Alfa Romeo Forums banner

How do I identify the cam & Piston CR

1062 Views 3 Replies 3 Participants Last post by  catsboy
The GTV6 2.5 I bought off EBay is supposed to have a "hot" cam in it. It has a rough idle, but that may be due to poor vac and tune setup. Having pulled out a NOS system that was half a**ed put in and some MSD ignition parts there is no telling what is really in there.

I am putting Gregg's silicone hoses on tomorrow, and will be taking off the valve covers to look at the cam and see what I can see. Where should I look and what should I look for? I will be putting some covers that I have bead blasted and painted to make the engine at least look cleaner.

Also how can I determine what the compression ratio is without taking the heads off? Would a compression check give me any clue? I also plan on doing a leak down test to give me an idea of how bad the PO's nitrous fiasco was on the engine bits.

Any help would be appreciated and i will get some pictures to post if I can figure out how to get them on the BB.

1 - 4 of 4 Posts
I am trying to determine lift/duration on some unmarked cams, myself. If the cams are marked, you have a real good shot at finding out what they are. There should be numbers on the shaft, itself, toward the 'front' of the cam. If not marked, the only thing I can figure out is to set up a degree wheel of some sort, and measure lift starting at a pre-determined clearance (.050 seems good). Anyone know where to find such, or point us to a thread for setting up our own?
On the the CR, the only solution I know of is CC'ing the heads. That means taking them off, and as such is not a solution for you :(. I have heard that a higher compression reading (180+?) could indicate high compression pistons, but there is no way to determine what the CR is, or if the readings were caused by other factors. At least not that I can figure.
Not much help, I know, but I am looking for the same answers, and thought maybe a bump would help. My engine is a 4 cyl.
The cams in the Alfetta don't have even one marking on them. Heck they don't even have a mark for TDC? They were a little tricky to put in.

So How?

Next time I see you (defending America on the 13th, so won't be then :(), you'll have to tell me how you determined TDC/0 degrees. Trial and error?
1 - 4 of 4 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.