Ok so I was going to put the Xr276hr in my Vortec 350 build I was doing but turns out I got the wrong version of the Xr276hr that’s for non rolling blocks that were converted to use roller camshafts, the one I need is out of stock and will stay out of stock until atleast June apparently. I already have the heads gone being set up for this cam with new valve springs but was wondering if there was another option that would be similar to this cam rather than waiting until June at the earliest to get this car together. Major screwed up here and I’m trying to salvage it as best I can if possible I guess is what I’m saying. In case anyone was curious I bought 12-423-8 and the one I needed was 08-423-8

 

Why not run a Holley cast timing cover and cam button ?

 

not an expert on cams so I’m really not sure, how would that make a difference? Is it like a different retainer plate essentially?

 

Ok I found the button and now I understand how it works but would that work for an engine that was just a stock roller and had a retainer plate?

 

The retainer wouldn’t be used unless you call comp ask them if they could machine the step nose of the cam. I think that’s the difference. Stock rollers, dog bones and spider tray would be used . But with the cam button to setup endplay I’d use a Holley 21-150 cover and matching balancer.

 

hmm in the installation instructions that comp sent with the cam it says if the engine had a retainer plate install it again. My problem with this cam is that it sticks out of the block rather than like the old cam had a ridge that the plate went around. If I called comp and had them machine it to be like that couldn’t I just use the retainer plate and not do the whole cam button thing?

 

I’d call comp, the directions could cover both part numbers. I think the retrofit version doesn’t have a step for a retainer.
so if they can machine you wouldn’t use a button.

 

To use a retainer needs to be machined like left image.

 

Tuned is right... you can use that cam, just include the cam button, and of course you'll need the early style timing set, since the bolt pattern on the front of the cam is different.

You can't machine the older-style cam after the fact to accept the retainer, because of the bolts. The bolts themselves would interfere with the retainer (or vice-versa, whichever way you want to think about it... they're incompatible either way). It would have had that rabbet cut in it, and the bolt holes drilled on the smaller circle, from the factory. Those are the only differences between what is now known as a "retrofit" roller (the kind we had all been using for all those decades before the factories caught on) and the factory style. You'll just leave the retainer out in that case.

 

yep that’s exactly my problem so now I’m wondering instead of trying to make this one work I can get a xr282hr with the step like the left image and it would actually be an exact match instead of having to change to a different chain and everything. So I wanna ask another question, would the 282 be too much for my engine? It’s not a lot bigger but I’m really not sure how much of a difference six degrees makes in duration. I’m running an rpm performer intake with 5/8” headers and a Holley 670 street avenger. I really feel like the 276 is the right cam but I don’t know if the 282 would be potentially better or worse. And the heads aren’t done so I could still change the lift my springs are being set up for. If the 282 won’t work I guess I’ll just make this one work haha but because this is my first engine build I’d like to keep it as simple as possible so I would rather just be able to put the cam in and move on rather than worrying about more stuff I could potentially mess up.

 

XR282HR is MUCH larger in a 350 than the XR276HR. More larger than the numbers would seem to indicate. I had one in a 400, and it was MUCH "larger" than the cams I had in the exact same motor before, which were a CS282 (solid Magnum)... it was the early 90s after all), and a XE274. Probably related to the ramp rates.

One of the "rules" in the hot-rodding world is, there's no such thing as "too much cam for the motor"; there's only, "not enough motor for the cam". Make sense? You got whatever motor you got, it's not enough for that cam.

You'd be better off to run the 276 you have, a non-roller timing set, and a cam button. Will work perfect, you'll never know the difference between the "retrofit" cam and the "factory roller", except whatever little effort, if any, is required to set up the cam button.

 

alright thanks a lot for the help, I’ll just go with the cam button, I bought a rolling timing chain so I guess I need to return that and buy a non rolling one? And don’t non rolling chains wear faster?

another thing I have noticed, the lobes of the cam seem to be just barely not centered to the lifters holes, is that normal? I can take a picture tomorrow if needed.

 

The roller timing set for the pre-roller system, which you need, is usually cheeeeeper than the one for the later-model setup. There is also FAR more variety available.

You won't really know where the cam lobes are in relation to the lifter bores until you put on the cam sprocket and push it up against the front of the block. Don't worry about it yet. Odds are though, it'll be fine. I don't think I've ever seen one that was too far off to work. And I've seen A SHIPLOAD of oddball block defects, you can be sure of that.

 

thanks a lot for the help man, I appreciate it 👍

 

sorry after re reading I noticed you said a matching balancer, I need a different harmonic balancer to match with it?

 

The cover & balancer together have a matched timing pointer location. You don't "need" the balancer, but that's part of the appeal of the set. Unlike the variety of mix & match (or not) stock ones.

Personally I don't give a rat fart what the timing "mark" and "pointer" and all that, say... I pay attention to how the engine RUNS and adjust accordingly, and it doesn't look at that stuff to figure that out. About all that knowing that "number" will do for you, is to put the timing back where it was, if you disturb it. Won't do A DAMN THING toward making your engine run any better.

