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Spark plug rec for 454 with 9.5 comp and 049 heads.

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Spark plug rec for 454 with 9.5 comp and 049 heads.

Postby jdavis » Tue Mar 24, 2009 2:18 pm

Alright fellas like the title says. I have a 454 here with 9.5 comp and some lightly ported 049 heads with a little weeny 230/242 hyd roller cam. The carb was suffering a cross leak and many other problems like super old gas that was at least partially non-flamible or burned so slow it was still doing it until the mufflers.

So as a result the spark plugs look like a mineshaft at midnight. Since it has been a long time since I messed with anything near this compression ratio much less with stock heads. Can somebody recommend me a plug that is pretty hearty or at least cheap so they have good resistance to fouling or can be replaced for little cost in case I missed something else (which is likely, i'd like to skin the guy that asked for my help for not doing so sooner but it is what it is).

I was thinking something like the ac r45ts or something along those lines but I am sure somebody has something that may work better. I know certain numbers of autolites have survived things that they shouldnt have for me in the past.

Appreciate all replies fellas. Sorry I have no reference on where the heat mark is on the ground, we will worry about that once I take care of the many other problems and get the tune close.
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Postby F-BIRD'88 » Tue Mar 24, 2009 3:05 pm

The 70's era BBC oval port street motors that use the small "peanut plug"
work well wiith a Champion RBL9YC , to RBL12YC.
The 9 is a little cooler heat range, suited to "high performance driving" including towing.
While the slightly hotter 12 is intended for more lite throttle, stop and go city driving.

Equivelents are AC R42T, R42TS Autolite #23
Gap at .035" If you have trouble with these plugs, regardless of brand, its not the plug, its a carb and or ignition system problem you need to address.
Once a spark plug is carbon fouled, (caused by a carb or ignition fault) its best to replace the set with new ones.
Any of these brands of spark plugs will work well for you.
Autolite has a good spark plug application crossreference site to help you find the equivelent spark plug in your perfered brand.
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Postby jdavis » Tue Mar 24, 2009 4:03 pm

Thansk F-bird, just got this as a side project for my uncle. I do believe the gas was celebrating its 2nd birthday in the tank if that tells you anything :shock:. The demon carb was the usual wreck that I find them to be in when i opened it up.

I am installing the standard arc welder type hot rod ignition system on it today and draining the gas from the tank/lines/carb. I believe I have the carb leaned out and with the stopped cross leak into the transfer slots stopped it should not kill plugs. I am also recurving the distributor while I have it apart, and tend to a few other wiring issues.

I appreciate this and anythine else anyone wants to add.
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Postby jdavis » Tue Mar 24, 2009 5:28 pm

Well I finally got around to pulling a plug and taking a look at what they were. NGK yr5 is what came out of it that crosses to a autolite 144 which is a heat trange 5 plug according to autolite. I know ngk rates thier stuff backwards heat range wise. F-bird the plugs you suggested are colder plugs than this. Should I stay with the autolite 23 or should I move up to a 24 which is the equivalent of the current model number RV12YC which i believe is the new number for the rbl12yc you said would do better for stop and go light throttle use.
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Postby rally » Tue Mar 24, 2009 6:12 pm

jdavis i ran the 049 heads on my strip motor, a 454 12-1 compression. i used the autolite 24 plug and it ran fine on the track. those heads were a nice combo for the 454. i now run a 468ci Aluminum head motor. good luck.
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Postby srv601 » Tue Mar 24, 2009 6:34 pm

a/c plugs are fine r45ts if it has a hei set them at 45 -if it has points set plugs at 35

change the fuel asap to new pump gas you will see a big difference then

good luck roger
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Postby jdavis » Tue Mar 24, 2009 7:47 pm

It has a now freshly rebuilt and recurved hei in it with a new 'sane' vacuum advance can. To aid in the spark it also has as of today a mallory 6al. I am going to finish up looking over the under dash wiring and inspecint the plug wires this week, the gauges were doing some funky things on me when I pulled it into the shop, I suspect mice have had a go at a couple of the wires or perhaps a bad ground.

I suspect the fuel was the bulk of the problem, it was a sight to behold when it was trying to run.

