[jarretts70]

This car is going to drive me crazy...

78 Trans Am. I've had a few threads about it before, but here is the quick back story: Original 220 hp 400/th350. Original engine long gone. I got it as a disassembled basket case 8 years ago. What was supposed to be a quick paint job & re-assembly has turned into a 8 year battle. However, it is finally almost there. Got it registered & started driving it about 3 weeks ago.

Engine is a 428. I had a recent thread where I was getting help with carb tuning & everything was going really well until last week. Last Sunday my family & I went to dinner with it, about a 35 mile round trip. Leaving the house it was fine, but on the way to the restaurant something changed. The engine started to sound different, and a rattle started coming thru the floor. Also seemed down on power. When I got it home & crawled under I found 2 muffler hangers had failed. Replaced them with new ones this week & assumed my problem was solved & fired it up. Noticed some smoke that wasn't there before, but figured it was just junk burning off the new exhaust parts & didn't think much of it....I only ran it for a minute.

Tonight went to drive it. Upon startup realized there was blue smoke coming from the drivers side tailpipe. And a noticeable smell of burning oil. It drives awful from a stop, no power & stutters. Cruises fine at speed.

Got it home & started pulling plugs on the drivers side. Note plugs are new, changed them as part of the tuning process in my last thread. Number 1 is an oil soaked mess. 3&5 looked fine, and the motor was too hot for me to wrestle around the brake booster to check #7.

I'm pretty sure I know the answer, but I might as well start with a compression check. But to be honest it's been a really long time since I did a compression check. I loaned my gauge to someone so long ago I don't remember who....I'll get one. Any tips on what to look for, & how to proceed?

If I have to pull the motor on this car I'm going to snap. Or cry. Maybe both.

[jarretts70]

Here are a couple not so good pictures of the beast. Forgive me the wheels with bow-ties. I borrowed them from a friend with a Camaro. I've got a set of 15x8 snowflakes but haven't got them restored yet.

[chiphead]

Pull the valvecover. I'm betting a valvetain failure.

Remind us of the parts in this build?

[jarretts70]

428 from a 68 or 69 Grand Prix, can't remember exactly..

I bought the engine as as assembled long block from a classified ad many years ago - 2004 or 2005. I was going to use it in a different car & wound up going a different direction. Guy I bought it from had the receipts for the machine work - local shop with a very good reputation, still in business. I got the receipts with the motor but lost them somewhere...Fairly basic rebuild with some mild upgrades. Hyperutectic Keith Back flat top pistons, .030 over. Crank turned 10/10. Block was decked just enough to clean it up. I lost the cam card with the other papers but from memory is a flat tappet 220 degrees @ .050 or so. It sat in my garage oiled & bagged up for years until I decided to use it in this car. I pulled it apart to put fresh assembly lube on the bearings, cam, etc....everything looked good. No rust or anything from the long term storage. Super pissed at myself for losing the papers....

The entire top end is fairly stock stuff as well. 6x-8 heads, cast intake, quadra-jet. Ram Air III manifolds from a 68-72 A-body. Proper dual exhaust. I crunched the numbers way back when using an online calculator & figured the compression @ around 9:1, but the general opinion of others (on my last thread) was it would be lower, so call it 8.5:1

Got it running in the car about 2 years ago but the car was a long way from complete at the time. Broke it in with Gibbs racing break in oil. Had a old-school mechanical oil pressure gauge on it for break in, pressure was excellent. On the factory gauge now, still reads good. Because the car wasn't complete I never really drove it other than in & out of the garage. A couple weeks ago once I actually started driving it I did an oil change - ordinary 10 w-30 with a pint of Edelbrock zinc additive. Until now the car has run great, no smoke or sign of oil consumption. Starts & drives as good as my 2013 Silverado...My only issues were with the carb tuning, and as noted that was going in the right direction.

FWIW, I thought to stick my finger into the drivers side tailpipe tip. Lots of oil.....found a friend with a compression gauge I hopefully can grab tomorrow. But I'll pull a valve cover first to take a look.

[jarretts70]

OK, good call on pulling a valve cover....#1 intake.

This goes a long way to explaining the lack of power and weird engine sound, but I cant figure why the oil burning? Two separate issues?

In the morning I'll run thru all the valves & road test. Think I'll still do a compression test too. If I have good compression but still burning oil I'm thinking vale stem seals? I replaced all the seals when I switched the heads bu tmaybe I screwed something up...

[jarretts70]

Forgot picture..need to go to bed.

[surfsama]

You could get lucky and it's just a valve seal that's come off.

That's a beautiful car!

[steve25]

What are you running for rocker arm studs, the stock bottle neck studs?
At this point you really need to pull the Intake and valley cover to see if that lifter still has its plunger clip in place, or if it's popped out!

[jarretts70]

Yeah, stock studs & stock type rocker arm pivots & nuts (new parts, just stock type). Didn't think the cam was big enough to dictate new studs & poly locks, plus I want to keep stock valve covers on it and didn't think poly locks would fit. Going out to the garage now to pull the other valve cover.

Surfsama - thanks for the compliment. I'm going to try rig up a fitting to hold the valves in place so I can pull the springs & check for a bad valve stem seal.

[Tom Vaught]

Originally Posted by jarretts70

Yeah, stock studs & stock type rocker arm pivots & nuts (new parts, just stock type). Didn't think the cam was big enough to dictate new studs & poly locks, plus I want to keep stock valve covers on it and didn't think poly locks would fit. Going out to the garage now to pull the other valve cover.

