Booker T Posted February 1, 2011 Report Posted February 1, 2011 I am in the process of getting my engine back together and back in the car. As a part of this I am installing Langdons HEI and also adding a PCV setup. I am running an Offy dual intake and it has several holes (currently with plugs) tapped into it. After talking to Tom Langdon he suggested that I run the vacuum advance off my intake instead of the carbs (based on the cam grind I will be running) and I believe I will also need to run intake vacuum for the PCV setup from the posts I have read on this site. In the picture below, would the top two holes be suitable for this application and would one be better for one application than the other for any reason? Additionally, curious if anyone knows what the tapped hole in the "intake heater" portion would be used for? Sorry about the picture quality, they were taken with my phone... Quote
Don Coatney Posted February 1, 2011 Report Posted February 1, 2011 Your intake manifold is water heated. Follow this link. http://www430.pair.com/p15d24/mopar_forum/showthread.php?t=15678 Quote
Alshere59 Posted February 1, 2011 Report Posted February 1, 2011 I think you will find Offys are heated by the exhaust not with water. Easy to check can you see the plug looking down into the carb mount? If so feel free to use either one. Quote
Andydodge Posted February 1, 2011 Report Posted February 1, 2011 No, its NOT water heated........sorry Don, I have that same Offy intake manifold and the two upper holes that Booker refers to go into the intake plenum and are for a vaccum line or PCV valve , I just went and checked mine and they are in the same spot on my manifold, see attached pic.......the lower hole goes into the exhaust riser chamber on the Offy intake that matches and bolts to the stock exhaust manifold heat riser box...........the drilled & tapped hole is for a heat tube line/hose that would connect to a carby choke.........the only way this intake manifold gets any heat is if a stock exhaust manifold is bolted to it.......I am running a split exhaust with no exhaust heat riser as you can see, if I need to I'll fab up a plate to bolt to the centre of the intake with a pair of water outlets on it & run it to the water pump. ........Booker I have a Langdon HEI on my 41 Plymouth and its getting its vaccum from the non stock Stromberg single barrel carby port, see pic...........as for the PVC, on my intake the front hole is larger than the rear, think its 1/2" against the rear being 3/8" so the front may suit a PVC hose fitting better.......the HEI is the best thing I have done for the Plymouth.....hopefully the rest of the engine will be built soon.........its still on the stand.......regards, andyd Quote
martybose Posted February 1, 2011 Report Posted February 1, 2011 I'm glad to hear that Tom may have seen the light. I've been running manifold vacuum to my HEI for years, and have been arguing that it made more sense on a modified motor. Try 4 degrees BTDC with the vacuum disconnected and blocked as a starting point. Marty Quote
hkestes41 Posted February 1, 2011 Report Posted February 1, 2011 My Offy is water heated. You can see the plate bolted to the bottom of the intake with elbows for connection of the heater hoses on the way to the heater. Quote
Frank Elder Posted February 1, 2011 Report Posted February 1, 2011 Does your savoy have vac. wipers? Quote
Booker T Posted February 1, 2011 Author Report Posted February 1, 2011 Does your savoy have vac. wipers? Nope...the wiper motor is electric which has caused a couple of issues with the 12v conversion but I think I have my solution figured out. Quote
Booker T Posted February 1, 2011 Author Report Posted February 1, 2011 [ATTACH]23960[/ATTACH]No, its NOT water heated........sorry Don, I have that same Offy intake manifold and the two upper holes that Booker refers to go into the intake plenum and are for a vaccum line or PCV valve , I just went and checked mine and they are in the same spot on my manifold, see attached pic.......the lower hole goes into the exhaust riser chamber on the Offy intake that matches and bolts to the stock exhaust manifold heat riser box...........the drilled & tapped hole is for a heat tube line/hose that would connect to a carby choke.........the only way this intake manifold gets any heat is if a stock exhaust manifold is bolted to it.......I am running a split exhaust with no exhaust heat riser as you can see, if