Few random Q's about 318 and gauge wiring

[MopaR&D]

1.) I finally got a vacuum gauge hooked up to my stock '70 318 and after playing around with my idle mixture a bit, I only got it to go as high as 15 in-Hg. Is this acceptable? I do have the stock divided-plenum low-rise single-plane intake (BOO :angry7 and I only got a reading on the driver's side plenum, but I assume it would be similar on both sides. I tested the cranking compression on cylinders #1 and #3 (didn't get to the rest) and it was around 92 psi, and I'd assume the rest would be close to that because my starter stays the same pitch when cranking for an extended period.

2.) I read in an article about converting an '80's truck smogger 318 2-bbl. to a 4-bbl. that most/all of the old 318 2-bbl's (no matter the year) develop a bad hesitation off the line that has to do with the carb. Is this true, and what makes it happen? My 318 has done this since I got the car.

3.) I'm putting some aftermarket gauges in my Duster and I don't know what I should do as far as wiring goes. Do I splice into an already-existing circuit, or do I create a whole new circuit? When I put my tach in I just hot-wired it straight to the fuse connections in the fusebox, and I know that's definitely not the proper way to do it.

 

[Mopar318Guy]

the tach should have 4 wires. black green white and red. black is ground. white is to your lights. on the left of the steering theres an adjuster that turns. turn all the way to the right and get the click that should be your hookup for that wire. red is hot i splice that in with the white. and finally the green is to the coil -. if you havent done this before get someone else to do it for you. it may be a paint. put one in my S10 and it was a total pain in the ***. and you can get a 4bbl intake from most junkyards. grab the carby too. youl need it. 2 bbls just bog out cuz they suck eggs. 4bbls are more fun. good luck!!

 

[Thrashard340]

1.) I finally got a vacuum gauge hooked up to my stock '70 318 and after playing around with my idle mixture a bit, I only got it to go as high as 15 in-Hg. Is this acceptable? I do have the stock divided-plenum low-rise single-plane intake (BOO :angry7 and I only got a reading on the driver's side plenum, but I assume it would be similar on both sides. I tested the cranking compression on cylinders #1 and #3 (didn't get to the rest) and it was around 92 psi, and I'd assume the rest would be close to that because my starter stays the same pitch when cranking for an extended period.

2.) I read in an article about converting an '80's truck smogger 318 2-bbl. to a 4-bbl. that most/all of the old 318 2-bbl's (no matter the year) develop a bad hesitation off the line that has to do with the carb. Is this true, and what makes it happen? My 318 has done this since I got the car.

3.) I'm putting some aftermarket gauges in my Duster and I don't know what I should do as far as wiring goes. Do I splice into an already-existing circuit, or do I create a whole new circuit? When I put my tach in I just hot-wired it straight to the fuse connections in the fusebox, and I know that's definitely not the proper way to do it.

I'll answer what I know. Hopefully someone else can fill in the blanks.

1) 15" of vacuum is acceptable. I would check compression on all cylinders and look for uniformity in the #'s.

2) A bad hesitation off the line on a stock carb generally has to do with the accerator pump on the carb. I had this issue on a '77 Dodge van, 360, 2bbl. It was an easy adjustment. I just bent the rod to the accerator pump until the hesitation went away. 1980 is right on the cusp of computer controls so let us know the exact year and chassis of the motor you are describing so making adjustments to the carb is not that simple and out of my realm of knowledge.

3) I've done all that you have mentioned. I'm definitely no expert in wiring.

 

[MopaR&D]

Actually after reading it again I'm only getting 14" max at idle. I'm going to try capping off all the vacuum sources (including PCV) and getting another reading; hopefully it's a vacuum leak. Would something like a nice new multi-spark ignition (the entire system, including distributor/plugs/wires) allow the engine to pull more vacuum? Or what about a free-flowing exhaust (I have the awful single 1-3/4" system)? Or rebuilt ThermoQuad carb? I guess what I want to know most of all, what is the idle vacuum that a stock 318 2-bbl. in good condition should be pulling/has pulled in anyone's past experiences?

Also, I'm thinking about tapping into the instrument panel wiring somehow to power all my gauges. How do I physically go about doing this? As in do I splice, or just connect directly to the fuse...?

 

[Mopar318Guy]

splice. unhook your power. cut a 1 inch section of your wire insulator off leavin the 1 inch of copper exposed. do this to your wire with your gauges. i split my wires. so its actually 4. i splice the 2 pairs then twist them with my fingers as tight as possible and bend it around and cap it off with electric tape. it worked on my truck. it should work with your car. and ill sell you a 4 bbl intake for 50 bucks. just bolting on a 4 barrel intake and carb can boost u up to 50hp. and if you drive sensibly you can still stay around the same mpg

 

[MopaR&D]

Thanks Mopar318Guy, but I already have a ThermoQuad and iron intake off of an '83 truck 360. Honestly, I don't know why I've been waiting so long to do the swap... I think I'll get the stuff and do it soon (after dual exhaust though).

