FrankenFerrari - V12 Ferrari 308

In reply to mke : They're under the bucket on TCST too 

On second thought there is a fine line between tweaked and dangerously bent so I think I'm not going to take any chances and just go to go ahead and replace these valves....

It is not my night....my valves are discontinued.  I found something I think is very similar from a better company (ferrea instead of kibble white) but in 29mm instead of the 28.5  and $47 each+$20 shipping  .  More money and I have so I will need to cut them down but I think they'll work

The valve people sent an invoice and it says I'm getting a FREE sticker.....life it good!

Unrelated and I think I talked about this before I'm seriously thinking of swapping the 3/4 masters for 5/8 masters to lighten up the brake pedal a little.  I remember I was worried about volume but the pedal doesn't move more than about an inch including all the lash so tons of travel left.  The only issue is I just bought gaskets and valves so I may need to hold a couple weeks.....

Is it possible that the reason that some cylinders didn't seal is that they sank below deck surface ?

dave215 said:

Is it possible that the reason that some cylinders didn't seal is that they sank below deck surface ?

Yes, absolutely.  this block was designed for the liners to pass through the deck and sit on a flange at the bottom of the water jacket.  But that tends to make the liners go out or round.  Remember the basic engine design was done in the early 60s long before FEA and light weight and track side rebuild were high on the design requirements list, and the 400i/412i were the end of that design era.   I thought it was a good idea to convert to the modern 80s to current design of the liners sitting on a flange on the deck, a deck never designed to hold that load so yeah, they probably move a bit and some more than others. 

Also TR heads are notoriously unstiff.  I'm told the center of the head will move .003" or more at torque so the liners need to be quite proud, at the high end to over factory spec on a stock engine to get a reliable seal with stock gaskets.  I'm sure I didn't make that any better when I when I the things I did in the name of flow....I removed a lot of material.

Then I made the  bores as big as I dared which made the top of the lines quite narrow.

Given all that I'm kind of throwing my hands up and just admitting I don't have a normal engine head sealing situation and continuing to treat it like a normal engine will likely continue to result in failure.   What I'm thinking with the new bits I ordered is that normal engine clamping forces simple can not be achieved and what compressible gaskets are doing is making all the flexing worse.  The new plan with the aluminum shims is to better support the head so force up in the middle doesn't cause the outside to over compress the gasket and drop, sealant will hopefully seal the water.  Then the rubber oring should seal with the head to sleeve +/- .005" of target gap....at least in theory.  If this doesn't work I'm still pondering keeping alum shim and grooving the liners for .023 or .031 wire, solder the ends, and use a wider copper ring to replace the oring.....or weld the heads on :)

would it be feasible to make copper cylinder shims -

dave215 said:

would it be feasible to make copper cylinder shims -

Do you mean like copper head gaskets or shims to raise the liners or similar?

raise the liners 

My thought on shimming the liners up is that stickout could be verified by making a test head -maybe unnecessary but I would also run a bead of sealant under the flange with the test head there would be enough working time to set the sealant .

dave215 said:

My thought on shimming the liners up is that stickout could be verified by making a test head -maybe unnecessary but I would also run a bead of sealant under the flange with the test head there would be enough working time to set the sealant .

I think I understand where you're going. Let me show you this pic

I can make steel or copper shims to go under the liners but there is no way they would seal under the liners because there is no deck under a part of it so water will also leak up between the liners.  Maybe I could cut a groove in the side of the liner flanges for RTV to sit in and maybe that would seal between them?  

The alum shims and copper rings are already bough and due  to ship Jan 26 so the plan is get the valves fixed and heads ready to put on to be ready...then test it. I don't install cams or timing or any of that until after leak testing and I['m kind of starting to understand that no leak means NO leak not just a very small leak. If its sealed Yay!  If not maybe I pull out the liners and try RTV or shims plus RTV under them?

Since most of the cylinders were sealing before your new plan there is a good basis to to be optimistic about your improvements sealing the deal .

