Do I need a dentist? Am I one tooth off?

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grantgsr
Posts: 15
Joined: Mon Apr 28, 2008 12:11 am
Your car is a: 1971 124 spider

Do I need a dentist? Am I one tooth off?

Post by grantgsr »

OK I got the timing belt on on my 71 a week or so ago. It took me a while to get everything else hooked back up and filled before I really wanted to let it run much. This morning I finally finished filling the radiator, so I thought I'd take it out. I had noticed it had a slight miss while idling, but it did before I changed the timing belt (I just bought the car a month ago) and I haven't yet installed new wires so I thought it might be that. However, when I tried to drive it, it would lunge every second or so and would not accelerate smoothly (please no jokes about operator error here, it was more than just knowing how to drive a stick). It did not do this before I changed the timing belt, so the question is, am I one (or more) tooth off in my timing belt install? What other signs/symptoms should I look for?

Also, assuming I have to reinstall the belt, can I make that adjustment without removing the radiator this time? Again, its a 71 with a 1608. The thought of having to drain/remove/install/fill/burp again is really demoralizing. Thanks.

Grant
So Cal Mark

Re: Do I need a dentist? Am I one tooth off?

Post by So Cal Mark »

it's pretty easy to check the cam timing; just put the crank on tdc, then look at the holes in the backside of the cam gears. They should line up with the boss on the cam housing. You have an interference motor, so I'd suggest checking it without running the engine any longer. If you are a tooth or more off, it can be corrected without removing the radiator
pwilliam
Posts: 174
Joined: Fri Nov 02, 2012 4:30 pm
Your car is a: 1972 124 Sport Spider

Re: Do I need a dentist? Am I one tooth off?

Post by pwilliam »

Thought this might help solve my rough idle issue. What is the boss on the cam housing? Is that the pointer that you align the holes on the cams too, or is it another casting mark that is used to help align the cams?
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aj81spider
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Posts: 1526
Joined: Fri Mar 11, 2011 9:04 am
Your car is a: 1974 Fiat 124 Spider
Location: Chelmsford, MA

Re: Do I need a dentist? Am I one tooth off?

Post by aj81spider »

If you look at the back of the cam gears you can see it. It's a nub that points up at the hole in the gear from the back.
A.J.

1974 Fiat 124 Spider
2006 Corvette
1981 Spider 2000 (sold 2013 - never should have sold that car)
grrrdot
Posts: 225
Joined: Mon Jan 02, 2012 11:14 pm
Your car is a: 1967 124

Re: Do I need a dentist? Am I one tooth off?

Post by grrrdot »

You can see the raised fins on the cam boxes lining up with the holes on the cam wheels in this picture:
Image
I borrowed the image from this thread: http://www.fiatspider.com/f15/viewtopic.php?t=30655
pwilliam
Posts: 174
Joined: Fri Nov 02, 2012 4:30 pm
Your car is a: 1972 124 Sport Spider

Re: Do I need a dentist? Am I one tooth off?

Post by pwilliam »

Turned the crank to TDC,

Photo 1: Intake Cam
Image

Photo 2: Exhaust Cam
Image

Does anyone think I am off a tooth or is this negligible? If it is off one tooth on the exhaust, would this cause the 25 degrees advance timing my car seems to prefer at idle (distributor adjusted to produce highest rpm, set by ear not by marks on belt cover)?

Thanks in advance!
ORFORD2004
Posts: 1120
Joined: Wed Mar 17, 2010 9:48 pm
Your car is a: 1983 PININFARINA
Location: Sherbrooke, Qc, Canada

Re: Do I need a dentist? Am I one tooth off?

Post by ORFORD2004 »

From pictures you look good
pwilliam
Posts: 174
Joined: Fri Nov 02, 2012 4:30 pm
Your car is a: 1972 124 Sport Spider

Re: Do I need a dentist? Am I one tooth off?

Post by pwilliam »

Photo 1 looks dead on. Photo 2 shows the exhaust a bit behind the casting mark. Again, not sure if this amount is negligible or not. Maybe I'm overthinking it?
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