Just wondering, thoose of you who have ported your exhaust ports up 1/4th an inch or more, how is your idle quality? Will the car still idle at 750 rpm with little to no braping? will it idle at 850 with no braping? Please state Approx how far up you ported with your wisdom. Thank you.

 

This is how low Itook mine and I was able to have a nice idle at 800rpm.

 

Depends on how restrictive the exhaust is.



With a stock exhaust it'll idle just fine, down to as low as maybe 500rpm.



With a super restrictive super quiet exhaust, it'll have a little bit of a lope, in the 600-900 range.



You might find it gettling brappy if you crank the idle up to 1200-1500, say if you have a carburetor and you're running on the choke. Idle mixture also plays a part in this.



This is with roughly doubling the height of the stock port, going entirely upwards.



Go for it! You'll love the increase in low end and midrange grunt.

 

How far up and down are thoose FD3boost? they look nice and huge.



Wow double size Heretic, Isnt that almost a half inch up? If that will idle I should have no problems.



I've got a degree wheel on her, I think im going to shoot for 65 Degrees closing and 80 opening, thats ~1/4th up and a little less then an 1/8th down.

 

Keep in mind that opening earlier will make the engine louder, so you'll need a more restrictive exhaust to quiet that puppy back down again, and you might run into rough idle issues.



But as someone once said, life is too short for smooth idles, and I tend to agree with him.

 

Thats why im only going down 5 degrees, it really barley any at all. Loud doesnt bother me as much as lopeing,.. it needs to pass inspection,.. even if it is with a gallon of ethonol in the tank and straight air to the cats..

 

https://www.nopistons.com/forums/index.php?...topic=35643&hl=



Check out the ports in the link. Motor idle solid at 900rpm's. Starts easy. Idle AFR in the 12.2-6 according to the plx with the sensor 12-15 inches down on the down pipe. Idle timing is at -5 Atdc while motor is pulling -10-12 vacuum. Under a load with afr's in the 10.8-11.2 range the egt never go above 1450deg with 17-20deg of advance after 4000rpm's. On a free rev in neutral, the motor makes 4-6psi of boost by 6500rpm's. .96 p-trim.

chuck