Derek's 308 engine rebuild

I didn't put anything on them and don't plan to unless someone has a good idea. Years ago I put polyurethane clear on some carbs and it was nice for a year or two but then turned yellow and started coming off.

 

Brian, I thought about this a bit and read a few papers on belt design/failure. Most timing belt failure is fatigue related and originates inside the belt where the stress concentrations beneath the tooth root start to form cracks at the rubber/cord interface. The trapezoidal toothed belts have a higher stress concentration due to their shape while the round toothed have lower stress concentration and require lower tensions due to the bigger surface area of the deeper teeth. So they are better.

The question then is whether you will change your belts less often (in time or miles) if you use the round toothed belts. For a car that will see a lot of miles in 5 years, I would definitely go with the round toothed belts as the advantage of lower stress concentrations are important. But for the low mileage most of these cars do I would worry about age hardening of the rubber long before they have any real miles on them. I'll probably stick with the square toothed belts unless a bunch of people want round teeth and an order becomes cost effective. I would change either belt at 5-7 years depending on mileage and climate (hot is worse.) I'd mostly want to check the tensioners and drive bearings but would put in new belts while in there.

 

Not mine, but gives an idea:
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... unless you have almost 40 year old plastic pulleys! Mine had tiny cracks and dye penetrant went deep into cracks where the guide flanges meet the teeth. These are known to break off. I'm amazed they have lasted this long given the years and heat.

 

Paul, you may be right. I couldn't get a piece of piano wire into them so they are either solidly blocked or hardness indentations.

After baking the manifolds the stuck-on gasket bits were quite brittle and crumbled with a sharp chisel. I blunted the sharp corners and held it upside-down to reduce the risk of gouging. Tried some Goof-Off on a few hard to reach gasket bits and it worked far better than the gasket spray.

After the gasket was all off I sanded it with 320 paper on our nice flat granite counter-top. You can see where coolant has etched the surface after sanding it all smooth and flat.

I plan to clean the other castings this week and start on the carbs or the gearbox.
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So I picked up the Suzuki G15/16 0.5mm rod bearings and filed off the back of the tab so I could check them in a 308 rod. The Suzuki rod big ends are 47.018mm ID and the 308 is 47.13mm so I didn't expect them to have any crush given that the .112mm diameter difference would give .112x3.14159=0.352mm in circumference difference (about .014".)

They fit as expected and I think anyone wanting a 5 thou or 15 thou regrind should go this route. Resize the rods to 47.018 and cut a tab groove on the other side. The bearings are 18mm wide and the tabs 3.95mm wide at the edge of the bearing (on the left if the Ferrari bearing tabs are on the right, see pic.) Best part is you can get King or Clevite bearings for about $50-80 (or these ACL bearings for $12 x 2.)
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For those not following the cam pulley thread, I figured out a clever way to make the pulleys easily adjustable about 10 degrees. I'll get a couple of the pulley dowel holes made 9-10mm to take an eccentric pin and sleeve. This would allow about 10-12 degrees of adjustment with very little extra cost and complexity. The drive torque is usually not through the dowel pin but through the friction between the flange and the cam but the sleeve will be locked in place by the cam bolt head anyway. Anyone who doesn't want to play with the timing can just use the fixed holes.
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I did the same cleaning trick with my timing cover-- Gunk degreaser soaked for 15min, scrub, dunk in hot water and laundry detergent, left it overnight, scrubbed again 5 min with brass brush and rinse.

Picked up some bearings today (pilot and cam drive.) The SKF pilot and inner drive bearings were made in Bulgaria and Argentina, but look where my outer NTN C4 with viton seals and good grease were made!
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My local bearing shop (General Bearing Service.) They were CA$15.62 each. They are NTN 6203LLUA1C4 (A1 is the standard aftermarket grease which is Mobil Polyrex EM.) If you don't find any, send me a PM and I can send some next time I'm in the US (March break I'm down in Orlando giving the rat my wallet.)

 

I'm ordering JK some of the bearings and also some similar NTN viton 6202 C3 bearings for my water pump. Before I put in the order, does anyone else need some? $40 for 2 incl. post.

 

Scott, The hard part is finding ones with C4 clearance and hi temp grease. The original SKF with HT51 is no longer available and was never available with viton seals. I asked a friend at SKF and they are not available. Best I found was HT22. These are a weak link since the nitrile rubber seals of the originals can't cope with the heat so the seals fail and then the bearings. C4 clearance is also required due to the running temperature. If you use standard bearings they won't last very long!

 

You seemed to be suggesting that standard 6203-2RS bearings are suitable. So do you suggest 6203-2RS with C3 clearance are suitable?

 

I would still go for a C4 since, as you point out, the ranges overlap a fair bit and about a third of C3 bearings will be in the standard range and may be too tight. Why risk it? I would also go for a high temp grease since most standard greases will be near their limits so will break down faster. Nitrile seals are also near their limit and will degrade much faster than viton/FKM.