Engine break-in timing and exhaust popping

have around 20 degrees at 2000 with the vac adv disconnected. Also getting popping at random through exhaust pipe. Ideas/thoughts from you engine builders?

How hot is too hot?

What's the popping from?

 

what engine is it? how hot is too hot....what hot are you asking about, spark plugs? water temp? oil temp? women? Do you have open exhaust? manifolds or headers? we need some more info before we can guess!!!

 

yep need more info... I had that happen from NO OIL PRESSURE.

It could be anything- do you have guages hooked up?

 

Pontiac 389. 60 lbs oil pressure. Running about 16-18 degrees timing at 2000. Runs right up past 240 degrees unless you shut it off. Runs a little lean if anything. Engine break-in always makes me nervous, but I know they get hot with all the friction from new parts...

Gotta drain oil and recheck the lifters, point gap, dwell, timing, idle mixture screws, then we'll see how it really runs.

 

Running a hydraulic cam?

Sounds like you may have it adjusted overly tight.

A lot of guys like to use the "spin the pushrod till it stops and then adjust" technique.

I find that you end up with overly tight adjustments doing it that way.

Much easier to lift the pushrod up and down while tightening the adjustment until you can see - intake manifold off - or feel that the pushrod has no clearance.

After that, tighten the adjustment to where you want it.
1/2 turn, full turn etc. whatever is recommended.


Far as timing goes, I like to set the engine at the initial setting - 6 to 8 degrees for my 462" Buick - then set the distributor so it fires at that point.
Doing it this way is no different than setting it up at the zero point.

Got a vacuum advance distributor?
For street use it's the only way to go imo.
Hook it up with the vacuum source selected to full time vacuum.

That should hold the overheating to a minimum.

Helps too, to have a big fan in front of the radiator to help keep things cool.
Heck two fans be good....

 

Shot plugs can cause it too. Check, or change 'em out. They may be grunged up from initial starting.

 

got a vaccuum leak ...? brandon

 

The fans in front of the radiator are fine but I've always liked a hose with slow running water better. You can just play the stream over the core in the front while having someone keep an eye on the temp gauge. Be sure ot set the idle at about 2,000-2500 for the first 15-20 minutes and keep it running the whole time. Constant start/stop can be the death of a new cam. C9 has stated many times the importance of having EVERYTHING set so the engine will fire and run first crank. I'll just confirm.

Frank

 

I'm not sure how a 389 with hydraulics is, but my 67 400 cu in, the rockers are tightened all the way down, no adjustment. I found out the hard way, tried to set them like a chevy, haha, they would stop rattling, I gave em anothe half, ok for a second then rattle! Pontiac guy showed up and said, Hahahaha. Lippy

 

sounds like the timing is retarded by about 15 degrees....

 

That sure would be my guess too. A new engine with retarded timing will sure get hot quick!!!!!!

 

Timing retarded would be my guess, looking for about 35* advance or maybe even more.

 

In my experience, popping in the exhaust indicates a lean condition. That would also explain the overheating.

Of course, all this depends on everything else being correct....valve lash, timing, no vacuum leaks, etc.

Good luck.

 

35* seems high for 2000 RPM... It's not that it got hot quick - just hot - like therm stuck closed. We could run it for 5-7 minutes @ 2000 before it got too hot. We used a ton of comp cam lube, EOS, and Rotella T for the break-in, and I figure running for 5-7 minutes then stopping is better than trying to run it over 240...

How do you set initial advance on a new engine without firing/idling it?

Valves are likely too tight - need to be readjusted I'm almost sure. This particular engine has adjustable rockers. Maybe the later ones didn't?

I think it's lean too - the carb is off a whooped stock 326, had a few lean backfires on this 389, and it lessened when I closed the choke by hand while he was running it & RPM went up. Already looking for jets - anyone have a good recommendation for a Carter size???

 

advance it till it either misses or won't crank, then back it off.

seriously...I always try to get the timing as close as I can before firing it, usually this means set the timing pointer to 10 degrees before and make it so the points are just opening, or if it's electronic so the reluctor "grabs".

30-35 at 2000 is probably just fine at least for now. Check the timing (vac disconnected ) at 2000, 3000, and 4000, and see what it maxes out at, should be around 35. My guess is it won't back off much when you let it drop back to 2000. then be sure to reconnect the vac advance

 

All Pontiac V 8's come stock with non adjustable nuts that bottom out on the step on the rocker studs. If you are using poly locks or roller rockers, that's a different story. In that case all you need to do is spin the pushrod when the valve is closed. When you feel a drag on the pushrod, turn the adjuster down about a half turn and lock 'er down. that's all you need. It sounds like you have a valve too tight.

To set initial timing, make a mark on the damper ring about 25 degrees before TDC. Line that up with the zero pointer. Hold the rotor with the centifical advance at maximum travel and install the distributor with the rotor blade pointing right at the no. 1 lug on the cap.
After you get in broken in and running good , use a dial back timing light and then set the timing at 32-34 degrees @ full advance. Then plug in the vacuum advance to manifold vacuum. If it pings at part throttle or on hills, get a Crane adjustable vacuum advance and tighten it up till the noise goes away. This is of course, if you don't have too much compression for today's pump gas.