 

Ah so I can just pick the timing set that comp recommends with my cam and then buy a cover and balancer together?

 

Could sell it or send it back and get an equivalent roller. Summit has a few similar cams in stock

 

actually I can’t because that’s what I wanted to do. The same came for an oem roller block is out of stock until atleast June. Same thing with the 282hr.

unless you know where I can find one or a specific cam you have in mind

 

i didnt say they had the same cam i said they have equivalent ones. Just search summit for instock cams for oem hyd roller blocks including lt1 gen 2 years. I seen a few in that duration range

 

Sum-8803 seems like a good replacement.

theres a 4x4 comp cam thats 230/234 similar to the 282hr

xfi 218/224 and a couple hot cam sized cams. Melling has a 220/224

 

that 8803 summit cam has .550 max lift, that’s wayyyy higher than my comp cams one which is what I’m having the springs set up for at the machine shop right now also it’s operating range goes all the way to 6500 rpms and those others aren’t even close to the 224/230 duration that the 276hr is

 

Yup, you're too deep in to change course now.

Any cam anything like the XR282HR is likely to be more than what you have motor for.

Just do the simple thing and keep the one you have, and get the early-style timing set and a cam button.

 

so I found the correct timing set but I was looking at covers and I honestly can’t tell them apart, like which one is the old one and which is the newer style one.

 

Is it a vortec block with plastic cover now ?

 

Well they are basically the same cam, the 276 will go to 6500 in the right setup as well. Both cams would be peaked out by 5800 most likely on stock vortec heads. Shift by 6200 imo

the others are within ball park 218-230 range and will run fairly well, probably wouldnt notice a difference. Hotcam specs run well, the xfi cam 218/224 has made alot of power for how small it is, although the 113 lsa is less than perfect with that intake

Springs are easy to change out, the heads should have been modified for higher lift anyway.

but nothing wrong with just using a cam button cover. You asked for options, there they are

 

yep it is.

 

The Holley 21-150 cover is for 96 up vortec blocks.
single row chain and cam button if your sticking with your cam.

 

yep I’m sticking with the cam, thanks a lot for the help, I was lost haha. Do you by chance know of a timing chain? Once again I can’t tell the different between old and new style, they all look the same to me or am I just confused and the older style chain just means a non rolling chain. The chain I currently have is a double so I’ll need to return that one.

 

Old style = larger bolt pattern where the sprocket bolts to the front of the cam

They had to make the bolt circle smaller on the new style to make the bolts fit inside of the retainer.

Look at the photo in Tuned's post, #8, with the 2 cams; note how much farther the bolt holes are from the hole in the center in the one on the right.

The new style is also thinner at the center, on the back side, to allow for the thickness of the retainer.

 

So how would I be able to tell that in a picture? Because I’ve looked at like 30 different sprockets and the bolt holes look pretty much the same in all of them.
And so I could still use a rolling chain? Also are there old style covers that I can use a double chain with because if possible that’s what I’d like to.

 

They're different. Blee dat.

Simple way to spot it by the naked eye, is to look at the bolt circle, such as is clear in those photos up there. If the cam dowel pin touches the bolt circle, then it's late-model, and won't fit your cam. If the dowel pin is well inside the bolt circle and misses touching the circle by about 1/8", then it's what you need.

Easiest way though, is to look at what they fit. If they're for 55-up or "all Gen 1" or some similar wording, they're what you need. If they're 87-up including LT1 then they're not. Another choice of words is something about "factory roller": you want one that DOES NOT fit that system.

As examples, https://www.summitracing.com/parts/sum-g6600r-9 or https://www.summitracing.com/parts/cca-3100 or https://www.summitracing.com/parts/clo-9-3500tx9

Yes of course you can use a roller chain. We've all been using roller chains since I've been in this hobby, which is coming up on half a century now, and they weren't new then. With old style covers of course, since there's never any such thing as "features from the future". Some covers are too "shallow" for a timing set like this. Some blocks also have trouble: I've heard that some later 880 castings have to have a little bit of metal near one or more of the cover bolt holes ground off because a wider chain like this will hit it. Also, the REAL CHEAP "roller" chains like you can pick up at AZ for like $20 are actually not "roller" at all. They're what we all call "truck roller" or "bushing roller"; they have links that look like rollers, but instead of rolling on roller bearings, they have bushings for the little round pieces where they are mounted on the pins that hold it together. That kind "stretches" (wears out and develops looseness) IMMEDIATELY upon first startup, FAR WORSE THAN a stock Link-Belt style of chain. They are GARBAGE and should be avoided like the plague. You can bet that if it calls itself a "roller" but costs less than about $40, it's that kind of TRASH.

The Vortec crank damper is slightly different from older ones, in that its "snout" isn't as long. That motor has the "reluctor" for the crank pos sensor, which is a disc with teeth that mounts to the crank between the crank sprocket and the damper. The damper is shorter by the thickness of the reluctor.