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Old 04-24-2010, 09:48 PM
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extended tip spark plugs?

Right now I'm running AC Delco R44TS spark plugs.. in a 350 with early 70's stock iron heads (67cc)

I'm not really sure how I got to using that part #.. I'm going to go up a heat range and that got me to wondering.. do I really need the extended tip plugs? (the 'S' in the part #)

these ARE tapered seat heads.

I'm running flat top pistons with compression somewhere in the mid to high 9's

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Old 04-24-2010, 10:11 PM
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If my "Geezer brain" remembers correctly. It was claimed that extended tip plugs ran cleaner, were more tolerant to heat range problems, quicker starting an engine. Then later they were used with the electronic ignitions with easier to gap wide plug gaps.

I doubt if you would see much difference with regular gap plugs
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Old 04-24-2010, 10:51 PM
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ok. I'm having troubles with the engine just *STINKING* at idle.. it did it with two different qjets, and two different holley's, including a brand new 650 dual feed vac secondary...

it makes your eyes water it's so bad.. i've set the mixture by rpm.. by manifold vac.. by ear... even purposely excessively rich.. and excessively lean.. just nothing I can do gets it under control...

i'm going to try a couple of heat ranges higher.. I can't remember off the top of my head if I'm running .045 or .060 gaps. I'm using an MSD 6AL with a Blaster 2 coil and MSD ProBillet dist and Taylor wires, so I'm not hurting for spark energy!

i can't find my notes on where the timing is set.. but IIRC, I'm running about 12-14 initial, along with vac. advance on manifold vac. and somewhere around 22 or 24 mech. advance.
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Old 04-25-2010, 12:59 AM
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Changing to a hotter plug isn't going to change anything for you, mixture is what mixture is, a plug change won't change that. Sounds like the engine would like more initial timing but you will have to modify the distributor to keep the total mechanical advance from getting too high. 20-24 initial is a good place to start.

Too many people these days seem to think everything has to come out of a box ready to go. True Hotrodding means modifying whatever you need to to get positive results, you are going to have to really work on the distributor and limit the advance travel, not just playing with the springs and weights.

The MSD Billet distributor should have come with several advance limit bushings with it. You will need the black 18 bushing, this will allow you to set the initial at 20 and limit the total to 38. You may have to limit the mechanical even more if you need to go above 20 initial, only testing will prove what you need.
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Old 04-25-2010, 07:14 AM
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I run the exact same plug in my small block in my truck, I had similar idle situation that you had too rich. The problem turned out to be not the spark plugs or heat range, but too much fuel pressure. I had an Holley H.V. mechanical fuel pump, which after getting a gauge had 9 P.S.I. of pressure. Installed a regulator and the idle and richness cleared right up. Also like Eric Nova 72 said, I had too spend alot of time on tuning up my distributor. Also, set fuel pressure at 5 lbs. Hope this might help, Ken
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Old 04-25-2010, 07:39 PM
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Fuel pressure is limited to 6psi by a dual port regulator, fed by a mechanical fuel pump. (already been down that road)

it's a summit racing brand cam.. 214/224 @ .050, .442/.465 lift.

the cam seems to want to make power high up in the rpm range.. so several people have suggested it might be installed 'retarded'.. i didn't degree it when i built the engine (big mistake, I know)

if I get bored this summer I might pull the front end off the engine and check it.. and maybe move it to the +4 setting on the timing set any way just to see what happens


remember, I'm actully idling on the 14 initial plus whatever more the vacuum advance can offers. according to MSD 10 @ 15" vac.. someone on the msd forums said they measured it at 16 @ 14.5"

currently, my car is 75 miles away from me where I'm doing a lot of body panel replacement, so i can't run out and check it right away. next time I have it running I'll get my advance light on it and see what it's idling on.

would more idle speed help at all? I'm already idling a little on the high side.. around 800rpm in gear and nearly 1,000 in park. once I fix my stuck TV Valve in my 700r4 I might be able to go a little higher.. but right now it slams into drive too hard to go any higher.
the engine still responds to the idle mixture screws, so I don't think it's a case of having the throttle open too far.
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Old 04-26-2010, 11:33 AM
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I plan to degree the cam sometime soon.. the car is turning really horrible 60' times at the track too.. (in the order 2.0 seconds) with a 3.08:1 1st gear, 3.55:1 posi, and 10x26 MT ET Drag tires.
and contrary to what everybody is telling me.. the higher I rev the engine the faster my et's are. I _shouldn't_ be needed to take that cam all the way to 6000 rpm .. but that's what helps *shrug*

I know the TDC mark on the balancer is in the right place. I made a drawing in AutoCad that lets me lay the balancer face down on it, align the keyway with the drawing and then there are two lines that point to the two possible positions for the timing mark. I believe they are 2^ and 11^ from the keyway IIRC.

