Adjustable Cam Pulley Worth the $$$???

[Dougieb]

HI, just some background first.

Car: 1972 Spider
Motor: 1608cc with a 4-2-1 exhaust and a DMSA carb and single plane intake manifold

I bought the car fairly recently and upgraded the carb to the DMSA and have been very happy.
I am now going through things since I do not trust what the PO has/has not done to the car.
I am going to next change the timing belt and adjust the valves.

I am considering to spend the approximately $250 to get adjustable cam wheels while I am doing the timing belt.
I am not looking to upgrade the cams (yet) but just want to get the best out of the motor.

Question, is it worth it to spend the money on adjustable cam wheels for a mostly stock motor or not?
Or should I wait until I am going to upgrade the cams to something better than stock?

Just looking for opinions.
Thanks,
Dougieb

[narfire]

Car will run pretty good without the adjustables, but if you know the specs for the stock cams, I'd be thinking you might see an improvement if you can degree then in properly. Your right that new cams will light things up a bit compared to the stock.

[maytag]

I think it depends on how much work you are willing to do. We've heard reports of the stock cams being way out, so yes, they could probably benefit from some indexing. Don;t just buy the adjustable cam gears and install 'em "straight-up." There would be no benefit from this. And I will point-out that if you are not looking to mess with the cam-timing, and all you want to do is dial it in to factory specs, then you can do that by re-drilling the stock cam gears, for free. No need to buy adjustable gears.

Just my $.02

[fiat218]

I think it depends on how much work you are willing to do. We've heard reports of the stock cams being way out, so yes, they could probably benefit from some indexing. Don;t just buy the adjustable cam gears and install 'em "straight-up." There would be no benefit from this. And I will point-out that if you are not looking to mess with the cam-timing, and all you want to do is dial it in to factory specs, then you can do that by re-drilling the stock cam gears, for free. No need to buy adjustable gears.

Just my $.02

2 cent huh. What do the adjustable cams do,I rely don,t get it. More precise tuning,

[maytag]

2 cent huh. What do the adjustable cams do,I rely don,t get it. More precise tuning,

well, not to put to fine a point on it: they allow you to adjust the cams.

The cams are (or should be) precisely timed to create valve-events at exact moments in relation to the position of the crank / pistons. A performance motor can benefit from adjusting when (in relation to the crank) those valves open & close. you can tune the RPM range, and the curve to a large extent.

But unless you're looking to try several settings on a dyno, adjustable cam gears don't offer a huge benefit.
On a STOCK motor, they can be used to allow the cams to be set to exact;y factory timing specs. AND they can be used to adjust the cams to try to eek out a little more. But again, if you;re only planning to put it in one place and leave it there, you probably don;t need adjustable gears: just re-drill the ones you've got with a new indexing-hole.

one more common use: if you've milled the head or decked the block, then you have changed your cam timing through the reduced distance from the crank to the cams. Adjustable cam gears can be used to accommodate this.

[manoa matt]

In order to properly degree the cams you must remove the cylinder head, and use a dial gauge to find max lift of the valve. Even if you wanted to re-drill the pulley you would need to degree the cam and take some accurate measurements that would then need to be given to a machinist so he could drill the new hole with some level of precision and accuracy. It's not something to be done with a hand drill in 5 min.

Now you "could" install adjustable pulleys while everything is together, but you'll never know exactly where the cams are supposed to be timed at. From there you'd just be guessing as you advance or retard one side then another, but without a baseline you will be adjusting forever. The performance gains from a degree or two degrees might not be perceivable and would require a Dyno to perceive and plot.

You will likely see more benefit from having the valves adjusted than being off one tooth on the timing belt.

In the words of Ron Popeil: "Set it and forget it".

[majicwrench]

Save your money. Take a lot of work and skills for them to be of any use.
Keith

[manoa matt]

Although I've never done this way, I guess you could take the lift measurements off the top surface of the valve shim, provided the cam itself is not in the way. That way there is no disassembly and you know your baseline, but it would be a PITA

[maytag]

Now you "could" install adjustable pulleys while everything is together, but you'll never know exactly where the cams are supposed to be timed at. From there you'd just be guessing as you advance or retard one side then another, but without a baseline you will be adjusting forever.

In the words of Ron Popeil: "Set it and forget it".

I completely agree with everything Majic & Manoa said. I would add one more comment to Manoa's above:
if this is your plan, you'll likely end-up with bent valves. There is not a lot of room in the duration numbers before those valves smack each other.... and there's equally not alot of room before that intake valves starts beating the piston to a given location. Both scenarios resulting in some severe failures.

[fiat218]

Now you "could" install adjustable pulleys while everything is together, but you'll never know exactly where the cams are supposed to be timed at. From there you'd just be guessing as you advance or retard one side then another, but without a baseline you will be adjusting forever.

In the words of Ron Popeil: "Set it and forget it".

I completely agree with everything Majic & Manoa said. I would add one more comment to Manoa's above:
if this is your plan, you'll likely end-up with bent valves. There is not a lot of room in the duration numbers before those valves smack each other.... and there's equally not alot of room before that intake valves starts beating the piston to a given location. Both scenarios resulting in some severe failures.

ok so in standing in front of your engine, left side is the exhaust cam.right is is the intake. so in order for me to tell if there a mild cam, i need to look at the right side, not the exhaust right?

that picture was from the left side,exhaust side