Chuck's Baja Build

[chuckput]

A t4 takes 4 quarts/3.7 liters.
it can run 5 it its being thrashed. (oil ends up in the 3/4 head at cruise or higher rpm unless you do a couple easy tricks)

I meant to ask earlier Piledriver. . . What are the "couple easy tricks?"

[Piledriver]

Developed this playing with a >>450kmile 1700, with some ideas from folks on the board.
(particularly Ray Greenwood. FJCamper and HAM.)

started out with a ton of blowby, used as worst case scenario, daily drive ~80 mile/day, had heads rebuilt w/new ex valves.
74 914 porsche. by the time a truck rammed it into a guardrail over 350K later,the motor had ~zero blowby, the bores had developed a mirror-ish finish.
I ran various synthetic oils and Mobil1 oil filters from day 1.

Don't vent 3/4 valve cover, be certain valve cover etc leak free
feed a vent line from air cleaner to an adjustable vacuum break at vent port...(fresh air purge)
the vacuum break is basically an adjustable check valve, air only flows into the rocker box
requires running some case vacuum, a ton is not needed nor desired, just a few inches of water.

between ex valve guide blow by and the fresh air purge, it will easily overcome the windage from the crank filling the rocker box,
Also, if case is under slight vacuum its not likely to leak much oil if at all.

1/2 side can be vented, if desired, but not needed as the crank windage sort of keeps that side sucked dry.

Stuff a couple woven SS pot scrubbers in the oil chimney, and pull your block vacuum through those.
The block keeps them hot and vaseline-free, they make reasonably good oil traps.

I was running CIS injection in that version of the engine, so I just pulled the vacuum downstream of the fuel meter, not much, but always a slight vacuum, with a ton of available volume.

[chuckput]

Finally, I got a break in family commitments and honey-dos to be able to spend some time in the garage. Bled the brakes (passenger side rear produced the most bubbles). Took it out for it's longest trip in a long while. Took her out to Wheeler Rd. in the Superstitions, picked up the pole line and took that over to the Choo-choo Road. I then turned south to Plaster City. Then it was back home. In all about 60 miles of on and off road driving. Oil pressure stayed good and temps all stayed OK. I do see some front end work in the future - alignment and shock tuning. Other than that, the car is instilling driving confidence in me once again. Looking forward to more time in the desert.

[Ol'fogasaurus]

Yeah! I know how it feels to get things fixed and not having to worry about things... until the next time anyway. Always happy to hear good news from the STF group.

Lee

Happy to make it to XX-XX.

[chuckput]

Yeah! I know how it feels to get things fixed and not having to worry about things... until the next time anyway. Always happy to hear good news from the STF group.

Lee

Happy to make it to XX-XX.

Happy Barbara Walters to you too, Lee!!

[Ol'fogasaurus]

Yeah! I know how it feels to get things fixed and not having to worry about things... until the next time anyway. Always happy to hear good news from the STF group.

Lee

Happy to make it to XX-XX.

Happy Barbara Walters to you too, Lee!!

Did she pull that one also? My wife doesn't understand most of my "punnies" also. The funny thing is that even if you left the dash out of it then you have a whole bunch more of different potential interoperations besides being double-double crossed.

[Devastator]

My turning brakes are higher than my M/C. Where can I add residual check valves? Between the M/C and the turning brakes, or the turning brakes and the brake calipers?

[Leatherneck]

Good info, I talked to Joe and added them on mine, helped out a lot.

[Devastator]

Where, specifically, do you put them?

[chuckput]

Where, specifically, do you put them?

According to what I have been able to research, the general recommendation is to place them as close to the Master Cylinder as possible.

I am still undecided about installing them as the same research all said that as long as the master cylinder is higher than the brakes a residual valve is not needed. There are two things I have not been able to figure out. First, if I do install a residual valve on my hanging pedals will it hurt anything? If a residual valve is not needed because my MC is higher than the brakes, why does my pedal go soft if the car sits for a while.

[Ol'fogasaurus]

Where, specifically, do you put them?

According to what I have been able to research, the general recommendation is to place them as close to the Master Cylinder as possible.

I am still undecided about installing them as the same research all said that as long as the master cylinder is higher than the brakes a residual valve is not needed. There are two things I have not been able to figure out. First, if I do install a residual valve on my hanging pedals will it hurt anything? If a residual valve is not needed because my MC is higher than the brakes, why does my pedal go soft if the car sits for a while.

As near as I can tell, using them even with hanging pedals residual pressure valves are not out of the question. If you have 4 wheel brakes then the front are on a different circuit (even if the MC has a single outlet and a Tee is involved) that the rear brakes so there is one set of lines from the Tee for the front and one set for the rear.

For disc brakes the valve is a 2# valve and for drum brakes then it is a 10# valve with the # being the brake line pressure holding power to stop bleed back which (usually) gives faster brake application and no pedal pumping.

Putting them in the rear (no front brakes) using either drum or now disc brakes only I have no no complaints nor have I have heard of any.

Like I said, I don't have residual pressure valves and with my turning brakes and connections sitting on top of the tunnel I haven't had a problem as long as the connections to all the brake line components' are valid. With the height of swinging pedals and high mounting of the accessories with the slave cylinders don't have enough strength to push that much brake fluid forward. Again, the key in this case is the connections.

On a rail, with the MC and the turning brakes on the floor the problems are different and the residual brake valves should be strongly considered. Again, on a rail the use of front brakes does change things a bit and at both ends one should consider having them.

Lee

Update... remember gravity is a player in what is going on here so consider that in your decisions.

[Leatherneck]

Chuck I would install them and be done with it, as close to the MC as possible.

[Ol'fogasaurus]

The placement of the residual pressure valves has been bothering me for several reasons: after doing a couple of searches the answers/opinions don't always agree.

https://www.wilwood.com/PDF/DataSheets/new_rpv.pdf

Read not only the warning box but the design facts below it.

In the newer vehicles (I don't remember when this started but it has been a while) the MC, for each chamber has a RPV built in; if not built in opinions differ. Wilwood and others generally agree that the valves should be close to a low mounted MC (at or below the brakes because of gravity mostly) but with hanging pedal assemblies the opinion to use them seems to be somewhat optional.

Wilwood decries 2# or 4# for disc brakes and the conventional 10# for drums but then if you have a mix of braking styles (not unusual it seems in buggies such as Bajas').

The bottom box in the URL refers somewhat to the below:

If you look into brake design the front brakes are usually bigger (front engine weight for example) than the rears... does that affect a single valve... don-no. The same with the longer rear brake lines with more connections than the front brakes have... does that affect things... don-no.

Again, in my applications the low mounted MC has to be connected to a higher mounted turning brake system then to the rear only brakes which would be somewhat tantamount to the hanging pedals one would think.

Anyway, for what it is worth.

Lee

[Devastator]

Appreciate the link Lee. Does anyone see a problem with running the 10# valve, mounted between the MC and the turning brakes, even with disc brakes, (conversion)?

[Ol'fogasaurus]

I think either the 2# or 4# RPV would be more likely for the rear with discs. The way discs vs. drum brakes work (such as the brake springs) discs probably have less problem with fluid "walking back" up the brake lines.

If your running a mix of discs and drums then I would call someone like Wilwood just to be sure.

An opinion.

Lee