What spark plugs and gap should be used bearing in mind I can only get 98ron fuel in Australia.
What ever is on sale. ;D
BF45 is the current Motorcraft offering. However, if you're not planning on concours judging I would suggest you run NGK WR5, STK#2438. They run much better than BF45 and are better heat range wise. I am running them in my 67 GT500, The BF32 are prone to fouling.
-Keith
BF 32 is the installed and recommended plug, I put on over 80,000 miles on my KR, never fouled a plug, put on 10,000 miles on my 66 427 Cobra, never fouled a plug, put on over 10,000 miles on my 72 Pantera, never fouled a plug, I say old wives tale!
Good to know.
Thanks or the details.
I just want to make sure I don't have to pull them out any time soon since its not he easiest of jobs.
Quote from: CSX 3183 on February 28, 2019, 07:23:26 PM
BF 32 is the installed and recommended plug, I put on over 80,000 miles on my KR, never fouled a plug, put on 10,000 miles on my 66 427 Cobra, never fouled a plug, put on over 10,000 miles on my 72 Pantera, never fouled a plug, I say old wives tale!
Fouling BF32's is often a sign of a weak ignition. 32's are what to use. 52's will melt the tops of the pistons. 42's are about the limit and would only be useful to about 5,000 rpm. Over that they may lean/misfire in a performance application. I've been running 32's since 1968 in Kindergarten. ;)
Sounds like great advice.
so 32's it shall be.
The issue with BF32's is they are a cold plug and the vehicles usually aren't driven enough. All dual quad cars run rich at idle. I'll guarantee my ignition isn't weak with the igniter II and matching coil. The NGK U groove is a much better plug than the BF32, and they are NOT available from the parts store. Jay Brown and a couple other FE builders will also tell you to stay away from the BF32. If you're competing in Concours, then you might want to run them. Otherwise its plain stupid to waste 7-10 a plug on stock poor plugs.
Ok so ill check what I've got in it and see how they've been burning.
If they're clean with no build up of carbon or excessive wear ill replace them with what's currently in there.
Quote from: 1967 eight barrel on February 28, 2019, 09:42:34 PM
The issue with BF32's is they are a cold plug and the vehicles usually aren't driven enough. All dual quad cars run rich at idle. I'll guarantee my ignition isn't weak with the igniter II and matching coil. The NGK U groove is a much better plug than the BF32, and they are NOT available from the parts store. Jay Brown and a couple other FE builders will also tell you to stay away from the BF32. If you're competing in Concours, then you might want to run them. Otherwise its plain stupid to waste 7-10 a plug on stock poor plugs.
Mine doesnt run a dual quad as its a KR with the Holley 735.
My issue is it currently backfires underload but drives along ok until I accelerate hard then it goes off with backfiring. Carby has been rebuilt, timing set, new points and condenser, coil is fine so the only thing left is the plugs.
I just want to make sure i put the right ones in due to the difficulty in changing them. If it was my 66 GT350 it wouldn't be an issue as access is easy.
So just to be sure is BF 32 the right ones that won't give me issues??
Quote from: GT350AUS on April 03, 2019, 12:59:23 AM
Quote from: 1967 eight barrel on February 28, 2019, 09:42:34 PM
The issue with BF32's is they are a cold plug and the vehicles usually aren't driven enough. All dual quad cars run rich at idle. I'll guarantee my ignition isn't weak with the igniter II and matching coil. The NGK U groove is a much better plug than the BF32, and they are NOT available from the parts store. Jay Brown and a couple other FE builders will also tell you to stay away from the BF32. If you're competing in Concours, then you might want to run them. Otherwise its plain stupid to waste 7-10 a plug on stock poor plugs.
Mine doesnt run a dual quad as its a KR with the Holley 735.
My issue is it currently backfires underload but drives along ok until I accelerate hard then it goes off with backfiring. Carby has been rebuilt, timing set, new points and condenser, coil is fine so the only thing left is the plugs.
I just want to make sure i put the right ones in due to the difficulty in changing them. If it was my 66 GT350 it wouldn't be an issue as access is easy.
So just to be sure is BF 32 the right ones that won't give me issues??
If all those things have been rebuilt and set properly it does sound like you have one or more fouled plugs or even carbon build up on the pistons which is causing detonation. BF32 is what came in your car from the factory .They are a colder plug and need the be driven hard to stay clean. If a lot of slower city driving many of use go with the next hotter plug like the BF42.That is what we always did back in the day when we drove them everyday. The BF 42 will not foul out as much. If you want the most horse power performance stick with the BF 32 or equivalent and just expect to change them or clean them often. If the highest horsepower is not your goal and you don't want to mess with changing the plugs often then go with the BF 42.
