I have a 37 Ford with a 350 bowtie in it.. I've ran the same motor and stuff for 60k plus over 10 years. Changed the plug wires from cheapos to MSD 8.5 , replaced the AC plugs with the same, and reset the timing from around 12 degrees advanced to 7 btdc. Within 20 miles I fried a plug cap boot off the #4, Replaced the plug boot... 35 miles later it fried again. Now in less than 200 miles I've replaced 6 boots - most on #4 and #8. I reset the timing to 10 advanced .. Any ideas on why I'm burning up the plug boot .. yes the headers are very close but why after thousands of miles is it doing it now? My hunch is that when I reset the timing it was too retarded and allowed the combustion flame to exit too soon hence flaming the headers ... any other ideas?
the tiing had slipped to advanced and I was getting hot start problems ( another cause but I didn't know it at the time) so I reset the timing. Somewhere on the web it said that sbc were 6 - 8 degrees advanced. I set it to 7 . car ran fine.. but then it strated fryin the plug boots
It was only 5deg... Roger, It doesn't sound like you changed it enough to cause that much heat, but that would really depend on how much advance is in the dist. If you have an advance timing light, try setting total timing at 34 and see how that works. I'm also guessing that the MSD plug boots are much bigger than the ones you had on there before??? Could be that the old ones had just enough air gap to the headers to let them live...
Are the boots on your new wires thicker and closer to your headers,making them burn. Its not the timing that's doing this. Did you switch from angle to straight boots or vice-versa,sometimes I have to use straight boots on some cylinders and angled on others.
What is the total advance of 34 degrees. I have a regular timing light and a timing tab that goes to 12 degrees. I pulled the vac off the dist and capped the vac then I set the timing at 10 degrees this time .. When I speed up the engine the timing moves mush farther but it's off my timing tab so I can't tell how many degrees it is. Any advice would be appreciated
the boots are very very close to the headers less than an 1/16th... the MSD boots are huge - but the replacements are normal... I had 90 degree and I stayed with them .. I even pulled a boot off an old wire and replace the end with that - did better thant the MSD but still fried... same headers as before
Reading it is done with the same timing light. You just need a mark that is 34 degrees away from 0º (TDC). You would need a stick on timing tape, in the proper size for your balancer, with the degree marks on it, or to mark it by hand, using the maths. What diameter balancer do you have?
I have a set of what I think are the same wires out here with fried boots. They worked great with the cast iron manifolds but after I installed headers the cooked fairly quickly. If you are having to move the timing around are you sure that the timing chain is in good shape? That's usually the first indicator that it is getting worn.
Most of my chevies like at least 10 degrees advance,with vacuum disconnected,thats where I always start and adjust from there. Every motor is different ,too,some like ported vacuum advance,some like intake vacuum. My blower motor likes no advance,vacuum or mechanical. Don't think Ive seen a damper that only goes to 12 degrees,except maybe the atdc side of the scale.
I think it's 6 inch .. bone stock 350 crate low end HP. I had always set the time by ear so I knew it was advanced .. but hey I had a timing light this time and so I tried to be correct. I'm running a couple of th eold wires on it now and with the timing more advanced it still runs fine so I may test it at this setting of 10 degrees at idle.
You will need a timing light with an advance knob (or button if digital). this allows you to factor in the advance that is built into the distributor. Rev the engine until the line stops moving, hold that rpm and dial the line back to your zero mark with the light. Whatever the advance number on the light is = your total timing.
the motor didn't have a timing tab - I installed later but it fits to the water pump bolts and only lines up with two bolts in the curve of the pan so I am pretty sure it's right. I'll check with a couple of guys at the next cruise in or whatever to see what they have on their SBC
thanks on the 34 degree lesson. I'll have to check with some bddies to see if their lights are able to do that - mine is just a cheapo.. actually I have two and neither have it.
