The Stovebolt Site Forums The Shop Area Engine Shop Running engine with header exhaust leaks

I've been told that there is the possibility of damaging valves by running an engine with a header leak that occurs at the head. Can someone confirm (or dismiss) this? Thanks.

Only time that I've heard of warping a valve happened when they were running uncapped headers in the winter.........yep racing.

Does this mean the 500 hp 292 is running?

very funny chiphead.

Yep IT'S ALIVE!!!

What's your take on the subject? The truck is now at an uncle's (where the engine and tranny were installed). It's an hour (and approx 65 miles) away and I can't fix the exhaust leak at his place. It'd be much easier to do at home in my garage. I was thinking of driving the truck home in said condition but don't need to waste a valve (or valves) by running it if the risk is great.

I'd rather pay 150 bucks to have it towed rather than spend twice that (or more) on headwork.

Thanks,
-tyler

p.s. To be exact, chip the engine dynoed at 402 HP and 396 lb/ft of torque at 5850 RPMS. Yes. Of course I'm lying! :p

I assume you have a slight to moderate leak between cyl head and header flange? You check gasket fitment and bolts already? Exactly how bad its it? You prolly will only ruin the exhaust gasket and get some soot on the motor. However, any new engine doesn't need to run at sustained speed for that long. So far I've been on three 25 to 40 mile jaunts with my 235/sedan setup to seat the rings. I've been accelerating in 1st and second and letting the engine slow the car back down, to work the rings. You could prolly drive 20 miles, stop at a gas station and check stuff out, let it take a break then continue another 20-30 miles. Lather, rinse, repeat. Bring some tools, a cell phone and a fire extinguisher with you.

Have you done the cam break in? Have you driven it yet? How does it run?

chip

How does it run? Heh, the old stock 250/1 bbl it replaced seemed to have twice the power. Literally! I'll worry about that later - adjustments and breaking in will take care of that. I've driven it about 10-12 miles in 2 to 3 short trips to break the engine in. My uncle may have driven it more this week, but probably not much.

I do want to get this thing fixed asap. I can drive the truck home at around 2k easily, now that I have overdrive. So turning lots of RPMS is a non-issue.

The engine has been started many times (maybe a dozen and a half by now). So the cam should be well broken in.

-ftyler

You could buy a $5 tube of JB Weld and hope it holds between for the trip home...?

FYI we had a 40's **** flatbed truck that we used every year during harvest. It had a manifold leak when we bought it, and it had a manifold leak when we sold it 20 years later... No apparent damage.

But, better safe than sorry...!

-Boyo

Drive it.

In theory, with open headers, you can draw enough cold air in to maybe cause a problem. But a leaky gasket? Fuggedaboudit! Drive the thing. I've driven for years with exhaust leaks, BFD. Never had a problem.

Cheers!
George

Once burned a wee pie shape out of the #2 exhaust valve of a 250-6. Had a huge hole in the exhaust (several inches open) just below the manifold flange and that took 7 hours of sustained high RPM hyway (Toronto to Quebec City) to cause. Loss of exhaust back pressure will effectivly lean the engine out at hi RPM, but that's a big hole you're talking about. A gasket leak, or a manifold crack at reasonable revs shouldn't hurt anything. Is there a running 292 out there that DOESN'T have an exhaust leak??? What do they sound like?
Drive it!

Jim,

An exhaust leak under the hood is very distinguishable. You'll hear the air very clearly put-put-putting away from the side of the head. And in my case since the engine is running a tad rich you can clearly see black exhaust smoke blowing from the rear three cylinders at the gasket.

Think I'll just change the oil and drive it. If nothing else I've got Triple A Plus to tow it the rest of the way if it breaks down. Thanks guys!

-ftyler

I'm going to go against the grain here (that's nothing new) and recommend you fix the problems before you drive it anymore. For a baseline, understand that you have TWO known problems. That engine is too good looking to accept what you describe as very poor performance. If you had a bad exhaust leak from the get-go, you very probably also have a vacuum leak. Same gasket, same clamping.
I know you're very fond of the method you used for installing the manifolds, but I think it's the source of your problem and will continue to be. If you look back to Our previous discussion you'll remember what I'm talking about.
look at the picture at the bottom of page 95 in Leo Santucci's book you'll see that he also uses the studs. I think he copied my idea. Ha,Ha.
The felpro gaskets I was referring to are #1257-int, #1448-exh. Do not use them.
I've been wanting to ask you this question for weeks. Did you put that engine in the truck with the headers on it and the front sheetmetal on the truck?? I can't shake this nightmarish vision of sliding that thing in there with the waterpump pointing straight up in the air and the headers pointing straight down.

Richard,

To answer your question - yep! We dropped that baby in with the headers in place. That's also how I ended up with a leak, apparently. Those headers were completely sealed before dropping the engine in. How do I know? The front header is leak free. The rear header (which sits lower than the front) banged the tranny crossmember on the way down. And i'm convinced that's how I got the leak.

I wanted to drop it in that way because I know how difficult tube headers are to seal on inline 6s. So I spent hours getting everything sealed before hand. As I was lowering the engine in I took it down a little too fast and banged the exhaust. I knew then I would have problems and, lo and behold, leakage problems I do have.

