3.2 noisy top end
 

I bought my 86 Targa 5 years ago At the first valve adjustment, I saw some pitting on a few cam lobes and changed them out with a good used set. The car runs flawlessly, no oil consumption to speak of and leakdown numbers around 5%. The problem is a pretty noisy valvetrain once the car is warmed up. At 111,000 miles, and the known 3.2 guide problems, a no brainer right? Almost hating to pull a good running engine, but knowing that health issues may prevent me from doing it next year, out it came. Top end looks surprisingly good to me. Valves all original part numbers, margins good, very minor pitting on valves and seats, seat width 1.6 mm. I do not have the guide checking tool but a dial gauge on the exhaust valve head and at full lift, I can get max .007" side to side movement. The intake is more like .003"

What do these numbers translate to in terms of valve to guide clearance? Thanks


Dave

Some more info:
When I bought the car, I thought I had the complete service history, now I think there may have been a top end (or more rebuild) on it. The heads had magic marker numbers 1-6 on them, valve guide seals were Teflon on the exhaust, brown metal jacketed rubber on the intake. The oil return tubes had light pinkish/orange O rings at the head end green at the crankcase. Does this sound like original to you? If it was rebuilt, they missed replacing the Dilivar stud but they were about as perfect as the day they went in.

While I am there, I plan on splitting the cases and checking out the bottom end, ARP rods bolts will go in.
After all is done, the last thing I want is to have a noisy top end, kinda defeats the purpose! Any other possibilities for the cause of the noise?

Thanks for your input.

I ve seen noisy rockers that sound like piston slap in the cylinders. Turned out to be bad rockers, adjusted properly but still noisy..
Bruce

Upper end noise can be caused by worn rockers (as Bruce wrote), worn rocker shafts, worn guides, and naturally, excess valve clearance (some of which is caused by the above). Your exhaust guide clearances are at the end of spec and the guides should be replaced. Valves should be measured for taper as well.

Sounds like somebody worked on the engine to some degree since teflon guide seals were never OEM on these cars. The orange oil return tube O-rings are the older silicone ones while the green ones are the more modern Viton.

I would certainly go through the whole engine VERY thoroughly so you know precisely what you have so it will last a long time.

Many thanks to Bruce and Steve for their respected advice. When I changed out the cams a few years ago, I made sure to check the condition of the rocker faces, bushings and shafts. They were very good. So, sounds like excess valve to guide clearance is most likely the cause of the noisy top end. And yes, the whole engine is coming apart for a good look at everything, no sense in going half way. With the amount of snow we are getting this winter, I should be good to go who knows when!

Could this noise be caused by the loose wrist pins you noted in your other thread?

I'll put money on your suggestion Craig. I agree it was probably a combination of guides and wrist pin clearances that were past their service limits - not by a whole bunch but collectively, they made for a noisy top end.