it is possible I have the wrong the timing tab.. I'll check on that when i can get near the engine again. (it's a gm tab)

I don't THINK i have blocked air bleeds.. on 4 different carbs, including a brand-new-from-the-box holley..

wires are fairly new Taylors. .cap and rotor are brand new MSD parts
power valve is also a brand new from holley piece.. but I do realize new doesn't mean good..and I don't have metering rods. (holley 4150 650cfm vac secondary)

i'll check for a vac. leak too. that's something I haven't looked into. right now the plugs ARE fouled... that's mostly from a stuck choke recently. which is why I was looking at new plugs and maybe a bit hotter.
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Old 04-26-2010, 02:57 PM
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Quote:
Originally Posted by kc8oye
Right now I'm running AC Delco R44TS spark plugs.. in a 350 with early 70's stock iron heads (67cc)

I'm not really sure how I got to using that part #.. I'm going to go up a heat range and that got me to wondering.. do I really need the extended tip plugs? (the 'S' in the part #)

these ARE tapered seat heads.

I'm running flat top pistons with compression somewhere in the mid to high 9's
The nice thing about extended tip plugs is they push the electrode closer to the center of the cylinder with these big chamber heads. But the problem they usually present is the reverse of yours which is they get hot and tend to cause pre ignition. This is whay there are usually run in engines suffering from low compression and high oil consumption.

This engine sounds like its running rich, the list of causes is long. Float level too high, fuel pressure too high you said it has a regulator but is your 6 PSI a measurement with a gauge or just hoping the notches on the regulator create the pressure they say they do? Maladjusted idle screws or throttle plates. Look in the throttle bore at the bottom there will be a slot and lower down a small hole. The slot is the idle to main transition. At idle, all of this slot must be above the top of the throttle plate, otherwise both the idle and the transfer circuits will put fuel in the engine. On four barrels you also need to look in the secondary bores as well. While there is no idle hole, unless this is a 4 corner carb, there will be a transition slot. The throttle plates on the secondaries must also reside with the top of the blade below the slot, if its above, the slot will supply fuel at idle.

You mention the plugs being wet form over choking, I'm afraid once plugs get like this they're junk. This can also be caused by a failure of the ignition system to supply enough spark to light the mixture. A repetitive set of misfires will fuel foul the plugs. It's also a sign that the plugs aren't getting hot enough, that can range from the engine never being fully warmed up, too much choke for too long, weak spark, failing camshaft and lifters, bad rings pumping oil and or loosing compression, rich idle settings, failed PCV valve.

There's lots more but I need to chase some problems around here for a while.

Bogie
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Old 04-26-2010, 04:18 PM
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i run TSX series plugs in all my engines especially higher mileage ones or ones with fuel rich issues or oil issues

works well

X= extended tip

and same price as non X plugs

always seem to be quicker easier starts i can make even the carb engines start right up without touching the gas pedal by using X plugs and setting timing with the vacuum guage
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Old 04-29-2010, 11:38 PM
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my engine definately isn't high milage. and I don't believe it burns oil.. but it does leak a lot of it.. lol

at this point, i don't believe the problem is carb related (the stuck choke was an unrelated issue) i've checked, double checked, and tripple checked everything. and unless this holley carb was deffective out of the box (possible, but not likely) i just don't know any more


i'm going to stick with the extended tips for now.. and go up one heat range just because I can. (it's gotta have new plugs) later this summer I'll degree the cam when i get the car back home. I have a set of vortec heads waiting to go on it.. which will push the compression to more like 9.75:1 and then I'm sure all my tuning is going to change.

Is it possible my 1" open plenum spacer is causing issues with the vac signal to the carb? (I can swap the insert to make a 4-hole spacer) but I *HAVE* to have the spacer due to clearance problems.
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Old 04-30-2010, 02:05 AM
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The spacer won't cause the problem unless it is providing a huge vacuum leak that would be opvious, the motor wouldn't idle well. The spacer doesn't effect the vacuum signal.

Did you verify that when the piston is at TDC in the block that the balancer and tab also match at this point?? Just checking that the balancer line is in correct relation to the balancer keyway does not validate that the balancer line matches true piston TDC.

By not degreeing the cam you opened the door for a mis-machined timing gear keyway location hurting you, or that you might have missed matching the dots by a tooth...if the dots were even machined right. It has happened....

Something from your first post,... no early 70's head is 67cc unless it has been milled a good deal, all are pretty much just 72-74-76+cc. The only thing close to 67cc is a 60's Double hump head. What is the casting # of the head you are using, and what type(dome, dish, flat?) of piston are you using?? Got a part # or Brand??

If the compression really isn't what you think it is and is in-the-toilet low it will lead to a good part of what your complaint is. Reason I ask is your estimate of a Vortec head taking you to 9.75-1. Working backwards from that statement and using actual cc listings for 70's heads puts you near 8-1 and maybe less depending on the piston used.

