Want 1600 racing cams, high comp. pistons

[Brian]

I have an Alfa 1600 in a Bobsy Sports Racer, and am interested in getting cams better than the stock ones. Also, if anyone knows a source for high compression pistons, that would be useful as well.

[Bruce Colby]

Stock cams varried with the model. Do you know what cams you actually have? If they are stock Alfa cams, they should have some part numbers cast onto the shafts, something like 105-02-03-200-00 or 105-02-03-200-01 or 101-21-03-200-00 or 101-21-03-200-01 or 105-32-03-200-99. I believe these are all cams that appeared in various 1600's but there could have been others I am not aware of. If you can't find a cast-in part number, do you know the duration and cam lift?

[genericwood]

Paul Spruell's web site lists high-compression pistons for 1600's.

Erik

[geh458]

Quote:

Originally Posted by genericwood Paul Spruell's web site lists high-compression pistons for 1600's. Erik

[Brian]

My cams have almost the entire partnumber missing. All I can see is "2032000" with no dots or dashes, cast into part of the intake cam. That is all that fits on the casting area. On either side there is a more machined area, and the partnumber is truncated both before and after the digits shown. I think the exhaust cam has the same numbers. I am not even sure if the two cams are supposed to be the same. Articles I have on prepping a competition Alfa have enormous detail on theory of cam timing, but lack basic things like firing order, torque settings, etc. Then I get wildly different head torque suggestions from people I figured would know the straight goods. Makes it really frustrating to figure out what I have. This is my first Alfa, and it may well be my last. I have had more problems than I could ever imagine trying to get this thing to run on all four cylinders, develop good compression, and not leak water out edge of the head gasket. And I tried Googling "Paul Spruell" and got a variety of hits, but nothing crisp to pursue. A full URL would be much appreciated, thanks.

[genericwood]

Try www.paulspruell.com. Regarding head torque, the book usually specifies about 45 foot pounds cold and 48 pounds hot. If the head is straight and the gasket good, it should seal.

Erik

[Brian]

That is a good example. 45 lbs is the lowest value I have heard. Some say as high as 65 lbs. I have sort of settled on 55-60, and will see if that will keep the darn water from dripping out the edge of the gasket. Any recommendations on using any type of gasket goo on the head gasket ? My machine shop said no, after they took a couple of thou off the head to get it straight again. But the bottom line is to keep the water inside the engine.

[papajam]

Hey Brian. Welcome to the BB.
I suspect that the wide range of torque specs you're hearing is that Alfa has different torque specs depending on engine displacement.

These specs are from Alfa technical bulletin Gr. #01 Sh. #01 dated 12 May 1976;

Cold after reassembly -
1300 & 1600 - 46 lb/ft
1750 - 53 lb/ft
2000 - 58 lb/ft

Warm up engine and torque to -
1300 & 1600 - 48
1750 - 55
2000 - 61

After 500 miles, retorque one at a time cold after oiling threads -
1300 & 1600 - 50
1750 - 53
2000 - 64

Of interest to all 2l owners is Alfa TSB Gr. #01 Sh. #10 dated 9/80 which amends the previous 2l specs to;
77-79 cold
86-88 hot
86-88 cold after 500 miles

For the other stuff, the intake and exhaust cams are the same, the firing order is 1, 3, 4, 2, and the prefered headgasket is made by Reinz. Do not use sealer on it.
Knowing the first five numbers of the engine number will help in identifying the original cams. The engine number is located on the rightside of the engine just to the rear of the distributor and I'll guess will probably be AR00502*XXXXX or AR00536*XXXXX.

[Bruce Colby]

Brian,

The numbers on your cams suggest they started life as rather low performance ones, ones that wouldn't likely run very well in a high CR engine. It also sounds like your car has been around the race track for some time, so it seems justified to suspect that the cams have been reground. Consequently, I'd suggest taking them to a cam shop and get them profiled. I think that's the only way to know for sure what you've got.