Dropping the long engine in with headers that extended 10 inches beyond the back of the block without removing any sheet metal or inner fenders was a 2 person job. It would have gone off without a hitch if I just hadn't taken the ram of the cherry picker down too fast. :mad:

-ftyler

That's my point, it shouldn't take but 5 minutes. With the studs in place,

• set the gasket on the studs
• set the headers on the studs
• set the intake on the studs
• set the clamping hardware on the studs and tighten the nuts

You don't have to hold anything. You don't have to fight to line anything up and the nut has a fine thread, which gives you more clamping force with less torque on the nut.
I'm assuming here that you checked for any interference between the manifolds and that you massaged the clamps so that they compensate for the two different flange thickness.

I should add that when I first put my headers on, they leaked really bad and that was with the $30 Felpro Protoseal. I put the studs in and the cheap gasket and all was well. That was ten years ago and still no leaks.

I remember well my Uncles dirt track Flathead V8's were run without exhaust manifolds. Never a vlave problem.

FT- If you've got no power, check your vacuum and ign timing. Its a cumulative thing: Any one issue won't make a diff, but running an engine for 60 miles thats got a header leak, intake leak, running too rich and ign timing off is baaaad.

chip

You'd figure that with...

a 292 straight six, bored .060, .464I/.490E lift cam, 500 cfm 4 barrel, headers, HEI, 3.73 ratio 12 bolt rear end, and 3.09 first gear 4 speed tranny

I'd at least be able to turn one tire on gravel! But anyway...

How'd you do the valve adjustment? Is this a hyd or solid lifter cam? Valves aren't too tight or clattering, eh? You sure you got the cam/crank phasing correct?
Whats your ign timing set at?
How do your plugs look?
How much vac you got at idle?

For example here's my 235 setup
'60 235 bored .060"
'54 crank cut 10/10 balanced
badger cast pistons balanced
'61 recon rods, balanced
head shaved .040", block shaved .010" .040" gasket
M4F cam 220 dur .420 lift, metal timing gears
holley 390 4bbl on water heat intake, 53 pri jets, 6.5 power valve.
fenton split exhaust, 2" pipe w/smittys
recurved stock dist with petronix. 12 degrees BTDC. 16 inches of vac at 750 RPM. Runs strong & quiet. (knocks on wood)

So I figure your motor is prolly just out of tune, cuz a 292 should have plenty of torque from idle to 4000 rpm at least. But don't wind it that high yet....

chip

Chip,

I pre-adjusted the valved before the engine was fired. I wasn't around when it was fired the first half-dozen or so times. My uncle fired it first. Didn't notice the header leak until the exhaust was completed from the collectors back.

The cam is hydraulic - I set it the typical way. Set #1 piston's valves by adjusting the rocker arms to "zero lash" plus about 1/2 turn. I rotated the crank to #2 position and repeated. Did the same for each cylinder.

My first concerns are the leaky header and fixing the temp gauge. I'll change the oil Saturday and see if I can figure out the "hissing" sound that we hear when the engine is shut down after running a few minutes. Some people say that it's air in the system. It's most pronounced on the lifter side of the block. I'll figure all this out once the exhaust header problem is fixed.

-ftyler

Try plugging the vacuum advance line and see if you still hear the hissing after shut-down.....

Luke,

What would that tell me?

Did you soak the lifters in oil before you installed them? A vacuum gauge will tell you a lot at this point. like if your valves are set right, if you've got a leak, if your ign timing is close, if your carb idle adjustments are close, etc.

chip

I did not pre-soak the lifters. I only dropped a few drops of oil in the tops (and of course use moly lube on the bottom) before I installed them.

One thing that I've found out is that the standard stock 292 oil capacity is six quarts and I only bought five. Guess it would help to add in the extra quart, huh. :rolleyes:

But chiphead I can't see the problems from not presoaking the lifters now that the engine has been run a few times and has 5 or 10 miles on it. :confused:

-ftyler

I just wanted to make sure that you didn't collapse a lifter when it first fired up. I assume you'd notice a miss or noise or something if any valvetrain parts had gotten damaged.

I'd suggest tuning it a bit before driving it home.

good luck!
chip

Maybe become a member of AAA and have it towed home after all. Or rent a trailer and do it with a buddy's truck. You asked these guys too many questions in the past 6 months to blow it now. Someone would start yelling wasted bandwidth or something...

ftyler: Here is a voice of reason. Example; we run our stock car dirt track on open end headers, pull the heads the last 3 yrs and have not seen one bit of trouble out of our 350 running high RPM's maybe we're lucky I don't know but everybody does the same thing.

New motor I would be concerned because of the seat time, also you said it smokes a little, you'll have to clean motor when you get home baked on oil not easy to remove if the motor freshly painted. If you feel good about motor go for it if not do as above. Rent trailer or get buddy and get it home! popcorn The Truth is Out There (Good luck and let us know)

Tony M your points are well taken.

popcorn,

The smoke is not oil, but gas - where the engine is running a bit rich.

Guys I hope to get this thing home this weekend. I've got about 2, maybe 3 weeks to get the bugs worked out before the truck is set to the side for at least six months. Our second little one (we know it's a boy) is due November 13th. If anything goes up for sale you guys will be the first to know.

Thanks for the help guys!
-ftyler