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#1
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Spark Plugs tapered or not??
i have been reading through and am a bit confused.. LOL i have a 78 trans am with a 72 400 block with a butler stroker 461 rotating assembly. xe274 cam, qjet. stock intake.. 6x -8 heads from original 78 400 engine. head and intake have been milled now roughly 94 cc.. my question is.. what type spark plugs should i be using.. tapered or gasket? also i have been looking at the ngk plugs and want to stay towards a cooler plug. i saw some of the info with a spreadsheet that was discussed but im mostly confused if i need tapered or not.. lol.
also i did pick up ac delco R44TS.. are these wrong?? Last edited by 77poncho; 06-24-2021 at 12:45 AM. |
#2
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Tapered seat.
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'65 Tempest 467 3650# 11.30@120.31 |
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#3
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With the early heads that are machined with the flat for the crush gasket you can use the latter taper seat plugs also if your playing around with tip lenght for better flame travel and combustion, or if you just in a pinch and can't get the plug you need.
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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
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#4
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I ran TS plugs in my first set of '71 no, 96 heads with no problems
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1979 Trans Am WS-6 .030 455 zero decked flat pistons 96 heads with SS valves 041 cam with Rhoads lifters 1.65 rockers RPM rods 800 Cliffs Q Jet on Holley Street Dominator ST-10 4 speed (3.42 first) w 2.73 rear gear __________________________________________________ _______________________________ 469th TFS Korat Thailand 1968-69 F-4E Muzzle 2 |
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#5
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R45 TS (taper seat) or R45 TSX(Taper Seat Extended tip) for the 0.060 factory gap on a 78 motor.
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Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
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#6
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Just a thought but in my experience before about 1991 Delco ignitions were marginal at .060 and more reliable at .045.
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#7
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NGK ur5 should work and use the smaller gap.035. Taper seat. Are they dished pistons? Flat tops would give 9.5 compression. Prolly need pretty good fuel with that cam. I have similar combo with ram air 4 cam and still need at least 89 octane and a good spark curve
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69 Firebird, 462 turbo 400 3000 stall, 8.5 323 rear |
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#8
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Neill, how are ya?
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
#9
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yes flat top with a 6cc valve relief.. also i made a typo on my chamber size they are around 96 cc not 94.. but yes agree should be 9.3-9.5 range on compression according to multiple calculators i used.. yes.. i run 93 sunoco.. im thinking at some point i might do an msd ignition. but dont know if i will really benefit from it..
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#10
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Don't run a 45 plug. Alcohol in fuel makes engines run Plenty hot enough. If
you have AC I would not go over a 43 . Running a tapered seat plug in a flat gasket seat really limits the seal contact area. " S" are extended tip plugs and are typically used where a recessed piston is used.
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"The Future Belongs to those who are STILL Willing to get their Hands Dirty" .. my Grandfather |
#11
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Hmm, i have found suffix T is tapered seat, S is extended tip and X is extended gap.
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#12
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/\ THIS /\
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#13
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OK I stand corrected-just never seen T plugs just TS or TSX.
Regardless an AC 45 TSX are what is on my spec for my original 78 6x-8 180 HO motor.
__________________
Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
#14
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The 'T' plugs are mostly used in trucks or heavy-duty applications.
I've never had very good luck with them. They seem to foul much sooner - probably because the center porcelain is completely hidden inside the shell and there is no turbulence to clean it off.
Here is a pic of both styles, courtesy of my Uncle Rock(auto): |
#15
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All Pontiac V8 engines uses plugs with extended tip from factory, suffix S.
Added suffix T for 1972 and later heads, added X for extended gap used with HEI ignition. Suffix T alone not for Pontiac V8 engines. |
#16
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So...AC 43 TSX or AC 45 TSX on a 70 400 with HEI??
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1970 GTO (Granada Gold) - 400 / TH400 |
#17
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Quote:
Have yet to run across the same situation on other late production '71 D port heads, but would not surprise me.
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Buzzards gotta eat... same as worms. |
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#18
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On a 70 400, unless you've changed the heads to a later model, that engine should take an AC R 43 S Which is a larger 13/16 plug with a gasket and the extended tip. Pick your heat range, 43-44-45
The "T" is the taper seat small 5/8 plug for the 71-72-ish and later stuff. |
#19
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No, 1970 heads uses plugs w/o suffix T, as in Tapered seat", since in 1970 Pontiac uses plugs w/gasket.
If you need plugs with extended gap for HEI usage in 1971 and earlier heads use plugs with suffix SX, then youŽll get plugs with gasket, extended tip and extended gap needed for usage of HEI ignition. SX plugs usually has .060" gap that may need to be adjusted to .045" in other than "smog"-applications. Also, you may get by with S plugs having .035" gap adjusted to .045". If you are using 1972 or later heads you need to add the T suffix to either S or SX plugs. If you for some unknown reason need plugs with .080" gap, extended tip and tapered seat there is plugs with suffix TS8. Hope this makes some sence. |
#20
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Quote:
Lots of design changes appeared going low compression in the "smog"-era. |
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