Hi Bob,
Thanks for your prompt reply.
The car has origina 32,000 miles on it.
It doesnt get driven much at all. Lucky if I do 500 miles in a year and they would be highway miles.
I don't drive it hard so maximum horsepower isn't a priority.
Just the occasional squirt when I take it out and it warms up.
So BF42??
I have BRF42 CU Motorcraft but they are resistor type I think for al later model Australian ford.351 I think
Ross
Quote from: GT350AUS on April 03, 2019, 01:44:12 AM
Hi Bob,
Thanks for your prompt reply.
The car has origina 32,000 miles on it.
It doesnt get driven much at all. Lucky if I do 500 miles in a year and they would be highway miles.
I don't drive it hard so maximum horsepower isn't a priority.
Just the occasional squirt when I take it out and it warms up.
So BF42??
Ross
That is what I would run given the driving details. If that doesn't solve your symptoms it may be carbon build up on the pistons but the plug situation will be solved . Also make sure you have a high octane fuel or use a additive to raise the octane . The stock engine is not designed for todays fuels and you may have to retard your timing some so it doesn't detonate. Try the plugs first . If they haven't been changed in a while then a fouled plug is probably it. Keep us posted.
My plan is to get to it next week.....once I've summoned the courage to tackle the tight fit.
Bob I have BRF42 CU plugs here would they be ok although not concourse??
I can't get the concourse ones here so I may even try the NGK AP5FS as they seem to be a replacement alternative.
Your thoughts??
Just pulled plug out of number 1 and found it to be a NGK AP6FS which on cross reference is a either a
Mototrcraft BF22 or BF32
Looks like its too cool for the driving I do.
I think that you need to go back into the carb. I would say the issue is highly likely that you have a bad power valve.
You can't just install a new one "out of the box" and presume that it ok. These things are so bad and such crap even brand new that it is REQUIRED that you test them.
I had literally 12 brand new ones, never installed, and when I tested them, six were no good.
A bad power valve will give the symptoms that you are describing.
Yes that was my initial thought but I had the carby rebuilt by a reputable builder and tested.
The problem began after sitting for 3 years in a workshop where the guys would start it when they needed to move it and it just idled and fouled itself.
Power valves dont go bad suddenly when not being driven but occasionally started so the diapghram which is the common cause of a bad pv is not the centre of the problem.
I have a mach 1 that suffered similar issues and after rebuilding that carby. The pro b lem continued so I elimated the car by as the problem at bolting on my gt350 715 to the mach 1 and the problem was still there. The cause was found to be fouled plugs.
So this path seems likely to me.
Once I've changed the plugs I'll eliminate that as an issue and get back to you all with my result.
Quote from: GT350AUS on April 03, 2019, 07:05:25 AM
Yes that was my initial thought but I had the carby rebuilt by a reputable builder and tested.
The problem began after sitting for 3 years in a workshop where the guys would start it when they needed to move it and it just idled and fouled itself.
Power valves dont go bad suddenly when not being driven but occasionally started so the diapghram which is the common cause of a bad pv is not the centre of the problem.
I have a mach 1 that suffered similar issues and after rebuilding that carby. The pro b lem continued so I elimated the car by as the problem at bolting on my gt350 715 to the mach 1 and the problem was still there. The cause was found to be fouled plugs.
So this path seems likely to me.
Once I've changed the plugs I'll eliminate that as an issue and get back to you all with my result.
To me, the only one that is reputable is me. I WANT to see the results of testing it myself. I don't want to get this call from the Vet, "I'm sorry your puppy is dead". Dying has got very specific symtoms. If you ignore them, there is no fixing anything.
Your question to the carb rebuilder should be, "did you actually test the power valve WITH A POWER VALVE TESTER?" If he says no, I just put a new one in, then there you go. ;)
Just my perspective on having gone through this before and offering a likely cause. If you want to keep chasing a phantom that is right in front of you, I can't help. Best of luck on finding the culprit. ;D
I agree with Doug. For 7.00 put a power valve in it. Remember that engine vacuum also plays in the selection of the correct one. Also a point to note is the original Holley carbuerator does not have power valve protections incorporated, so one backfire through the carbuertor and the valve is usually blown.
-Keith
I do agree regarding the pv howvere I put a new one in before having the carby rebuilt and the problem hadn't changed so I decided to have it rebuilt.
I guess I've got nothing to lose by trying another pv again.
