bill's 308 engine project

Hi Crowndog and ferrariowner,

Thanks for your feedback.

I'd love to see a photo of your knock sensor installation. I like the idea of a knock sensor option and my xdi-2 programmable ignition system can read the knock sensor's voltage spike and with an adjustable trigger level. I wish I had a wide band accelerometer and maybe a digital storage oscilloscope to analyze the knock sensor signals at various sensor locations. Some knock sensors are tuned to a nominal 7 khz, others may be tuned to other frequencies. 7 kHz corresponds to the primary theoretical knock frequency for an 84 mm bore. There are both resonant and non resonant sensors. Some knock sensors are tunable.

I talked to my engine builder and there have been a couple of hiccups. The attempted build up last weekend was aborted because the liner seals were not correct for 328 liners. We will try again this weekend. We need to do a trial assembly to verify deck heights and bore dimensions before we can order the custom pistons. Final valve pockets will be machined on site if necessary. This capability could also give us good control over chamber and intruder volumes. One would like to be able to go further and look at things like how the shape of the combustion chamber and piston crown surfaces affect the flame front propagation. That would be a fun project probably best explored using CFD techniques, although just assuming ignition at the spark plug, the flame front would propagate outward like the layers of an onion, but restricted to the volume between the chamber, piston, and cylinder surfaces. The higher CR should increase squish, for better combustion.

I'm having discussions with MWE about having some one go through my gear box, but the in-house expert is not available at this time. So, I'm currently looking for someone. One possibility is Miller Motor Cars of Greenwich, Ct, who have a dealership about a block or two from the old Luigi Chinetti (of NART fame) business location. The other thing I learned from my conversation with the service manager is that they go to MWE for their their vintage engine builds.

I talked to MWE yesterday and he said he had conversations with Miller Motor Cars where the reliability of the transaxle, with the uprated engine, was discussed. My plan is to replace all the bearings, seals, and synchros if possible. Tear down could reveal additional problems. The other issue is the transfer gear system. Apparently there were changes made to the 328 transmission for increased robustness, although it's not yet clear what these changes were. Has anyone reported a transmission failure with an uprated engine? The 1975 GTB engine put out 255 bhp (SAE net) and more importantly 210 ft lbs at 5000 rpm, according to the owner's manual. I'm expecting a max torque of about 300 lb-ft from the new engine. My plan is to also go with a Modena Engineering transfer gear system. Frank says he can do a quiet system that my grand kids will one day drive. Wouldn't that be great?

Bill

 

Hi Brian,

The primary reason for the custom drop gears is to arrive at a taller 5th gear. The increased spacing between all gears is also a plus assuming greater available torque.

Bill

 

Hi derekw.

One of the interesting things I learned from my friend John Stowe is that OEM jaguar engine bore spacing changed over time. The combustion chambers are no longer centered over all bores. John has contracted with the Jaguar Club of the UK to produce a replacement head that, among other things, will correct this geometry problem, improve the metallurgy and perhaps make some other improvements

I talked with MWE yesterday.

1. The sleeves are in the block and their bottoms are sealed with special O-rings, because of the machining and geometry.
2. The crank is in the block and all (std/std) clearances, including rod clearances, are acceptable.
3. The pistons were defined and ordered last week from JE Pistons I believe. Lead time is 3-4 weeks.
4. Valves were ordered

MWE told me their gearbox guy is having health issues and his part time work hours are uncertain. I asked John Henkel at Miller Motocars (Greenwich Ferrari) to go through my transaxle with the intent of replacing all bearings, seals, and synchros. John expressed concern that the drop gear train was not up to the torque of an uprated engine. Ferrari 328’s feature extra outboard bearings for drive the shafts, which earlier 308’s lacked. If I can work a deal for a 3-ratio, quick change, drop gear conversion, the cover is already fitted with the necessary extra bearings. John sent me an email yesterday saying he would be picking up the transaxle from MWE for transport to the Greenwich workshop for an instructional tear down, which I will observe. MWE is doing a Ferrari 250, 12-cylinder for Miller Motor Cars, so transaxle pickup will be a byproduct. Thanks to John and the team at Miller Motor Cars.

I haven’t heard much about drop gear or transaxle failure or unusual wear. Yet Ferrari clearly saw a need to change the 308 design for the increased torque of the 328. How can it be that all the uprated 308’s running around are not having drivetrain issues? Am I just being paranoid?

Bill

 

Hi finnerty and Patrick,

Thanks for sharing your experiences and insight.

