Good video. It really does depend on application. My 79 F350 has a built .30 mild cam with 4 BBL and it needs manifold for a good clean idle. The only thing I’d say is stop adjusting your idle with the idle screw. You set idle with timing. Set the transfer slot to a square on your carb and check it by using a vacuum guage on the ported vacuum port of the carb. It should always read 0. Then you can adjust idle and mixture as needed
Great video. Another addition to the great ported/manifold debate😁. It comes down to giving an engine the timing it wants. On a mild cam engine, either could be made to work with an adjustable vaccum can and a curved mechanical advance. Depends on the engine, weight, stall speed, cruising rpm. On a choppy low vaccum cam engine, manifold would be a better choice. Needs more timing at idle. You can set you initial as high as you can without causing kickback on the starter and use the vaccum advance to give you the rest of the timing you need to idle. Then adjust the mechanical advance curve. At WOT vaccum advance doesn't matter only max timing (initial+mechanical). At light throttle and cruise the vaccum and mechanical have to be adjusted for an optimal curve.
we need to consider the application. At high altitude, we typically use manifold vacuum for a stock, daily driver. Eliminate the accumulator and let's see how your A/C and heat behave!! This is always a good laugh!!
Thanks for your help! I’ve been seeing a lot of different views on this topic. I’ve been running a fairly high performance engine for years, and I’ve always tried the trusted ported vacuum. I’ve always believed that my engines could make a bunch more horsepower. I’m starting to believe that straight manifold vacuum, could make a big difference. I’ve been setting my initial, and mechanical advance at around 36 degrees, and have always seemed to have low, low end power. That’s why this manifold vacuum thing seems like it might make more sense. Heck! I’ve even drilled holes in my primary throttle blades, to get my transfer slots in order. I realized, that drilling the plates bumped my idle up as much as changing my vacuum, from ported to manifold. I have another 750 without drilled plates, and I’m gonna give manifold vacuum a shot. My engine runs around 230 degrees in traffic, and nobody knows why. I’m talking to friends who race, have street rods, and oval track. This is definitely something that I’m gonna look into!! Thanks!
Now I’m curious. I’m gonna go play with the timing and go to manifold vacuum and see how it runs and just carburetor a little if it needs it thank you I’m Kevin Jenkins, I started driving in 1975. My first car a 1956 Chevy four-door wagon. He got wrecked in front of my dad’s house. I’m on my second one which I bought 1983 been sitting in my garage for 30 years. I think it’s time. I bought my CJ5 in 1987. I keep it running. I parked the 56 Chevy because I’m not mature enough to drive it. But I think it’s time. I have a 327 in it 11 inch clutch and a Muncie for speed.
Good video mate. I am trying to set my distributor back down in the hole and now my engine builder has made it to the next round so I can't ask him timing questions. On a Ford 351 should the distributor trigger be set to cylinder 1 with same cylinder at TDC or a little prior that like 10 degrees advanced? There are so many variables. I have a Mallory Unilite.
Yes. I usually put a sharpee mark on the body with the cap on, lined up with the number 1 plug wire. Put the engine on number 1 tdc and drop the dist in. I believe on 351's, the rotor will be at 1:00. then set the timing with a light.
That depends on how much swing the dist has. Is your timing mark a pointer or a scale? The timing at idle isn't as important as total advance at speed. If you have a scale timing mark, run the engine up to full advance, (3000 rpm ish) and set it at 15btdc at the 20 degree mark for a total of 35 degrees BTDC. That would be a good starting point. I also have another video on finding 36 BTDC.
@@NoCarLeftBehind I'm afraid that I was previously a no-nothing consumer and just went to a job so my engine guy did not teach me anything other than what oil to use. I wish I had asked him more questions but I had no reason to. I overpaid a racer guy to get the thing running. When my water turned slightly acidic corrosion started taking over front timing cover and seeping, so I took the balancer off and cleaned all things there, then applied fresh paint where he had left 3 marks that seem about 10 degrees from one another. I just replaced the wires and primed the engine, replaced oil pan and pickup so nothing is as it was.
Awesome. I'll try it. Curious, after setting total timing as you mentioned (36°), Do you ever find the scenario where you have no more idle speed and mixture screw adjustments left to reduce the higher RPM (to an acceptable Idle) , that you now have to retard the Mechanical timing to compensate for a ideal idle speed? I just would hate to go from 14-17°, down to 8°. Feel like id be robbing the total timing value when the VA is no longer a factor when driving around. Thanks.