Thanks for all who have responded.
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Postby bigjoe1 » Tue Mar 24, 2009 8:02 pm

I ship all my street engines out with NGK number 5 plugs in them-- I tell every one that you should run the hottest heat range you can find untill you want do do some racing. The hot heat range has always worked out for me-I also have a startup proceedure sheet that tells the new engine owner how to startup and warm up is new motor- I stress that you DO NOT LET THE ENGINE IDLE SLOW WHEN IT IS COLD-- since I have been doing this, noone ever calls and tells me that they have black spark plugs

JOE SHERMAN RACING
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Postby jdavis » Tue Mar 24, 2009 11:27 pm

Alright I will let this stunt slip up in light of what Joe has said. I have never been able to get the electric chokes to work on demon carbs there is no pull off on them and they are finicky. If you close the flaps down like bg has it set with the linkage to get on the fast idle cam good, you end up with the locomotive looking exhaust and dead plugs. So what I do is I take the choke flap and unbolt it from the little cross bar. Then I can set the fast idle screw to make the engine rev up and idle at 1600rpm when its dead cold and I can also set the pull off time for this event by just twisting the electric housing to preload the little spring. It has worked for me better than I could have dreamed for starting hot rods and keeping them running when cold until some heat gets into the manifold to make spark plugs live.
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Postby F-BIRD'88 » Wed Mar 25, 2009 6:22 am

All the plugs I outlined are within the typical working range of a high perf street BBC motor.
Non of these plugs will foul or cause drivability issues on a properly tuned motor. If the carb is flooding or the ignition is cross fireing etc you are going to get plug fouling reguardless of the plug heat range being a little hoter or a little cooler. The cooler heat range are better for heavy throttle load extended WOT, towing and/or a day at the track. They offer a little more detonation/priignition protection and will colour a little darker. If you are a lead foot these are the right plug for you. The hotter range in this series will run a little lighter colour 'cause the tips runs hotter. Better for warm up/engine breakin, idling, stop and go driving. I always used the Champion RBL10Y{C} or equal in my old oval port 454 Chevelle SS.
I like to run a slightly cooler non projected tip plug with nitrous.
I used to and still do get 2 years out of a set of plugs.
AC and Autolite and conventional NGK seem to work just as good. Never had good luck with the NGK V grooves.
I haven't used a choke on a holley carb in 20+ some years. I do just as Joe said. Get it started and keep the idle up above 2000 rpm till you get some heat in the manifold.
A automatic choke on a holley is like hyd cams. BigJoe will tell you about them. Especialy in BBC's.

just kidding, You run your holley the way you want... :D
If the Autolite #24 (RBL12YC/RV12YC) suits your driving style the best, go with it. Now that you got some fresh gas, the carb sorted out and the ignition recurved, I don't think you'll have spark plug issues either way.
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Postby jdavis » Wed Mar 25, 2009 9:02 am

Its really not a choke at all without the flap is it? Its just a fast idle cam that pulls off after a bit so you dont have to babysit it :wink:.
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Postby jdavis » Thu Mar 26, 2009 8:32 pm

I really cannot catch a break with this thing. Put the carb back together and went to attaching linkages things after priming the electric fuel pump and checking out float level looking for leaks. Well I am unhappy to report that this demon with very little use has the throttle shaft play of a 30 year old quadrajet... real nice qc.. =D>. I noticed this when I had to depress the throttle to attach the linkage, the squirter dribbled out a little fuel and not too much later a throttle shaft and linkage slightly wet with gasoline. *sigh*

Does anybody have any ideas to cure this and help prevent it from happening again? This carb has literally under 500 miles on it! I guess next this masterpiece will disintigrate before my eyes because thats about all thats left for it to do wrong besides drop a booster into the motor *cross fingers*.
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Postby OBSESSED » Thu Mar 26, 2009 10:19 pm

Have throttle shaft bushings installed. I've done thise on many q-jets and some hollys.That takes care of the looooose throttle shaft issues.
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Postby F-BIRD'88 » Fri Mar 27, 2009 12:29 am

If you pump the throttle on a holley (enough) and squirt (enough) fuel in, without starting the motor, then its going to sit on the throttle shafts and migrate out on the throttle shafts. Check the throttle shafts for actual wear/slack. If there is not noticable free play on the shaft in the carb base, consider this normal. If there is a lot of slack, then you're going to need to correct it.

Whenever one of my carbs has been sitting for a while I routinely give the throttles and other linkage pivot points a shot of light lube like WD-40 to lube 'em up a bit. Helps avoid accelerated wear. Do your car door, hood and trunk hinges and latches too. A well lubed race car is a happy race car. :D
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Re: Spark plug rec for 454 with 9.5 comp and 049 heads.

Postby rcamacho » Wed Feb 24, 2010 12:16 pm

Resurrecting an old thread. I'm running a BBC402 with milled 454 oval port open chamber heads. CR is 9.2. My builder spec'd NGK YR5 plugs but I'm curious if the projected tip plugs (UR5) would work in my combination.
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