308 Engine Rebuild & CIS to TWM Throttle Bodies Conversion Thread!

You might want to just try your 1/2" gun again, they might pop off.

 

Already tried it, no such luck.

Will wait till I get the new adapters.

 

Rcvd new adapters. Good news is I didn't break a new adapter, but also didn't break a nut loose. Even worse, started off by putting the tool onto one of the loose RH nuts with the wrench setup to loosen a LH thread(DUH). Yup, you guessed it, then couldn't break it loose afterwards.

Sat back & said why the heck am I putting all this effort into breaking loose nuts that are going to be replaced anyway.
Decided it was time to throw in the towel & cut the $#@%s off.

I covered up/masked off each work area so I wouldn't have a tranny full of abrasive dust. Then put a hose clamp on the shaft in front of the nut so if I slipped I wouldn't nick the shaft(see pics).

Got out my trusty HF micro die grinder , a fiber cutting disc, & went to work(see pic). About an hour later I had 6 ring nut halves on the floor.

TIP: You can't get the cutting wheel into position to cut all the way thru a nut. Cut each side of a nut as deep as I could w/o nicking the transmission case, then lay a cold chisel in the cut & gave it a love tap. If the nut doesn't crack with a easy tap, you need to cut a tad deeper. You must cut both sides of the nut so there isn't resistance to the chisel expanding the cut.

Shameless pitch: I love these little variable speed HF micro die grinders(see pix). They're nice & compact so you can get them into tight places a std Dremel would never fit. My impression is that they're also more powerful than my Dremel (Birdman calls his a 'Dremel on steriods'). They come in a nice little box with an air fitting & oil mister. Also, you can't beat the price. I think I paid $19/set for mine on sale, but they're now on sale for only $9.99 on HF's web site!!!

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=47869

With the ring nuts off things ought to come apart very quickly.
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My knees feel queasy!

Chris, how you doing?

Verell, YOU DA MAN!

JIM

 

Jim, Chris is driving to Florida, Just spoke with him.

 

Chris,
Spent a couple of hours pulling a shopping list together for you. I want to double check it & will eMAIL it to you tomorrow or Thursday.

 

on the QV and I think the 2vi all 4 cams are the same and about .305 lift, so that's right as far as I know. The 328 got .348 lift, but the earlier cars were .305.

There is nothing odd about a 2Vi, I see no reason for bucket under until you get over .380 lift. Just tell them you will have bucket under and ask them to grind the cam. Ferrari used .348 stock on the TR and 328 with the smaller QV buckets and I think .360 on the 2V engines, so .360 is completely safe and .380 should be just fine

 

as we spoke this morning - ask for Laurie Dunlap; for frequent street use I'd recommend as much lift as they can (prob .380 or so) and close to stock durations if you are keeping the stock pistons, perhaps up to add 10 degrees.

Previous FChatter Kermit showed on the stock 2v the flow kept rising significantly until over .400; And, I would just do the intakes.

I would avoid shim under unless you are making a 'monster engine' with specialized long term support.

 

I run the Webcam modified cams with 247/239 deg with shims on top of the bucket. There was no hint by Webcam that it should be the other way round. No problems with a few 1000 km on it, even on longer fast runs. I did not yet open the cam cover to have a look at possible premature wear of cams or shims.
Be prepared to have top power at 7500+ rpm with these cams. Nevertheless, still a good street setup.

Regards
Harry

 

I had .406 lift with stock shim setup but had the shim and cam failure. Discussing this with the shim under guys in person with parts in my hand they made the comment that the "shim under style buckets" are not as robust as factory valve shims and when they have failures it's finger pointing between the cam and bucket manufacturer.

This made me want to stick with shim over even more for now since it is a proven part . .. jury's still out as far as I'm concerned regarding the longevity of the weld & regrinds . . .was warned about this but billets are such an expensive route . .. I hope they last this time around.

Sean

edit: new valve springs required for this much lift

 

I have recently learned a lot about cam wear - it's a function of not only lift, but ramp and duration as well. We were fortunate enough to send WEBCam a test qv head to develop the lobe we used, and the final shape is a little more lift than stock, but actually a bit smaller in both duration and lift than the cam we had put in before. This was all based on wear patterns seen during development - with only 15K miles there were 2 lobes with wear; you could see on the shims the lobe was contacting ALL THE WAY across the the shim - highly not good. So after trying some other lobes, Laurie came up with a cam that provided the most lift with near stock durations that contacted the shim surface in a safe manner that promoted reliability and long term use. See pic below with explanation.