While I have never had that problem, I have heard of people that did. I would not give up timing to get the idle back down. Maybe find a way to limit the vacuum swing. Thanks for watching!
Not as cut and dried as emission era either. Plenty pre emission cars ran ported. Plenty emission cars then ran ported until X engine temp then swith to manifold. Some ran a retard cannister during warmup, ported at normal operating temp and manifold at high temp OR with AC on. So many different scenarios.
Dear Sir I’m still left confused 😕 as I’m going to fit a vacuum distributor to my 1938 side valve 4 cylinder car because at the moment it doesn’t have one only the bob weight , now the carb has a ported take off type blank on it so I could fit to either manifold or port and looking on you tube has only confused me even more 😢 what would your advice be please?
While I'm not well versed in side valve/ flat head engines, as long as you are careful with the timing, you should be able to try both methods and see which it seems to like better. It might not want any more than just the mechanical advance. Most of that era would have a hard line threaded into the source. Good luck.
After some thought I have some questions. Did the car come originally with the vac can and was removed at some point? It's probably more of a city/country road car than interstate car? Do you know where the total advance should be or the initial advance only? I'm thinking since it is probably a low RPM engine, it might benefit from ported. But if you know its total advance happy spot, and have a timing light that has advance capability, you could run no vac can and once set at the correct total advance it would give it more initial which might give it lower under hood temps. If you know its total advance happy place you can try any combo.
hi & thanks for your reply, these were a low end/ cheap cars and the engine was of a very early 1930 designs low revving long stroke engine of 1,100 cc and they never had a vacuum fitted like the more expensive models like MG or Triumph cars of the same period, the type of distributor I’ve acquired is the type that turns the whole distributor as the base plate inside are fixed, it’s a 40 bhp engine 😅
One of the best explanations regarding this debate I have seen. Thanks for taking the time to share your knowledge and perspective.
Thank you for the comment and support!
Good video. It really does depend on application. My 79 F350 has a built .30 mild cam with 4 BBL and it needs manifold for a good clean idle.
The only thing I’d say is stop adjusting your idle with the idle screw. You set idle with timing. Set the transfer slot to a square on your carb and check it by using a vacuum guage on the ported vacuum port of the carb. It should always read 0.
Then you can adjust idle and mixture as needed
Great video. Another addition to the great ported/manifold debate😁. It comes down to giving an engine the timing it wants. On a mild cam engine, either could be made to work with an adjustable vaccum can and a curved mechanical advance. Depends on the engine, weight, stall speed, cruising rpm. On a choppy low vaccum cam engine, manifold would be a better choice. Needs more timing at idle. You can set you initial as high as you can without causing kickback on the starter and use the vaccum advance to give you the rest of the timing you need to idle. Then adjust the mechanical advance curve. At WOT vaccum advance doesn't matter only max timing (initial+mechanical). At light throttle and cruise the vaccum and mechanical have to be adjusted for an optimal curve.
Exactly! Too many variables to only use one method. Thanks for watching and the comment.
we need to consider the application. At high altitude, we typically use manifold vacuum for a stock, daily driver. Eliminate the accumulator and let's see how your A/C and heat behave!! This is always a good laugh!!
Thanks for your help! I’ve been seeing a lot of different views on this topic. I’ve been running a fairly high performance engine for years, and I’ve always tried the trusted ported vacuum. I’ve always believed that my engines could make a bunch more horsepower. I’m starting to believe that straight manifold vacuum, could make a big difference. I’ve been setting my initial, and mechanical advance at around 36 degrees, and have always seemed to have low, low end power. That’s why this manifold vacuum thing seems like it might make more sense. Heck! I’ve even drilled holes in my primary throttle blades, to get my transfer slots in order. I realized, that drilling the plates bumped my idle up as much as changing my vacuum, from ported to manifold. I have another 750 without drilled plates, and I’m gonna give manifold vacuum a shot. My engine runs around 230 degrees in traffic, and nobody knows why. I’m talking to friends who race, have street rods, and oval track. This is definitely something that I’m gonna look into!! Thanks!
When I tried ported in my Z car, the temp went way up. I deleted the vac can and just run mechancal at 38 degrees now. Good luck.
Very well described! Thank you!
Thank you for watching.
Finally a good video I can understand 👍👍
Thank you for watching!
