Boxer engine/gearbox build

I will be interested to see how the 365 cams work. I am not really in agreement that it will be successful based on my prior experiences in recamming CIS cars. BBi's were not made to comply with SMOG regs. They were designed and built for the home market. CIS cars world wide and industry wide had very mild cams with RV like overlap even in markets where SMOG was not an issue. Years ago I spent quite a bit of time with Ron Iskiandarian trying cams in a Mercedes 6.9. What a complete waste of time that was.

BB's of both types do respond well to compression and exhaust improvements though. Should be able to find some HP there.


While you are in the distributor throw the plastic advance mech bushings in the garbage where they belong and install some steel pieces.

 

This might be a question for Brian. Something I've noticed after many-many hours bent over the running Boxer motor is that the CIS goes crazy if the idle speed / flow gets too low. Is it possible that a higher idle with more aggressive cams might make it happy? Maybe it might be a lot higher like ~500+ revs? On the 6.9 Mercedes, was the auto tranny interferring with the idle speed parameter?

I use to race at the Virginia City Hillclimb put more aggressive cams in his 2Vi, and made it work. He took my first place victory from the previous year, so I'd say it works very well. I don't know what cam recipe he used. IIRC it was an Elgin formulation.

For the wrinkle finish on the intake parts, I used silver wrinkle powder coating.

Also - What plastic bits in the distributor?? Advance mechanism bushing that are plastic??
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Ahhah, this is coming at the perfect time for me!
Time to do the belts etc, plus the new carrier installation on my car.
I was also thinking about checking the bearings, syncro rings, in the transmission for any wear. I don't know if that can be done without taking the bearings out though?
And hey, cute kid you guys have!
John

 

Newman,

If you want to know what's gone into the race motors, shoot me an email.

CW

 

Air flow is exactly the issue and I could be wrong but I doubt that with the difference there is in timing numbers that simply raising the idle will be a cure. But the good part is Newman is going to find that out for us and we don't even have to get our hands dirty.

In the 6.9 the auto was an issue but we were not talking about a couple of hundred RPM to make the difference.

In an OE BB distributor the bushings on the advance weight pins that slid in the slots on the cam were plastic. They were trash. They swell and stick on the pins and inhibit proper advance function. All the prior distributors had steel bushings and are far superior.

 

It's about frikkin' time!!! I've been hoping you would get around to testing the cams in the BBi before mine was in for the rebuild!!!
As Paul knows from our discussions, my rebuild was bumped up a few months by a mischievous cam drive bearing......and is getting torn down over the next few days.
As we spec'ed the details Friday, we've got a slightly adventurous set-up for the build - maybe halfway/two-thirds-in to what we discussed, beyond the forged/new pieces themselves. I'd love to see your results from the 365 cams before mine starts to go back together, but until then, I'm going to stick with the stockers for piece of mind.

And I got to fond-, er, see my carrier for the first time. Purty. I almost don't want to hide it away in the car.

Have you got any info on whether lightened flywheels were used to allow them to idle at less than 1500rpm? We're still trying to figure out how much mass can be removed there.

 

Definitely lightened. I'll have to check by how much, though.

CW

 

Even though early on, this thread promises to be one of the best Boxer threads ever. Can't wait to see this braintrust go to work over the next few months!
W

 

So are you only replacing the exhaust valves if the intakes check out ok? What is the Ferrari protocol when all the guides are replaced? All valves as well regardless?

 

The last full rebuild I did has been some time ago, but it was on a Maserati Merak SS engine with quite a few miles. Surprisingly, the guides were just a little worn and the intakes and ex valves were all within spec. The ex valves were replaced as a matter of precaution due to them being sodium filled. I had Ferrea make me up a set.

 

Paul - I posit a different failure mechanism. That you valves have sustained 38,000 kilometers suggests that you have a good set. They have withstood the test of time. If the stem diameters are within specification, then I would be tempted to re-use them. The risk of installing new valves is that a manufacturing defect will be discovered at your cost. As it is, the manufacturing quality of the valves in your car were established under someone else's dime.

Failure of sodium filled valves, from reports on F-Chat, seem to be at the junction of the stem and valve body. Perhaps a bad weld. Not unlike the differential carriers, most are good, a few are bad. The bad ones make themselves known. The good ones no one hears about.

Jim S.

 

The posts/reports on failed custom made aftermarket ex valves are even more rare than that of failed sodium ex valves. Plenty of cars have suffered broken sodium ex valves at mileage higher than that of Paul's car. Better safe than sorry here is my route.

 

As for the valve replacement, I wonder what, if any, consideration needs to be given to the difference in weight between the original hollow sodium filled vs the solid steel or SS new ones. The new ones will no doubt weigh more, and I wonder if the valve spring force will be enough to keep them from floating at higher revs?
I know others have made this change and haven't mentioned the possible problem,,, well at least not here.
I guess you could buck up to titanium valves for a lighter weight.
John

 

Good day Jim,

From what I have seen posted and have heard is that the failure is typically after some level of valve seat work. If this is the case, then perhaps there is a heat dissipation issue (reduced because of less valve contact area with the seat) and thereby provoking the valve to break. I have had a sodium filled valve failure a long time ago on my first Ferrari (GT4). The engine had around 50K Kms and so the failure was not do to infant mortality. However, the day it happened, the engine temp and outdoor temp were both very cold (engine temp just started warming up, outdoor temp -15C)... so in this case, there may be some evidence regarding a temperature differential provoking a failure. Regardless, I have never seen an absolute reason why these valves have failed... lots of opinions/hypotheses, but no real concrete evidence to prove what actually causes the failure.

Cheers,

Sam

 

Paul - at $10 per valve they would make great paper weights. On second thought, maybe FNA buys used valves at $10 each and resells them at $400?

Emotionally I agree with you 100%. The engine is out, why not renew the valves. Professionally and statistically, however, there is something to be said about 24 proven valves versus 24 unproven new valves. Absent a defect, the failure mode of a valve is the stem wear and clearance in the guide. Solid valves don't snap. If the theory is that sodium-filled valves snap owing to a defective weld, then they should be tested prior to use. Your valves have enjoyed this test.

What was Carobu's experience?

Jim S.