I need to I'll fab up a plate to bolt to the centre of the intake with a pair of water outlets on it & run it to the water pump.........Booker I have a Langdon HEI on my 41 Plymouth and its getting its vaccum from the non stock Stromberg single barrel carby port, see pic...........as for the PVC, on my intake the front hole is larger than the rear, think its 1/2" against the rear being 3/8" so the front may suit a PVC hose fitting better.......the HEI is the best thing I have done for the Plymouth.....hopefully the rest of the engine will be built soon.........its still on the stand.......regards, andyd I'm glad to hear that Tom may have seen the light. I've been running manifold vacuum to my HEI for years, and have been arguing that it made more sense on a modified motor. Try 4 degrees BTDC with the vacuum disconnected and blocked as a starting point.Marty When I talked to Tom he suggested that because of the cam grind I have (sorry, don't have the numbers handy) that I should use the intake vacuum over the carb vacuum because of needing more advance at idle. Although the numbers he quoted for advance are a lot higher than 4 degrees (15 I believe, which I thought sounded very high). Thanks for the suggestion...I will use that as a starting point. I have the block off plate with inlets for the intake and plan on hooking it up this time around... Quote
Andydodge Posted February 1, 2011 Report Posted February 1, 2011 Booker, is the block off plate you have the same as that shown in the pic?......if so where did you get it?.......it as I mentioned will allow the manifold to be heated but the intake doesn't have an in/out water jacket like some intakes have..........andyd Quote
Booker T Posted February 1, 2011 Author Report Posted February 1, 2011 Booker, is the block off plate you have the same as that shown in the pic?......if so where did you get it?.......it as I mentioned will allow the manifold to be heated but the intake doesn't have an in/out water jacket like some intakes have..........andyd Yep, it looks exactly the same. I got it from Langdon's when I got the carbs... Quote
martybose Posted February 2, 2011 Report Posted February 2, 2011 When I talked to Tom he suggested that because of the cam grind I have (sorry, don't have the numbers handy) that I should use the intake vacuum over the carb vacuum because of needing more advance at idle. Although the numbers he quoted for advance are a lot higher than 4 degrees (15 I believe, which I thought sounded very high). Thanks for the suggestion...I will use that as a starting point.I have the block off plate with inlets for the intake and plan on hooking it up this time around... 15 is fine if you are using ported vacuum (which isn't present with the throttle closed), but it is way too high with manifold vacuum. I tried his number first, and didn't like the results. I pick up almost 19 degrees with vacuum applied and another 13 from centrifugal advance, so 15+19 was 34 degrees to turn over with the starter, and add 13 more at speed for 53 degrees at a fast cruise!! My car was hard to start and would start overheating on the freeway. After switching to manifold vacuum and experimenting with initial advance, I now have 4+19=23 to start, 4+19+13=36 at fast cruise, with 4+13=17 if I stand on it at speed. The last could probably be more if I wanted to modify the distributor for additional centrifugal advance, but I don't. I can live with this. Marty Quote
Booker T Posted February 2, 2011 Author Report Posted February 2, 2011 15 is fine if you are using ported vacuum (which isn't present with the throttle closed), but it is way too high with manifold vacuum. I tried his number first, and didn't like the results. I pick up almost 19 degrees with vacuum applied and another 13 from centrifugal advance, so 15+19 was 34 degrees to turn over with the starter, and add 13 more at speed for 53 degrees at a fast cruise!! My car was hard to start and would start overheating on the freeway. After switching to manifold vacuum and experimenting with initial advance, I now have 4+19=23 to start, 4+19+13=36 at fast cruise, with 4+13=17 if I stand on it at speed. The last could probably be more if I wanted to modify the distributor for additional centrifugal advance, but I don't. I can live with this.Marty Thanks for the info...sounds like a great place to start when I get this thing back together! Quote
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