Author Topic: Early let vs late let  (Read 2921 times)

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Offline carlossuperstar

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Early let vs late let
« on: January 15, 2014, 13:07:41 PM »
I have a let out of a 92 calibra that has the twin belt set up i also have the later lets that have the longer single belt.... what is the differences apart from the pulleys? i am under the impression that the inlet was different as is the alternator mounting ... also the rounded teeth cam pulley changed to square teeth and a cam belt tensions was omitted from the later ones ... am i right in all this and was there any other differences? ... and too sum up am i better off rebuilding the early let or the late one?



Offline tommygards

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Re: Early let vs late let
« Reply #1 on: January 15, 2014, 13:33:09 PM »
I've had both types of let and all the parts you can swap between the 2. I now have a later type c20let but have removed the aircon and ribbed pulley system and replaced with a v setup. I am also using the different alternator mount and alternator. i have also changed the crank pulley and using vernier pulleys with the round teeth. you can pretty much do what you want.

Offline carlossuperstar

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Re: Early let vs late let
« Reply #2 on: January 15, 2014, 13:36:54 PM »
is there anything to be gained by using one or the other? early inlet manifold is bigger? is it significant?

Offline tommygards

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Re: Early let vs late let
« Reply #3 on: January 16, 2014, 01:02:19 AM »
nothing significant i am aware of. I know early Coscast heads (the early early ones) had bigger valves so had better flow but nothing I am aware of regarding power. I imagine the only difference is for reliability (square teeth to prevent cambelt slipping etc)

Offline carlossuperstar

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Re: Early let vs late let
« Reply #4 on: January 16, 2014, 08:23:17 AM »
Early early coscast heads were the ones on astra gte 16v and the early non cat red top calibras? the later square tooth has a different amount of tensioners? i remember years ago the early ones had problems with tensioners and the tensioner got redesigned in metal ? does that sound right?

Offline tommygards

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Re: Early let vs late let
« Reply #5 on: January 16, 2014, 12:24:00 PM »
I couldn't tell you to be honest mate. Redesigning from round tooth to square tooth seems a reliability modification. other than that I don't know.