I have a 400 small block chevy with KB hypereutectic dish pistons with brand new vortec heads.. what kind of spark plugs could i run in these heads would like ac delco rapid fires work? or what are your guys recommendations?

9:1 compression - AC - 45 heat range - I think the plug is a R45TS
9:75-10:1 - AC - 44 heat range - R44TS

I don't know about the rapid fire platinum plugs... I think their heat ranges are a different # system than the regular AC plugs...

Vortec heads use a .708" reach plug. Champion RS10YC or RS12YC is good.

A R45TS will not work at all in this cylinder head. It has a .460" reach.

You can get the R42LTS, wich is the longer reach plug, but a bit cold. Not sure if it comes in a 44 or 45, but the local GM dealership should be able to tell you.

does it have to be a 708 reach or could it be a 750 reach?

Are you like this every day?

well i just see limited options for the 708 plug and more for the 750

Like smashed valves, crunched pistons or something. Give your head a shake Its too firggin long.
The champion RS12YC is all the plug you'll ever need for your vortec motor.
Go buy a set, install them and shut the hood and leave it alone.

well i'm only in high school so give me a little break about the questions..if i knew it all i wouldnt be asking you guys.

i have learned that asking questions will prevent costly mistakes and i'll learn something new and save time so like i said give me a break

I'm using a Champion 7013.

Excellent attitude. Glad you asked. Glad to give my opinion.

My personal opinion is that "I wouldn't run a Champion if they were free". Based on my years of experience, and of others I know well.
In the past month I have pulled NEW Champions out of 2 "customer" cars that were brought to me because they wouldn't run right.

Engine engineer/builder David Vizard, who often bylines in PHR, wrote on his web site about Champions being down 100 hp on the dyno from other brand. He didn't actually say it, but its reads like he won't run Champions.

In over 35 years of building, racing, repairing cars, boats, bikes, skidoo's, and a few skate boards, using Nitrous, supercharger, Alcohol, pump gas, race gas I've never had a faulty or defective Champion spark plug. Or trouble with the performance of these plugs.

In my testing over the years I have had some trouble and inconsistancy with some other brands (NGK V Groove, Autolite specificaly) Not sure why.
In my testing I have not found a specific advantage of one brand over the others (of the ones that work well AC , Champion, normal NGK etc)
I have not found any advantage of any of the weird expensive speciality plugs.
A big waste of money. Including AC Delco rapid fire. (They run fine, just no advantage to justify the extra cost.)

I've had the same Champion RS12YC spark plugs in my 11sec S/S car for 3 years now. Maybe next year it will be time for a new set.

With all respect to DV, Could you post the specific link to the page where David Vizard coments on Champion Spark plugs?

Sure will. I thought I saved it but am looking for it to post here.

As far as my circle of friends and Champions....
after you have a couple sets that won't run well right out of the box.......
or break down in a couple thousand street miles.....
We just don't spend the money and effort to mess with them anymore. period.

Switching to another brand of comparable plug solved the problems 100% in every case.

I met one shop owner about 2 months ago who likes Champions and hates Autolite. Last week I was in his shop and he was installing the 3rd set of Champions into a customer's car in less than 3000 miles...... for free.....
........ but he likes em.........go figure

PS, I have also never owned a set of Splitfires that lasted longer than 3000 miles without missing. OH ya, they did make a noticeable difference in power compared to a brand new regular plug... but they won't last. Had 2 sets from random stores in 2 different cities 100 miles apart.

Here ya go....
David Vizard's problems with Champion spark plugs solved by installing Autolites.

http://www.gofastnews.com/board/tec...s-part-3-a.html

Similar problems that we have discovered in Mopar V8 and Ford V8.
I experienced this 45 years ago and as recently, as noted, the mechanic changing the 3rd set last week.

Ya well if you read the whole thing ya get the rest of the story.
They fouled the champion plugs by flooding the engine. Naturely once the plugs were changed with fresh ones the motor ran better. Again naturely by reinstalling fouled plugs the power nose dived again. No suprise there. A fouled plug does not recover once it is fouled. Also read the part about the experimental super power ignition box.
Probabily hot enough to melt a resistor type spark plug. poobibly so friggin much voltage output that the distributor cap was ionizing.
Super hot ignitions with excessive spark power cause more headaches than they cure.
Their problems had nothing to do with the brand of spark plug.
If you foul a spark plug, you have to install fresh ones. Those plugs are finished. (carbon tracking)
These are racing plugs, they are very very cold, Easy to foul. (especially with flooding. Once fouled , they do not recover. Even cleaning them will not work.
If they had replaced the fouled plugs with fresh Champions the power would have been exactly as with the fresh autolites. (or better)

Any engine will eat up spark plugs if it is not tuned right. Any plug will foul if you dump enough fuel at it. (missfireing, flooding, glazing, etc etc improper AFR, timing etc etc) Especially a cool heat range racing plug. Untill you correct the underlying cause (ignition fault, carb issue etc), the new spark plug (reguardless of brand) will have a short life.
Any time you replace a fouled plug, or an old spark plug with a fresh plug, reguardless of brand name, naturely the engine will perform better. Cause it has new spark plugs in it.

And now you have the rest of the story.