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

Chris,

Are you sure you were talking to the right kind of web cam girl???

Hats off to you, by the way. Nice project!!!

Hans

 

Typically, Laurie (Dunlap) at Web will give you a choice of grind options for your specific application and discuss the effect each will have when compared to your stock set up.. As you can see the Speis has less duration than the 2v carb set up, as it is designed for a qv which requires less duration - thus you would lose with that grind in a 2v. Be sure she knows you have a TWO VALVE as the grind and cam profiles are VERY different from the qv.

 

Lots of very good advice to go around, and I do agree holeheartedly with Verell, at least talk to Mark and Russ's guy about the heads.

If you are planning new pistons, you will want to give the piston builder information you dont know yet. They would really like to know valve head to piston clearance during overlap, and your not going to know that until you have cams. You have some big decisions to discuss with yourself.

How are you going to drive the car, and where? Do you plan to track it, or would you prefer it be a nice happy fuel miserly engine to take on trips?? Ive had P6 cams in my car with 9.7 pistons. Its quite manageable on the street. But fuel mileage will suck, and engine life will be shorter, especially on the heads. The higher the lift the harder your valves work, the faster they wear. No free lunch. I have the stock pistons and cams in car #2, and once sorted out it ran awesome. Ive returned fuel economy over 20 mpg, and if I let her unravel she flies. And runs fine on 87 octane too, I might add. I certainly wouldnt go any less cam than a stock early cam, thats for sure. So use the stock early as your minimum acceptable requirement, and the P6 as your absolute max.

Stock duration on the early carb cars @ .50 mm (.020"). timing clearance:

intake open 34 BTDC (260 duration)
intake close 46 ABDC

exhaust open 36 BBDC (254 duration)
exhaust close 38 ATDC

lift intake 8.849
lift exhaust 8.323

P6 cams:
Image Unavailable, Please Login

 

I've chatted with Chris, My understanding is he's looking for a high perf. street car, tracking it is not precluded, but not a major goal, fuel economy is whatever he ends up with. Must run on readily available pump pump gas, at most 93 octane SUPER, not 100 octane, race or Aviation fuel. This means he wants a wide power band with lots of torque down low. Not a narrow power band with it's peak up close to redline like the P6 cams would give.

Chris, If I've got this wrong please set me straight ASAP as I'm basing subsequent recommendations on this understanding.

Yes, that's a degree wheel, it's part of what you use to precisely setup/measure cam timing, along with dial & TDC indicators. Don't go out & buy one, let whoever's doing your block & installing your cams do the setup, it's not something a novice should be tackling. However, you should do your homework so you understand how to interpret/read the results & cam diagrams like Artvonne posted. If you really believe you need one, you can borrow one of mine.

 

Those situations are why you want a wide power band. In a street car you want to have plenty of power/torque available in just about any gear & driving situation. 'Lots of torque down low' means that there's usable torque from around 2000 RPM or so & smoothly increases to a broad peak. This means you'll have power on tap in jut about any driving situation from to pulling away from that ricer who gave you the bird at a stop light, as well as for highway passing, on-ramps, etc. The OEM engine has a pretty wide, fairly flat power band (See 1st pic) which is what makes the 308 so driveable. If you read Russ & mk e's posts, that's what they are tuning for. It's my goal which is why I went with the SC I did (See 2nd pic - That's the dyno curves when mk e had it on his car).

A narrow power band would give you a lot of power concentrated in a very narrow, high RPM range, say from 5000 to 7500 RPM, the torque would be 'up high' which would mean that it starts up around 4000 RPM & builds to a peak at maybe 5500 RPM). You have to keep the revs up to have any power at all, which means constant shifting to stay in the power band. Works in a track/race car where you're always trying to drive flat out, & gives you a high peak HP on the Dyno, but doesn't work well on the street where you're often cruising along at 2000 - 3000 RPM. Also doesn't work well when you're trying to maneuver the car in parking lots, or around in your home parking pad, into/out of the garage, etc. Hmm, with a narrow power band you'd have a lot of trouble getting up that very steep driveway you have. Either you'd have to slip the clutch on the way up, or would have to go up fast & brake hard just as you get to the top.
Image Unavailable, Please Login
Image Unavailable, Please Login

 

where did you find those parts?

 

Read some of the previous posts, smg2 collected everything, was going to convert his Mondial to carbs, then decided to develop a SC system instead. So he sold them to someone else. The other person decided to not do the project & offered everthing to Chris.

 

But those are on what looks like a SB chevy, that won't help you....wait a minute, are you putting a chevey in your car?












Just kidding. Cool present!

 

Pointed out to Pizzaman that as expected, the 1st & 2nd gear synchros were badly worn. Zero clearance between the synchro & the gear.

3rd gear synchro is getting thin, I'm pretty sure the clearance will be well under spec when bench tested.

4th & 5th gear synchros appear to have almost no wear! Will verify on the bench of course.

The pointed ends of the narrow teeth on 1st, 3rd, 4th,5th, & reverse look quite good, still come to a distinct point. However, there's a distinct flat, maybe 1.5mm wide on 2nd gear instead of a point. I have a few concerns:
a) The missing point may make shifting into 2nd harder whenever the synchro teeth aren't reasonably well in line with the small teeth on 2nd gear. There's nothing in the spec about wear limits here, do any of the pros have rules of thumb?
b) The side of the gear facing the synchro may also be worn, making the gear thinner. This needs to be checked carefully.
c) The 2nd-3rd gear slider may have the points worn on the 2nd gear side of it's teeth as well.