Guys what size power valve should it be running just in case the wrong size is in it I want to be sure i replace it with the right one?
6.5 would be stock.
Guys, Just as a side step to the carby backfire issue let me throw something out there.....
I had the tilt steering looked at and the workshop got it working. Apparently it was a bad relay.
The backfire problem has started since the tilt was sorted. Now the tilt away doesn't draw the steering to tilt away for some reason yet to be looked at but the relay is working off the door because I can hear it switching when I push the switch in and out.
If there is a leak in a hose or if a hose is not connected to the vacuum canister on the tilt steering can this cause the manifold to leak so much that it would lean out causing the backfire I'm getting under load??
Quote from: GT350AUS on April 16, 2019, 02:45:00 AM
Guys, Just as a side step to the carby backfire issue let me throw something out there.....
I had the tilt steering looked at and the workshop got it working. Apparently it was a bad relay.
The backfire problem has started since the tilt was sorted. Now the tilt away doesn't draw the steering to tilt away for some reason yet to be looked at but the relay is working off the door because I can hear it switching when I push the switch in and out.
If there is a leak in a hose or if a hose is not connected to the vacuum canister on the tilt steering can this cause the manifold to leak so much that it would lean out causing the backfire I'm getting under load??
The vacuum hoses in that system tend to be there forever. Some of the orginals on my car were on the engine when it was painted. What happens with that is it makes them inflexible and when you are working near them or try to bend them, the rubber in them along with the paint cracks.
So yes, it is possible and the percentage of likeliness of broken but not obviously has risen .
In addition, the vacuum can, under the battery also has the tendency of rotting out from the interior, without any or at least any significant outward signs. The thing is just made of "tin" and because of the material it uses, does not have necessarily much longevity.
Put a vacuum gauge in the car. It will help. Your issue seems to be vacuum related. The tilt mechanism can be one of the sources of failure, sure.
Doug by using my vacuum gauge would I be looking for a drop in vacuum reading and where do you suggest the best place to connect it would be....base of the carby?
Connect it to the intake. Back of the carb where the existing vacuum fitting is now.
1) you want to see what you have at idle now. With a stock KR I'd presume 15 at idle. Maybe 17.
2) you want to drive the car. See what the vacuum normalizes at. 3) what it reads when the car backfires.
There are other places you could have a vacuum leak from. The brake booster. The heater control, etc.
These cars are not fun to find the leak at. Lots are hidden under the dash.
I personally permanently installed one in my dash in place of the clock (never worked anyway). I just find it a necessary animal to be there all of the time.
OK,
Learned a lot about cold plug issues and hot plug issues.
With that said>> A std for concours judging is;.
A BF 42,
star
autolite emblem,
Correct?
Bob, not to shift gears, but what is correct for a late oct build 67 gt 350?
Going to sell some nos plugs we have here, and would tear me up if I sold a set I truly need.
Respectfully submitted,
John
Quote from: Harris Speedster on April 16, 2019, 09:48:44 AM
OK,
Learned a lot about cold plug issues and hot plug issues.
With that said>> A std for concours judging is;.
A BF 42,
star
autolite emblem,
Correct?
Bob, not to shift gears, but what is correct for a late oct build 67 gt 350?
Going to sell some nos plugs we have here, and would tear me up if I sold a set I truly need.
Respectfully submitted,
John
A BF 42 with the star would be for a 67 GT500 according to the owners manual relative to Shelby. A 67 GT350 would use the BF 32 with the stars. I believe the plug graphic design changed eliminating the star sometime in very late 67 production ,probably after Shelby production ceased. At least that is my best guess until more compelling evidence is uncovered.
Quote from: Bob Gaines on April 16, 2019, 11:07:20 AM
Quote from: Harris Speedster on April 16, 2019, 09:48:44 AM
OK,
Learned a lot about cold plug issues and hot plug issues.
With that said>> A std for concours judging is;.
A BF 42,
star
autolite emblem,
Correct?
Bob, not to shift gears, but what is correct for a late oct build 67 gt 350?
Going to sell some nos plugs we have here, and would tear me up if I sold a set I truly need.
Respectfully submitted,
John
A BF 42 with the star would be for a 67 GT500 according to the owners manual relative to Shelby. A 67 GT350 would use the BF 32 with the stars. I believe the plug graphic design changed eliminating the star sometime in very late 67 production ,probably after Shelby production ceased. At least that is my best guess until more compelling evidence is uncovered.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Thank you Bob.
John
Doug and Keith
I will start a new thread in regards to the backfire because I think this thread has changed direction from spark plugs to carby to vacuum leak