It's interesting and an example of matched engineering that with the way the stock head is set up, the 3.2 cam provides as much flow as the stock head will flow and also is almost the largest cam one can use without excessive shim wear requiring the more maintenance-intensive shim-under followers.

Cam wear also has some history with the mid-engine Ferraris - 246 dinos have a history of similar cam wear as they tried to squeeze max hp out of 2.4 liters. If there was any marginal lubrication issues, it was not uncommon to wear out cam lobes. I think Sean is spot on in his assessment and judgement on cam vs follower wear - I'd stick to what is proven for a street car and keep reliability and ease of service.

Just as a generalization, I'll throw out that while the Rocco designed V-8s will tolerate larger lifts and duration for a while, the rough lift limit for long term lobe wear with stock buckets/springs is about .360, at least in a qv, and probably not that much farther if any in the 2v. Again, larger cams will fit and run well, but they will not have the life expectancy.

Of course, you can go shim under and run way wilder cams for a longer time.
Al above just my opinion based on what I have seen and read.

Attached is a photo from webcam of the full contact and wear pattern from my previous 368/235 cams. At that lift, if you'll imagine, the came lobe does not hit the follower squarely, but with only part of the lobe increasing wear forces, and then scrapes up across the rim until full contact is achieved. Ieally, the best pattern would be a full visible straight line the width of the cam on the follower:
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Hello from Finland (land of F1 champions!)

Newbee here. I have monitorod your discussion with great interest, since I will soon start rebuilding and restoring my 75 GT4. My previous rebuild was 2.0 Dino V6 engine. That engine had under bucket shims, and those later 2.4 engines had buckets with top shim for easy maintenance. Under bucket valve clearance shimming was quite a job each 6 tkm. Cams out and new shim in! The underbucket shim has its benefit on weight, since the system is much more lighter than thick (=heavy) shim bitween cam and bucket. Specially in case of grinded cams! Early V6 Dino engine rews hapily to 10 000rpm, without big doubs of valve to piston collision (lighter weight on valvemechanism). After I changed the light weight buckets to easy to maintain ones, the cams started to wear.. So my opinnion for buckets: Keep them as light as posible. Best wey for that is under bucket shim.

Juha

 

Got back to it yesterday, but just couldn't seem to get it to come apart.

Today, thanks to a couple of tips from luckydynes it all came apart in an hour or so. All 3 shafts & their gears are now out. I haven't disassembled the gear stacks yet, altho they're loose & can be pulled off by hand. I decided get everything out first. I was hoping that maybe the small needle bearings would be OK, but there's metal powder around them & you can see fine scouring marks if you look really close.

I'm planning pull the differential off tomorrow AM. Now that I know how everything fits together, I'd pull the differential & the sump cover first. Wasn't a big problem, but would have made a couple of things go easier.

I've got to get things written down this afternoon while they're fresh in my mind. There were lots of things that I'd get started taking off in one direction & then discovered they had to come off in the opposite direction. The service manuals weren't a lot of help, even reading the assembly procedure & trying to do it in reverse! Again, thanks for the tips Sean.

Still have to get the bearing races out of the trans. housing. They're pressed in. If the housing will fit into my powdercoating oven, I'm going to heat it up to 300F & I'll bet those races slip right out. Otherwise I'll try heating around the bearings 1 at a time with a heat gun, or maybe put the housing into a cardboard box with a couple of 250W work lights.

Now that I know how the whole thing fits together, I believe I could strip one down in 1/2 day provided the ring nuts broke loose w/o too much trouble. I actually think the 2nd pair of ring nuts would have broken loose pretty easily (the 1st 2 did) if the FPC hadn't lied to me so that I tightened them instead of loosening them. I'll have to look up the transmission disassembly time in my service times book.

 

Glad you got 'er done . .. I found putting the gearbox case in the Cali sun heated the aluminum up enough for the races to fall out . .. the two on the end and the one in the middle of the case . .. a beautiful thing.

