not a 351, but 302 problem i need answered
 

Here we go, i got a 93 gt, brand new 302 short block with modifications the rest of the way out, but at 2600 miles, it started blowin smoke bad(burnt oil). I therefore ran a compression check when i found oil on spark plugs, all cylinders fine! Runs and idles like a champ still, blowin smoke like mofo! ok then oil in puddle in upper intake? has pcv valve, dont know what it could be with that much oil. Is it oil control rings you think that didnt sead all the way, or maybe valve guide seals but it wouldnt smoke that bad and let that much oil and they were brand new afr 165's so any answers please would help!

Re: not a 351, but 302 problem i need answered
 

starting with the simplest thing: Is the oil level correct, is it overfull?
Now to the not so simple things:
It sounds like oil is getting past the rings - I'd blame the valve guide seals if it happened under deceleration, or after sitting from a stop when there's vacuum. I'd blame oil rings if it's under acceleration. you'll get oil up in the intake from the scavanging pulses in the intake sucking back oil. Especially with oil on your plugs i'd say oil control rings/bottom end problem. What is odd is that it's on all the cylinders....hmmm.....Did you double check the clearance between the pistons and cylinder walls, or post-machining measurements on each cylinder? I've heard of alot of rebuilt engines having problems real fast because of slight machining errors/miscalibration.
The problem with compression testing a vehicle with an oil bypass problem is that the oil itself with help seal the combustion chamber.
....this is all i can think of.

Re: not a 351, but 302 problem i need answered
 

Be very aware.....I've seen soooooo many problems with AFR heads right out of the box that I'd question everything about them. Check the valve stem seals at vacuum conditions like 84GT says. You may also need to pull the upper and make sure that you're not sucking oil past the intake gasket. Pull the heads off and have them gone through by a good shop. Check the valve guides and seats carefully. Also have the springs checked while the heads are apart.

Re: not a 351, but 302 problem i need answered
 

Wow - I take you at your word Jeff, but I have rarely seen anyone else mention this problem on the boards - maybe AFR steps up, handles it right and when it's all over the customer thinks he's been treated well and doesn't biatch much.............AFR are the "darling" heads right at the moment seems like..........

Re: not a 351, but 302 problem i need answered
 

Want the 'darling head' for performance, look to what the guys in the heads up racing classes are running. Go through FFW, NMRA, OSCA, etc. and you won't find hardly anyone that runs AFR and wins with it.

Re: not a 351, but 302 problem i need answered
 

Our shop has been in business less that a year and I've seen one broken rocker stud (causing more damage), one broken spring (causing dropped valve....engine damage), and one complete head with whooped out valve guides in less than 1500 miles....all with this brand of head.

Re: not a 351, but 302 problem i need answered
 

LOL - like I said Jeff, I take you at your word, but you'd be "unpopular" on certain sites (close relationships with suppliers,spnsors and dealers & "clicks") and with certain dealers........it's good to hear the other more "independent" side.........and I have noticed what heads are used in the classes on winning cars but I don't get away - I watch what's in the pits at the WFC here in town.

Re: not a 351, but 302 problem i need answered
 

Yep, most everyone who's winning is using Trick Flow or Edelbrock heads. But, of course, hardly any of them are "out of the box" either.

Re: not a 351, but 302 problem i need answered
 

I thought I remembered someone else having this problem. Anyhow, if the engine was freshly rebuilt, It is possible there could be an issue at the machine shop, but I doubt that they would have screwed up all 8 cylinders. I personally agree and would look hard at the heads.
Ryan

Re: not a 351, but 302 problem i need answered
 

This may be my first post on this site, but I do have some first hand experience with this issue.

Everyone needs to calm down a little. Most likely this is just a crankcase ventilation issue.
First, are you using the stock screen that goes under the pcv?
Second, do you have the baffles in place on the valve covers?
These 2 very small and easy to overlook details can cause tremendous problems.

You know you have oil in the intake. The critical question is where the oil is coming from. If the TB/VC hose is wet with oil then look at the valve cover baffles.
If the line between the pcv and intake is wet, then maybe an oil separator will solve your problems. Steeda offers a kit, but you can also pick up an air compressor kit from Home Depot for a little less $.
If you are getting good numbers for leak down and compression tests, then I would think that the rings and valve guides/seals are just fine.
Wish you luck
jason

Re: not a 351, but 302 problem i need answered
 

Valve stem seals won't show anything in a leak-down or compression check. If the seals are bad, or have worked themselves off the guide, when the valve is open at idle and part throttle the engine vacuum will pull oil down past the valve stem and into cylinder, especially on the intake side. Some racers will actually run without any exhaust valve stem seals since there's no real mechanism to pull the oil into the cylinder from those locations. If the car smokes badly at idle and part throttle, I'd suspect the valve stem seals.

Re: not a 351, but 302 problem i need answered
 

maybe this is cause I just woke up, but I am not sure I am all that excited anyhow......
Ryan

Re: not a 351, but 302 problem i need answered
 

My Bad valve seals will not show on those tests
I just re-read the original post,
Do you have the screen under the pcv? Alot of times these don't get reinstalled on rebuilds.