Two ways to go about finding 34 degrees. Either spend about ten bucks and buy a degree tape for you damper, or a bit more and buy a dial back timing light. A dial back timing light allows you to set a specific timing event and see the pointer at 0 degrees. Say I set 34 degrees on my light, and the engine is at idle. I'll flash the pointer and it won't be anywhere close. Rev the engine up to or past it's full timing speed, and my light will now flash at 34 degrees if that is the where it's set. If not it will be at a mark close and I can bump the distributor to where it needs to go to set it correctly. Sounds allot trickier than it really is, and once you do it, it becomes quite self explanatory. My Harbor Freight dial back set me back all of about 35.00 or so a few years back, and came with one of the best passages I have ever read in an instruction manual... "Congraurations you have made purchase of velly fine timing right!" I kid you not! Sounds just like my girlfriend - she's from Hong Kong!
may see I can fab up a tool to dimple the header at that point. I have a tilt front end so I can get to them. it just bugs me that after all this time it started doing this with such minor changes..
Man everybody on the planet beat me to that one! As far as the MSD wires, I have had them on the Plymouth for quite awhile now, and I have to say that my reviews are kind of mixed. Down here in the heat, the ends kind of turn to a weird jelly like substance after awhile. And as far as the cooking deal, I do know that MSD makes a boot protector/ heat sleeve deal that they recommend with headers.
Measure your balancer. Convert the measurement to decimal, and then multiply that number by 0.29671. The result will be the distance in inches, measured along the curve, that the 34º mark would be away from the 0º on the balancer. In the case of a 6" balancer, that would be 1.78024" which is about 1-25/32", which is just a tick past 1-3/4". Unless I missed the math. Feel free to double check me.
I know about those instuctions.. I had some for a cast iron wood stove that were so funny I framed them and hung them near the stove,.. one more question. If I get this right the 34 degrees is the point that I see the light jump to when I raise the RPM... the dial on the timing light just tricks the flash into showing on the conventional timing tab. IS that it .. ?
"You right up my Rife..." Karaoke night with her friends... I'm literally a walking broken Asian/English translation dictionary.
Errr,Ahhh, YES?! I think I'm reading what your saying. I think you have it. With the gun dialed at say 34 degrees and the engine running at past it's full advance, the light will flash the line at the TDC mark.
I forgot to say I did run some heat shield sleeves on these but that lasted about 100 miles.. there is just no room between the header and the plug. I might switch to header plugs - but again I'd just like to figure out why now am I burning plugs boots. I ran that thing across Fl. on I-4 at 75 MPH just before I did the change and the heat index was 105 degrees ... didn't burn a boot them .. but now it's buring them with local cruisin
If you have say an 8" balancer add a paint mark 2 3/8" before the 0º timing mark already on it and that will be damn close to 34º (8" x π [3.1416] = 25.1328" ÷ 360º x 34º = 2.374" or close to 2 3/8") Set your high RPM all-in mechanical advance to, or with "good gas" a few degrees above that, then hook up your manifold vacuum sourced, vacuum advance. (On good premium I can go to 38º) This is for a good pre-smog 12º advance vacuum unit. Newer "Smog Distributor" Vac units can go all the way up to 24º and require 0º initial and run hotter than hell on purpose and shitty to boot. The arm on a 12º unit will only move the points plate about 1/8"
I think it's looking more and more like the wasn't advanced enough. Everyone is pointing toward more timing.. That fit's my theroy that the "fire" is still burning in the cylinder when the exhaust is opening. This late flash is letting the flame out into the header.. more advanced would let the fire start earlier and burn out before the exhaust opens... but I may go to the shorty plugs just to gain room and ease of installation... thanks
I have to agree that 7 degrees is no where near enough for an SBC. 10 degrees is a minimum, 12-14 more common and up to 16 not unheard of on a performance motor. You are correct about it firing so late it holds more heat in the headers as well as in the cylinder walls. On top of that I'm sure those overkill MSD wires are just too fat for your headers. Go up to 12 or more degrees!
Thanks everyone. I am going to increase the timing. The motor is a crate motor that I bought new and it only has 60 k on it, so I know it's in top condition as far as timing chains and lifters .. Everything else like headers and carb are the same ones that were on it so I eliminated them as the problem. I know the wires are a little fat - but I wanted that look - fat fender car - fat wires ?? . They are loomed so they don't come near the headers. It was just the boots. Thanks again. PS I am looking intot he shorty plugs though.. they might be just a little easier to install...
The Jalopy Journal
