fuel mixture or jet adjustment nut settings

[240260280]

Try 15btdc with max ~ 36degerees

[jalexquijano]

okay i thought that for this type of camshaft the recomendable idle timing was 12 BTDC and no more than that! Now i remember that when i bought the car the previous owner had a twice pipe installed and a FAR 311 race cam and it didnt pop on or backfire on deceleration! Just the straight twice pipe kit period and no popping whatsover! THis takes the reduced back pressure cause out of the list!

http://www.thezstore.com/page/TZS/PROD/classic19i/15-6031

Anyone???

[jalexquijano]

Well i thought there could be some opinión now that i have provided this last fact to the case in hand. Why didnt i had deceleration backfire when i reléased the gas pedal in 2nd and 3rd gear when the car had the MSA twice pipe system installed by PO:

http://www.thezstore.com/page/TZS/PROD/classic19i/15-6031

Now that i took it all away and installed the MSA PREMIUM EXHAUST kit for Stock manifold, i do experience backfire on deleceration:

http://www.thezstore.com/page/TZS/PROD/classic19j/15-6302

Is it due to:

1. The type of material of the pipes of the  MSA Premium exhaust is aluminum. Twice pipe is Steel.

2. MSA Premium is 2.5 inches diameter all the way. Twice pipes  features a 2 1/2" inlet that splits into twin pipes measuring a little under 1 3/4" (from the head pipe back) that terminate with two glass-pack mufflers and a pair of 2 1/2" diameter chrome tips.

I don´t think that my Schneider 274F camshaft is the reason as PO had a Far 311 Race cam installed and it never popped under deceleration at any gear. 

[Patcon]

Typically what sets off the excess fuel in the exhaust is a hot point. If you have a thin piece of metal in the new exhaust that gets really hot, it might even glow, it will ignite the extra fuel like a spark plug would.

[kully 560]

I have a color tune and had the same problem with checking the color reading would not change when turning the mixture nuts. turns out I had a dirty fuel filter ,car drove fine but it effected the final adjustments. it screw up the color tune reading so I changed the filter and all is good .now when I turn the mixture nuts the color tune plug changes with the adjustment .

[jalexquijano]

it only backfires on the exhaust when releasing the gas pedal on 1st and 2nd gear.  If this exhaust is providing me 6hp more comparing with the stock exhaust, i think i can live with the popping on deceleration.

[Jarvo2]

It’s the lack of backpressure with the new exhaust. Stick some steel wool in the exhaust tip and the popping will most likely go away until it falls out. You’ll also loose you HP gain by limiting the free flowing of the exhaust.

As many other members have Pointed out, a 40+ year old car is not going to perform like a modern car!!


Sent from my iPhone using Classic Zcar Club mobile

[jalexquijano]

4 hours ago, Jarvo2 said:

It’s the lack of backpressure with the new exhaust. Stick some steel wool in the exhaust tip and the popping will most likely go away until it falls out. You’ll also loose you HP gain by limiting the free flowing of the exhaust.

As many other members have Pointed out, a 40+ year old car is not going to perform like a modern car!!


Sent from my iPhone using Classic Zcar Club mobile

How many horses have i gained with this MSA PREMIUM EXHAUST FOR STOCK MANIFOLD?