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Discussion Starter · #1 ·
Adjustable cam sprocket, how\'s yours?

I just inspected my cam belt after approx. 20,000 mls and I found the belt very loose and the alloy sprocket is obviously worn. The belt had half of a tooth missing also.
Anyone else checked their belts ??
Alf.
 

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Re: Adjustable cam sprocket, how\'s yours?

EEK!! How is your tensioner? Pictures??
 

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Re: Adjustable cam sprocket, how\'s yours?

I'm almost 100% sure that there is a difference between the 1.3 sprocket teeth and the 1.6 teeth. I was about to put an adjutable one on mine. Walked out and checked it and I find out that it matches the 1.3 belt. (Mine is a 1.6)

Could this be your problem?
I am not going to disassemble mine until I find out for sure. Anybody know without a doubt?
Kerry
 

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Re: Adjustable cam sprocket, how\'s yours?

Hmph, I thought the 1.3 SOHC 8v and the 1.6 SOHC 8 valve cam sprokets were the same?

I know the 1.3 DOHC 16v and 16v SOHC, and the 1.6 16v SOHC cam sprokets seem to be different..
 

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Re: Adjustable cam sprocket, how\'s yours?

Been awhile, But I seem to remember that I had to change the sprocket when I changed my Isky to the 1.6 SOHC engine.
Could there be a year issue? '87 1.3 to '91 1.6
Kerry
 

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Re: Adjustable cam sprocket, how\'s yours?

EEk! I know the deck height is taller on the 1.6, I thought the cams and some others were the same? Oh well, www.search.com, haven't been there in a while

I do not know for sure..
 

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Re: Adjustable cam sprocket, how\'s yours?

FYI to anyone interested. I just got a timing belt for the '91 1.6 SOHC. The teeth are rounded and the spacing is different than the square tooth '87 1.3 SOHC belt. Guess I'll be sending my adjustable sprocket back.
Kerry
 
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Discussion Starter · #8 ·
Re: Adjustable cam sprocket, how\'s yours?

The sammy 1.3 has square teeth on the sprockets but the late model mid 90's went to round teeth.. The Gti and 1.6 have round grooves with flat tops. (round tooth belt.)

I am using a Gti short block and have left the crank sprocket as is. I have fitted a 1.6 adjustable cam sprocket to match the crank sprocket.
I have a 19 mm wide round tooth belt. This will be a Vitara belt and I s'pose it is a few mm longer.
The tensioner was at maximum tension and the belt must have stretched to cause the looseness.
The alloy cam sprocket has signs of wear where the belt ran. This must have been caused by the loose belt.

I have fitted a new belt it's a Dayco QTB308 and am modifying the tensioner to get max. tension.

I will then degree the cam in and check the dist. for end play.

Sorry, no digicam so no pic's.

Alf.
 

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Re: Adjustable cam sprocket, how\'s yours?

Just a note about the cam sprockets for those interested . I've heard of some complaining that they had wear issues with the aluminum sprockets . It seems from what I understand that max tension needs to be maintained to keep wear down , evidently the loose belt will cause wear on the face of the teeth . I've had mine on the 1.3 now for over 60k with no wear marks at all but I do keep my belt fairly tight and replace it at any sign of wear at all . Hope this helps,
Sarge
 
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Discussion Starter · #10 ·
Re: Adjustable cam sprocket, how\'s yours?

Sarge I believe you're correct. My new belt seems to allow more adjustment of the tensioner so I will keep it nice n tight.

But a Q please. I need to get the centre lobe spec's of my cam as I had a regrind but never received the spec's.
So to save me from removing the head I figure if I remove the dist. assembly and undo the tappets and screws that hold the rods I will be able to partially remove the rods and access the cam lobes. Yeah?

TIA
Alf.
 

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Re: Adjustable cam sprocket, how\'s yours?

Ok, let's see if my tired mind is still working . Put your degree wheel on the crank, set the thing on one cylinder at TDC with a stop tool . Make sure the cam is also at TDC for that cylinder , easier if you use #1 and set the timing marks at 6 on the cam , 12 on the crank . Now, your are not going to be dead accurate since the cam sprocket , ect , can be off a degree or two and that compounds onto the cam timing in a accumulated manner , but it does help to find a baseline . With the timing belt off and all the rockers loosened to the point of no drag you can rotate the cam and read the height of lift of each lobe . Multiply that by 1.6 as the ratio , and that is total cam lift . Duration is fun ! With the timing belt on and set to tension , remove the cylinder stop and rotate the engine to get the duration figures . Most cam's advertised lift/duration specs are measured at .050" of valve lift , this is a bit more accurate in determining overall engine effect of the cam . You can find the point at which the lobe starts to open the valve , when it stops on the downstroke , and the overlap between TDC and the cam's duration of lift . Hope you understand all this , there are some better and maybe more clear instructions from some of the cam manufacturers online .
Sarge
 
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