sheepers

i finally got around to buying and installing a new clutch for this car.

i chose today, the hottest day since records began coupled with absolutely zero wind to attack this job. which was sensible.

the clutch was full of oil which is why it was slipping. i think the rocker cover gasket has been leaking and its been running down the back of the head and into the convenient cutout in the top of the bellhousing that was obviously designed to make sure the bellhousing could get all the oil it needs.

so gearbox out, clutch and flywheel out, new rear main crank seal installed.

then i resurfaced the flywheel in the lathe and put it all back together.

just got the drive shaft to go back in and hook up the handbrake cable and its done.

then ill put a new rocker cover gasket in it to and hopefully that should stop the clutch from filling up with oil.

lifter discussion.

so Clint rightly pointed out (in the wrong discussion thread) that the increase in pressure or flow to the lifter gallery could result in lifter pump up.

i thought about this and did some more dummy assembly and reading.

the Toyota lifters dont work the same way as a conventional V8 style lifter. you dont pre-load the lifter in any way and according to the factory manual they should work at full extension at all times and if they compress any more than half a mm they should be replaced.

the lifters ive been using to test things have a spacer in them so they cant compress and are extend to max length, that way the clearances and interference i was measuring would be the absolute worst case scenario.

the thing thats interesting/a bit concerning is that the lifter is designed (as far as i can tell) to live its whole life at max, or close to max extension. in my mock up assemblies there is no clearance between the cam and the cam follower. so if things get hot an expand a bit in theory it will open the valve on the back of the cam. im a bit confused by this because everything in this collection of mating parts is stock. the base circle of the cam has not been altered, everything is as it should be.

i cant see how the non return valve inside the lifter can bleed a bit of pressure to allow the lifter to shorten when things heat up and expand?

maybe im over thinking it and it will all just be fine, as i say everything is stock so it must work somehow?

ill have to test it as i continue to build the motor.

one good thing about having the oil pump driven off a lay shaft is i can spin the pump while the rest of the motor is stationary. that will allow me to experiment with things and see if the lifter will compress with oil pressure behind it.

i was wondering if i could raise the oil pressure in the lifters just a bit to compensate for the heavier springs and increased ramp angle of the new cam.

the 5M head has a pressure relief valve which feeds the lifter bores. ive never really looked at it in any detail but its got a spring and a big nut to holding the spring in place, how hard can it be?

so i pulled it to bits and had a decent look at it.

what i saw was worrying and left me with a feeling of no confidence with this doohickey at all. but i had to remind myself that it does work and they have worked for many years and they're not raised as an issue that ive ever heard.

the problem is that the oil feed for the entire lifter circuit has to pass through a tiny hole, i couldn't measure it but it would be less than 1mm. so that's not very much oil flow. i couldnt open up the hole even if i wanted to so i just decided to settle for upping the pressure a bit.

i did some science and figured out roughly what pressure the relief valve opens and its approx 7.6 psi. i was thinking of raising the pressure by about 10 percent but that calculated out at a shim about 0.4mm thick.

but more importantly the errors in my measuring methods were more than 0.4mm. its pretty hard to accurately measure how much weight compresses a spring by exactly how much when you don't have anything but a vice and some weights.

so after some thinking about it and calculating what different shim sizes would do i decided to add a 1mm shim which should see the relief valve open about 10 psi.

fuck it, ill try it and see what happens.

all finished.

was a pretty messy job and took two days but its done now.

i removed 400g of material from the ports.

it will be interesting to see if it flows any better. ill get it back on the flow bench as soon as i can and see how it compares.

fun fact, i ported one of these heads about 25 years ago and i cant remember how crazy i went with it (im guessing not very) but it made no difference to the motor at all.

tbh that motor was a stock turd with stock intake and exhaust so porting it was a fucking waste of time but that was the style at the time. i think i planed the head to try to raise compression but that's a waste of time too given the stock piston design.

ANYWHO, thats done. i took the exhaust from about 31mm to 37mm and removed a fair amount of material from the bowel, the intake went from around 31 to 38mm with the same stock removal from the bowel area.

ive sorted most of the clearance issues with the dash 10 crossover pipe but until i get a 4M sump i cant finalise everything there.

so now its time to get on with the head.

i needed to mock it all up again and remeasure everything because its been so long since i did it the first time id forgotten everything.

so i put it all back together and checked valve piston clearance again (have never checked it with the actual oversized valves so it was worth doing)  just to be 1million percent sure it was all going to play nicely together.

no dramas with all that so that's good.

what is a problem is the clearance between the spring retainer and the valve stem seal. currently there is negative 2mm which is about not enough.

i need to machine the valve guide pedestals down so there is a gap between the back of the valve retainer and the stem seal. i reckon 3mm should do it.

ill have to shorten the valve guides as well but that super easy.

now i had reestablished all my measurements (and written it down this time....) all that's left to do is to do a rough and dirty port job on it.

no sciences were harmed in the making of this porting job, i used the "hog it out a bit and hope for the best" method which has been used since the dawn of time.

to some degree of success.....

i actually have flow bench numbers for this head in totally stock form so once Ive finished butchering it ill re-do it and see if its made any difference.

New toyota can belt, tensioner and tensioner bolts and it's back together and running. 

Still have no idea why it skipped the cam belt but it did. 

And just like that,  dash 10.

There are some (many) clearance issues but I'm pretty sure I can overcome them. 

Mostly. 

Pickup will need to be moved/modified to suit 4M sump but I don't have a spare 4M sump so I'll have to fit that when I actually pull the other engine out.