4-2-1

[opus10583]

Hi,

The first performance* upgrade of my car was finally effected last weekend:

I replaced the exhaust system of my '78, a collection of parts store remnants and the original manifold and downtube, with a pre-'75 4-2-1 manifold/downtube combination and one of the NOS Abarth exhausts available here in Parts for Sale.

I don't have timings, don't have dyno sheets but; if you have a '75 to '78 Spider you really should ditch that 4-1 system for the earlier one or a header.

The torque curve is manifestly fuller and flatter and the car is much more enjoyable to drive as a result. You're still not going to outdrag your neighbor's daughter's KIA, but you'll no longer feel the car fighting you to get to the next gear: Those last 10-15 degrees on the tach needle are now welcoming, rather than off-putting. Can't see my rings lasting much longer.

I can heartily recommend the exhaust as well, PM me.

Ciao,
Mark

* I am after remediating the Clean Air kludges and emissions-test-gaming systems, not drag racing 'Vettes.

[Dawgme85]

I just got my '77 back from Ray at Performance Apex after he went through the head (performance valve grind, minor port matching, machined all 5 surfaces), installed a ceramicoated 4-2-1 manifold, and re-jetted the 32adfa carb.
After driving it home I thought, "this is nice" (it was raining). Then I drove it to work yesterday with the top down, and thought, "WOW!"

Where before, shifting at redline was something I waited for, now it comes so fast I have to be on my toes to shift it before passing redline. And it pulls like crazy through the gears, with no hesitation. It reminds me of the way my old RX-7 loved to rev!

Last night I took the twisty way home and the grins just kept coming.

I, too, whole-heartedly recommend this upgrade!

WOW!

[opus10583]

I just got my '77 back from Ray at Performance Apex after he went through the head (performance valve grind, minor port matching, machined all 5 surfaces), installed a ceramicoated 4-2-1 manifold, and re-jetted the 32adfa carb.
After driving it home I thought, "this is nice" (it was raining). Then I drove it to work yesterday with the top down, and thought, "WOW!"

Where before, shifting at redline was something I waited for, now it comes so fast I have to be on my toes to shift it before passing redline. And it pulls like crazy through the gears, with no hesitation. It reminds me of the way my old RX-7 loved to rev!

Last night I took the twisty way home and the grins just kept coming.

I, too, whole-heartedly recommend this upgrade!

WOW!

Hi,

Yeah, I had a confirming experience as well last night, smooth power delivery from way low to redline, a real treat. Grins all around!

Do you know what jets they put in your carb?

Thanks,
Mark

[Dawgme85]

"Do you know what jets they put in your carb?"

Ray told me he bumped both jets up one size. Don't recall what size they started out, though. Sorry.

There is still a bit of sorting out to do, however. Somehow, I ended up with only the muffler (no resonator) when all was said and done, and the result is a very "raspy" exhaust note. I kind of like it, and it turns heads on the street, but I'm trying to decide whether to put a new resonator on, and whether it will actually ADD HP, by canceling out exhaust pressure waves through the exhaust, as I've briefly read about. When I spoke to Ray this evening to "complain" about how he changed my car, he asked me to wait on the resonator, as he has some NOS for a 131 on his shelf that might do the trick.

Anybody know about the effect of resonators, apart from lowering noise levels by cancellation?

Thanks,

Dawg

[Dawgme85]

I decided to tone it down a little by installing a new catalytic convertor. The raspiness has been tempered, and performance doesn't seem to have been hurt much, if at all. Now, if the drive train just holds together I'll be happy!