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| distributor recurve https://slantsix.org/forum/viewtopic.php?t=42635 |
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| Author: | Aggressive Ted [ Wed Nov 24, 2010 11:43 am ] |
| Post subject: | Distributor Recurve |
Quote: "the 15R governor is best for mileage". I've read this before, could you elaborate? Is this because the longer slots allow control over more of the advance curve?
That is true if your not driving a dump truck or towing. I have found the 15R governor is the most flexible to tune of all the SL6 governors. The spring post are adjustable for fine tuning, the slots are long enough that you don't need to worry about bouncing off the ends of the slots which can result in erratic timing. You can run zero degrees initial timing up to 16 degrees or any where in between depending on the springs you choose to run. If the springs are heavy enough you can limit the travel to act like 7.5R governor. So it is quite flexible.If you have nice light car you can set a 15R up to get some great mileage and a very spunky feel. I found the SL6 in a street car with an automatic likes lots of initial timing and a fairly fast mechanical advance which gives you a very responsive feel. As Doc, Wjajr and others have pointed out you want 32 degrees total when you add the initial plus mechanical timing together. The vacuum pod fine tunes the overall response depending on the vehicle you have; car, truck, van, work truck, tow truck, etc.... |
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| Author: | The Kenosha Kid [ Thu Dec 02, 2010 10:40 am ] |
| Post subject: | |
Hmm. Yes, I understand that 32 is the goal. One could reach that magic number using any governor, provided the base timing is appropriate. Why is the 15 governor better for fuel economy than, say, a 9? Is it because it starts with less initial advance (2 BTC)? This subject is near and dear to my heart. My '73 Dart Custom gets a lousy 16 MPG, and spending so much money on gas is depressing I have 3 distributors I'm playing with. None of them have any adjustments for the spring posts. Wish they did. Sorry for hijacking the thread. This question has been bothering me for a while, and you seem like the people to answer it. |
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| Author: | Aggressive Ted [ Thu Dec 02, 2010 11:31 am ] |
| Post subject: | |
The Kenosha Kid, Quote:
Why is the 15 governor better for fuel economy than, say, a 9?
A 9R governor is only able to supply 18 degrees of advance and that is by running light springs and hitting the ends of the slots. To get the desired 32 degrees you would need to run 14 degrees initial advance. If you can get your distributor to do that, try it and let us know how the engine feels. Generally folks run around 10 degrees or less initial an expect 20 degrees or more from the mechanical. So a governor with longer slots will provide more mechanical. It is all about balance and how the engine is loaded. Heavier rigs or towing vehicles would not do well with too much overall advance. As a test I used to run 16 degrees initial and 30 mechanical. It was fun and interesting.....got super mileage over 28 mpg but it was hard to drive. I had to drive it very gingerly. If I pulled out to quick from a drive way, intersection, etc. both wheels would break loose like a kid was driving it. My wife got after me after 2 weeks and told me to fix it......! So I put the stiff springs back in. The engine had some snap....but I had to run with a short throw vacuum advance dialed out as much as I could. On a car especially a light car you could get away with 50 to 55 degrees total advance for some nice mileage at cruise. Running 55 to 60 degrees the motor just goes flat at 70 mph, no punch. In a truck or van I would probably limit it to about 45-46 degrees total. |
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| Author: | Doc [ Thu Dec 02, 2010 11:37 am ] |
| Post subject: | |
There are 2 types of spring posts, the early ones are a simple tab... which you bend to change position, the other is a post with an eccentric base, you have to twist those to move the centerline. (change spring tension) In general, the 9X govener allows more initial timing with a "solid" end point to weight travel but the 15X can be used, if you have a stiff enough secondary spring, to stop the weight movement at 30 degrees total advance. DD |
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| Author: | Aggressive Ted [ Thu Dec 02, 2010 11:55 am ] |
| Post subject: | |
Quote: the 15X can be used, if you have a stiff enough secondary spring, to stop the weight movement at 30 degrees total advance.
That is how I am running my 15R governor. A nice super stiff long looped spring from a HP 440. HP 383's had them and some 400's. The primary spring I am using is a red medium tension spring. It provides enough spunk and is quite controllable in terms of wheel spin.
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| Author: | gato [ Wed Dec 08, 2010 5:28 am ] |
| Post subject: | |
Well. . . i got it improved with using only parts from my "donor" distributors. tested the vacuum pods and found the old, non adjustable to be expired. also expired was the pod from my EI dizzy. i put in the the one good working pod. got back to blazing the freeways, rite away. but after 1 day of use, that pod expired. had to limp home at very low RPM's. at least now i understand where my problems came from. i never had one of these pods go out b4. what a weird experience. so now, as many have suggested, I'm thinking to add a vacuum gauge. here's my question. . . will the length of hose/tubing i put between my tap point and the gauge affect the accuracy of a gauge? i'm working with an A108 van and getting up to my preferred gauge location, a shelf above the windshield, will mean 8" or more of hose. would that be a factor? D~~~! |
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| Author: | Aggressive Ted [ Wed Dec 08, 2010 9:41 am ] |
| Post subject: | |
Quote: will the length of hose/tubing i put between my tap point and the gauge affect the accuracy of a gauge?
