7.4 vortec cam specs and valve clearances help please

[400addict]

Well I've been snooping around here for quite a while and decided to make an account so I can ask some of the odd questions that I come across. So here goes and if this is in the wrong place or if the issue has been addressed already please point me in the right direction. I have a 98 k2500 7.4 nv4500 love the truck to death, however, there is always room for more tq and hp, I recently upgraded my injectors, fpr, coil, icm, distributor along with upper/lower intake and valve cover gaskets to address the inevitable hot start. Since the injector swap I have had an itch to upgrade my cam and I live close to jesse at wait4me so I'm going to have him do a tune for me in a week or two. I have been looking at the comp cams xr270hr-13

question 1) will I have valve clearance issues the cam specs are as follows

valve timing 0.006
lobe seperation 110 degree
duration intake-270 exhaust-276
duration at 0.050 lift intake-218 exhaust-224
valve lift intake 0.51 exhaust 0.51
lobe lift intake 0.301 exhaust 0.301

If I'm not mistaken the valve lift of the stock cam is 0.50 will that extra hundreth of lift cause clearance issues?

question 2) if I if have clearance, can I run the stock lifters push rods rockers etc. I'm probably going to change the valve springs at the least but would like to save some cash and run the rest stock.

any help from anyone that has changed their cam would be greatly appreciated. Thanks guys

 

[Christian Steffen]

Did you ever find anything out on your cam? I have that exact same cam in my truck but for the life of me I can't remember if I had to have the machine shop I used do anything special to the heads for clearance, actually I must not have because I remember seeing a super chevy article where they threw a comp 284hr into the stock heads, so you should be good to go. You'll be fine on the lifters as long as they aren't worn out.

I would change the springs to the ones matched for that cam, and I would also upgrade to adjustable valve train (someone makes a kit to convert it) and roller tip rockers will fit under the stock valve covers with short poly locks. Although roller tip rockers aren't a must if you're trying to hold a budget. The cam works great by the way.

 

[400addict]

I haven't gotten a chance to start that project yet my ol ladies jeep is a pos and keeps giving us fits and I just rebuilt my nv4500. How do you like that cam in your pick up is there still plenty of low end torque? And I have decided while I do it I'm going to throw all new parts in it with an adjustable valve train might as well while I'm there.

 

[Christian Steffen]

That'll be worth your time to do. I like the cam, it seems to have a good deal of low end torque but I also did this swap along with a stroker kit so I can't give a straight up comparison, according to comp it is supposed to work well for low to mid range power. I don't tow much with the truck anymore but when I did it worked quite well.

What are your plans for the truck? If you're strictly building a towing vehicle then maybe a bit smaller cam would work well? Something like their XR264 may work well too. Whatever you decide to go with you honestly won't be disappointed, you'll pick power/torque up across the entire rpm range when compared to the stock cam.

 

[Jrgunn5150]

Do these have adjustable valvetrains? The Mark V didn't.

And if not, you're limited to .500 of lift.

 

[400addict]

No jrgunn they didn't have adjustable valve trains they are supposed to automatically adjust.

Christian right now it is my dd plus towing and working around the farm. I plan on doing a sas, cam, valvetrain, maybe SC someday and maybe paint it unless I can find a 4 door dually without a motor or trans that I can put my power train in

 

[Jrgunn5150]

No jrgunn they didn't have adjustable valve trains they are supposed to automatically adjust.

Christian right now it is my dd plus towing and working around the farm. I plan on doing a sas, cam, valvetrain, maybe SC someday and maybe paint it unless I can find a 4 door dually without a motor or trans that I can put my power train in

I didn't think so, but I wasn't sure. In that case you are stuck with a .500 lift limit, but, ARP makes a stud kit that's 3/8 on the bottom to go where the factory bolts go, and 7/16 up top to use adjustable rockers.

I've been sitting on one of these engines for awhile now, because I haven't had anything to put it, but I've been looking at sticking it into my new 8600 GVRW work truck.

You shouldn't have to get too crazy with a 454 to make stupid amounts of torque.

 

[400addict]

It has decent power for my intents and purposes now but like I said always room for more. Plus who doesn't enjoy listening to a little lope.

 

[Jrgunn5150]

Absolutely, when I redo mine it won't be stock either lol.

Something like this, with your rocker of choice will set you up.

https://www.summitracing.com/parts/...XmvfyvHDqGCxNGBXD-2vEonvBvBSmrM1TbxoC9hjw_wcB

 

[400addict]

I saw that kit too. Looks pretty handy. There is a guy that has the same motor in a suburban I think and he slid this cam in just the cam and left everything else stock and said it's working for him I think I saw the video on YouTube so apparently the factory rockers and/or pushrods had enough give for him but I'd rather replace everything to freshen it up anyway but that's me thanks for the info and the link