Don Terrill’s Speed-Talk

So I guess the real question is if the contact pattern which one assume is better makes more or less power. I can understand why someone would want to do the work to make the geometry appear to be better but if a person is interested in making more power then that has to be tested. If the nicer look...

As for Pro Stock, the jelly bean guys killed it just like they killed NASCAR. I understand how it happens but when you make everything look the same nobody cares anymore. Pro Stock was cool back in the Pinto vs. Vega vs. Monza days. I understand how that cubic dollars and safety issues eventually le...

My opinion should be pretty clear by now, carb. And I'll give an example. A customer recently asked me to build a stretched carb for a high end build, the one that they had been running they were not happy with. This is a no expense spared BBF, 1500 HP range. They we unhappy enough with the origina...

The 500's are set up for DualQuad use, not for tunnel ram. And will leave power on the table on a tunnel ram too. The 650 and the 750 and the 800 carbs make more power on a tunnel ram than the 500's do ,even on a street motor. Who cares? It is a 427 in a street rod not a Pro Stock car. The dual 500...

I used some FAST ignition stuff recently on a magazine engine. Worked just fine. The ignition box appeared to be identical to the old Crane 6 box that I ran on my street car for many years.

A pair of the 500 cfm Edelbrock carbs which are designed for dual carb use would be perfect on that application. Spend the time in the catalog to get the correct carbs. You want the ones that say for dual carb use since they are calibrated differently. You don't need anything larger than the 500 cfm...

Interesting, if there could be a redo test with 2 different sizes of injectors per cylinder. Then shutdown the larger injector during low RPM. Yes that might be interesting. The OEM's used that idea for a while but they seemed to have gotten past it so I'm guessing they came up with another solutio...

In a recent article on the Hot Rod website a big BB Chevy is tuned with both a Dominator and a Holley Sniper system. It took them several days to dial in the fuel curve on the Dominator but the Holley Sniper learned its curve in just a few dyno pulls. The peak numbers were basically the same but th...

50 ft. lbs. of torque gone missing with EFI vs. a carburetor is a fine example of "you don't know what you've got 'til it's gone." #-o Andy, can you look at your data logs and see what the duty cycle percentage is in the RPM range where the power is down? I don't have the data logs handy ...

I'll see if I can attach a PDF of the carb vs. EFI test I ran on my 514. At the start of the pull the EFI was down by 50 ft-lbs but then it pulled ahead at the end and made a little more power at peak. I never came up with an explanation for the missing torque at 5000 rpm. We made a dozen or so pull...

In a recent article on the Hot Rod website a big BB Chevy is tuned with both a Dominator and a Holley Sniper system. It took them several days to dial in the fuel curve on the Dominator but the Holley Sniper learned its curve in just a few dyno pulls. The peak numbers were basically the same but th...

Any indication of the A/F ratios for the two systems? EFI might not have figured out the lower RPM yet. There is an AFR chart in the article. The carb appears to have a slightly smoother curve but I doubt the difference is really significant. For most of the pull the AFR is in the mid 12's for both...

427dart wrote: ↑Thu May 30, 2019 8:50 pm Could it be that at a lower RPM the reduced injector cycle plus fuel droplets to small as compared to a carb booster with a larger droplet size?
Just thinking here.

Could be I suppose. I don't know enough about injector physics to know if the duty cycle has an effect on the drop size or not.

In a recent article on the Hot Rod website a big BB Chevy is tuned with both a Dominator and a Holley Sniper system. It took them several days to dial in the fuel curve on the Dominator but the Holley Sniper learned its curve in just a few dyno pulls. The peak numbers were basically the same but the...

Andy, did you measure and record the air bleed and emulsion bleed arrangement and compare all those carbs? That would be great if you have that information. Apart from the obvious difference between larger and smaller carbs, the effect of flow restriction on manifold pressure and power, the bleed a...