Now I’m curious. I’m gonna go play with the timing and go to manifold vacuum and see how it runs and just carburetor a little if it needs it thank you I’m Kevin Jenkins, I started driving in 1975. My first car a 1956 Chevy four-door wagon. He got wrecked in front of my dad’s house. I’m on my second one which I bought 1983 been sitting in my garage for 30 years. I think it’s time. I bought my CJ5 in 1987. I keep it running. I parked the 56 Chevy because I’m not mature enough to drive it. But I think it’s time. I have a 327 in it 11 inch clutch and a Muncie for speed.
Very well done I think this ends the debate.
Thank you for watching!
Thanks for showing me the differance
Thank you for watching!
Good video and good explanation, thanks.
Thanks for watching!
Good video mate. I am trying to set my distributor back down in the hole and now my engine builder has made it to the next round so I can't ask him timing questions. On a Ford 351 should the distributor trigger be set to cylinder 1 with same cylinder at TDC or a little prior that like 10 degrees advanced? There are so many variables. I have a Mallory Unilite.
Yes. I usually put a sharpee mark on the body with the cap on, lined up with the number 1 plug wire. Put the engine on number 1 tdc and drop the dist in. I believe on 351's, the rotor will be at 1:00. then set the timing with a light.
@@NoCarLeftBehind but on the balancer he painted on 0 then 10 and 20 advance and not sure where that will be when spark fires on 1 according to dist.?
That depends on how much swing the dist has. Is your timing mark a pointer or a scale? The timing at idle isn't as important as total advance at speed. If you have a scale timing mark, run the engine up to full advance, (3000 rpm ish) and set it at 15btdc at the 20 degree mark for a total of 35 degrees BTDC. That would be a good starting point. I also have another video on finding 36 BTDC.
@@NoCarLeftBehind I'm afraid that I was previously a no-nothing consumer and just went to a job so my engine guy did not teach me anything other than what oil to use. I wish I had asked him more questions but I had no reason to. I overpaid a racer guy to get the thing running. When my water turned slightly acidic corrosion started taking over front timing cover and seeping, so I took the balancer off and cleaned all things there, then applied fresh paint where he had left 3 marks that seem about 10 degrees from one another. I just replaced the wires and primed the engine, replaced oil pan and pickup so nothing is as it was.
@@NoCarLeftBehind I wish that I had taken meticulous notes and taken pictures but i didn't
Awesome. I'll try it.
Curious, after setting total timing as you mentioned (36°), Do you ever find the scenario where you have no more idle speed and mixture screw adjustments left to reduce the higher RPM (to an acceptable Idle) , that you now have to retard the Mechanical timing to compensate for a ideal idle speed? I just would hate to go from 14-17°, down to 8°. Feel like id be robbing the total timing value when the VA is no longer a factor when driving around.
Thanks.
While I have never had that problem, I have heard of people that did. I would not give up timing to get the idle back down. Maybe find a way to limit the vacuum swing. Thanks for watching!
@ copy that thanks.
Not as cut and dried as emission era either.
Plenty pre emission cars ran ported.
Plenty emission cars then ran ported until X engine temp then swith to manifold.
Some ran a retard cannister during warmup, ported at normal operating temp and manifold at high temp OR with AC on.
So many different scenarios.
Really good info
Thank you for watching.
Dear Sir I’m still left confused 😕 as I’m going to fit a vacuum distributor to my 1938 side valve 4 cylinder car because at the moment it doesn’t have one only the bob weight , now the carb has a ported take off type blank on it so I could fit to either manifold or port and looking on you tube has only confused me even more 😢 what would your advice be please?
While I'm not well versed in side valve/ flat head engines, as long as you are careful with the timing, you should be able to try both methods and see which it seems to like better. It might not want any more than just the mechanical advance. Most of that era would have a hard line threaded into the source. Good luck.
After some thought I have some questions. Did the car come originally with the vac can and was removed at some point? It's probably more of a city/country road car than interstate car? Do you know where the total advance should be or the initial advance only? I'm thinking since it is probably a low RPM engine, it might benefit from ported. But if you know its total advance happy spot, and have a timing light that has advance capability, you could run no vac can and once set at the correct total advance it would give it more initial which might give it lower under hood temps. If you know its total advance happy place you can try any combo.
hi & thanks for your reply, these were a low end/ cheap cars and the engine was of a very early 1930 designs low revving long stroke engine of 1,100 cc and they never had a vacuum fitted like the more expensive models like MG or Triumph cars of the same period, the type of distributor I’ve acquired is the type that turns the whole distributor as the base plate inside are fixed, it’s a 40 bhp engine 😅
Simply the best video on topic...way too much STUPID confrontation on topic
Thanks for watching!