Cam wheel adjusment

[70spider]

Hello all,
I just got my first Spider and it has a little issue, it shoots fire out the tailpipe when down shifting. I read through all the suggestions on how to solve for a backfire problem and one was the cams are out adjustment, are these out of adjustment?
About is the current cam wheel position. I have removed the camwheel pointer (just changed the thermostat) but the indicator holes if rotated would not align with the pointer.
Also, are the wheels associated with the correct cam?
If they are out of wack, how to adjust them correctly?
Any help would be great, Thanks Pesto

Sorry about the pic but I think you can see the position of the camwheels well enough.

[bradartigue]

Can't tell from the picture. The motor has to be at top dead center, then the camwheels must align to the cast-in markers or the pointers on the head. Look here: http://img.docstoccdn.com/thumb/orig/122042439.png

[70spider]

Thanks for the pic. I'll set it at TDC and see if they line up.
Pesto

[Jimb]

Crank pulley to TDC (longest mark at the bottom of your front engine cover), as well as auxiliary gear mark in line with spring bolt (1:00) then line up the cam gears with the pointers.
Jim

[narfire]

I noticed from your signature you have a 70? Do make Damb sure it is all lined up properly before you crank that engine. I believe you have an interference engine, I know my 70(1438) was. If your cams are not lined up properly, a piston could be up at the same time a valve is down
The comment regarding the aux wheel is very important as well. At the end of the aux shaft is a lobe that is used to connect the arm on the fuel pump. Again if the aux shaft is not lined up properly when the engine is at TDC, that lobe could contact the #2 piston journal and with a loud bang, break the aux shaft in two.
On the chart that Brad has shown, take a look at #2. There is a raised rib behind the cam wheels that have to line up with the holes in the respective cam wheels. Do that in conjunction with the crank at the long pointer and you have the engine at TDC. Get the hole on the aux shaft wheel at the 1 o'clock position and good to go...
Good luck eh..
Chris

[70spider]

Thanks for the info. Once I get to TDC I'll post pics of the cam wheel position. Just a thought on setting the engine at TDC I was told to pull the plug on the #1 cylinder and then turn the crank until the piston is at the top of the stroke, is this correct?
If the camwheels were not aligned properly would that cause my backfire problem?
Thanks Pesto

[bradartigue]

A few things here -

TDC on a motor that has the timing belt installed is found by lining up the mark on the crankshaft pulley with the TDC indicator on the motor. When those are lined up the camwheels should align to their pointers; if not, they are set wrong.

You need a shop manual and you need to read the "GENERAL" section.

[baltobernie]

There are several possible causes of the problem. There's no reason to suspect cam misalignment unless you have changed the timing belt and the car now backfires. Is that what's happening?

I suggest you start with the most-likely causes. Too rich a mixture or too late a spark will both result in fuel being burnt outside the combustion chamber, causing noise and flame. Some pollution-control devices that are out of spec can also contribute to this.

Once you've checked and corrected ignition timing and carburetor settings, you can look for other causes, including your cam misalignment theory. The easiest way to check this is to hook a timing light to #4 cylinder, and aim it at the reference mark on the cam boxes. The mark is cast into the box, at the very forward tip. If the strobe illuminates the reference mark aligned with the pulley hole, all is well.

In rare cases, a noob will swap intake and exhaust cam wheels when rebuilding a motor, thinking they are identical. They are not. Intake wheels usually have an "A" in the casting; the exhaust has an "S". I see the "A" correctly on your intake wheel. Lacking these marks, a correctly built motor can be validated by looking at the front of the engine. With the cam box pointers aligned with the holes, the dowel pin on the intake cam should be 1 o'clock to the pointer, the exhaust 11 o'clock.

Lastly, engines like ours fitted with high-performance camshafts can backfire under normal operation when shifting.

