Hey guys had a few questions about selecting an flexplate on a already balanced engine. I had a 350 built 2 years ago which I got balanced and blueprinted. However, I did not supply a flexplate to the builder as I didn't have money at the time to buy one (as far as i can remember). The builder said at the time that any 1-piece rear seal flexplate will work as they are externally balanced already. They used a "TPI one" they had at the shop to balance the assembly. My questions are:

1. Is it bad that I did not buy a flexplate and will now be running a flexplate that is not balanced to my assembly?

2. If the builder is correct, can I run either a 153 tooth or 168 tooth flexplate?


This is one of my next items to purchase along with a starter. I would really like to run the LT4 denso-style starter, but it requires a 153 tooth flexplate. However the block (5.7L TBI block) came stock with a 168 tooth flexplate. I have no idea what diameter flexplate the builder used. The builder has since gone out of business and I cannot get ahold of him. I know it sounds bad but he was a reputable builder, a few of my friends are running engines he built for them without any problems. Any advice appreciated.

Thanks.

 

If as you say engine was balanced to std 1 pce seal flexplate then you should have no problems with whatever type you choose; 153 or 168 tooth.

 

Exactly: sounds like he set it up as "stock", where the engine is internally balanced with the last little bit of internal weight mounted on the flex plate.

There's a great deal of confusion about the meaning of the words "internal" and "external" when applied to that setup.Those words should be avoided: stick with "stock" as your guidepost, and it will all make MUCH more sense.

Just get a stock 12.8" 305/350 flex plate.

 

Thanks for the correction and information guys. Can anyone recommend a brand to get or stay away from?

 

Yerbasic Pioneer from the parts store is fine.

I'd avoid offshore cheeeeeeeeeeeepies, and $$$$racing$$$$$$$$ ones; and above all, offshore cheeeeeeeeeeeepie "racing" wannabe ones such as CAT and the like, often found on eBay.

 

I think I am going to with the Pioneer FRA160 I know it says externally balanced but I am going to guess that is because of what we discussed above... I also found this Quicktime RM932, not sure if they are a good brand, but it is reasonably priced and SFI. But I don't see the need to go SFI for my build. I will hopefully be in the 300 RWHP range, at least that was the goal.