Dan Cary Posted July 14, 2023 Share Posted July 14, 2023 Magnificent. I'm really new here, however, a long time enthusiast. .. "What is a Back Drop Manifold" .. they sound amazing, but did they serve a purpose? Addl: is it the same as a "Split Manifold"? Many Thanks. Respectfully, Daniel. Quote Link to comment https://www.bigmacktrucks.com/topic/41547-b-73-restoration/page/65/#findComment-534849 Share on other sites More sharing options...
Popular Post mattb73lt Posted July 14, 2023 Author Popular Post Share Posted July 14, 2023 The back drop dumps out the rear, versus a center dump. Additionally, it has an internal baffle that prevents the gasses from mixing until they leave the manifold, giving it a particular and distinct bark. A split manifold is actually two separate manifolds. 3 Quote Link to comment https://www.bigmacktrucks.com/topic/41547-b-73-restoration/page/65/#findComment-534850 Share on other sites More sharing options...
1961H67 Posted July 15, 2023 Share Posted July 15, 2023 Great explanation of the backdrop! And the pictures are worth a thousand words! In my collection of backdrops, (4) I have one that the baffle is almost burned out,, they most have had the fuel turned up on that old 220 ! 2 Quote Link to comment https://www.bigmacktrucks.com/topic/41547-b-73-restoration/page/65/#findComment-534856 Share on other sites More sharing options...
mowerman Posted July 15, 2023 Share Posted July 15, 2023 Ha thanks for that. I did not even know what a backdrop was till you just explained Quote Link to comment https://www.bigmacktrucks.com/topic/41547-b-73-restoration/page/65/#findComment-534919 Share on other sites More sharing options...
doubleclutchinweasel Posted July 15, 2023 Share Posted July 15, 2023 I can’t wait to see the next episode of “As the Bulldog Turns”. That truck is freakin’ awesome. Did you figure out what was up with the air pressure that one time? Governor, maybe? 1 Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/41547-b-73-restoration/page/65/#findComment-534940 Share on other sites More sharing options...
mattb73lt Posted July 16, 2023 Author Share Posted July 16, 2023 1 hour ago, doubleclutchinweasel said: I can’t wait to see the next episode of “As the Bulldog Turns”. That truck is freakin’ awesome. Did you figure out what was up with the air pressure that one time? Governor, maybe? No, i think it was just messing with me!! Hasn't done it since. I put another 50+ miles on it today, so I'm up to 210 miles total and 110 on the new motor. Admittedly, I'm still a little gun shy about running it after the first time it blew up. I'm alert to every smell, noise and vibration, but so far all is OK. I'll make a video soon of a road test. 2 Quote Link to comment https://www.bigmacktrucks.com/topic/41547-b-73-restoration/page/65/#findComment-534945 Share on other sites More sharing options...
1961H67 Posted July 16, 2023 Share Posted July 16, 2023 I have 100% Confidence it’s going to be just fine! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/41547-b-73-restoration/page/65/#findComment-534947 Share on other sites More sharing options...
mowerman Posted July 16, 2023 Share Posted July 16, 2023 Yes, I don’t blame you. I would be thinking the same thing.Bob Quote Link to comment https://www.bigmacktrucks.com/topic/41547-b-73-restoration/page/65/#findComment-534981 Share on other sites More sharing options...
HarryS Posted July 16, 2023 Share Posted July 16, 2023 15 hours ago, mattb73lt said: No, i think it was just messing with me!! Hasn't done it since. I put another 50+ miles on it today, so I'm up to 210 miles total and 110 on the new motor. Admittedly, I'm still a little gun shy about running it after the first time it blew up. I'm alert to every smell, noise and vibration, but so far all is OK. I'll make a video soon of a road test. They do that just to show who is boss. How is the ride without the body? 2 Quote Link to comment https://www.bigmacktrucks.com/topic/41547-b-73-restoration/page/65/#findComment-534986 Share on other sites More sharing options...
Popular Post mattb73lt Posted July 16, 2023 Author Popular Post Share Posted July 16, 2023 Just now, HarryS said: They do that just to show who is boss. How is the ride without the body? It sucks. The rear has no give and bounces pretty good over bigger bumps on the highway. Local roads are easier as the speeds are a lot less. I think the gearing is spot on. With the 4.62 rear, double over Triplex and 24.5 rubber it just floats at about 1650 RPM at 70 MPH. That's barely half throttle. If I come on a hill/grade, it's a quick downshift to 4th Hi-split and you're over it. I love the sound of the exhaust, but down the road I'm probably going to put a muffler on it. 3 1 Quote Link to comment https://www.bigmacktrucks.com/topic/41547-b-73-restoration/page/65/#findComment-534987 Share on other sites More sharing options...
Popular Post mattb73lt Posted July 16, 2023 Author Popular Post Share Posted July 16, 2023 The sheet metal is all together. I need to make a few adjustments and fill a few bolt holes, but it's looking good. Very happy it’s back together! 10 4 Quote Link to comment https://www.bigmacktrucks.com/topic/41547-b-73-restoration/page/65/#findComment-534988 Share on other sites More sharing options...
mrsmackpaul Posted July 16, 2023 Share Posted July 16, 2023 Maybe just lower the air pressure in the drive tyres until the tray is ready, some blokes go down to 55 on hobby trucks I think the ride will probably improve a lot once the body is fitted Paul Quote Link to comment https://www.bigmacktrucks.com/topic/41547-b-73-restoration/page/65/#findComment-534991 Share on other sites More sharing options...
