Dr.Jeff
True Classic
Cliff, it would depend on how much material is taken off the head, cam box, block, and possibly what cam is installed, so sort of hard to tell if you might need one or not.So no need for this adjustable gear then Bob?
Cliff, it would depend on how much material is taken off the head, cam box, block, and possibly what cam is installed, so sort of hard to tell if you might need one or not.So no need for this adjustable gear then Bob?
Thanks DocCliff, it would depend on how much material is taken off the head, cam box, block, and possibly what cam is installed, so sort of hard to tell if you might need one or not.
Bob Martin's Black Dallara had a Midwest Bayless ported head and camshaft. Bob purchased a variable timing pulley from another vendor for the camshaft and had his son put it together on his car. The car never really ran right and was difficult to start hot or cold. He had the car up here at my place and we took a look at it. The timing marks were off on the camshaft pulley as it was timed to #1 cylinder but also it was off about 2 teeth as well. I put the pistons at 90 degrees and we released the timing belt and rotated the camshaft to #4 and then did our best guess at #4 lobes pointing straight up. I put a paint marker on the camshaft pulley for reference and we cranked the engine, it started right up without issue. We then ran the car up and down the road and each run adjusted the camshaft pulley a little bit. Two runs we were gaining on how the engine ran, 3rd run it was dropping off, so we adjusted back a bit and I took a file and marked the camshaft pully to the pointer. He ran that way a couple of years until we did the Abarth engine swap.So no need for this adjustable gear then Bob?
Well that is the issue. ( 2 belt teeth) Plus Bob's son a mechanic at the time for Lexus thought all engines time to #1 cylinder and the rest goes south from there. I have a 1979 X purchased new in 1979 with original paint. I shaved the head a lot which now changes the timing of the cam shaft timing and I played with the 40-80 camshaft by moving it a tooth advanced and retarded. Advanced I had a poor idle with no real bottom end retarded a tooth and the bottom end and idle were a lot better. With that amount of overlap on the camshaft it is possible to play the camshaft timing a tooth one way or the other and still get what you want for driveability and performance. One tooth retarded worked better for me than advanced. Now remember I took .160" off of the head, so the timing shifts quite a bit as well due to that modification.How the heck can an after market pulley be off by two teeth (I assume you mean two belt teeth)?
Exactly. I have no idea if Fiat made different cam gears for any of the X's, but that was my point - it would not be necessary when the cam could incorporate the intended timing difference (if there was any) directly in it. So to me it seems any aftermarket cam gear with incorrect timing marks is a fault in the design/quality and not an intended change. If I understood the earlier description of the item in question, it sounded like the same one as others found fitment issues on. If that is so, then I suppose it would not be impossible for it to have multiple problems.Why would a manufacturer make different cam wheels when the cams themselves were different and you could accommodate any difference in timing by having the cam itself have a different dowel locating hole?
So not sure what you (Bob) are saying is quite right. #4 won't be 180 degrees out from #1. Unless I'm misunderstanding what was said.The Fiat SOHC engine, like most 4 bangers, has a flat crank. That means that cylinders #1 & 4 are both at TDC at the same time (2 & 3 too). Because of that you can set the ignition timing using #1 or #4.
Actually they won't quite line up - put the 1.3 cam marks on the 1.5 pointer (or vice versa) and the cam won't be exactly one-half turn off. It will be close enough that the motor will run if you set the distributor to fire #1 instead of #4, but still far enough off that it won't run well.at the cam, it will be 180 degrees. In other words, in the photo, if the cam sprocket was turned 180 degrees, the #4 valves would be open, rather than #1.
Then the 1.5 marks would line up.