intermittent Miss at cruise rpm

[Eds56]

Lets see Autplites a US company is problem and NGK is ok, I don't get it.

Well mark, I did order, the specific plug you recommended, and also an autolite platinum version too. In fairness, i intend to give them a try. Nothing to do with USA, instead more of the Ford vs. Chevy mindset. The name Autolite makes me think of That nasty 4 letter word beginning with F. The plus on the NGK for me is header clearance.

Thanks Rick, didn't realize it's been 30 years since the ford split, guess I just get hung up in the past too much.

[markm]

Spark plugs are not magic. There's no silver bullet.

Been my experience too, I do have an interesting story about the Autolite 85s that I ran in my 67 Camaro years ago they ended up in my Farmall A tractor replacing the 7/8 thread plugs that were wore out. My buddy at machine shop put 1/2 inch pipe plugs in head and drilled and tapped them for 14mm gasket style plugs. Those bracket car fresh Autolites have been mowing grass for 25 years. Today I see that heli-coils are available and this would not be necessary, but at the time we could not find anything.

[Eds56]

Good Morning All,

Just thought i would give an update and ask follow up questions--

1.) Replaced plug wires and now runs much better. Note: there were more bad places on the wires that i thought.
2.) Trying different spark plugs, as stated by others, there is no silver bullet. Nothing noticeable at this point from my trials, No biggie.
3.) Marks point above, about using a car plug in a mower got me to thinking, Anyone out there ever went the other direction and used a small engine (SHORT) spark plug, such as, lawnmower/chainsaw? Obviously one with the correct 14mm thread, .375 reach, heat range, etc. (such as Champion RCJ6Y)
4.) I've always used resistor plugs, but the only modern electronics in my car are radio & MSD. Are resistors a Must??
5.) I read online that it's best to have ALL the initial timing the engine can stand and the balance from dist. to get the 34--36 total. What i currently have is 16 initial + 18 dist with light blue & silver springs for my 34/35 total all in by 2800--3000 rpm. NOW that i'm going to the msd 8361 (vacuum) distributor, What dist. spring / bushing set up would you use?

Gotta get to work, Have a Blessed Day.

[Rick_L]

You can go too far on timing without having audible pinging, but with most small blocks it's pretty rare.

On initial timing, 16 may be a bit much. But if it's not pinging or kicking back against the starter when the engine is warm, it's probably OK. Your mechanical advance setup is pretty good (again provided there's no pinging).

When you install the vacuum advance distributor, don't change anything and monitor for pinging. I don't recall if the MSD distributor has adjustable vacuum advance or not? May want to limit how much.

[chevynut]

My BBC with a tunnel ram and two Holley 600 knocks down high teens in MPG on the highway.

At 30 MPH? No way imo are you going to get "high teens" MPG at highway speeds (70-75) with a tunnel ram, dual quads, no overdrive, and what rear gears? You better have your speedo calibrated.

[markm]

What speedo don't need them on hotrod, especially some aftermarket ugly POS based on brother in laws Garmin on a 125 trip. Who said I didn't have OD, TKO -600 with a 3.54 Dana. You are the engineer you figure it out.

[markm]

Good Morning All,

Just thought i would give an update and ask follow up questions--

1.) Replaced plug wires and now runs much better. Note: there were more bad places on the wires that i thought.
2.) Trying different spark plugs, as stated by others, there is no silver bullet. Nothing noticeable at this point from my trials, No biggie.
3.) Marks point above, about using a car plug in a mower got me to thinking, Anyone out there ever went the other direction and used a small engine (SHORT) spark plug, such as, lawnmower/chainsaw? Obviously one with the correct 14mm thread, .375 reach, heat range, etc. (such as Champion RCJ6Y)
4.) I've always used resistor plugs, but the only modern electronics in my car are radio & MSD. Are resistors a Must??
5.) I read online that it's best to have ALL the initial timing the engine can stand and the balance from dist. to get the 34--36 total. What i currently have is 16 initial + 18 dist with light blue & silver springs for my 34/35 total all in by 2800--3000 rpm. NOW that i'm going to the msd 8361 (vacuum) distributor, What dist. spring / bushing set up would you use?

Gotta get to work, Have a Blessed Day.

A Farmall A is actually a small farm tractor with a 113 now 123 CI four cylinder liquid cooled engine. I don't think lawn mower plugs would be a good plan.

[55 Rescue Dog]

Good Morning All,

Just thought i would give an update and ask follow up questions--

1.) Replaced plug wires and now runs much better. Note: there were more bad places on the wires that i thought.
2.) Trying different spark plugs, as stated by others, there is no silver bullet. Nothing noticeable at this point from my trials, No biggie.
3.) Marks point above, about using a car plug in a mower got me to thinking, Anyone out there ever went the other direction and used a small engine (SHORT) spark plug, such as, lawnmower/chainsaw? Obviously one with the correct 14mm thread, .375 reach, heat range, etc. (such as Champion RCJ6Y)
4.) I've always used resistor plugs, but the only modern electronics in my car are radio & MSD. Are resistors a Must??
5.) I read online that it's best to have ALL the initial timing the engine can stand and the balance from dist. to get the 34--36 total. What i currently have is 16 initial + 18 dist with light blue & silver springs for my 34/35 total all in by 2800--3000 rpm. NOW that i'm going to the msd 8361 (vacuum) distributor, What dist. spring / bushing set up would you use?

Gotta get to work, Have a Blessed Day.

The new distributor will come with the charts. I'm currently running the silver 25 degree bushing with 1 heavy silver, and 1 light silver. 10 degrees initial, and slower mech advance ramping from 1500 to all in at 4500 for a total of 35 degrees at redline. Runs great.

[chevynut]

What speedo don't need them on hotrod, especially some aftermarket ugly POS based on brother in laws Garmin on a 125 trip. Who said I didn't have OD, TKO -600 with a 3.54 Dana. You are the engineer you figure it out.

If you think you can get "high teens" on the highway (70-75 MPH) with a 454, dual 600 Holleys, tunnel ram, 3.54 rear (which OD ratio?), standard distributor, and the radical cam you talk about, I should be able to hit mid 20's with my 502, EFI, 410 rear, .50 overdrive, and relatively mild cam.

125 miles isn't enough distance to determine mileage very accurately. I'm not buying it.

[55 Rescue Dog]

With a engine built for fun and speed, MPG's doesn't really matter. But getting them to run the best you can with old fashion tuning is fun. Like with your new distributor you can do a lot off things using the vacuum advance. Try full vacuum, or ported to see how it works. I prefer full vacuum advance, if the engine likes it, because you can back the idle screws off a bunch, and run a little less initial advance. Seems to help combustion at idle.