First engine I ever played with was in a car I bought at 17, engine was supposed to be rebuilt, had a mild cam and 70's heads like yours, but the fool that put it together used a 327 crank with 350 pistons, pistons came up short at TDC by 1/8" making compression about 7-1. I tried out 3 cams, three intakes two carbs and every timing trick I could come up with, it ran just like you are describing but worse... 2.4 60' times with 3.73 gears and 2.64 first gear 4-speed manual. Wasn't until I finally decided that it must be the heads and tore them off and found the low pistons that I figured out what was going on.

Just an example, led me to always building my own and trusting nobody's word.

Just trying to cover all the bases.

Last edited by ericnova72; 04-30-2010 at 09:01 PM. Reason: spelling
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Old 04-30-2010, 08:38 PM
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Hi kc8oye, if the problems you have all came after the new carb were mounted, the problem is probably carb related. The way your engine is built will also influence how well or bad a fuel/air mixture is burnt. In an engine with domed pistons, the flame front simply has a longer way to travel than in an engine with flat-top pistons, and may need a lot more initial advance to get a complete combustion. The placement of the spark plug can give advantages with an extended tip in some engines, and in other engines no change. As an example, the Mopar SB have a better stock placement of the spark plug, and will often benefit from an extended tip to get a more complete combustion. The stink is most likely HC, stemming from unburnt or incompletely burnt fuel. In addition to the reason mentioned, it may also be caused by insufficient atomizing of the fuel mix, often caused by too cool runners in the intake manifold, causing the fuel to condensate on the walls, or too low air speed in the manifold and carb venturis to get good atomization, can be a too big carb or too wild cam timing. Going down in carb size may hurt top-end performance a bit, but will give you another engine regarding driveability. A spreadbore with small primaries will also be helpful. Also, check that your PCV-valve is in order. Be careful about dialing in too much initial advance, we don't want detonations!
Olaf

Last edited by olaf; 04-30-2010 at 08:54 PM.
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Old 05-03-2010, 11:23 AM
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whhhops.. small brain fart on my part.. the heads are 69cc, not 67. I can find very little on the casting #, but i did match the chamber to a picture in one of my chevy performance books.. I pasted a pic of my chamber onto a scanned image of the page for comparison sake. coincidently, the same page also lists f/t pistons in a 350 with 69cc heads as 9.9:1

this is what mortec says about my casting #:
3998920....72-73...350
this is a link to the scanned page... I know they aren't 76cc heads.. I had a pair of 76cc's kicking around for a while.. and they were huge chambers compared to what I have now.

http://home.comcast.net/~kc8oye/Engine/cc.jpg

my pistons are a Speedpro PowerForged FlatTop part #TRW-8KL2256F30
with their skirt coating. (I actully bought them from summit as it happens)

as far as detonation goes, that's what lead me to believe my compression is fairly high. I had to run very conservative timing to get this engine to run w/o pinging on 89 octane.. once I switched up to 92 only, I brought the timing up to where it is now and it runs like a raped ape for the most part...

This is the cam I'm using

I appreciate you covering the bases.. that's why I asked!! it's obviously something I haven't considered yet!

olaf: this has been an on going problem with 4 different carbs.. so either a) it's not the carb, or b) it's something I am doing to the carb.. two different Qjets, a holley 600 single feed, and a 650 dual feed (brand new)
i had to go to the dual feed because I was having fuel starvation issues with the 600 as i got near the speed traps

i'm pretty certain the PCV system is working. the valve rattles.. not sure how much further I can go with it pcv in the passenger valve cover, open element breather in the drivers.

i dont think my runners would be too cool.. it's just an Eddelbrock Performer RPM (with OUT the airgap)
i'm pretty certain my cam and carb aren't too big. cam is a summit racing cam.. that may be half the problem right there.. *shrug* it's a 214/224 @ .050 .442/.465"
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Old 05-03-2010, 11:33 AM
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something else I just thought of.. since you mentioned low piston height.. I remembered I have a picture of my engine while I was building it.. the pistons are about as flush with the top of the deck as you would care to get them.. so i dont' think it's THAT.. but I could be wrong..

New pistons in the block

edit:
also found this pic.. shows both ends of the heads if the casting marks help any
http://home.comcast.net/~kc8oye/Engi...nginefront.JPG
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Old 05-03-2010, 03:18 PM
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Ok, i remember that head now but didn't realize it was used on 350's, the 69cc I was familiar with was on the last 327's, and we've established that the pistons are correct. Be aware that compression ratio charts like the one you have shown are figure with a piston at zero deck height but most all pistons are .025 down the bore. The 2256 is this way, you have acrually around 9.5-1, whichn is still high enough to have detonation problems like you stated at some times.

Cam should be fine but still the possibility of it being retarded as it wasn't degreed in.

I'll have to think on this a bit and see if I can come up with anything else to look at.
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