they were so out of round in places I had to use the technique described above instead of using the standard cutting tool on the lathe bed.

Enjoying your porting threads OS - still want to learn more about squish areas etc.
I won't be using a flow bench, just gonna ask questions, learn & take a conservative approach, bolt her all up & see what results...

(sorry 4 writing a novel!)

[mattysshop]

kinda makes me want to give the old AE92 a head job.. the stem seals are a bit average, it's my daily driver so i would have to get another spare head to work on, and then just swap over one night..

out of curiosity, the later model AE101 and above - FE head, i read at the start they much better to begin with? are the stock cams bigger in the later heads or smaller?

good work OST!

[oldeskewltoy]

out of curiosity, the later model AE101 and above - FE head, i read at the start they much better to begin with? are the stock cams bigger in the later heads or smaller?

good work OST!

I've been told that the later engine has much more lift to the cams.... the head is better since Toyota moved the intake ports up about 15mm(+ or -) so that the port would have a gradual slant down to the valve.

here is that later type head... you can see the ports are a bit higher up on the side(behind the tape)...




here is a newer type "F" head... can you note the changes????



here is my "F" head

[mattysshop]

nice, yeh there are a handfull of changes i can note.

are the cams able to be swapped?? the later model cams in the earlier model head? (obviously adjusting clearances as needed)

curious as they both seemed to make similar power and torque, these changes must have aided in delivery/efficientcy?

[Sam_Q]

The three 7afe heads I have measured have had 8.6mm of lift, which is strangely high.

[mattysshop]

7AF cams bigger then newer generation 4AF cams?

i had thought the newer style F heads had the same cams?

OST are you including some larger stock cams in your head build?

[Sam_Q]

the new 4af and 7af cams are indeed different, my memory is vauge but I think I measured them at 7.8mm for the 4af

[oldeskewltoy]

There are a few obvious changes between the early and later types - cam cover mounts to cradle stud, instead of center stud... the location of the intake port @ the manifold flange has been rasied. The other BIG change... the ability to run big cams... or should I say bigger than the 6.7mm lift my 4AF is running. Look @ the bucket supports, note how tall they are on my head, compare then with the much lower casting of the newer F head.

The last generation F head can't really be compared to the 1st gen, or if you must, think of it in relation of a 20V compared to an early TVIS head... both bolt on to the block... but the similarity ends there.

The question has been asked if I plan on any cam mods for this "exercise".... the answer is seriously doubtful. The original hypothesis for THIS particular engine was to keep it running on the factory management, for this is for my daily, an AE95 sedan. The goal here was/is to improve things on a few fronts: 1) updated to 2nd gen manifold to improve low end torque - see 4AFE pdf about Toyota's 1990 model year changes to the 4AFE 2) bump compression a small amount from 9.5 to 10.0, and in doing so replace the known flimsy/ultra crappy bottom end, with substantially stouter parts - 4AGZE slugs on 4AGE rods on a full counterweighted 4AGE crank. again this is to also bump low end torque. With torque my goal, keeping cylinder pressures up requires "shorter" duration cams then most modified cams would offer, and besides the wimpy 188 duration cams still run to 6k rpm



This is also an exercise... to see if I actually know wtf I'm doing with porting cylinder heads. Part of my goal in keep things close to original is to see if my porting talents are just that...............

[oldeskewltoy]

making her all she can be back cut intake valves

[mattysshop]

how steep did you cut, looks almost 30 degrees?

nice macro