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Discussion Starter · #1 ·
Hello I am new to this forum as I am primarily a long time MOPAR fan. I recently purchased a 1969 SS396 (325 hp) and love it. Only had it a week and a half. It ran great when I first got it (it was restored by the way) after the initial dead battery problem was solved with a slow charge. I then took it to local well respected and trusted mechanic shop near me for a once over since I am not a mechanic. I got it back and was told it did not need much but they did replace spark plugs. The bill said 454 in the description for the plugs. I thought maybe they just typed it wrong as it is a small shop. When I drove it from their store to my storage garage, it stalled several times when I slowed to an idle. It did not do that when I first got it. A well informed friend came to look at the car today and said it sounded as if it was not hitting on all cylinders and instead of him adjusting the idle, I should take it back to the shop where It had been. I will do that Tuesday but wonder if you experts can tell me if there is effectively that much difference between 396 and 454 plugs. I looked for sizes on line and it appears most of the 396 plugs have longer threaded bases (at least in the pictures). Thanks for any other thoughts to throw out to the old time mechanic when I take it back Tuesday.
 

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Let me get this straight. The car was running and driving fine, you took it to a, so called, well respected and trusted mechanic. Now the car doesn't run and drive fine anymore? I'd rethink that well respected and trusted part! Did they test drive it or tell you to test drive it before they deemed the job complete?

Get your old plugs back and compare them with the new ones but of course they probably threw them out. :rolleyes: I've seen a poor running condition happen when one of these, so called, well respected and trusted mechanics stuck in some oddball brand of plug.
 

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I am wondering also long reach plug versus short reach plug. The short reach is usually a tapered seat the long reach plugs are usually washer sealed based. I would also check the heat range too.
 

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They might have put colder plugs in for a high compression engine. R43's for example are listed as original for LS6 cars and can be either tapered seats or flat, depending on the heads. They will foul easier, especially if running point ignitions, and idling a lot, than higher heat range plugs like R44's or R45's. The 44's or 45's are recommended for the lower compression motors, like yours. I don't recall exactly which would be correct for your car but you can look it up and as noted above, make sure you have the correct plugs before you start adjusting other stuff. I am referencing AC Delco numbers but other brands can be cross referenced. Also, if you have the correct plugs, check the gap. .035 should be about right for a point system but sometimes mechanics will set them at .045 as an example, which is usually fine for an electronic system with a "hotter" spark, but may miss a bit if using points. Then you can get into point settings, a bad rotor, cap, etc. Many parts made today are not made in North America and don't seem to have the same quality standards. I have had brand new caps be defective but when I put the old one back on, it ran fine. I believe there are still a few brands available that are made in the USA.

Hope this helps.
Oliver
 

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Discussion Starter · #7 ·
I am wondering also long reach plug versus short reach plug. The short reach is usually a tapered seat the long reach plugs are usually washer sealed based. I would also check the heat range too.
Thank you for the ideas. The place I took the car is one of the best places in our rural area. They have been in business for many years (maybe 30+). Bob, the guy that works on my 78 Indy Corvette and now this car is a hardened lifelong mechanic but he might have bought the wrong plugs for sure. I am thinking something like the long reach if the pictures online for 396 plugs are accurate that they seem to have longer base (thread area) than the 454 plugs. There are no young trainees working at this private facility (not national franchise or something like that). I am not a mechanic although I could pull a plug to see but will not mess with it until Bob can look at it again next week. Stay tuned.
 

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Found an old thread on here with good info that might help.

Oliver
 

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Hello I am new to this forum as I am primarily a long time MOPAR fan.

I recently purchased a 1969 SS396 (325 hp) and love it. Only had it a week and a half. It ran great when I first got it (it was restored by the way) after the initial dead battery problem was solved with a slow charge.

