Griff in Fairbanks
AK
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RvFNG76 wrote:small block 360 2 bbl wanna go 4 bbl but havent nailed it down yet. The engine in this monster is untouched except for the egr being removed (plate slightly leaks) by previous owner. Another fun little deal now is speedometer jumps and goes nuts every once in awhile checked the gear in the tailshaft but it looks fine any ideas?
Exhaust manifold -- I need a picture of what you have to see if one of my spares will work.
2bbl to 4bbl -- there are adapters for mounting 4bbl carburetor on 2bbl intake manifolds. Suitability is so-so and performance is less than optimal. Also, hood/doghouse clearance is often an issue. If you go with an adapter, definitely use a marine bilge blower ... the adapter will put the carburetor deeper into the hot air pocket under the doghouse.
You're better off switching from a 2bbl manifold to a 4bbl manifold.
Before you do it, check total cost. You may be able, for a slightly greater cost, to go to a multiport EFI manifold and system instead.
Speedo jumps -- clean and re-lube the cable, with graphite powder. (Clean with a solvent, such as kerosene, followed by brake cleaner or acetone ... flush thoroughly with each.)
Otherwise, the speedometer instrument in the dash is dirty or going bad. They can be cleaned and re-lubed. Be careful, some solvent can damage them. Dish soap and lukewarm water is best, along with small brushes and a lot of careful effort. Rinse afterwards with clear lukewarm water, followed by a denatured alcohol rinse. Re-lube sparingly with instrument grease.
Look for clearly worn plastic gears. I may have a spare speedometer, depending on what style you have. Alternatively, there's places on the internet that can rebuild old instruments.
1970 Explorer Class A on a 1969 Dodge M300 chassis with 318 cu. in. (split year)
1972 Executive Class A on a Dodge M375 chassis with 413 cu. in.
1973 Explorer Class A on a Dodge RM350 (R4) chassis with 318 engine & tranny from 1970 Explorer Class A
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Griff in Fairbanks
AK
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Instrument grease -- compatible with plastic gears. Check hobby shops that cater to RC car enthusiasts. Likewise, internet outlets that cater to experimental robotics hobbyists.
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Griff in Fairbanks
AK
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I just found a new idea for my motorhome ... turn signals that use actual blinker fluid.
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Eric Hysteric
Hildesheim
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Joined: 09/19/2017
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Thanks Griff, the PCV line is connected at the PCV Port. In most Edelbrock-threads, people advise to connect the distributor line to the timed vacuum port.
For example in this topic
'79 Dodge Sportsman 5.9 LA 360 TEC Campmate
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Griff in Fairbanks
AK
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Eric Hysteric wrote:Thanks Griff, the PCV line is connected at the PCV Port. In most Edelbrock-threads, people advise to connect the distributor line to the timed vacuum port.
For example in this topic
Read that forum thread (topic) again. People are arguing one way and the other, so some of them don't have a clue.
In particular, read RustyRatRod's post.
The Edelbrock literature assumes everybody has a newer vehicle, newer than your motorhome. If you dig deep enough in their literature, you may find some mention of older vehicles. (Or, they may assume anyone with an older vehicle knows what they're doing.)
Older vehicles (pre-1961) didn't even have PCV, just a draft tube off the crankcase. (My '47 Willys Overland and '49 Int'l Metro were both draft tube -- no PCV) The only carburetor vacuum fitting was manifold vacuum for distributor advance.
My '66 Dodge Polara, the '68 Chevy 283 in the '65 GMC stepvan, and '69/70 Dodge M300 Class A all had PCV plus a single manifold vacuum port for distributor advance. (All three had the brake boosters ported off the manifold rather than the carburetor, with a check valve.)
But, don't take my word or anyone else's for it. Try it yourself.
With the two vacuum lines connected one way, check your gas mileage (gas klickage?) and see how the engine performs. Then, switch the lines and run the test again. (Use the same route/course both times to eliminate road variations.)
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Griff in Fairbanks
AK
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Teaser headline in CNN's Tech section today: "Electric Winnebagos are coming soon."
Something else I'd better start studying and following.
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VintageMopar
Missouri
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There are 3 options for vacuum advance sources. Ported, manifold and Venturi.
Ported is zero at idle and goes up as engine rpm increases so dist advance increases with rpm, usually desired as long as detention /pinging doesn’t occur.
Manifold vacuum is high at idle, drops with rpm so all your advance is at idle and drops with speed. Better launch and low speed performance but not at highway speeds. A lot of cars we’re plumbed this way.
Venturi vacuum is similar to ported but slightly different rise. The thing with it is you have to use a vacuum amplifier as it is too weak a vacuum to actuate advance directly.
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Griff in Fairbanks
AK
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VintageMopar wrote:There are 3 options for vacuum advance sources. Ported, manifold and Venturi.
Ported is zero at idle and goes up as engine rpm increases so dist advance increases with rpm, usually desired as long as detention /pinging doesn’t occur.
Manifold vacuum is high at idle, drops with rpm so all your advance is at idle and drops with speed. Better launch and low speed performance but not at highway speeds. A lot of cars we’re plumbed this way.
Venturi vacuum is similar to ported but slightly different rise. The thing with it is you have to use a vacuum amplifier as it is too weak a vacuum to actuate advance directly.
Thank you, I was really hoping you'd chime in.
As you implied, really depends on how you're going to use the vehicle. For mostly around town, one way is best. Mostly highway? Another way is best.
Thank you also for mentioning venturi vacuum ... I overlooked that, in part because most vacuum ports originate below the throttle butterfly.
I try repeatedly to warn people: Pay attention to the context of what you're reading and advice you're getting. If you're using race car advice, you're probably (strike that, definitely) going to be dissatisfied when you're cruising the strip, profiling for spectators. Likewise, if you're following daily driver sedan advice, you may be less than satisfied when it comes to your heavy truck. (Hint, hint -- motorhome.)
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RvFNG76
Michigan
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Joined: 07/14/2017
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Ok less thought of question. What kinds grades of oil does everyone run in their rigs??
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Griff in Fairbanks
AK
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RvFNG76 wrote:Ok less thought of question. What kinds grades of oil does everyone run in their rigs??
10W40 for warmer nine months, 10W30 during Alaska winters.
10W40 makes engine last longer but results in a slight decrease in gas mileage. (EPA/government regulations and slightly better mileage is why manufacturers specify 10W30.) 10W30 because 10W40 makes it harder to start the engine in severely subzero temperatures.
I change oil and filter every three months or 3,000 miles, whichever comes first. Will skip a change if vehicle has been sitting idle and oil was changed after the last use.
Because I change so often, I use whatever is cheapest or convenient.
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