Dual Plane vs Single Plane Manifold with TBI
I used a Weand Excellerator on my lo-Compression 318, with an old Holley lo-pressure TBI System. I think it was 23psi or something.
The Excellerator is a small-plenum single-plain with the runners transitioned to the smallports . It seemed to work well enough until winter. Then I had icing problems. So I put a Thermoquad on it. And you guessed it, I sold the Holley, and the TQ stayed on.
Not long afterward, I found a small-port cast-iron dualplain, and that was even better.
So the take-away for me was the small-plenum, and small ports. And of course at my power level with the stock cam, the dualplane was the way to go.
But in all fairness, I never ran the TBI on the dual-plain.
I think the dual-plains are for working within the limitations of carbs at low rpms. I don't see them needed for EFI even TBI. However, Ima thinking a stock lo-compression 273 may have problems with a large plenum, at low-rpm, so if it was me,
I would find a single-plain with a tiny plenum, like the one posted by George in #27. Decades and decades ago, I had a 71Demon with a 318 and one of those; and it was a pretty sharp combo..... altho, it was the last of the hi-compression 318s,lol.
If the pad is too small for your Sniper, I would not bolt an adapter on tho; I would modify the pad.
But surely, some aftermarket company must have a small-plenum, small-port, single plain? Surely.......
I used a Weand Excellerator on my lo-Compression 318, with an old Holley lo-pressure TBI System. I think it was 23psi or something.
The Excellerator is a small-plenum single-plain with the runners transitioned to the smallports . It seemed to work well enough until winter. Then I had icing problems. So I put a Thermoquad on it. And you guessed it, I sold the Holley, and the TQ stayed on.
Not long afterward, I found a small-port cast-iron dualplain, and that was even better.
So the take-away for me was the small-plenum, and small ports. And of course at my power level with the stock cam, the dualplane was the way to go.
But in all fairness, I never ran the TBI on the dual-plain.
I think the dual-plains are for working within the limitations of carbs at low rpms. I don't see them needed for EFI even TBI. However, Ima thinking a stock lo-compression 273 may have problems with a large plenum, at low-rpm, so if it was me,
I would find a single-plain with a tiny plenum, like the one posted by George in #27. Decades and decades ago, I had a 71Demon with a 318 and one of those; and it was a pretty sharp combo..... altho, it was the last of the hi-compression 318s,lol.
If the pad is too small for your Sniper, I would not bolt an adapter on tho; I would modify the pad.
But surely, some aftermarket company must have a small-plenum, small-port, single plain? Surely.......