Popular Post mackaholic Posted July 16, 2023 Popular Post Share Posted July 16, 2023 1 hour ago, mattb73lt said: The sheet metal is all together. I need to make a few adjustments and fill a few bolt holes, but it's looking good. Very happy it’s back together! that is a gorgeous Mack!! Great job! 3 Quote Link to comment https://www.bigmacktrucks.com/topic/41547-b-73-restoration/page/65/#findComment-534992 Share on other sites More sharing options...
mowerman Posted July 16, 2023 Share Posted July 16, 2023 Excellent looks great. I would be happy to get 65 with mine right now 55 buried I’m changing the transmission soon. Hopefully the new one is taller gears Quote Link to comment https://www.bigmacktrucks.com/topic/41547-b-73-restoration/page/65/#findComment-534994 Share on other sites More sharing options...
Popular Post mattb73lt Posted July 19, 2023 Author Popular Post Share Posted July 19, 2023 Up to 150 miles, as of today. Trying to put 500 miles on it and then change the oil and filter on the engine. It really is running well. With no body on it, it just floats along at 70 turning about 1650 on the flats. Lots of thumbs up as I’ve been using I-91 from Meriden to North Haven for my runs. Mechaholic, if you want to go for a ride, give me a message and I’ll have you come over? I had a very close call in the B42, today, when I was picking up the hydraulic cylinders in Danbury. On the way back on I-84, I had a rear service brake line fitting come loose and separate. I didn’t know it until I needed to stop and had almost no brakes. I heard the rush of air and had the pressure gage dropping until the maxi-brakes started to come on. I was able to stop, but it was close, in building afternoon traffic. Tonight, I’ll replace my underwear. Tomorrow, I’ll replace all four service flex lines to the brake cans. Damn! 8 1 Quote Link to comment https://www.bigmacktrucks.com/topic/41547-b-73-restoration/page/65/#findComment-535199 Share on other sites More sharing options...
doubleclutchinweasel Posted July 19, 2023 Share Posted July 19, 2023 Glad you got it stopped, man. I’m sure the pucker factor was off the scale there. 1 Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/41547-b-73-restoration/page/65/#findComment-535202 Share on other sites More sharing options...
mrsmackpaul Posted July 20, 2023 Share Posted July 20, 2023 Not as many chances of stopping with a single drive I've had cans smashed off when in a road train and I dont even notice until I actually stop at a stop sign There are so many air tanks that it takes a good long application for the pressure to drop enough to notice Not a good thing but it shows the huge amount of difference those extra tanks of air and the extra cans make a huge difference Paul 2 Quote Link to comment https://www.bigmacktrucks.com/topic/41547-b-73-restoration/page/65/#findComment-535222 Share on other sites More sharing options...
mowerman Posted July 20, 2023 Share Posted July 20, 2023 Right on man have a ball with it. And yes, I’m glad it did not turn out ugly. Quote Link to comment https://www.bigmacktrucks.com/topic/41547-b-73-restoration/page/65/#findComment-535227 Share on other sites More sharing options...
Geoff Weeks Posted July 20, 2023 Share Posted July 20, 2023 well pre-121 is a single line system which also plays into it. One res for all brakes. Also tractors weren't required to have front brakes (steer brakes) until sometime in the 80's. Many did, but not all. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/41547-b-73-restoration/page/65/#findComment-535261 Share on other sites More sharing options...
Popular Post mattb73lt Posted July 20, 2023 Author Popular Post Share Posted July 20, 2023 This day took almost 25 years to make happen. Out chasing parts for the B42 and stopping by to see friends and their garages. One had me pull in to his air conditioned shop to show me the different aluminum polishes he uses and do a few test spots to see what worked best. The big dog didn't even mark new territory or leave a calling card on his floor. 200+ miles and counting!! There's a little video he took of me leaving below this picture. IMG_1003.mov 6 5 Quote Link to comment https://www.bigmacktrucks.com/topic/41547-b-73-restoration/page/65/#findComment-535286 Share on other sites More sharing options...
Mark T Posted July 20, 2023 Share Posted July 20, 2023 I'd love to hear that truck in real life. 2 Quote Link to comment https://www.bigmacktrucks.com/topic/41547-b-73-restoration/page/65/#findComment-535295 Share on other sites More sharing options...
Popular Post mrsmackpaul Posted July 20, 2023 Popular Post Share Posted July 20, 2023 Perfection Thats enough to put a horn on a jelly fish You gotta be proud of that result and all the hard work as well to achieve it Thanks again for taking us along on the ride Paul 2 1 Quote Link to comment https://www.bigmacktrucks.com/topic/41547-b-73-restoration/page/65/#findComment-535303 Share on other sites More sharing options...
Brocky Posted July 20, 2023 Share Posted July 20, 2023 Sounds Great!! Love the Backdrop.. Earlier you said you might have to put a muffler on it??? Would one of the old "Pancake" Mufflers keep the great cakkle??? Quote Brocky Link to comment https://www.bigmacktrucks.com/topic/41547-b-73-restoration/page/65/#findComment-535309 Share on other sites More sharing options...
1961H67 Posted July 21, 2023 Share Posted July 21, 2023 Congratulations! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/41547-b-73-restoration/page/65/#findComment-535316 Share on other sites More sharing options...
Popular Post mattb73lt Posted July 21, 2023 Author Popular Post Share Posted July 21, 2023 1 hour ago, Brocky said: Sounds Great!! Love the Backdrop.. Earlier you said you might have to put a muffler on it??? Would one of the old "Pancake" Mufflers keep the great cakkle??? I'm thinking about it. I might just do a resonator. Something to soften it just a little. The Jake brake is just obnoxious when it goes off. It does keep idiots away, though!! 2 1 2 Quote Link to comment https://www.bigmacktrucks.com/topic/41547-b-73-restoration/page/65/#findComment-535319 Share on other sites More sharing options...
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