Technical Straight headers=burnt valves?

That's pretty much what I thought, but all of this discussion is like going back to school for me. I've never gotten into any exhaust science.

For my little car it's going to be a matter of 3 into 1, and there won't be any choice in clocking. At the ends, the 3 pipes will be side-by-side.



I have managed to find flat 3 into 1 collectors for 1.5" pipes in, and 1.75" out, and only 6" long...so if I'm not happy with the individual pipes, I will have an option.

BTW...The guy who mows our yard, who is a Harley guy, is lobbying for 3 fishtail tips on each side...LOL

 

Holley: Chapter 1 verse 1 reads........ " thou shouldest err on thou side of enrichment & readest thy spark plugs porcelain, striving & holding steadfast for chocolate browness of color. Lest thou shouldest scorcheth a valve whenceforth it mayest not seateth proper. ". Flux

 

I always scoffed at the warped valves thing. Sounds like total bullshit to me, but then...... A buddy had a Rambler with a 6, he took the exhaust off because he wanted to redo it and was driving open manifold. I told him it was fine until he got his exhaust done. After a month, it started running rough and shaking like crazy.
His dad said we warped the valves with no exhaust. I called BS and we pulled the head. Every exhaust valve was cracked and seating poorly.
So we had the machine work done on the head and new valves installed. Put it together and had it running right.
Well, he's lazy and never got to the exhaust, running open manifold for a few months and guess what....
Started shaking again, we pulled the head to find the exact same cracks on the exhaust valves. It got exhaust after that valve job.
I still dont totally believe it, but there is no other explanation.

 

Retarded ignition timing.

 

I am no computer guy put there is a proram called pipemax that ALOT of FAAAAST CATS! use as a formula telling how long and what size to build an exhaust system for any given application with the specs you enter... I am talking about a header that MAKES POWER!!!

 

I had a 3 wheeler I rode with no exhaust, made great power accelerating, the cold air on deceleration snapped the exhaust valve off making a big mess, maybe less of a big deal if not getting airflow directly into the exhaust port.

 

There are good programs for calculating exhausts.
On a 4-stroke any contraption works...more or less...
On a 2-stroke you actually cant win anything without a good exhaust.
And its always a choice between torq low/high end and hp so 2 different can be as good but for different aplications.

 

Correlation does not equal causation.

 

Way too lean from running no exhaust.

 

Open exhaust-no valve problems. Bad valve job, lean mixture, retarded timing-yes. You know, when de-accelerating, the exhaust does not go up the exhaust pipe. It still goes out.

 

LOL we used to laugh at the guys with fishtails.

 

i been spraying form oil in my headers of my boss-9 34 cpe to fog mosquitos, do you think that will burn the valves? bugs run when they see me comin.

 

But it wasn't. This is what we checked on the first go-round.
Only engine that has ever given me this issue.

 

calculates a HELL of a lot more than just exhaust size/length.

 

One thing missed in all this discussion is exhaust manifolds (whether they're cast iron or straight tubes) act as heat sinks, drawing some of the heat away from the valves. Open pipes per se won't cause this issue, but none or very short ones can.