[Hans Buijnink (72challeng]

Hi there, does anybody have a digital version of the nhra rulebook or know where it maybe could be downloaded? Or is anybody able to answer my question.

Last race when the pro's where judging my car if it may enter the strip they said to me that I had to tape (read close) the breather on my passenger side valve cover, the one that normally connects to the air filter housing. They said this is an NHRA rule preventing oil leaking on the strip when the car would flip over during an accident.

But through this breather (in combo w/ the pcvalve on the driverside) the engine should 'suck' air for regulating the pressure in the engine. So when I close one of these I may damage the engine. Or am I missing something here??

[Andy Neal (Tweety)]

Hans the best thing to do there is IF the tech guys continue to give you a hard time get a couple of the Moroso push in breathers and a couple of pieces of pipe and simply put the ends of these into a couple of 'catch cans' Beer cans work just fine!
You can then reconnect your stock PCV stuff when you leave the track.
In answer to your question the NHRA does have an on-line tech help thing where you can e-mail in questions, I used it once, I'll see if I can find the link for you, best of luck

[Hans Buijnink (72challeng]

Know what you mean Andy, thought about that myself too. But these catch cans have to be closed also. So then it still makes vacuum or not? The radiator overflow is already 'connected' to the window washer bottle. That time I wanted to put the hose from the breather into that bottle too but wasn't allowed.

Let me know if you get that link Andy, thanks.

[Dave-R (Roppa440)]

If your car flipped over in an accident with no roll cage they would be mopping up more than a little oil from your breather!

The breathers are there to stop the crankcase getting pressurised by the gasses that get past the piston rings.

Obviously if both are sealed then that pressure will build up.

So as long as you have one valve cover open to air pressure or a PCV valve connected to your carb the pressure you will be ok.

Some drag cars have breathers that connect to the exhaust.

Better to run with the air filter connected anyway Hans.

[Andy Neal (Tweety)]

and lots more just vent to the atomosphere, which is all I do, Hans K+N make some little ones that are sold by Moroso, these are weleded into the top of the valve covers, I have them on both the hemi and the smallblock.
I was never a fan of crank case evacuation using the exhuast to 'pull' the gases out.
I've never seen one that works yet, for now just vent it safely and when you get serious , buy a vacuum pump like those dang Chevys and Fords use

[Hans Buijnink (72challeng]

thx guys! Dave, why you say better to run with the air filter connected? One thing I still don't understand Andy; the weld in ones from moroso, if they are able to vent, then oil should also be possible to come in/out. Actually I was hoping to be able to show them it's allowed, so if you can find the link please pass it through.

[Andy Neal (Tweety)]

Well not really Hans they are baffled inside the tubes and the vapour that would come out is trapped by the element.
I've run the car at 3 NHRA tracks and never had any problem at tech. My buddy was racing in SuperComp in England at 8.90's with some and I don't think he ever had a problem. Check with your local tech inspector though, they may have a different view on this?
Best of luck mate and go kick some big blocks where it hurts, it's great fun

[Dave-R (Roppa440)]

If your air filter is restrictive then you are not using the right filter.

Every time you run the car without the filter on the carb it will suck in dust. Most of that gets blown out of the exhaust of course (after it has scratched your cylinder walls and valve stems like a micro sand blaster) but some of it gets in the oil too which is never good news no matter how good you think your filter is.

A good K&N filter should flow more than enough air for your small block. Have you seen how small the air filter is on a 440 six pack?

Having the PCV system hooked up should shut the "jobsworth" tech inspectors up too.

[Andy Neal (Tweety)]

Hum I've been involved in the debate about running airfilters at the track before, I can't make my mind up, but I don't run one, I figure the car really only travels 3/4 of a mile tops, then it gets shut off again. I have a plastic tool tray that goes over it when it's sitting around.
Dunno the answer to it really, a lot of racers swear that airfliters slow you down, but whether this is fact or fiction, who knows? And I'm certainly not going through all the hassle of re- jetting the carb to find out!

[Dave-R (Roppa440)]

That's the point. You only need to re-jet if the filter alters the amount of air going into the engine. A bad filter design means you have to jet leaner because there is not enough air. A good design means you jet the same or richer than before because the airflow is the same or better.

The 'big boys' of the sport don't bother because they have high tech air scoops etc and a filter would get in the way. They change engines every year or two anyway.

But for us 'normal' people a filter can HELP performance because a good one directs and smooths the air flow around and into the carb meaning you get more air in than without.

Remember that thing years ago (mid '70s?) when a lot of people in the US found that inverting the lid on their filter improved mileage by a large margin? That was because their filter lids had a buldge in the top which caused drag on the air going into the engine. Inverting it so it was dished increased the air flow into the carb and made the engines leaner.

This is why I don't use a stock lid on my six pack. I have the choke horn cut off and a dish in the middle of the lid.

Also think of those bits of grit hitting the valve stems at high speed. Some of them sticking as the valve retracts into the guide.

[Alex (Alex)]

An interesting point is when I had the Runner, it was a fresh air car so it had the 6bbl filter set up but on a 4bbl carb, if I ran with the filter on it was slow, if I ran with the filter off it was better, but, if I ran with the base on to shape the airflow but left the element off as well as the lid, it would pick up nearly a whole second! I never did work out why such a drastic change happened!

[Dave-R (Roppa440)]

Yeah. I feel the base of the six pack air cleaner is very good but the stock lid is terrible and the element is WAY too short. Not a lot we can do about that under a stock hood but a K&N filter and a little work can just about make up for that. You 4bbl guys have no excuse though.

Andy. When I looked at your Barracuda I saw you had a plastic thing on your carb to help air flow into it. A filter does much the same thing only some are good and some are BAD!

[Andy Neal (Tweety)]

yeah I threw the K+N snubstack in the bin though Dave, it was always in the way and since I did away with the air filter and just use the metal base plate nowto get the air flowing in the right direction, there was no point in me having it there.
I discussed this whole thing with Mr B and in his humble opinion it's all a load of cobblers anyway, the hemi cars run just as fast with or without anything to get the air into the carbs.
The only reason I still run mine is becasue I spent hours making that box and sticking the foam to it to seal round the scoop!

[Graham Shortreed (Transma]

Hans. We've got a Super Gas Big Block C*** sitting on the floor in our warehouse. This engine came out of a NHRA approved, race active car, and the breathers are indeed welded into the valve covers. I personally don't know if it an NHRA rule or not, but car is, as I said an active racer. Oh, and no air cleaner, just a couple of large Holley carbs on the intake.
As far as the air cleaner debate goes, I don't know who is correct. Personally, I think that when you invert the lid of the air cleaner, more of the element is exposed, hence, more air-flow than through a single or dual snorkle/inlet air cleaner. When I had my 340 Duster back in the 70's I did it when I raced it, but on the street, put it back the way it came from the factory. Can't remember if it gave me any better mileage, but for any normal or long distance driving, it was just too darn noisy for me.
Sure sounds neat though on the race track.
I know that at our 2 local race tracks here, I don't see too many cars running any kind of air cleaner or filter. There's a National meet coming up in Seattle in the next couple of weeks, and I'll have a look at the cars there. And hopefully, if I remember how the darn software works with that digital camera I got for my anniversary, I'll post some photos.