I then took it to local well respected and trusted mechanic shop near me for a once over since I am not a mechanic. I got it back, and was told it did not need much, but they did replace spark plugs. The bill said '454' in the description for the plugs. I thought maybe they just typed it wrong as it is a small shop. When I drove it from their store to my storage garage, it stalled several times when I slowed to an idle. It did not do that when I first got it.

A well informed friend came to look at the car today and said it sounded as if it was not hitting on all cylinders and instead of him adjusting the idle, I should take it back to the shop where It had been.

I will do that Tuesday but wonder if you experts can tell me if there is effectively that much difference between 396 and 454 plugs. I looked for sizes on line and it appears most of the 396 plugs have longer threaded bases (at least in the pictures).

Thanks for any other thoughts to throw out to the old time mechanic when I take it back Tuesday.


Ok, now (I've re-arranged it a bit) I can read your post (PLEASE use paragraphs and punctuation).

Before you take it back, simply make sure all the connections are secure (both at the distributor and the plugs). Also, make sure the plug wires are run to the proper cylinder. It's easy to futz those up, and simple to correct.

Here's a link:


Another simple possibility is the vacuum advance got disconnected.

Pete

Or, said another way: Ok, now (I've re-arranged it a bit) I can read your post (PLEASE use paragraphs and punctuation). Before you take it back, simply make sure all the connections are secure (both at the distributor and the plugs). Also, make sure the plug wires are run to the proper cylinder. It's easy to futz those up, and simple to correct. Here's a link: Chevy Engine Firing Orders 283, 327, 350, 400, 427, 454 and More. Another simple possibility is the vacuum advance got disconnected.

Which response version do you prefer? ;)
 

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Discussion Starter · #10 ·
They might have put colder plugs in for a high compression engine. R43's for example are listed as original for LS6 cars and can be either tapered seats or flat, depending on the heads. They will foul easier, especially if running point ignitions, and idling a lot, than higher heat range plugs like R44's or R45's. The 44's or 45's are recommended for the lower compression motors, like yours. I don't recall exactly which would be correct for your car but you can look it up and as noted above, make sure you have the correct plugs before you start adjusting other stuff. I am referencing AC Delco numbers but other brands can be cross referenced. Also, if you have the correct plugs, check the gap. .035 should be about right for a point system but sometimes mechanics will set them at .045 as an example, which is usually fine for an electronic system with a "hotter" spark, but may miss a bit if using points. Then you can get into point settings, a bad rotor, cap, etc. Many parts made today are not made in North America and don't seem to have the same quality standards. I have had brand new caps be defective but when I put the old one back on, it ran fine. I believe there are still a few brands available that are made in the USA.

Hope this helps.
Oliver
Thank you Oliver. I am hoping a change to other plus will make the world of difference. I have had a number of great classic cars over the last 20 years and this one was running better than any, even more fun than the 68 Hemi Road Runner I got about 3 years ago. Have a great day and thanks again for your input. I only wish I was a mechanic but am not and thus have to rely on trusted friends for help.
 

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Discussion Starter · #11 ·
Ok, now (I've re-arranged it a bit) I can read your post (PLEASE use paragraphs and punctuation).

Before you take it back, simply make sure all the connections are secure (both at the distributor and the plugs). Also, make sure the plug wires are run to the proper cylinder. It's easy to futz those up, and simple to correct.

Here's a link:


Another simple possibility is the vacuum advance got disconnected.

Pete

Or, said another way: Ok, now (I've re-arranged it a bit) I can read your post (PLEASE use paragraphs and punctuation). Before you take it back, simply make sure all the connections are secure (both at the distributor and the plugs). Also, make sure the plug wires are run to the proper cylinder. It's easy to futz those up, and simple to correct. Here's a link: Chevy Engine Firing Orders 283, 327, 350, 400, 427, 454 and More. Another simple possibility is the vacuum advance got disconnected.

Which response version do you prefer? ;)
Thank you. I printed out the right 396 firing order and will check this weekend. Even I can do that. LOL
 
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