The Stovebolt Site Forums The Shop Area Engine Shop Modified 292 questions

Hi all! My '65 chevy pickup has a 292. It has dual exhaust headers from stovebolt engine co, a clifford intake, an edelbrock performer 500cfm four barrel and HEI. First, has anybody goofed around with this carb at all? I think I might need to change metering rods or jets to make it run right. Second, what would be the proper plug gap and ignition timing with the HEI? Is it different than stock? What are the best plugs? Lastly, does anybody have opinions on what mufflers sound the best in a dual header situation? The ones I have right now are el-cheepos. Thanks

Wellcome aboard, Dude!

First i'd suggest You getting a book on the carb. It's basically a carter AFB, but has it's own particularities. No big deal anyway. As for the plug gaps, You can go between 040" and 060". The Hei allows You to run a bigger gap than the standard points type ignition.

dieselmo34,

Hi. I have almost the same setup as you do verbatim! I have a '66 shortbed stepside with a 292. Setup is an Offy 4 barrel with the 500 cfm Edelbrock 1403 (electric choke) carburetor. I have long (36") tube headers and HEI and a mild RV type cam that's a little "hotter" than stock.

My Edelbrock is a running a little rich with my setup, and I haven't changed the primary jets. I'm going to try re-gapping the plugs or maybe going with a higher performance plug and playing around with the idle mixture screws and timing.

Our engines are very similar in setup, and therefore in power too, depending on your cam choice and head work. You shouldn't have to do much more than maybe step down your primary jets and play around with your plug gapping and timing to get squared away. I don't think I'll need to step down my primaries to lean out my rich condition. If the rest of your engine is stock (especially the head and cam) you might have to.

For exhaust I have a single Flowmaster DeltaFlow muffler. It has a single 3 inch inlet and dual 2 1/4 inch outlets. I run the 2 1/4 inch pipes straight out back. Sounds great. A nice low rumble - sounds like a v8 when running at idle. If you must have dual pipes out back, I recommend a single muffler (Flowmaster, Borla or whatever you like) with a single inlet and dual outlets. With your engine, the performance won't change. Low end may actually improve with the single muffler. I wanted to get as low and deep of an exhaust note as I could without sounding like a "razzy 6" at idle. The Flowmaster was the perfect solution. I recommend a 2 1/2 inch inlet and dual 2 inch outlets. The Flowmaster I have is too large for my engine.

I personally don't care for the split six sound. I like a deep, husky but smooth exhaust note. If you don't use a crossover pipe in your exhaust system with the straight six the notes will sound lumpy like you have a burnt valve or a really radical cam. And it will be very "six cylinder-like."

Turbos are another good option. Cheaper than the flowmaster and produces great sound. I don't know if they make a single inlet/dual outlet system or not. Check Ebay.

-ftyler

Ofcourse that system is nearly 50% less efficient than true duals creating some back pressure affecting hp and powerband.

Yeah, but its not like he's bracket racing this thing. We'll talk optimal pipe sizing when he installes the 2-stage NOS kit and Mallor rev limiter.

Same thing for the smaltzy plugs- AC delcos or autolites gapped at .045" work in my 235 and my poncho's 350.

And on the carb, change the metering rods and springs to affect part-throttle cruising mixture. Summit or Jegs sells a big Edelbrock carb tuning kit with all kind of extra rods, springs, & gizmos for your carb. Main jet size comes into play near WOT and is also affected by airbleed sizing, which is prolly close enough from the factory. If you can close down an idle mixture screw and stall the engine at idle, the jets aren't too big. Playing with your secondary opening rates can also help tune for problems on part throttle tip-in and hard accelleration.

I would go with a single muffler due to the fact that dual mufflers will move the powerband into a higher rpm range. These sixes do not like to turn high rpms. If you plan on racing the truck, and therefore will be running high rpms, then go with the true duals. For street use and a load hauling, go with a single muffler.

I have a 261 bored .60, shaved .20, ported/polished, stock cam, HEI, with 390 Holley, Clifford 6=8/Fentons, turbos. Ended up with 52s for primaries and bored 60s for secondaries and weaker than standard pump spring. Cooler plugs on back 2 cylinders and hotter plugs on front 4 cylinders.

Plugs burn even, starts well, runs like a scalded cat, mpg in mid teens with 3 spd OD. Took a bunch of trial and error this spring and summer to get it where it is.

Hey 56-

I've got a similar setup on a 235. I've got 53 jets in the primary, and metering block on secondary. I've got a tip-in bog below 2000 RPM. What accel pump cam are you using? What 2ndary spring are you using? I've got the red pump cam and brown spring.

thanx

chip