As for the water leak problem, I'd guess that the cylinders aren't sticking up out of the block according to spec. or that either the head and/or block aren't properly flat. I guess I'm assuming there aren't any cracks or pits anywhere critical as well. As for the exact torque for the head, it's probably not critical as long as it's constant across the head and close the the values Papajam indicated. Too little and the gasket won't contain the gases/fluids, too much and it'll pull the studs out of the block.

[Brian]

Actually, I think this engine is a street engine that was re-built to install in my car, and it has a total of maybe 15 minutes gentle track test day use. I don't think the cams were re-ground - they look un-touched. I would only do the high-compression piston bit if I could also get good cams. I am looking at the pistons because in trying to nail down the cause of the low compression readings, we may say "Nothing else to do but change the rings." If we get to that, we might as well go with high compression ones, and find a moderate cam to go with them. That will delay the appearance at the track, certainly. I paid a fair bit of money to have this engine built by someone who was supposed to know what he was doing, and I have been disappointed in the results. After I had the head re-surfaced, I checked to see the liners were flush with the block, and that seems OK. I also found no oil seals on the valves, and one of the valves stuck in the guide a few minutes ago, while taking out a pair to measure for some work by a friend with a valve seat machine. That one will probably need a new guide, and maybe even a new valve. Hopefully all that will get the compression back up. I will stick with the standard cams and pistons for now, IF we get normal compression readings. The car has not run for 25 years, as it has just completed a complete restoration.

[papajam]

What were the compression readings?

[Brian]

120 on 3 and 4, and 90 on 1 and 2. A leak down test revealed leaks out both intake and exhaust ports on 1 and 2. They SHOULD be around 160, I think.

[genericwood]

Brian, hope I'm not repeating the obvious. You mentioned that the liners were flush with the top of the block. They should not be. They should stick up several thousandths beyond the surface of the block. Regarding cams, they will make a significant difference even with stock pistons. And they aren't that expensive.

Erik

[Brian]

By flush with the top of the block I meant they were not below. THAT would have caused the low compression for sure. I was not so worried about them being higher, although I guess that would cause the water leak. When we re-installed the head and ran it a second time, the gasket leak seemed to be cured. Maybe the head was warped, although it took only a very few thou to clean it up. But now we have those terrible compression readings from the valve seat leaks. Valve sizes are 41mm and 37mm, which I presume is stock. Without a twin-plug head, I don't see much room for bigger ones. And the block number just behind the distributor ? Nothing. There is a cast-in area about 2-3 inches long, about 4 inches aft of the distributor, which looks like it was meant to have a number stamped into it, but mine is blank. There are other numbers on the exhaust side of the flange where the gearbox adapter mates up....AK01600 075713. The oil filter mounts on the side of the timing cover, which makes this engine something around the late 1960's, I believe. In order to run vintage class, the engine must be of the same period as the car, which is a 1964. Thanks to those who have offered suggestions. If we can get the engine working properly, it will be a sweet little car. I have a picture of both my cars, but they don't show the Alfa engine installation. I got a digital camera recently, and will take some of the engine once we get it back together, and the snow goes away for good !

[Brian]

I had the valve seats professionally done by a local machine shop. I re-installed all the parts, and put the head back on the block. But that tensioner is causing problems again. I loosened the screw just a half a turn, so as not to lose the key (which I think happened the last time), and the spring drove the gear out against the cam chain. But it is not staying tight. Rolling the car back and forth while in gear (to check valve lash) causes the chain to compress the tensioner gear, so much that the chain almost jumps a tooth. The tensioner is almost fully retracted into the bore. If I press the chain down between the two cams, the tensioner retracts, and stays there, leaving a sag in the chain. Surely this cannot be right. Is the tensioner partly pressurised by oil pressure when the engine is running ? What do I have to do to get the stupid chain to stay tight ? Second question, what are acceptable valve lash clearances ? With the seats done properly, the clearances are less, and have more variance than before. Thanks for any suggestions.