Surfsama - thanks for the compliment. I'm going to try rig up a fitting to hold the valves in place so I can pull the springs & check for a bad valve stem seal.

What are the specs of the camshaft that you put into the engine? Please post this info.

Tom V.

[ponchjoe]

Originally Posted by Tom Vaught

What are the specs of the camshaft that you put into the engine? Please post this info.

Tom V.

"I lost the cam card with the other papers but from memory is a flat tappet 220 degrees @ .050 or so.

What type of break in procedure did you do when you fired it up? Did you use break in oil? I hope you have not flattened a cam lobe.

[chiphead]

Either the rocker arm nut backed off, or the pushrod bent. If you're lucky, it was pumping oil past the rings due to the intake being stuck closed. That would clear up once the valvetrain is fixed correctly. All that vacuum during the intake stroke with the intake closed is going to pull something from somewhere.

Were the nuts torqued to factory 25 ft/lbs, or was it set to zero lash like an adjustable valvetrain? Did you check the pushrod to verify it was straight?

I would be worried about maintaining proper lifter preload, and avoiding valvespring coil bind. Do you know what springs and IH was used? Were the guides cut for Viton seals? Stock guides are big and tall, and will likely hit the stock retainers above .480 lift or so.

You've got to do the detective work to ensure all the parts will work together.

[jarretts70]

Break in: Gibbs racing break in oil. Comp cams additive. Set up a big fan in front of the car in the garage set on stun to keep air moving thru the radiator.

It started right away, so I did not have to spend a bunch of time cranking it. 15 minutes of non stop varying rpm, between 2000-4000. Changed oil, repeat for another 15 minutes. Changed oil again. Ordinary 10w-30, with a bottle of Edelbrock zinc additive.

I don't believe I've wiped a cam lobe. The oil has been clean of metal particles when changed and the car was running really well until this point.

[jarretts70]

When I pulled the engine apart after its long term storage I did the following: I knew I had lost the cam card, so I set up a dial indicator, using an old solid lifter on the cam. Pushrods were new. Total cam lift was right around .305, so I believe I should see .460 at the valve (stock replacement rocker arms)

I also mocked the engine up. One piston/ring assembly & valvetrain, used a lightweight checking valve spring. Lots of piston to valve clearance with the old play doh test. Contact pattern on the valve stem tip was within reason so I called the geometry good. NOTE: I thought the spec on the rocker arms was 20 pounds, not 25. So I would be loose on all of them. I'll adjust all of them accordingly.

This morning I checked the pushrod the only way I know without tools I don't own - rolled it down an inclined piece of glass. Appears straight as new. Just in the process of setting up an air fitting to hold the valve in place so I can pull the retainer & check the seal.

[gtofreek]

I'm pretty sure the torque on those rocker nuts is 20 ft. lbs. If they are torqued too much, the chamfer at the bottom side of the nut[where it jams up against the taper on the stud] will get micro cracks, and it will spread when torqued down, and the nuts will not stay tight.

[jarretts70]

Here is where I'm at:

Double checked all the drivers side rocker arm studs, they were all still torqued to 20 pounds. The only loose one was the one in the picture, and no apparent reason why it would have backed off. Maybe I never torqued that one in the first place? (hopefully it's that simple). My attempt at a homemade air tool to keep the valves in place was a fail (need to go get some parts), so I haevn't checked the valve stem seals yet.

Decided to give it a try - put the rocker arm back together and to see what would happen. Started & idled fine, still a bit of oil smoke but less than before. Took it for a short drive, around 2 miles. Power is back & it sounds normal again. Oil smoke situation getting better as it runs more.

My best guess is that as chiphead suggested it was pumping oil past the rings, then back out the exhaust valve where it would build up in the exhaust. As soon a the exhaust got hot the built up oil would start to burn, hence the smoky & oily tailpipe. At least that's my prayer...

I'll let it cool down, then pull the valve covers again to make sure none of the rocker nuts have loosened. Still plan to do a compression test, a friend with a guage (and experience!) i supposed to come by later...

[MarkS57]

I had a rocker fail on me years ago. The ball actually pulled through the bottom of the rocker arm, have you looked over the arm itself? It was a stock cam set up, nothing more.

BR's,

Mark

[gtofreek]

Did you check the taper on the nut for cracks?

Piston rings rely on combustion pressure to seal up, and clear the oil ring groove of built up oil. Ring tension on the compression rings is not enough to seal them. When combustion takes place, the pressure pushes down, and gets behind the top ring and pushes it down against the piston ring land, and out against the cylinder wall. The pressure that gets by the top ring, then goes past the second ring[which is not a compression ring, but rather an oil scraper ring], and blows down into the oil rings, and clears the oil out of them. When no combustion takes place, the oil builds up in the oil ring groove, and starts pumping past the compression rings, causing oily top end of cylinders.

[1973ramairman]

I have a similar problem with my motor, started running rough and no power a bit of smoke on wide open throttle . Posted a thread got some good info , possiable valve seals or guides, did a vacuum test and found the indicator vibrates at idle , according to diagnostic cards this seems to be the issue for me. Very easy to check get a vacuum gauge and hook it up to manifold vacuum and see what it does. Check against diagnostic charts on line and this could help with out pulling apart the engine at this point.

[STEELCITYFIREBIRD]

Most new compression testers have a quick connect for the gauge to hose that easily doubles as a hose to pressurize the cylinder for valve spring removal!
HTH