[70spider]

Baltobernie,
Thanks for the input. I just purchased the car, but the previous owner never drove it allthough he did have some engine work done( pistons, rings, belt and some carb work: about 1K worth) probably so that it would run so he could sell it. Any way I plan on putting new plugs and wires and see if the timeing is right, after that I'll tackle the carb.
Thanks for the help.
Pesto

[phaetn]

Hello all,
I just got my first Spider and it has a little issue, it shoots fire out the tailpipe when down shifting. I read through all the suggestions on how to solve for a backfire problem.

Ok, since no one else has mentioned it, I will: You have a spider that shoots flame out the pipe and that's a *problem*?!! I'd view that is an awesome feature!!

My favorite moments of trackwork with the PCA in a race-prepped 911 we're backing right off after full throttle application and hearing an incredibly satisfying "pop" as a two foot flame shot out the four inch pipe!

I'm getting my Spider within the next weeks or so (just enduring one last snow storm for the year and selling my motorbike) and then I'll have it on the road.

Seriously, my first purchase for the car has been a fire extinguisher, but a small flame out the back would be cool if it was a little rich and otherwise ran well.

Congrats on the new ride -- I'm envious!!

Cheers,
Phaetn

[pooldoctorstl]

It looks like it will be in time when you pull it over to TDC, but check it. I would also check valve clearence because if they did head work and didn't clearence the valves correctly, an exhaust valve could be hanging open a little after it warms up and everything expands a little.

[70spider]

Thanks for the thumbs up on setting Kansas on fire when I down shift , I think its cool too .

It looks like it will be in time when you pull it over to TDC, but check it. I would also check valve clearence because if they did head work and didn't clearence the valves correctly, an exhaust valve could be hanging open a little after it warms up and everything expands a little.

I'll check the clearence, your correct in it only backfires after it has warmed up. Anyone know the correct clearence? I'll look it up. The best thing about the Spider is I can find almost anything I need on the net.

Funny thing, even after all the engine work that was done they seemed to have put the old plugs and wires back on it
Thanks for the help
Pesto

[70spider]

Hello,
I finally got the chain vise-grip thingy tool so that I can turn my crank pulley without removing the oil cover. This is what I came up with. I couldn't get a pick of the whole front of the engine due to the tight space so I created this;

Note: the auxiliary pulley was not intially lined up due to my earlier attempt (stupid) by trying to rotate the the belt using the auxiliary pulley, what happen is it slipped moving the pulley about 10 degrees so after I removed the belt I returned it to the correct possition acoording to the Fiat diagram.
Also, I have never worked on a car that did not have a harmonic balancer with the timming marks. so is the mark on my crank shaft pulley the timming mark?


Last I am not sure if the #1 cylinder is at TDC in the position in the first photo.
Any advice on what to do to get it all lined up correctly would be appriciated. Also should I get a degree wheel?
Thanks Pesto

[baltobernie]

I don't think a degree wheel is necessary, as you can't adjust the factory cam sprockets.

It does appear that you have everything properly aligned. The Fiat TC does not have a harmonic balancer; if you were to remove the crankshaft pulley, you will see a series of indentations on the back side near the rim. They appear is as if they were made with a drill bit. This is the external balancing done at the factory after the engine is assembled. (It's also why you don't want to swap crank pulleys from different engines) TDC is a thin groove on the pulley; it looks like the PO highlighted it with a Sharpie. Most guys use a bright-color paint pen or tire crayon to fill in this groove. Of course, you need a mark somewhere on the engine for reference. Your car uses cast marks in the timing cover, three of them, to indicate TDC, 5° and 10°. If you don't have a timing cover, we'll need to get creative.

[70spider]

Thanks for the input. I have the original shop manual for the car and looked all this stuff up, just found it in the bottom of the box of spare parts that came with the car. I have to remove the auxiliary pulley, a little nervous not to move it to much, to expose the timing marks. The manual says to set at 5deg. BTDC.
Thanks, Pesto