Reviving the con-rod bolts & nuts discussion

Hey all, I just joined the forum and this is my first post! :smiley: First, I’ll give a brief intro/background and then get down to business. Thanks in advance for reading my post and for any help/advice given.

TL;DR: Skip to My Question to get right to the point.

About Me: I live on Florida’s sunny Space Coast and have for just about my whole life. I would call myself a Jaguar hobbyist as I have only recently begun scratching the surface on classic Jaguars. I haven’t started this journey by choice but by necessity… my dad is the original Jaguar enthusiast of the family and it’s his cars that I’ve been staring at just sitting in the garage for 40 years. He has always enjoyed taking things apart but has never been as fond of putting them back together. He’s too old to do much wrench turning now and still not very interested the work. I’m determined to see these cars on the road, and thankfully now I’m in a position to get it done.

About The Cars: The easiest way to describe the condition of the cars is to call them a “barn find”. As I mentioned, my dad liked taking things apart and that’s the current state of the cars. My first project (my car) is a 1968 E-type S1.5 DHC. My next project (my brother’s car) is a 1958 XK150. As I said, I’m determined to see these cars on the road so any effort to warn me off of this undertaking will be wasted. I’m taking more of a restomod approach than a concours approach to these rebuilds.

I’m early in the rebuild of the 4.2L engine of the E-type. I’ve had the block refurbished and gotten it ready for the crank. I have new pistons connected to the original con-rods. I’ve been pouring over the many forum posts regarding con-rod bolts and nuts and have read most of them, but not all. I haven’t come across one that addresses my specific question, so I figured my best hope would be to actually ask my specific question. I have 12 original bolts but 11 original nuts… so I need to, at least, replace the nuts as the originals are the castellated ones designed for use with a split pin. I’ve already been warned to replace these by several sources and will do so. Now, on to the matter at hand…

My Question: I’ve seen much discussion mentioning the ARP replacement nuts and bolts offered by Moss Classic Jaguar (formerly XKs Unlimited) and how they must be modified in order to achieve a proper fit with the con-rod. I’m not interested in doing that if I can avoid it as I’m not a machinist and don’t have quick, easy access to one. I haven’t seen any mention of the hardware offered by Welsh Enterprises in Ohio. They claim that their hardware is manufactured in England by the same company that supplies OE equipment for Jaguar (the phone rep wouldn’t give me the company’s name). He also dropped names like Donovan Motorcar Service and others to strengthen his sales pitch. So, does anyone have any experience with Welsh’s hardware? Or can anyone offer an opinion on whether or not their stuff would be a good way to go?

Your best bet is to use OEM bolts: they are perfectly adequate in all but the most extreme modifications.

Get in touch with SNG, and they have the proper factory bolts. ARPs have a known problem and require modification to fit the rods.

Thanks Paul. I haven’t reached out to SNG yet, but I will. I’m still curious about the Welsh nuts & bolts. Any thoughts on them specifically?

Are they aftermarket, or OE?

The use of anything other than factory or ARP (and they can be made to work fine, but on a streeter, they’re overkill) would be a non-starter, for me.

Jaguar 4.2L XJ6 Ser 2 parts always worked for me, in all 6-cyl engines I have had 1947-1975. YMMV.


The sales rep said they were OE… then he dropped some names as part of his pitch.

Never mind the names: be pushy as to their provenance.

This is why I trust SNG Barratt: you can take it to the bank if they claim OE stuff.

I just installed a set of ARP rod bolts in my 4.2 as suggested by Bill Terry. My engine is slightly modified with GTJ cams, ported and polished and larger valves, headers, and Ray’s EDIS. It is true that as you tighten the bolt it wants to turn since you can’t really insert the entire bolt into the cap when the piston is already in the engine, aligning the bolt with the rod seat. As I tightened the bolt I kept an eye on the turn and with a small punch, tapped the bolt back into its proper position and torqued it a little more. Not a big deal at all. Bill suggested that i follow the ARP recommended torque of 50 ft lbs with 30 weight oil.

That’s funny, I used ARPs but there was no issue inserting the bolt all the way home into the rod. Of course, the bolts I used needed the “bevel modification” as was the case at least several years ago with the ARP fasteners for Jag rods. If anything, the ARPs were a bit looser fit than the original Jag parts.

I’m installing bearings in the engine without taking the pistons out so I have very little leverage to overcome the minimal tight fit between bolt head and rod flat.

So I reached out and spoke with one of the names the Welsh rep mentioned, Donovan Motorcar Service, to verify what I was being told. The story I got from them didn’t exactly corroborate the story from the sales rep. But, he gave me what I think is good advice… he recommended keeping the original bolts and updating to the ARP nuts. That’s the route I’m gonna go since my bolts are all in great shape and already installed. My machinist cleaned them up for me when he was working on the rods.

A (possibly) less-expensive solution is SBC rod bolt nuts.