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Billy
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Swapping camshafts

Post by Billy »

Hello to all of you,

I’m currently rebuilding my GTV6 2.5 L. and precisely working on the heads
these days.

I have a question in mind which may appear silly to you but here it is :

Is it possible to swap the original GTV6 camshafts with 12V camshafts
coming from an Alfa 164 ?


Both camshafts look quite the same but the 164 shows much higher lift.

Some minor modifications should be done to the heads in order to get extra
space for the cam lobes turning freely.

Of course, GTV6 uses L-Jetronic when 164 is managed by Motronic.

Has someone already tried this solution ?

Thanks a lot for your help and regards.
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Murray
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Re: Swapping camshafts

Post by Murray »

Billy for a long time the prefered swap has been to use the 164S camshafts in the 2.5L.I have run these in my engine for a long time and am very satisfied.The Hp.increase is mild approx. 6 Hp.but the torque curve is flatter and somewhat more satisfying particularly above 4000 rpm.I did not have to make any modifications to the heads (no interference) and I have put these cams in 3 different engines.Unfortunately the price of these cams has risen to the point where some of the higher performance cams are now in the same range and might bear consideration.I'm not sure how the 164 (non S) compare but would guess that they are slightly less aggressive - but I've been wrong once or twice before :oops:
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Re: Swapping camshafts

Post by Billy »

Thanks a lot Murray for all these useful information.

Based on your answer, I’m suddenly a bit more optimistic regarding this swap.

“S” or non ”S” camshaft type, I don’t know the exact type of camshaft I have
but to make things clearer, please take a look at the attached pics here below:

First, is it somehow possible to confirm the exact type of camshaft it is by looking at these pics ?

Does someone in this forum have some dimensions or information that would be easy to use or measure in order to confirm the type of camshaft I have in my hands ?

As you can see, there are some interferences between cam lobes and the heads which are parcularly visible on picture #1 and can be describe as follow :

- Admission lobes hit the head on their side (against the wall where the exhaust tappet is located)
- Exhaust lobes bottom out against the exhaust tappet hole chanfer.

Now, you have to know that the V6 engine I’m currently working on was originally installed in an Alfa 90 2.5. Is there any possibility that the heads of this engine were slightly different than GTV6 heads ? If yes, this would explain these interferences, what do you think about it ?

Looking forward reading you comment and thanks a lot to all of you for your help.

Kind Alfisti Regards.
Attachments
Camshaft #1.jpg
Camshaft #1.jpg (55.65 KiB) Viewed 9990 times
Camshaft #2.jpg
Camshaft #2.jpg (61.26 KiB) Viewed 9990 times
Camshaft #3.jpg
Camshaft #3.jpg (55.97 KiB) Viewed 9990 times
Camshaft #4.jpg
Camshaft #4.jpg (51.41 KiB) Viewed 9990 times
Camshaft #5.jpg
Camshaft #5.jpg (24.5 KiB) Viewed 9990 times
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Re: Swapping camshafts

Post by Billy »

Oups, I forgot one last picture that could help :
Attachments
Camshaft #6.jpg
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Re: Swapping camshafts

Post by Billy »

Wow, I thought this forum was full of real GTV6 specialists.

Come on guys, a GTV6 based in Switzerland needs your help to be back on the road !

Looking forward reading your answer.

Best regards.
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Re: Swapping camshafts

Post by Mats »

What kind of answer are you looking for? The cam lacks clearance to the casting, it dosen't fit. The only way it would fit is if you grind away some material.

If you are comfortabel doing that and is willing to take the risk of a failure, do it. If not, don't.

Simple. :wink:
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Re: Swapping camshafts

Post by kevin »

Billy , first step would to purchase jk book . From my side in the ass end of afrcia we have found the heads are different and the cams do not fit as you have discovered .
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Re: Swapping camshafts

Post by Billy »

Thanks a lot Mats for you very helpful answer.
OK, perhaps I wasn’t clear enough when writing the questions and I will therefore summarise it as follow :

a) Is it possible to swap the original GTV6 camshafts with 12V camshafts coming from an Alfa 164 ?
(S or non S type)

b) Is it somehow possible to confirm the exact type of camshaft I have by looking at the pics above ?

c) Does someone in this forum have some dimensions or information that would be easy to use or measure in order to confirm the type of camshaft I have in my hands ?

Thanks a lot kevin for confirming that some heads may be different than others.
So, some more questions :

d) When you found the difference, what have you done then ? Modify the head or give up the camshaft
change ?

Regards.
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Re: Swapping camshafts

Post by kevin »

Billy we discovered this problem when we lost (some one stole) a cam shaft from a 164 12v when motor was in pieces . We tried to use a gtv6 cam but did not fit . Also I think they were also longer . But that was a long time ago . Motor is still in pieces . We never got the 90 or 75 here in sa , so I am not much help. There were probably only half dozen 164 3.0 that came to South Africa
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Re: Swapping camshafts

Post by Murray »

Billy this is a link to a past discussion that relates to identifying the 164S camshaft.Hope it helps.If you are finding that the 164 cs. doesn't fit without clearance issues then no doubt the heads from an Alfa 90 2.5 are slightly different from a GTV6's where there are no issues. I would certainly feel comfortable grinding off the contact point to create appropriate clearance.

viewtopic.php?f=2&t=2801
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Re: Swapping camshafts

Post by Billy »

OK, it seems that the camshafts I have are 164 S type.

The heads are now modified and the camshafts turn freely.

Does anyone of you know the exact value of the valve clearance
I should now consider when installing everything back in place ?

Compared to the original GTV6 2.5 camshaft, the lift will be higher.
Therefore, do you think that I should change the valve springs for
stronger ones or are the original springs adequate ?

Thanks for your comments and best regards.
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Re: Swapping camshafts

Post by Murray »

Billy I have always set "S" cams to the same spec.as stock and this works just fine.

Intake .475-.5 mm
Exhaust .225-.250 mm

I always adjust to the lower/tighter end of this spec.

As for valve springs I elected to go with "high-performance" springs simply because I take my car to the track and have been known to ignore the tachometer :twisted: From what I've read these springs are not actually different from stock it's just that the quality control is tighter so the chances of failure or float at the limit is reduced.Have worked for me for a lot of miles and revs.
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Re: Swapping camshafts

Post by Jim K »

High performance valve springs are definitely harder than stock ones. I have bought and measured the ones from Arricambi, Spruell and Centerline and they are all capable of higher lift and much higher rpm than stock ones. I would say they are surely needed if you keep the standard (heavy) valves and do any track work. Keep in mind that springs age and become weaker after ...20 years or so. If you are resourceful, you can replace them without even taking the heads off!
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Re: Swapping camshafts

Post by Billy »

Thanks a lot Murray for the values.
As it seems to work so well on your engine, I will use it in order to set the
valve clearance on my engine.

Thanks a lot JimGreek
I will for sure buy a new set of springs. You're right, after 20 years of use,
the original springs might be a little bit tired.

Beside IAP, do you know a good adress to get it from at reasonable price ?

Regards.
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Re: Swapping camshafts

Post by Jim K »

Centerline has a very good springs at an equally good price:

https://www.centerlinealfa.com/store/2056

Jim K.
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