 

Umm, well, here in MA it got up to a whopping 39F in the sun this afternoon...

Just measured my oven, it's about 2" short in both width & depth. If it were just 1 I could probably fit it in on an angle, but not with 2 of them too small(sigh). Guess it's heat gun & work light bulbs time.

Hmm, maybe I can just prop it up in front of the garage's IR heater. 28,000 BTU/H should warm it pretty quick. I've seen people cure powdercoat using the same type heater.

Again, thanks for the late night tips.

 

You're welcome mate!

Cheers

 

Went to pull the differential & decided that I really didn't want to deal with the amount of dirt that was on the case. Also didn't want to get the grime into the differential's internals.

So I took it outside with a container of my citrus parts cleaner & a stiff parts brush. The parts cleaner was in a cold corner of the garage. As a result it was a little strange: very thick, almost jelled which actually worked out great. I could brush it on & it would stay where i put it & soak into the grime. Worked the brush into all the heavy deposits, let it set for 5 min or so, then brushed again followed by a water rinse. Then repeated to get the spots that didn't come clean.

WOW, what a difference, the areas `I cleaned look almost new, just a few dark spots here & there.

Then got to work & pulled the differential apart/out of the case. Straightforward, no surprises.

Was hoping that the differential bearings might have escaped the metal bits. Actually couldn't tell, & it doesn't as the bearing races were pretty badly corroded & pitted. Bearings have a Timken logo & p/n, so hopefully we can source them locally. Same for sourcing the seal. it's got the GACO logo & a p/n.

Next step is to get the bearing races out of the transmission housing. Put a 250W work light inside the case with a paper towel up above it. I figure half an hour or so & it'll be warm enough for the race to slide out.

 

Are the base circle dia's the same between the 2V, 4V, and 246? It's .940 from memory on the 2V.

It's been explained to me this base circle is extremely important because there is a "minimum radius of curvature" that must be looked at when grinding a new cam profile. If this radius is too tight you get pre-mature cam and shim failure due to excessive force/load at start up and low rpm. He also chatted a bit about this being a "hertz stress"/oil film breakdown which I faintly remember something about from school but not much . .. surface finish i.e. polishing all the running pieces matters at this point.

The low rpm load makes sense intuatively especially since you're supposed to keep the engine above 2k for initial cam break in. The "minimum radius" concept might be simply stated as a profile that works fine on one cam may not work on another cam with a smaller base circle. I wish I had pic's of the .406 cams now . .. I might somewhere . .. the radius of the nose was probably .03 . . .that's not a typo either. Those were relatively low duration cams . .. newer cams are way more rounded and less lift-more duration (.380 lift I think). Exhasut cams are the same as what failed before and the radius looks pretty tight on them again . .. like .06 from memory.

I can live with the shortened life running in the red all the time. I had 175 hrs on my motor and they were almost all at 4-8k rpm with no oil additives, 40-60 hr oil change intervals, and I might of even had a floating event when I had the limiter at 8.3k. I thought my piston to valve clearance was so tight that such an event would have been catastrophic but I guess that depends on when/where the float is occuring? I don't want to increase spring pressure if I can help it 'cause that seems like that will accelerate the wear thing even more.

To complicate what to do even more I know there's been a lot of discussion about not using oil additives but this may prolong life in these extreme cases along with coatings and attention to details like polishing the cam lobes and shims which you don't have to do for a stocker . .. might do this with just a little more spring . .. . decisions, decisions.

Thinking about this is getting me geeked up to get my "generation II" motor done. I stalled out for a while thinking about honing the sleeves the easy way or the hard way (in block tq'd or out in fixture) . .. thinking the easy way today 'cause my "generation I" motor screams and I honed the sleeves the easy way. I've put about 42 hrs (all at 4-7.7k with stock cams and valve train ) on her since the cam incident and she really seems like she's running better and better . .. rings seating perhaps.


Sean

edit: the motor that I beat senseless was a seized fire motor that was left for dead in a wrecking yard . .. this is all important research

 

This is a shim from the .406 lift cams at 25 hr inspection . . . lobe running pretty close to the edge.
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Not sure if you can tell how pointed the intake lobes are from this pic.
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15 Min. heating was plenty. The case was warm, not even hot, maybe 125-130F, & the bearing races could be worked out by hand!