Holley stubstack

-
I don't have one anymore but when I did, I found that my particular combo needed to be 2 jet numbers richer because it helped airflow enough to lean it out that much. It did help ET a bit but don't recall how much.

Naturally it helps to have your jetting as close to optimized as possible.to begin with. Otherwise, if you're on the rich side, adding a StubStack can lean the engine out a bit and be faster right off the bat. If it's lean to begin with, you could lose ET by putting it on.

I've has an engine lean out a bit just by taking off an air cleaner but retaining the base to keep the airflow consistently smooth. This was with a K&N air filter and it does depend how restrictive the air cleaner is to begin with.

Test, test. test!
 
Last edited:
Yes, they definitely work. Like the guy said, you will need to reject. The K&N air filter will give you more power as well.
 
I’ve got to agree with Locomotion. I found exactly the same results. The best result I found at the time was the taller the filter I put on the better it was. Clearance above the carb made a positive difference. In my case, it was a 600 AFB. Tallest filter I used was a 4 inch IIRC.

Engine masters did a similar test, no stub stack though, but found it the filter was taller it performed better. Check out there air cleaner test.

The only thing I’d like to re-try myself is a K&N filter lid and start testing filters at 3 inches in height and go taller from there. Perhaps mimic the engine masters findings? IDK, but I wanna try it. I thought about this before I seen them do it and had a thought that it may work. I reasoned this with the use of velocity stacks seen from the old days of racing.
 
rumblefish360 said:
I’ve got to agree with Locomotion. I found exactly the same results. The best result I found at the time was the taller the filter I put on the better it was. Clearance above the carb made a positive difference. In my case, it was a 600 AFB. Tallest filter I used was a 4 inch IIRC.

Engine masters did a similar test, no stub stack though, but found it the filter was taller it performed better. Check out there air cleaner test.

The only thing I’d like to re-try myself is a K&N filter lid and start testing filters at 3 inches in height and go taller from there. Perhaps mimic the engine masters findings? IDK, but I wanna try it. I thought about this before I seen them do it and had a thought that it may work. I reasoned this with the use of velocity stacks seen from the old days of racing.
Click to expand...
I have the 3 ince now I just ordered a 4 inch, my lid is close to the choke horn.engine masters great show.
 
A word of caution on using the K&N filter lid. Make sure your tune is spot on (which I know you will fish) or if there is a back fire it could, just like the edelbrock triangular foam filters become a fire starter.
 
Taller is better with filters, as long as you have hood clearance. But if you're trying the K&N Filter lid that is also a filter, do some careful testing. I don't know if it changed the clearance above the vents and/or if it had something to do with the pleated filter which caused the air to pass through the filter top in many directions (turbulence) so close to the carb entry, but the standard solid metal air cleaner top worked better than the filter top! (14" x 3.5" filter with a drop base.) I didn't get around to checking if jetting was a factor in this case. It was faster, I was happy and left it alone.
 
Nothing wrong with a standard lid.

The K&N filter top has a mild increase in height. A very small amount.
 
My lid is an edelbrock had a 5 inch pape, got the K&N kit 3 inch filter lid and the drop base also for 90 Canadian, but when I put it all together I swear the idle drops a tad, so now it's 4 inch K&N should be hear Tuesday, now for the stub, I have a 650 VS front jets are now 69.still thinking about the stub glad you all like it .cheers
 
You must log in or register to reply here.
-

Back
Top