TR4/4A TR4A conn rod bolt opinions needed

[PeterK]

I'm doing a rebuild of my 4A engine so, to do the right thing I ordered 8 new connecting rod bolts (from Paeco Racing - they sell all stages of TR engines from street to full race). Their price was good, just $5 per bolt. But when they arrived I received 8 grade 8 3/8-24x1-3/4" bolts. Just plain old 60cent bolts. Am I missing something here or are they still laughing?!
If these are OK, I'll just order a 25 pack for $*.64 from McMaster Carr and send these back. They also have more thread than the originals are are .060" smaller at the shank so they're loose fitting in the rod cap.

I will contact them but would like others opinions, still fell like I'm getting screwed. Tanks, /ubbthreads/images/graemlins/crazyeyes.gifPeterK

 

[Geo Hahn]

I was under the impression that these bolts come in two flavors... one stretches as you torque it and does not require the locking tab (not reusable) and the other is a more ordinary bolt that requires a locking tab (possibly reusable).

I had the latter and reused them apparently w/o a problem (20 years but no racing). Not sure what you've got there.

 

[PeterK]

You're right that TR2-early TR4 used tab washers, but TR4 from CT34072E-TR4A used self locking rod bolts.

Paeco sent plain old grade 8 bolts which I would think wouldn't be ideal even for use in early engines because the non-threaded portion of the bolt is only 3/8" long and the fit is imprecise.

 

[Alan_Myers]

Hi Peter,

I'd ship em back, get a refund and see if you can get something better. You're right and your motor should have the stretchable, self-locking type (unless the conrods have been swapped for earlier ones) and so shouldn't reuse the ones you've got or try to use a standard bolt.

I'm sure TRF or Moss or VB have the correct item, if you want original quality bolts.

I think Ken Gillanders at British Frame & Engine sells ARP upgrade bolts, www.britishframeandengine.com

Ken has built more than his share of TR motors, and might be able to give you good advice, too.

John Swauger at TRF could probably give advice, too, if you prefer.

Alan Myers
San Jose, Calif.
'62 TR4 CT17602OL

 

[TRTEL]

Peter,
Send them back! I would not use those bolts under any circumstances and am surprised they sent them. The shoulder from the hex cap to the threads should be the same depth as the rod cap. And just a slightly loose slip fit to boot since it is acting as the locating device on the non dowelled end of the rod cap. We switched to a variety of aircraft grade bolt years ago(not so much an increase of PSI strength, but rather no stretch at high rpm's). The torque used was 75 to 80 fp's and rod bearing life improved significantly. They had round caps and required an allen wrench for tightening. If your wanting a performance bolt I'm sure they could be found at a bolt supplier. Seems like I remember them costing about 3 to 4 bucks each circa 1972.
Tom Lains
Be sure when they rehab the rods to pull the dowels and remove an even amount off both the cap and the main rod body for resizing. I see way too many shops get lazy and just do the rod body, which slighly changes the distance between the wrist pin and the crankpin.

 

[Bugeye58]

Paeco? I'm surprised that you didn't get grade 5 bolts from them.
I would seriously consider the ARP rod bolts.
Jeff