Brian Wilson

I've noticed after driving some 944's with rebuilt engines that they seem to run quite a bit stronger than mine and others that are stock. Where do we lose that much power. There must be one place that we lose a lot of it.

Also, how do you check your rings? How do you know if they're good or bad, to rering or not to rering...

billybones

Well way back when 1982. When I went to school to learn automotive repair, at Denver automotive and diesel repair (DADC). I was told that most engine power loss 90% is due to wore out valves, valve seats, and wore down camshafts and lifters. Thus cutting down the time to move mixture in and out and leakage at the valves. Thus less compression. we were told rings were a last resort thing. Now that was waaaay back when when aluminum engines were just getting going. I am currently putting together the stuff to replace all of the top end stuff. Will preform a comp test and a leak down before and after and will report if this will make a difference. I know this is not the answer you were looking for. But that is what I have..

Edit: I have refreshed heads and cams on older push rod types with good results. This is my first OH cam I will try..

Brian Wilson

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by billybones:
<strong>I know this is not the answer you were looking for. But that is what I have..</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Nope, that is pretty much the answer that i was looking for. I was wanting to do the same kind of thing, but when it comes to that kind of stuff, I'm lost!

Thanks, I would be really interested to know how it turns out.

JLeake

As your rings wear, they do a poorer job of sealing the piston to the cylinder. This results in more blow by gasses, and therefore less work being done by the exploding air/fuel mixture. The best way to check your rings (that I know of at least) is to use a compression tester. Low compression means worn rings or a leaking valve. The compression tester is basically a pressure gauge that screws into your engine in place of a spark plug. You disconnect the coil and turn your engine over build pressure (it holds the highest reading until you reset it).

EDIT- Good point Billy Bones...I had forgotten about cam wear (but then again most engine rebuilds don't include replacing cams). I had a '75 Stingray in college. One of the cam lobes was so worn that it was barely opening the valve! I pulled away from the shop (that replaced the cam) under moderate throttle and chirped second gear. Over the next year or two I lost lots of power and starting burning oil. I replaced the heads, but that didnt' help (rings were shot, I presume...sold the car).

billybones

Burning oil comes from the top. bad seals and guides.

JLeake

Doubt that was it as I had a valve job done and installed new seals, springs, and retainers when I put the "new" set of heads on. I assume they replaced the guides too. I had low compression (around 100), even across all cylinders. That car had been severely abused by it's PO. Long story how I got it, but it's irrelevant.

Robert D

I recently had my head reworked, valves/springs/camshafts replaced....the car runs absolutely great now. I'm still hunting down the rough idle, which is most likely my TPS and/or head temp. switch.
-Robert D.