 

[SRT_DSTRHOLC]

if im right, i can get like 20psi of vaccum from my 318

 

[Mopar318Guy]

Thanks Mopar318Guy, but I already have a ThermoQuad and iron intake off of an '83 truck 360. Honestly, I don't know why I've been waiting so long to do the swap... I think I'll get the stuff and do it soon (after dual exhaust though).

should work nicely. are you leaving stock manifolds or gettin headers. exhaust is an ok thing to do. just get some flowmaster 40s and youll be good to go. do 2 1/4 inch pipe though. and when you go to put the intake on get copper permatex for your gasket sealer. intake gaskets are bout 15 bucks and the permatex is like 5 for a tube. just make sure you seal it up good so no oil gets out. and work just takes time and money. somethings not all of us have. you should also get a carb spacer. 1/2 to 1 inch. lil extra mmph. not extreme. but 2 or 3 extra hp never hurt

 

[rumblefish360]

1.) I finally got a vacuum gauge hooked up to my stock '70 318 and after playing around with my idle mixture a bit, I only got it to go as high as 15 in-Hg. Is this acceptable? I do have the stock divided-plenum low-rise single-plane intake (BOO :angry7 and I only got a reading on the driver's side plenum, but I assume it would be similar on both sides. I tested the cranking compression on cylinders #1 and #3 (didn't get to the rest) and it was around 92 psi, and I'd assume the rest would be close to that because my starter stays the same pitch when cranking for an extended period.

15 in-Hg is fine. If you think you should have more, spray some carb cleaner or WD-40 around all the mateing areas where a leak may appear. The vacuum reading from the intake will be the same from anywhere else.
You can safely assume, but check anyway.
Better dead on balls accurate in knowing than assuming. It'll take 1/2 an hour to do this with coffee in hand right? Take a few min.'s.

2.) I read in an article about converting an '80's truck smogger 318 2-bbl. to a 4-bbl. that most/all of the old 318 2-bbl's (no matter the year) develop a bad hesitation off the line that has to do with the carb. Is this true, and what makes it happen? My 318 has done this since I got the car.

Like said above, that is a carb issue 90% of the time. Timing is another issure. A little more advance can't hurt much ethier. Just take the time to tune the set up real well.

3.) I'm putting some aftermarket gauges in my Duster and I don't know what I should do as far as wiring goes. Do I splice into an already-existing circuit, or do I create a whole new circuit? When I put my tach in I just hot-wired it straight to the fuse connections in the fusebox, and I know that's definitely not the proper way to do it.

Ethier way, new circuit or splice into an old existing one, would be OK.
I do a new one myself. It takes a little longer to do, but, when something goes south/bad, you know exactly where to go. Also, it is not taxing the OE wires further and when something goes, (Fuse) your not taking out anything else with it like as in what ever your tapped into.

 

[MopaR&D]

Okay, so if I make a new circuit for the gauges, where do I start it from (what's the source)?

 

[rumblefish360]

You can run a line from the battery terminal.

 

[C130 Chief]

What is your elevation? What was the temperature that day? Altimeter setting? Manifold vacuum will vary depending on density altitude (pressure altitude corrected for temp). 15" is what it is for you engine. Use it as a baseline.

Bigger things to look at are EVEN compression across all cylinders and STEADY vacuum at idle.

If you switch to the TQ make sure it is rebuilt and adjusted correctly (good carbs but easily screwed up). Make sure you have the engine running good before the swap, keep the timing the same etc...

If you still have the stock 2" single exhaust don't expect much. If you still have the same cam, don't expect much. If you still have the original cam sprocket don't do anything else until you replace the timing set (good time for a new cam).

That being said, a stock 318 will respond pretty well to a MILD cam, dual exhaust and a 4 barrel.

 

[MopaR&D]

What is your elevation? What was the temperature that day? Altimeter setting? Manifold vacuum will vary depending on density altitude (pressure altitude corrected for temp). 15" is what it is for you engine. Use it as a baseline.

Bigger things to look at are EVEN compression across all cylinders and STEADY vacuum at idle.

If you switch to the TQ make sure it is rebuilt and adjusted correctly (good carbs but easily screwed up). Make sure you have the engine running good before the swap, keep the timing the same etc...

If you still have the stock 2" single exhaust don't expect much. If you still have the same cam, don't expect much. If you still have the original cam sprocket don't do anything else until you replace the timing set (good time for a new cam).

That being said, a stock 318 will respond pretty well to a MILD cam, dual exhaust and a 4 barrel.

Hmm, I hadn't thought about the elevation. My town is at about 6900 ft. above sea level, and when I tested the vacuum the ambient temp was around 70*F. The vacuum is also steady; if the pointer does move at all, it's barely discernible. My plan was to get a dual exhaust first, then TQ swap, then a cam/timing set (depending on how much slack is in the original chain, I may replace it first). BTW, is it possible to do a cam swap with the engine still in the car? I think it would be quite a hassle pulling the engine if I'm not going to rebuild everything.

 

[C130 Chief]

15" Hg at 6900 MSL is pretty good.

Slack in the timing chain isn't the issue. The OEM cam sprocket has Nylon teeth which get brittle and come off with age. Result is bent valves usually.

you can do a cam swap with the engine in the car easy enough. Pull radiator and grille. Might have to jack up engine slightly.

 

[MopaR&D]

Okay, good. I guess I'll go out and get that timing set and a gasket set while I'm at it. I think I'll also swap in a Crane H260 cam and lifters too.

 

[C130 Chief]

That would be a good cam for a stock 318.

If the TQ doesn't work out an Eddy 1406 or a good old Holley 1850 will do the job nicely.