Next will be to pull the end cover, ring nuts, & we'll have a big pile of (hopefully labled) parts!

 

I'm having lots of fun (NOT) trying to get the main shaft ring nuts broken loose. TI'm using my trusty IR-231 1/2" drive air wrench with the correct tool. The IR-231 is rated at 450 lb reverse torque @90 PSI. I had to crank the air pressure up to 150 PSI & to get the 2nd lay shaft nut to break loose! If the wrench's torque increases linearly with air pressure, then I'm whacking those nuts with serious torque. ie: 150/90 x 450 = 750 ft-lb!

No sign of red loctite on anything so far. Other than a severely rusted on Dodge stealth crank damper bolt, these are the 1st fasteners that I couldn't bust loose with that air wrench. Tried borrowing another 1/2" drive impact wrench, but it doesn't hit as hard as mine does.

I've borrowed a 1" air impact wrench & finally located a 1" -> 3/4" adapter to mate up with my 3/4" -> 1/2" adapter so I can use the ring nut tool. I'll have another go at those !$#@% nuts after supper. If this doesn't crack them loose, I'm breaking out the hot wrench & cooking them a bit before I rap on them.

BEWARE LEFT HAND THREADS:
In general, the threads on one end of any transmission's shafts will be LH, while the other end will be RH. This is to reduce the chance of them coming loose. Good thing I halfway remembered this rule of thumb & asked a pro before trying to break those ends loose. He confirmed that the two p/n 104252 nuts on the clutch (driver side) ends of the shafts are LEFT HAND THREADS. The p/n 104253 ring nuts on the shaft passenger side ends are RH threads. I haven't found anywhere in any of the 3x8 WSMs or FPCs that tell you this useful tidbit!

 

Mine came right apart with the sawsall the other night.

 

Hi Verell.
Do you have a good drawing of the gearbox assembly with the parts number you use? Can I download it from somewhere?


Harald

 

Don't think this is right (no pun intended)

I just checked my gearbox . .. on clutch side:

Input shaft right hand thread
Output shaft left hand thread


On passenger side:

Input shaft left hand
Output shaft right hand

Sean

 

Sean,
I'm hoping you are working from an actual tranny & the FPCs are wrong, or else I'm missreading them. Of course, if the FPCs are wrong, then I've seriously torqued those nuts on at this point.

Pls ck my FPC drawing reading, here's the dwg ref #s that I'm seeing on ALL FPC tranny shaft drawings, only the TAV#s vary for different models:

Clutch end Ring Nuts:
Main (input) Shaft TAV24 dwg ref # 8 - p/n 104252
Lay (output) Shaft TAV25 dwg ref #14 - p/n 104252 - Got this off, so know it's a LH thread

Passenger end Ring Nuts:
Main (input) Shaft TAV24 dwg ref # 9 - p/n 104253
Lay (output)Shaft TAV25 dwg ref #15 - p/n 104253 - Got this off, so know it's a RH thread

Anyway, as you can see from the attached picture, I've got to make a trip to an auto supply store before I can make further progress.

BTW, it's not a good idea to be holding onto the 1"->3/4" adapter to take up slack when the 3/4" -> 1/2" adapter shears off. Instant sprained wrist!

I'm primarily using a one-off GTSi/GTBi FPC hardcopy. However, except for the TAV #s the downloadable copies of the Mondial8 & the GT4 thru 328 FPCs show the same nut p/ns being used in the same locations. Even have the same drawing reference #s.

You can download some of these manuals from:
Steve Jenkens Private Document Collection
http://ferrari.jenkins.org/books/

Search will help you find other download locations:
There was a recent thread with a link to a downloadable QV FPC, other threads for the GT4 & 328 FPCs.
Image Unavailable, Please Login

 

Verell,
I just pulled mine a part, and you're numbers are wrong. You're turning the wrong way.

On each side of the trans there is 1 right hand and 1 left hand nut becasue the shafts turn in opposite directions. Each shaft has 1 right hand and 1 left hand nut because the nut goes on form the opposite side and therefore spind the opposite way relative to the nut.

Spin those 2 nuts opposite of what you've been doing and off they'll come.


BTW, I made my tool from a 3/4" drive socket if you need to borrow it.

 

Oh, Frap,
Thanks Mark, that makes complete sense. . It has to be that way with a synchromesh tranny's counter-rotating shafts(DUH).

THE FPC TRANSMISSION P/N TABLES ARE WRONG FOR EVERY 3X8 MODEL!!!

I've probably hammered them on so tight I'm going to have to cut them off..

 

On the bright side, you might of just done an unscientific experiment on how much torque the 308 shafts can withstand

 

Would be a tad more scientific if I knew the specs, or at least the make & model of the 1" impact wrench I've got borrowed.

I've got a couple of Snap-On replacement adapters coming. Guess I'm not the only one to break the 1/2" nose off, Snap-On got smart & made the 1/2" nose replaceable!