I prefer to upgrade to the quick change system rather than convert to the the 328 transaxle. A lot depends on what we find upon tear down. Going in it shifted with effort and one could be at least one of the synchros. The other big concern is the limited slim differential. Individual repair parts generally are not shown in the Parts Catalog. I do see aftermarket friction plates plates here:

https://www.ebay.com/itm/Ferrari-Limited-Slip-Differential-Autobloccante-Clutch-Plate-kit-Rebuild-set/263501134304?fits=Make%3AFerrari&hash=item3d59e439e0:g:H0kAAOSwl29ahxQw:rk:1f:1&frcectupt=true

I hadn't heard from Frank Capo at Modena Engineering in weeks and was getting concerned, so I called and found out that Frank has been on a European trip for a couple of weeks and would contact me next week. So the quick change option is still viable at this time.

Bill

 

Hi guys,

derekw,

Thanks for the heads up on the potential fit issue with early 308 engines and the round tooth drive pulleys. I asked MWE to check this. Good point on the sticky tires, still there will be more torque available at the flywheel. I hope the spider gears are in good shape. Are these parts even available new, other than as complete assembly? The PC shows 1067869 for the differential assembly. What was your conclusion regarding Swiss Army Vehicle's 7102225611 offering for $275.50 USD? Is this really a suitable ZF1249304278 part (1-3 synchro)?

Ferrariowner,

You have lots of bhp with the trubo. Any idea what your max torque is and how often you use it?

Patrick,

Are you saying you replaced the entire differential assembly for 300 GBP’s? When did you make the purchase?

This past week has been about trying to get the transaxle refresh going. I ordered synchros from Algar Ferrari in PA, who have a small quantity on clearance. They are NOS, ribbed type, 150628’s (4-5 gears), were still coated in Cosmoline, and were delivered in about 24-hours. Great job

I ordered three, 106040 (1-3 gear) synchros from another supplier, who gave a terrific price, but were sadly unavailable at this price. The supplier did offer to supply these parts at a much higher price, but I declined and cancelled this order. So I’m back to looking for 106040 synchros at the best available price. A review of postings has not shown a clear alternative to the Factory part. Smg2 sugggested equivalent pieces made by RBT may be made of a different material, as the GT40 ran in different oil? What gearbox did the GT40 run?

derekw suggest s ZF part numbers 1249304278 or 1249304570 may be suitable for the 1-3 synchros. IndyGuy posted ZF part number 1031.304.153 and 1031.302.177 were internal ZF numbers for the Ferrari 1-3 and 4-5 synchros, respectively. I want to replace all synchros with new, so I need three 106040 (1-3) synchros.

Anybody have 106040's on the shelf?

Bill

 

Hi derekw and Ferraridoc,

Thanks for the heads up on the spacers. I've asked my engine builder to check the drive pulleys but it may be premature, as we are early in the assembly stage, waiting for pistons to be delivered. Did you put the Swiss Army synchros in your tranny and are they indeed made by ZF? One supplier can offer both ZF and a less expensive Chinese sourced version. They recommended the real ZF part. I was looking for a GT6 back in the 1979 when I came across a 1966 Lotus Elan, S2, SE, RHD, and bought it instead. Your point about the high loads resulting from sticky tires is taken. My 26R uses an all aluminum T9 transmission with a custom gear set and special, shock absorbing drive shaft, CV joints and high strength output shafts and axles.

Bill

 

Hi derekw,

I just got back from a 2 week holiday in Orlando.

Did you write down the ZF number from the Swiss Army synchros?

The folks at Miller Motor Cars tore down my transaxle while I was away. Basically, it's a piece of junk. Extensive internal corrosion, abnormal wear, and broken (synchro spring) pieces. The diff pieces were even worse. Lee at Miller Motor Cars made a multiple videos of his evaluation of all the major pieces.

I'm on a search for a replacement transaxle core, where I will replace all the usual stuff to bring it up to snuff. I talked to Bill Young of GTCP today and he recommended a late 328 transaxle for my application. I'm not sure about clutch actuation, is it cable or hydraulic on the 328? The speedo sender is the later type so incompatible with my speedometer. Compatibility is gained by replacing my Speedometer with a later type. The benefits one gains with a 328 transaxle are a stronger drop gear system, the taller euro, 1st and 5th gears, and a pump driven lubrication system, . A quick change transfer gear system is now easier to do, but maybe not so necessary for strength.

Bill

 

Hi hyenahf,

Have you done a 308 on a 328 trans?

It looks like all the 328's cable operated clutches. I need a 328 clutch cable?

I had Palo Alto Speedometer do a 180 mph face on my current speedometer. It works and looks great. I'm thinking a replacement speedometer from an i or QV might work as I believe these models use a magnetic speedo sender. How about Nisongers in NY?

Bill