Multipass

Is there a way to check the rod bearings that without taking the engine apart?
Wouldn't they progressively slow the engine down, instead of abruptly making the engine stall at 5K? The car accelerates fine until that point.

Did you have similar experience in your car?

67rschev

Inspect cap and rotor closely . Fuel pressure ? . Double check cam timing all though would be more of a constant issue . What about reference sensor to reluctor gap on flywheel ? Reference sensor ?

Multipass

The cap/rotor/wires/plugs are all new, I could swap the old cap/rotor to see if anything changes. Fuel pressures all checked out OK. I'll check the reference sensor. Thanks.

Rock

Yeah this is true. But that wouldnt stop the car from revving past 5k. If it were one of the vaccuum signal lines, those could all be disconnected and the car rev past 5k.

If it were a larger line that is leaking, chances are it would run like crap in the lower RPMS and stall out on idle.

FWIW- I dont think its the rod bearings either. If they were binding they would be spun and you would be throwing rods if you kept it up

Your car, it isnt a 2.7Litre by chance is it? 2.7L N/as have knock protection. It will cut the engine out if it detects knock. The exact same thing the turbos have. There was a problem a year or two back where someone had a 2.7l N/a that was hitting the knock protection. He switched gas to 93 and it went away.

carlege

I think he has to be joking. if your oil pressure is fine and you dont hear any knocking then the bearings are fine.

931guru

Check for a broken intake valve spring, causing float and backfiring into the intake manifold at 5000 rpm or so.

Multipass

Rock, it is a 2.5 N/A. Good to know in case I get 2.7 in the future.

How do I check for a broken valve spring, compression tester? Do I have to take the head apart? I just had it put back on for a HG replacment.

Multipass

Just checked the resistance of both the speed and reference sensors and they both read about 1000 ohms between the pair of sensors closes to each other, so that is within spec.

On both sensors the resistance between the terminals farthest apart was infinite, should be over 1 M ohm so I guess that is within spec too???

See: http://www.clarks-garage.com/pdf-manual/ign-02.pdf

Rock

It has to be something that happens at a specific RPM. If the speed and ref sensors were faulty, you would usually experience intermittent starting problems.

Valve springs are a possible cause however. Did it do this before you pulled the head off to replace the headgasket?

Multipass

No, this started after the car was put back together. I had a shop machine and clean the head, so they should have noticed if a valve spring was faulty, although it could have snaped after installation.

Multipass

Can I use the 951 valve springs? They are a lot cheaper, over $100 savings for a set of 8.

During a search, I noticed a lot of people saying that normal valve spring compressors don't fit and the C-clamp spring compressor is the one to use, but what does that look like? Is there a specific one that people have used on a 8V N/A head?

Thank you all for your help!

Multipass

So I got to the valves and they all look fine under close inspection. I also pressed down on each one to see how stiff they are and they all felt the same.

Is there anything more I can do to check? Can they look fine but still not function properly?

By the way I was able to do this with without taking off the balance shaft belt, just loosened the T-belt and slipped it off the camshaft pulley.