Cam bolt size ?

[adk-roadrunner]

Hey guys I'm looking for some info that some of you guys out there with big blocks that have cams with single bolts might be able to answer. I am currently in the process of building a 440 for my 73 roadrunner and I purchased a comp cams came kit for it which includes the cam,lifters,valve springs and timing chain and gear set. The kit is K21-306-4 the can is the comp cam 270H I believe which is a single bolt cam. My original plan was to use the bolt from original cam which a comp technician assured me would work as they show the stock Chrysler bolt as a 3/8-16. I tried the stock bolt and it doesn't seem to fit and I believe its a 7/16-14. What do you guys use for a bolt to hold on the cam sprocket and did anyone else notice a difference between the stock size and what comp uses?

 

[lewtot184]

stock single bolt is 7/16-14. if i remember correctly 3 bolt is 3/8-16.

 

[MOPOWER871]

Whatever you do use a good quality fasteners, ARP....I found this on youtube I wonder if the single bolt failed,in proper tourqe,?inferior washer?durty threads? https://youtu.be/PIQtaUzObHI

 

[adk-roadrunner]

Just got off the phone with comp cams resident mopar guy and what he told me was that 80 percent of single bolt cams had 3/8-16 bolts. He then went on to say sometimes if threads were repaired or what not in the factory they were tapped to 7/16-14 and that's probably why my stock bolt size is different than what their cams have. I then asked him if he could recommend a part number for the bolt I need and he said to go to the hardware store and get a grade 8 bolt and thick walled washer and I'll be all set. I'm looking and can't seem to find an arp bolt and washer for a single bolt cam.

- - - Updated - - -

So I just off the phone with a guy from 440 source as they sell single bolts and he said they are 7/16-14 and to his knowledge a mopar 440 has never had a single 3/8-16 bolt and he doesn't understand why comp would sell a cam for mopars with a different bolt size and not include said bolt. He suggested I call them back again after gathering a little info. Can anyone out there who has used a comp cam with a single bolt tell me what bolt size it took and what they used.

 

[lewtot184]

typical comp cams. that's why i don't buy from those clearasil junkies. all single bolts were and are 7/16-14; grade 5, from the factory.

 

[adk-roadrunner]

When I talked to the guy from 440 source he said a good machine grade grade 8 bolt in 3/8-16 should be fine. He said I shouldn't worry about the bolt breaking just needs to hold it tight so it can't get loose and break the dowel pin.

 

[A383Wing]

the comp cams guy is an idiot....I have never seen a single bolt Mopar cam with a 3/8" bolt holding the cam gear on. He says they drill and tap the cams to 7/16"??, What a dumb-*** he is

 

[Seventy]

return that cam, lol.. I used a comp cams and I dont remember buying a special bolt...

 

[lewtot184]

When I talked to the guy from 440 source he said a good machine grade grade 8 bolt in 3/8-16 should be fine. He said I shouldn't worry about the bolt breaking just needs to hold it tight so it can't get loose and break the dowel pin.

the 440 source guy isn't much smarter. 7/16-14 grade 5 (minimum) torqued to 35ftlbs with some loctite on clean threads. a grade 8 bolt is ok but i'd be careful of over torquing the washer.

 

[A383Wing]

the washer is really thick...you won't do any damage to it with a 3/8" bolt or even a 7/16" size....those washers are tough

 

[adk-roadrunner]

So the single bolt cams you guys used used the bolt from your stock cams? I'm thinking that it's the cam and the tech guys don't know what they are talking about at comp

 

[Cranky]

I quit using Comp products a long time ago. A buddy wanted me to do an top end job on a 302 for his old Bronco and wanted to use a Comp cam and rockers etc and I told him not to and why not. He did anyways and ended up sending half the stuff back....twice....then he wanted to know what the hold up was. All he got from me was a dumb look. Yeah, use a dab of Loctite red on that bolt.

 

[adk-roadrunner]

Found some specs on the Web it shows cam bolt sizes and the only one with a 3/8-16 is the 426 hemi http://www.mymopar.com/torquespecs.htm

 

[Hemirunner]

All the B/RB single bolt cams are 7/16 and all B/RB three bolt cams are 3/8. I prefer the 3 bolt setup and use it exclusively.

 

[Seventy]

Found some specs on the Web it shows cam bolt sizes and the only one with a 3/8-16 is the 426 hemi http://www.mymopar.com/torquespecs.htm

Is your cam a hemi replacement? Or hemi series of some sort, or they sent the wrong cam? if they used it in the hemi, just go buy a grade 8 bolt and be done with it I guess..

 

[adk-roadrunner]

Nope not a hemi cam its a cam for a 383 or 440 supposedly. I know others that have used this came on here maybe I should pvt message them and see if they had any issues using their stock bolts. I'm wondering if maybe the cam was tapped to the wrong size maybe. Here's the came card for it don't think there is any relevant info.

 

[adk-roadrunner]

Lol not sure why I didn't think of it before why not just order a cam bolt and washer for a 426 hemi since they are a 3/8-16.

 

[Seventy]

Nope not a hemi cam its a cam for a 383 or 440 supposedly. I know others that have used this came on here maybe I should pvt message them and see if they had any issues using their stock bolts. I'm wondering if maybe the cam was tapped to the wrong size maybe. Here's the came card for it don't think there is any relevant info. View attachment 268237

I talked to my father about this last night, we used that exact cam in his rr 383 and he said we never bought a cam bolt, we used the one from our bin, my father is cheap when it comes to buying bolts, he wont buy stainless kits for $32!!! He takes his motors apart and drops every bolt in a 3 gallon bucket with a big handle magnet in the bottom {looks like a kettle bell}, he pulls the magnet out and drops it right in the parts washer then sticks ever bolt in a piece of that wall board with all the hanger hole sin it, over the years he has drilled a thousand holes in that thing, he primes them and paints them in that board on a set of saw horses, my point is he is **** about it and reuses everything, I think he would remember buying a special cam bolt...

Now, if you are in a hurry, already installed the cam, or cant return it- I would just go grab the bolt and washer brand new grade 8 from a local source, since the cost of the bolt will be insignificant and it will probably be less effort and definitely less time...

good luck, stuff like this makes me pull out my hair...

 

[Hemirunner]

Nope not a hemi cam its a cam for a 383 or 440 supposedly. I know others that have used this came on here maybe I should pvt message them and see if they had any issues using their stock bolts. I'm wondering if maybe the cam was tapped to the wrong size maybe. Here's the came card for it don't think there is any relevant info. View attachment 268237

Send it back and get the three bolt version instead. Problem solved.

 

[lewtot184]

you don't need a 3 bolt set-up with that small of a cam. a 3 bolt comes into play with high spring loadings. 3 bolt cams didn't come into play until the '66 street hemi. the 65 race hemi was a 1 bolt, but used a heavy valve spring that may have caused some failures. the 64 and down race wedges used 1 bolts but didn't have high valve spring loadings like the hemi's. the 69 6-pak was the first year for 3 bolts and to my knowledge 6-paks were the only wedges that cam from the factory with a 3 bolt.

as for that cam i'm not fond of them. they're very short duration with too much advance ground into them. it would be ok for 8:1 compression engine, especially a 383, but make too much cylinder pressure in anything around 9.5:1 compression. simply put, they close the intake valve too soon.