Gary Lewis Posted February 6, 2019 Author Share Posted February 6, 2019 Yes, the smaller carb should help with both of those, but just won't have as much top-end power. However, Ford put a 600 CFM carb on the 460 from the factory, so it should work out well. But, it isn't happening today. I had some errands to run this morning and was out in the 40 degrees and 110% humidity too long, so am now on the porch w/a cup of hot chocolate and a quilt. And the guy bringing the 23 binders of TSB's is supposed to text just about any mo to tell me he's rolling into T-town, so I'll just warm, not chill, for a bit and catch up on forum stuff. Well, the Edelbrock 1406 (600 CFM) is done and on Big Blue. And, it pulls 21" of vacuum at idle with that carb, which is about 2" more than with the 750 at the same RPM. I don't understand that, but 'tis true. And, note in the video the oscillating vacuum reading. I'm pretty sure BB has one or two burned valves as he's been dropping one cylinder at idle and sometimes two since I got him. Well, the EFI heads are supposed to be ready in a couple of weeks, so that should cure him of that habit. As for how BB runs w/that carb, I say STRONG. In fact, if I didn't know the 750 is even stronger I'd have been quite satisfied. I wound that 460 up over 5K and only then did it run out of carb. But below that point the 600 was plenty of carb. However, it isn't jetted as rich so the throttle response isn't quite as strong - at least that's what it seemed like. But when you mash the throttle it GOES! Link to comment Share on other sites More sharing options...
1986F150Six Posted February 7, 2019 Share Posted February 7, 2019 Well, the Edelbrock 1406 (600 CFM) is done and on Big Blue. And, it pulls 21" of vacuum at idle with that carb, which is about 2" more than with the 750 at the same RPM. I don't understand that, but 'tis true. Link to comment Share on other sites More sharing options...
Gary Lewis Posted February 7, 2019 Author Share Posted February 7, 2019 Well, the Edelbrock 1406 (600 CFM) is done and on Big Blue. And, it pulls 21" of vacuum at idle with that carb, which is about 2" more than with the 750 at the same RPM. I don't understand that, but 'tis true. Link to comment Share on other sites More sharing options...
1986F150Six Posted February 7, 2019 Share Posted February 7, 2019 I wouldn't have thought that the primary size would have made any difference in idle vacuum. But, something sure is different. That is true. It seems that the engine is being met with more resistance to taking in air? Smaller idle circuits? Link to comment Share on other sites More sharing options...
Nothing Special Posted February 7, 2019 Share Posted February 7, 2019 That is true. It seems that the engine is being met with more resistance to taking in air? Smaller idle circuits? Generally more vacuum means more resistance to pulling the air in. More resistance generally means less air is getting in. Less air generally means lower power. Lower power (at idle) generally means a lower idle speed. Assuming you aren't just looking at a lower idle speed, all of those generalizations must not be applying here. So is it mixing the fuel/air better so the engine is making the same power with less air? Link to comment Share on other sites More sharing options...
NotEnoughTrucks Posted February 7, 2019 Share Posted February 7, 2019 Generally more vacuum means more resistance to pulling the air in. More resistance generally means less air is getting in. Less air generally means lower power. Lower power (at idle) generally means a lower idle speed. Assuming you aren't just looking at a lower idle speed, all of those generalizations must not be applying here. So is it mixing the fuel/air better so the engine is making the same power with less air? Well, I'm feeling inadequate today. Got a message from the fellow I sold the engine to out of my beloved war wagon. Going into a T bucket. Link to comment Share on other sites More sharing options...
Gary Lewis Posted February 7, 2019 Author Share Posted February 7, 2019 Well, I'm feeling inadequate today. Got a message from the fellow I sold the engine to out of my beloved war wagon. Going into a T bucket. Join the crowd! But, you have to admit, that thing is pretty. And, he has good taste in carburetors. Link to comment Share on other sites More sharing options...
Gary Lewis Posted February 7, 2019 Author Share Posted February 7, 2019 Generally more vacuum means more resistance to pulling the air in. More resistance generally means less air is getting in. Less air generally means lower power. Lower power (at idle) generally means a lower idle speed. Assuming you aren't just looking at a lower idle speed, all of those generalizations must not be applying here. So is it mixing the fuel/air better so the engine is making the same power with less air? Oops, I meant to reply to your comment, Ray. I had the engine idling at basically the same RPM in both cases - I think. But, when I swap back I can check that out and make sure I compare apples to apples. Or, I may put the Street Demon 750 on. Its been sitting on the shelf since Tim had Dad's engine on the dyno, so why not use it. Link to comment Share on other sites More sharing options...
Jochen1964 Posted February 11, 2019 Share Posted February 11, 2019 Moin Jungs. I was busy with moving house the last couple months and didn’t have the time to follow here. The truck was actually a big help during the move and is now with clearing the garden, somehow a bit of payback time. Getting back to normality I was able to check the brake system of my truck today and get the air out. What a difference now with a pressure point at half of the pedal way. Next check will be the coolant leakage. The ole problem is back. Other then that the truck is great. One surprise though: I expected the bolts and nuts to be in inches but I find a mixture of inch and metric. Is that normal for a 1986 US truck? Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted February 11, 2019 Share Posted February 11, 2019 Moin Jungs. I was busy with moving house the last couple months and didn’t have the time to follow here. The truck was actually a big help during the move and is now with clearing the garden, somehow a bit of payback time. Getting back to normality I was able to check the brake system of my truck today and get the air out. What a difference now with a pressure point at half of the pedal way. Next check will be the coolant leakage. The ole problem is back. Other then that the truck is great. One surprise though: I expected the bolts and nuts to be in inches but I find a mixture of inch and metric. Is that normal for a 1986 US truck?6FCCF139-3B3B-4134-A9B0-0545DB752AE2.jpeg Lots of metric body and chassis fasteners in this era. Drivetrain would still be inch fractional. Back in the 1970's there was a big push for America to finally convert to metrics The United States Congress had approved and sought adoption 100 years prior to that, in the latter half of the 1800's And yet.... here we are. Isolationists in the fine company of Paupua New Guinea and Liberia (with whom we practically share a flag) Link to comment Share on other sites More sharing options...
Recommended Posts