Q-jet Questions

[a pontiac]

For the newbies, please reread Danny's last paragraph. Its the core, the best builder, the best flow bench, the prettiest rebuild will not make a fast q-jet. Borrow a known fast q-jet, buy several cores, rebuild them, run them on the track. Then get the best one done by a good builder. Just my experience. I don't think the same process works for stocker heads any more.

[oldskool]

Originally Posted by Bill Diehl

...there is more to be gained by the proper valve job than there is in testing heads. This pertains to my combo, the Boss Ford, which happens to be one of the highest flowing "stock" heads on the planet...your mileage may vary on other combos though

Yeah, I can understand that you can't be choosy when rare heads are involved. But what I'm talkin about is when your dealing with a very common and cheap head like the Pontiac 6x.

Anybody who has ever put a stock size intake or exhaust gasket up to the head and checked out the port size, knows that the size and shape of the ports can vary greatly even with exactly the same spec heads. When you just do a simple gasket match, you will need to grind different amounts, in different places on each head.

Therefore, not every 6x Pontiac head is created equal. Common sense says that some will flow slightly better than others. And since no porting is allowed, my thinking is that even the best valve job in the world can't make a worse flowing head, make more power than the better flowing head with the same valve job.

Now this is just country boy thinkin. If I'm wrong, somebody please explain to me how the head builder can make the worse flowing head make more power than the better flowing head, without porting. Hey, I'm not talkin 50hp difference here. But it seems that class racers are always lookin for hundreths and even thousandths of a sec. Correct ?

[Bob]

Originally Posted by oldskool

Yeah, I can understand that you can't be choosy when rare heads are involved. But what I'm talkin about is when your dealing with a very common and cheap head like the Pontiac 6x.

Anybody who has ever put a stock size intake or exhaust gasket up to the head and checked out the port size, knows that the size and shape of the ports can vary greatly even with exactly the same spec heads. When you just do a simple gasket match, you will need to grind different amounts, in different places on each head.

Therefore, not every 6x Pontiac head is created equal. Common sense says that some will flow slightly better than others. And since no porting is allowed, my thinking is that even the best valve job in the world can't make a worse flowing head, make more power than the better flowing head with the same valve job.

Now this is just country boy thinkin. If I'm wrong, somebody please explain to me how the head builder can make the worse flowing head make more power than the better flowing head, without porting. Hey, I'm not talkin 50hp difference here. But it seems that class racers are always lookin for hundreths and even thousandths of a sec. Correct ?

If you don't believe stocker heads and intakes are being ported, you have an education coming. I'm not saying that to be mean, I'm saying it so you know what you are up against. It would be tough to find a truly untouched head on anything that runs more than .50 under (unless you are running a odd combo or a turbo).

For cores, yes you want the best cores....head, intake, or carb. What you start with affects what you end up with.

Listen to Danny Ashley. He knows his stuff.

[ustahava67]

Some good Q-jet info here for DIY people
http://racingfuelsystems.myfunforum....forum.php?f=26

[oldskool]

Originally Posted by Bob

If you don't believe stocker heads and intakes are being ported, you have an education coming. I'm not saying that to be mean, I'm saying it so you know what you are up against. It would be tough to find a truly untouched head on anything that runs more than .50 under

So, what you are saying is that most all the really quick cars are running acid ported heads that will pass tech. Is that correct ?

Hey I've done some dirt racin. I know all about racers running illegal stuff and getting by with it.

So are we talkin several 10th's difference when using these "ported but legal" heads ?

I'm just curious. For you guys who have been around this for a long time, have ya'll seen some racers disqualified for these "ported' heads ? Or have the top head guys gotten so good with it, that the tech guys can't detect it. Or do the tech guys know all about it and just let it slide ?

[Dave Noll]

Originally Posted by oldskool

if I'm wrong, somebody please explain to me however the head builder can make the worse flowing head make more power than the better flowing head, without porting.

Swirl ?

[Dwight Southerland]

Anybody who has gone through the process of flowing a bunch of truly raw heads thinking that the ones with the best flow number in that state will be the best after legal prep only to find out that what really matters is the area from the top of the valve seat to about a half-inch below after the work is done can attest to the fact that you can go very fast without acid porting heads.


Long statement, I know. Digest it.

[Bill Diehl]

Originally Posted by Dwight Southerland

Anybody who has gone through the process of flowing a bunch of truly raw heads thinking that the ones with the best flow number in that state will be the best after legal prep only to find out that what really matters is the area from the top of the valve seat to about a half-inch below after the work is done can attest to the fact that you can go very fast without acid porting heads.


Long statement, I know. Digest it.

Exactly....that's what I meant earlier


and...if you are flowing heads before that work is done....you are wasting your time gathering meaningless information

[oldskool]

Originally Posted by Bill Diehl

Exactly....that's what I meant earlier


and...if you are flowing heads before that work is done....you are wasting your time gathering meaningless information

So then, if I'm understanding this correctly, you guys are saying that even if you use a set of heads in which at least one or more of the ports are badly misaligned with the gaskets, there are guys who can make up for this with their expert valve job, and those heads will make just about the same power as that same valve job done on a set of heads in which most all the ports are fairly close to the size and shape of the gaskets ?

In other words, your saying that the shape and location of the stock ports will make very little difference to the power output of a stocker engine ? But the power is all gained from the valve job ?

That is VERY interesting ! I'm glad I ask the question. You see, I've been living in the world of bracket racing, since there is no class racing close by, or wasn't until recently. All I've heard is that you always need to port iron heads or at the very least do a simple gasket match.

But if what you guys are saying is true, then unless I'm shooting for #1 qualifier at Indy, I'd be wasting $ to pay "Heads Up" for their " better than acid porting" head treatment which they advertise on their website ?

Next question: The Pontiac engine shops get nearly $2000 for a set of 6x Pontiac heads with their valve job and CNC porting. So aprox what would it cost to have one of the Stocker head shops do just their magic valve job on a set. I don't need an exact figure. But for some of you guys who have had this type of head job done recently, was it about $2000, $2500, $3000, OR ?

Now for an opinion question. Do ya'll think it's possible to run just slightly under the index with one of the good Pontiac 350 or 400 combos, with just the usual 5 angle valve job that most Pontiac shops advertise ? Or is there enuff power difference in the real Stocker heads to make them a requirement to get you under ?


Hey, ya'll will just have to excuse the dummy questions. I don't have any Stocker buddies to ask. So it seems to me that the best guys to ask are those who have been there and done it. OK ?

If I decide to build a Stocker, I don't want to buy a $1000 valve job, only to later find out that I needed a $2000 job from somewhere else to get the car under.

Thanks for all the info guys !

[GTX JOHN]

Not a problem to run well under the index with a budget Pontiac.

On our cars the difference between the best magical stuff and a
set of stock heads ( with a decent valve job and CCd ) is only a
couple of .10s of a second.

You can learn a lot by a careful inspection of ports and valve placement
just by eye. We used to go to a lot of swap meets and just look at the
heads for differences.

NHRA polices the heads and checks runner CCs much better
and closer than it used to be several years ago.

Heads Up races do not happen every race and I have seen very successful
racers in Stock on a very tight budget. Give it a shot!