Torque Converter Bolts

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Demonx2

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I haven't found any thread discussing proper torque converter bolts for performance converters so I'll ask it here. Using the usual B&M SFI flexplate (#10230) that is 0.150" thick, what torque converter bolts do you use for a converter that has the 7/16"-20 bolt holes? The ARP#240-7302 bolt shows the underhead bolt length at 0.500" so that would mean there is only 0.350" of thread (0.500-0.150=0.350") into the converter lug. That doesn't seem like enough for a 7/16" bolt. I don't see anything listed for other bolts in the 5/8" length range.

ATI sent bolts with their 8" Treemaster converter but they have washers that make the head too thick and they then kiss the block. I called ATI and was told just not to use the washers but with the small hex head, it doesn't seem to cover as much clamp area as the more rounded-head 12-pt ARP bolts. These ATI bolts are, however, 5/8" long in underhead length so that part would be much better with about 0.475" thread engagement.

Thx for the help - I'm sure many of you have been down this road already and know the solution!
 
I've used those ARP converter bolts with success. You may want to call them and see if they have any 5/8 long. Maybe another application would fit (e.g., a different trans)?
 
Sometimes a 5/8" bolt is too long. I had some from (mancini?) once and they would bottom just a bit too soon. I also use the 10230 plate on a PTC (and have used it on other converters) and the ARP kit is just right. I also like the ARP bolts for the thin-profile heads....as you know on the 727/B-RB space is already tight.
Sounds like the ATI bolts might be made a little longer for use with their washers, if space permits.
You can thread a bolt into your converter, snug it, and see exactly how much depth is there..but really the depth that the ARP gets is plenty.
 
Thank you fellas. I called ARP to see what the might have and the Mopar bolt #240-7302 is the only one with a 0.200" head thickness. They have other 7/16-20 tq conv bolts but the heads are .220-.250" thick. So I measured my tq conv lug depth and they appear to be in the 0.560" range (hard to measure with the oil pan hanging down there!!). But they're at least that depth so after a relook at the ATI bolts, I went with them. Rotating the engine, I measure about 0.065" clearance from the block to the bolt head so should be ok. For reference, the ATI bolts also have a thin head...about 0.205". (That's probably more clearance than I had on a car I did 30 years ago!) Again, I appreciate the input.
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I use some hardware store Grade 8 bolts and washers I cut down so they would screw into my torque converter as far a possible without bottoming out.

If I screw them in to the converter before installing the flex plate, the underside of the bolt head will be just about to touch the pad. The thickness of the flex plate adds enough extra standoff to allow the bolt to be fully torqued without bottoming out in the converter for maximum thread engagement.

I also always use a dab of loctite to them after cleaning them with brake clean.
 
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