JETS vs. TURKS

[Turk]

Hello ERA brethern.

Some of you probably have been through this before. I am willing to learn from your trials and tribulations.

I could use the help of anyone else who has a similar set up as I have.

427SO
Low Riser Manifold
(2) Holley 4160s
570 cfm
Mild cam
9.6:1 Compression
MSF 6AL
Top Loader

I had Holley Custom Shop restore the carbs to original. Don't even know what jets are in them.

The car seem to run fine, but the popping noise during decellaration, is beginning to sound more and more like mini backfires. Sounds really COOL!
Quite an attention getter at traffic lights. They all hear me coming. I have been told I am running too rich.

My question is, has anyone else have gone through this and finally found the correct jets for these carbs. That way I can use those as starting points for my engine.
Any help would be appreciated.

TURK

[Trans-Am Jim]

Turk:

I have basically the same motor; only difference is my CR is 10.5:1 and it has a slightly-more-than-mild cam.

I'm assuming you mean 570 CFM rather than 57 ;-)

After much trial and error, I've ended up with 60s on all jets. Car runs clean and strong.

About the burbling and popping on decel, it's probably due to the slip-fit on the header/side pipe connection. I've tried various high-temp silicones to seal the connection - all to no avail. They all deteriorate within a few days or weeks, depending on how much I drive the car.

Hope this helps -

[Jim Holden]

Turk:

The fit of the primaries into the sidepipes can be part of the problem. Weber carb cars are particularly sensitive to an airleak. I have the same problem on the left side of my car.

'Course I still have a long way to go to get my Webers sorted out (something like 75 miles each way...)

Jim Holden

[cobrajeff]

GEEEZ, Turk!

Aren't you EVER satisfied? I mean, some guys have to pay EXTRA to buy spark plugs to install in their exhaust pipes to get those kind of flames!

With flames shooting out your side exhaust, some people will think you must have a REAL English roadster with those funny little EYE-talian carburetors......... 'course, it'll be given away when they see that your headlights are not flickering to the pulses of the generator.........

On the serious side, I have had my side-pipes off a few times, and used a variety of tail-pipe shaping tools to open-up or close-down (as required) the fit of each collector to each individual pipe. You'll need to do both (pipe-fitting AND jetting), I think, to cure this problem. Good luck!

cobrajeff

[Turk]

It looks like this weekend and maybe the next will be spent looking for manifold, and exhaust leaks.

Thanks for all the input friends.

TURK