Engraver

Well, I thought the rebuilt motor and tko600 was complete but....
today I determined there is bad blowby through the rings into the crankcase.
I've driven it 5 miles so far.. babied it through the gears, put it in 2nd and took it up to 2000rpm and let off, and then 2500 and again at 3000. Did this for a few minutes.. about 5 miles worth. Next time out should I work it harder to help seat the rings? It has a total running time of probably 2 hours with a bunch of 10 minute runs in the garage while figuring out a head stud thread leak problem and an oil leak out around the distributor. I've just changed oil again. I had valvoline 10w30 in it but decided to switch to the valvoline 20w50 race oil. Is the 20w50 going to make it harder for the rings to seat?

Here are the pics...

RAT502

Kiss those rear tires goodbye!

stingraymaniac

Glassbowtie77

Very nice ride.

Pauld

Very, very Great looking motor and car

VETDRMS

How did you determine the rings were not seated? I would give it at least 500 miles before you make that determination.

Looks good, I am sure it will be fun.

stingry

I've driven it 5 miles so far..

Thats not enough to seat the rings IMHO. I followed the techique some people use. Take the car out and give it some high RPM and back it off several times. Do a search on google for breaking in engines and there are articles by motorcycle guys who talk about this technique. You need the back pressure from backing off full pressure to get the rings to seat on a new engine. Do that 2-3 time on differnent occasions (heat cycles) so that the engine comes up to temp and then cools down. Supposed to help seat rings better.

My engine has 1100 miles on the rebuild now. For the first 500 miles it blue smoke and ran hot. Now it is cooler and no smoke.

Good Luck

Pete

rcread

It's so pretty. Just park it in your living room and pop the hood.

Matt Gruber

after 2000 miles (PO rebuild) my 72 had 125
at 3000 it was 165
now it is 185 (head cange)

Fubba

Great idea!

Engraver

Matt, Are you talking about a compression test and that after the miles you mention it got better and better? I always thought after the first 500 miles or so the rings would be seated as good as they were going to get. That is great if not.

I found info for crate GM breakin :
http://www.sallee-chevrolet.com/Info..._break-in.html

Engraver

I wanted to put a pool table in our living room and my wife wouldn't let me do that. Do you think I'll get away with placing my vette in there? Come to think about it... who is boss around here anyway? I would like the vette and a pool table in my living room. My mistake last time was asking. I won't ask this time. I'll keep you posted. Please pray for me.

GOSFAST

The days of seating rings by driving passed about 40/50 years ago, just around the last year the "good-old-flathead" came off the line. If the block is done right and you choose the right ring combo, they'll be seated by your first road test. If not, find someone else to hone your block and pick your rings. We "leak-down" cylinders before we mount the engines on the dyno, then we check 'em after and there's no measurable difference. Build it, dyno it(sometimes), and run it. Don't let any engine builder tell you otherwise. Ring seating now is close to immediate. Thanks, Gary in N.Y.

bobs77vet

can i have the vette before the divorce attorney gets it?

chevymans 77

I do not see a PCV valve. Do you plan on running one? The face of the rings will seat to the cylinder in a fairly short time as long as the cylinder has a good hone gob on it and it is true, the time it takes the rings to seat to the piston grove will take longer.

Neal

LFZ

nice ride.

Engraver

The PCV valve is on the top rear of the passenger valve cover... breather on the other. The pcv valve can't keep up with the blowby. The only way I can get it to keep up is to remove the inners of the pcv valve so that the carb is sucking without any restriction on the valve cover. I've been testing if it is keeping up by feeling if the other valve cover is blowing or sucking. I'm planning to purchase a fiber-optic bore scope on Tuesday and look at the cylinders through the sparkplug holes. I want to do this before running it anymore to make sure a ring didn't break and is tearing up a cylinder. Did a leak down test and pretty much all of them are leaking past the rings. Number 3 is a lot worse than the others.

I notice something else... when it first starts I hear a slight knocking noise. If I hold my head right over the carbs it is loudest there. After 5 minutes of warm up it goes away or maybe changes to more like a slight valve train noise. I have a hydraulic roller cam and roller rockers. I've checked and rechecked that the rockers are set right and they are. They are 1/2 turn in from 0 lash.

I've talked with my friend at NAPA machine shop who put the bottom end together. He was over and helped with the leak down test. He is concerned too and assured me if there is a problem he will help remove the motor and get it to his shop so he can pull it apart for no charge for labor or parts. Right now I'm just hopeful the rings just aren't seated yet but the builder seemed pretty concerned that it shouldn't be leaking past the rings as bad as it is. He said he did a vacuum test on the cylinders there at NAPA after installing the pistons and they were sealing good then... and no way as bad as it is now.

Gordonm

I have always been on the understanding that they should seat very quickly if the machining was done correctly. I have never broken in a motor by varying rpm and backing off the throttle etc. I just break in the cam and drive it like I drive it all the time. My motors have never smoked and never had a problem The machine work is what needs to be done correctly. Mine did loosen up after about 500 miles but they were very hard miles.

1pfieffer1

The last engine I had to have rebuild was 5.7l from a 97 Tahoe. I was worried about breaking it in because I had to go to Connecticut to trailer a jeep back. Engine builder said that would be the best thing for it, just like a dyno run, just vary the speed while doing it. Worked out very well.