No. Since you have van which can get extra hot, just use good quality hose, silicone if they have it. Take a look at my carb pics on the red link below my name. I am running a "T" off the vacuum actuated choke pull off. I am using about 5' of hose since the gauge is mounted under the dash between the glove box and radio along with my tachometer. Both are mounted in a swivel pod aimed at me. As much driving as I do I find this location easier to monitor and it is out of sight from the casual passer by when parked. |
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| Author: | Reed [ Wed Dec 08, 2010 10:00 am ] |
| Post subject: | |
I installed a vacuum gauge in the dash of my brother 83 B150 van. It sits directly above the doghouse, and I had to run about four feet of hose. I tapped into a non-ported vacuum nipple on the base of the carb. I used the stiff plastic hose that came with the gauge. It lasted several years, but I just had to replace it because the end by the carb got cooked and brittle. I believe this was due to the heat of the engine compartment and also to the fat that a small amount of gas would occasionally work its way into the vacuum tube and react with the plastic. The other thing the plastic tube did was collapse. It still operated the gauge, but it was sucked almost flat. I don't know if silicone is rated to not collapse and to not be degraded by gas. Those are the three factors I would consider when deciding what hose to purchase- heat resistance, compatibility with gas and gas fumes, and collapse-ability. |
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| Author: | oldblue [ Wed Dec 08, 2010 12:36 pm ] |
| Post subject: | |
What vacuum readings did you get on the van? |
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| Author: | Reed [ Wed Dec 08, 2010 12:40 pm ] |
| Post subject: | |
My brother's van? Best I ever got was 21 inches idling in neutral. There is something up with it right now and it is only putting out about 17-18 idling in neutral, but I know I need to adjust the valve lash and carb. |
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| Author: | Aggressive Ted [ Wed Dec 08, 2010 12:52 pm ] |
| Post subject: | |
Reed, Since we both have the same RV-10 cam grind...... I have found that a larger lash on the exhaust is required. Your running .012 on the exhaust? Vacuum went down the tighter I went and as I opened it up the vacuum went up. Set at .012 intake and .022 exhaust netted 20"-21" per Doc's recommendation. Running a little tighter puts it at 18"-19". When your in there, can take a picture of the O2 sensor? |
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| Author: | Reed [ Wed Dec 08, 2010 1:51 pm ] |
| Post subject: | |
Ted- I wish I had an O2 sensor manifold on this van. i would love to install a sensor and a gauge to help with tuning it. However, I am running regular old manifolds without the sensor. I will see if I can locate a factory diagram for a slant manifold with an O2 sensor. I definitely want to loosen up the valve lash. I only put them this tight to try and quiet down the lifter noise. But since the Mobil 1 has quieted the lifters down, I am definitely going to loosen up the exhaust and possibly the intake. Once I get the valves done and hopefully increase the vacuum, I am going to set up a distributor like you recommended with a 15R governor, a heavy spring with a long loop, and a medium-light spring. The van cruises at 2600-2700 RPM, so I really want to try and get about 28 degrees of mechanical advance in by 2600 RPM. I want to do it somewhat slowly and evenly since this is a hauling rig, but it only weighs about 3500 pounds minus the payload, not much more than a mid 70s A-body. The van really seems to like a lot of initial base advance. I know the base timing right now is set at 12 or 14 degrees BTDC, but I need to double check that. I will need to fine tune the vacuum advance pod once I get the mechanical advance and valves all done and get a new baseline for the vacuum reading at cruising speeds and RPM. |
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| Author: | Aggressive Ted [ Wed Dec 08, 2010 4:00 pm ] |
| Post subject: | |
Reed, Quote: I will see if I can locate a factory diagram for a slant manifold with an O2 sensor.
Thanks! that would be great. I want to set mine up so I can put an A/F gauge on mine also.On the pod, don't get a 11R VC-208 like I am running. The engine might go flat with too much vacuum advance. Look for a truck pod, like a 7R. I prefer to run more initial than 10 degrees with this cam. It really liked 16 degrees initial for some reason. As soon as the ported vacuum line started pulling, it provided some real nice pep! I might have to dial the cam in with a little more advance when I take it apart to install the dual roller chains and gears. It is also one of the last Direct Connection sets. So we should be have pretty similar motors when I am done. I think the Engine Builder valves may be just a little smaller than your though, but close enough. |
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| Author: | Reed [ Wed Dec 08, 2010 5:02 pm ] |
| Post subject: | |
Thanks for the pointers. I already want to swap out the vacuum can that I have. it doesn't start advancing until 10 inches, but in this van any acceleration puts you well below ten inches of vacuum. The motor only sees more than ten inches of vacuum on deceleration or on *VERY* light throttle opening. I need a vacuum can that can be adjusted to start working at around 7 or 8 inches. Now I need to track down a part number for a different vacuum can. I was looking at Dan's list of vacuum can specs and I see that VC233 is not on there. VC233 is the can specified by rockauto as the stock can for my brother's 83 Dodge van. Anybody know the specs for a VC-233 advance can? Otherwise, I am leaning towards ordering a VC93. It starts working at 4.9-7 inches of vacuum, ends at 13 inches of vacuum, and provides 5.25-7.5 degrees of advance. This sounds like just what I need for a big van doing hauling duty. In fact, rockauto shows the VC93 can was used on the slant six distributors found in 1966 W300 trucks. That's quite a beast for a little 225 to be pushing around, so I think I will try that vacuum can out. Base timing of 16 degrees, 15R governor in the distributor with heavy long-loop spring and medium heavy short spring, most advance in by 2600 RPM, and vacuum advance coming on between 5 and 7 inches and ending by 13 inches. I need to give that setup a try. I might use an 11R governor on the distributor though. 46 degrees mechanical is a tad much, especially with another 6 degrees of vacuum. |
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| Author: | gato [ Fri Dec 10, 2010 4:29 am ] |
| Post subject: | |
does anybody know if the trigger wheel in the factory EI distributor will trigger a Pertronix ignitor? i have a 15R governor for that dizzy. it doesn't have the regular points cam in it. |
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