FASST LN

I had a H/C build done about a year ago and my builder told me to use TR55s which we did.
I've noticed at the track that as I'm getting into 4th gear and at WOT I often get hesitation.

I had my tuner take a look at it yesterday and he said everything looks fine on the computer but he could feel and hear the problem. He suggested I should run TR6s instead of the TR55s. He also mentioned that one of my rockers might be over/under torqued or that I should possibly be using a shorter pushrod.

I'm running the heads/cam in my signature with the stock GM head gasket and was told a 7.400 pushrod was the correct length.

My question is, since everyone recommends running a TR6 on higher compression H/C engines (or FI), what would happen if you didn't? What would the symptoms be?

Thanks!!

dbaker

I believe the TR6 is a step colder than the TR55.

Did might want to check the gap.Sometimes a too wide of gap will cause a skip or hestitation.

I run a .045 gap on my 02Z w/Tr55's. A .035 gap might be better for your application.

I assume your wires are in good shape.

\db2
Carolina

FASST LN

Yes, plug wires are relatively new (maybe a year old) and are the GM high performance ones.
Maybe that hesitation is what I'm getting, but only at pretty high rpm and under full throttle?

0HorsePowerAddicts

With the power your car is making you should be running a tr6. Its is a bad thing to have to hot of a plug. A hot plug can ignite to soon and cause knock. If you have a good tune then you shouldn't have any knock. Knock definatly would feel like a hesitation at high rpms. Swap in a set of tr6 plugs and log the car with hptuners(or equivalent) to check for knock.

vettenuts

TR6 is one step colder then TR5. Notice that it is TR5. The second five in TR55 denotes the gap, which is much wider. Try the TR6's and see if it corrects the problem. It is always better to error too cold then to hot on a plug but I don't think one heat range is going to be a killer. If this is a recent issue, then the pushrods shouldn't be the source but you should have really measured and not used recommendations for the length you are using.

By the way, NGK has a lot of very good information on their web site including an explanation of the part number. They do recommend you drop 1 heat range for every 100 hp added with performance parts from a stock setup.

FASST LN

Well, I swapped the plugs and made a couple of runs last night and the car seemed to behave fine. Hopefully that was the fix, since it was pretty easy and cheap to do.

Thanks!