The reason I suggested copper shims was they would compress and be an effective water stop -I think .Hopefully you won;t need to do any of that !

i was thinking the shims would go under the liner  flange --could also shim both under liner flange and base 

The valves came today so cop saw, mill, lap, cut the keeper groove and cut the OD down

Then I was feeling a little wood chucky and ground the seats on the lathe

but they came out just fine

I messed around with the new valves longer than I planned today.  Yesterday I cut the OD and ground the seats to make them look about right but when I measured how they were sitting I had to cut off another .010 and .012.  The intakes are pretty critical to get the springs setup right since the cams are .452 lift and the spring are good for .460, but the exhaust lift is only .420 so +/- .010  on installed spring height is just fine. Then setup the shims so cam in and out of the head 3 times to get the clearances right, then start cleaning.  Tomorrow more cleaning so everything is ready to go when head gasket stuff arrives.  I need to place some other parts orders too, other engine gaskets I'll need, CV boots, and I'd like to switch to smaller master cylinders to reduce the pedal pressure, its ok but I think I'd like it better if it needed a little less force so 3/4" cylinders out, 5/8" cylinders in is the plan.

In reply to mke :

That's all an old school valve grinder is - a lathe and a stone at an angle, just dedicated to a single task.

If you have a lathe and a tool post grinder, you have a valve grinder.

5/8 seems a bit excessive unless you have a fairly low pedal ratio, but that's just me.  .700 bore masters are pretty common, I collect them for this reason.

In reply to Pete. (l33t FS) :

If my math is right a 5/8 will reduce the pedal pressure about 30% from where it was with a 3/4.  That seems about right, but honestly I would like a 50% reduction which means 1/2...but that is a go-kart mastercylinder

I have a feeling you are going the wrong direction with your brake master cylinder. If you want to make it easier you need to increase the bore size. Just going with practical experience while messing around with a hydraulic clutch. We did the same thing and went smaller and could barely push the pedal down.  So we went the other way and got a 1" bore and it was easy as the stock one. Took a bit of mind numbing calculations to finally figure it out.

brad131a4 (Forum Supporter) said:

I have a feeling you are going the wrong direction with your brake master cylinder. If you want to make it easier you need to increase the bore size.

Nope.

Pressure is force divided by area. Pounds per square inch (psi).

So to achieve a desired pressure, smaller area requires smaller force.

1 psi = 1 pound divided by 1 square inch

1 psi = 100 pounds divided by 100 square inches

brad131a4 (Forum Supporter) said:

We did the same thing and went smaller and could barely push the pedal down.  So we went the other way and got a 1" bore and it was easy as the stock one. Took a bit of mind numbing calculations to finally figure it out.

That sounds right if you were messing with the slave cylinder rather than the master-cylinder?  Small master + big slave = easy clutch

Remember that on the smaller bore you need enough stroke to displace the volume in the pistons. 

DrMikeCSI said:

Remember that on the smaller bore you need enough stroke to displace the volume in the pistons. 

Yes, 30% less force means 30% more travel whether its achieved with changing the mechanical ratio or changing the hydraulic ratio.  That is why I have the .75", I thought they were the safe choice.  I just measured and right now the pedal sits 10" off the floor.  It will go all the way to the floor while bleeding the brakes so that is the real available travel and I remember when I was setting it up I set the mechanical ratio full stroke in the pedal was not quite full stroke in the master so nothing would get ever damaged.  Pressing as hard as I can I get it to 8" off the floor pedal  so 2" of travel is being used.  A 3/4" is 0.442sqin and a 5/8 is 0.307sqin, or 69%.  Force will drop and travel increase 31% so after the swap then I guess it will be 2.6" travel with 7.4" remaining...that seems a more than plenty safe travel reserve.  I could probably get way with  1/2 bore masters which would need 3.3" travel but only seem to be a standard as a gokart item, and this car does feel a bit like driving a gokart so maybe that's the answer 

It warms my heart to see people doing brake math. :-)

Reached out to a buddy with a 348 who just did a tilton pedal box in and logs fluid pressure.  He says the rear should be about 50% the front.  I have F430 calipers and rotors which are all 4 the same size as are the 348.   A 308 used smaller rears both rotor and piston size...so I probably have a pretty unbalance system and I just haven't driven/tested enough to know.    I kind of knew that but figured since the F430 is setup that way because it does help under very slick conditions....when I would realistically NEVER drive my car but in theory it could help.  I have both a balance bar and an adjustable proportioning valve so it would probably all work out fine once adjusted. 

What I did today was order a single 5/8 master I'll install on the front system thinking that will let me start with a much closer to balanced system.  It won't drop the pedal pressure as much as I was hoping but I guess once I had to start cranking in the proportioning valve that would have increased the required pedal pressure anyway so its probably a wash.

Once I got done thinking about brakes as a way to delay cleaning engine parts I got back to clearing engine parts and I think everything is clean and ready to assemble.  I also got the grime out of Ferrari and beveled the cam covers so there should be no more o-ring cutting happening.