building a 350

[79malibu]

350

oh f*** me! :x when i got the shortblock done i forgot of getting better rod bolts in. when i think back now the machine shop never even asked me about it. f***, anyone know what stock rods with rod bolts are good up to power wise and rpm? some guys have told me that 5 to 5500 is limit then playing with fire. i already have a comp xe 268 cam and cam is said to rev up to 6k so i think i may be in trouble. what you think?

 

[8GPLE7]

Re: 350

...anyone know what stock rods with rod bolts are good up to power wise and rpm? some guys have told me that 5 to 5500 is limit then playing with fire. i already have a comp xe 268 cam and cam is said to rev up to 6k so i think i may be in trouble. what you think?

I think the peak hp with that cam is around 5000, so running up to 6000rpm shouldn't be that much of a concern.


http://compcams.com/Technical/DynoSheet ... 10_001.asp


I have the same cam, and I like it. The only prob is its kinda noisy. I still have to check out the valvetrane geometry. Here is how it sounds,idle is around 900rpm here:


http://s193.photobucket.com/albums/z223 ... around.flv

Cj

 

[85 Cutlass Brougham]

With regards to the rod bolts, The big issue is rod bolt stretch and that is something you check when doing assembly. If you didn't check it and it is already assembled and installed, I wouldn't worry about it. I have a set of ARP rod bots in my engine as insurance, but the stock rod bolts in my Nissan truck have yet to fail and the engine sees it's 6500rpm redline 10-20 times a day-with 267k miles on it.

 

[megaladon6]

the 1.6:1 rockers may be okay but usually when you change rocker ratio it screws up your geometry and you have to use different pushrods. its a royal pain in the f@#kin' a$$ to correct valvetrain geometry! gm engines can be reved to 6-6500 stock but they usually don't breathe after 5k. as long as you put in the springs that compcams recommends you should be fine. remember the engine doesn't actually spend THAT much time at peak rpm's. if you have not installed the block you can still swap the rod bolts. i would simply because they are used and you do not know if there are stress cracks. the ARP Wave-loc bolts are very good. oh, the entire compcams xe series is noisy, but it has been tested and will not cause damage. it comes from the very aggressive ramps. the plus side is that they are comparable to an equivalent or even slightly larger roller cam.

 

[85 Cutlass Brougham]

It really all depends on the flow numbers of the heads you have. Ported heads are not always a good thing as doing the wrong thing can make it flow less, not more. I for one, would stick to the 1.52 rockers for the sake of simplicity. If you don't have a lot of money to deal with, it's not worth risking the purchase of something that may require additional parts to function correctly. Even with all the work, the 1.6 ratio rockers are usually worth less than 10 hp at the most. Just be sure you have screw in studs and not the pressed in GM studs as they will pull out with the cam/valve spring combo you should have.

Oh, and yeah, the XE262 cam I run is a little noisy. It sounds like a loose rocker at idle with the ticking, but I checked the rockers and they are all properly lashed, so I guess it's just a normal trait of the cam. BTW, I also have the 1.52 Magnum rockers and will say that they are a nice quality part and worth the money. I didn't change the springs when I did my cam swap, but the engine was built with .500 lift springs so I seem to be ok.

 

[8GPLE7]

I remember I read somewhere that with the XE series you don't need 1.6 ratio. I can't remember the specifics, but there was a test done with a small block and an XE cam. The motor made less power with the 1.6 versus the 1.52 magnum roller rockers. I wish I could remember everything, but when I bought my parts for my motor the guy behind the counter recommended I go with 1.52ratio. I wanted the 1.6 at first but the guy knew his stuff and said the 1.52 was the way to go.

Cj

 

[79malibu]

350

so most of you guys agree to not use the 1.6 rockers for the gain would be minimal? heads are the 441 stock exept for the full porting and polishing in and out with port matching but does have the bigger stainless 2.02/1.6 valves. can't fit tall valve covers so i guess i can only run magum rockers.

the old block never went over 5k in its life cause of truck cam and only had just over. 100k miles on it. it sits on a stand currently but since i live in the country i am 83 miles away from my machinist. when i called him today he said he recomends the arp rod bolts but they are not necasarry. said it be about 140 to do it all. only thing i would ever add for power to this would be a 100hp shot of nos in the future if need be but thats not anythime soon. i also noticed that when i put in the cam that the 2 dot marks dont even match. the crank dot is actusally off by maybe 1/4''. i think i may need to get the rod bolts and get the cam degreed. WOW there is so much sh*t in specking ur own engine, wish i had the money for a crate motor. 😢
wow, i watched that vid and i have heard before that xe cams are noisy in the valvetrain but you can totally hear that ticking!

 

[85 Cutlass Brougham]

If the timing marks are off by that much, it likely won't even run when you go to start it the first time! You need to reset the timing again by removing the cam gear to remove the chain, then align the marks and reinstall the chain. It's not hard, I did it when I did mine.

If you plan on nitrous in the future, I would definitely run the ARP bolts. Also, what did you do to check the balance of the engine? Lower cost rebuilder pistons typically have a fairly large weight variation between pistons. I had mine rebuilt by someone else, and what he did in lieu of actually balancing it was to pair the rod/piston pairs in such a way that they weighed around the same for all 8 cylinders, thus minimizing any balance issues. My engine however, was built as a low buck short block in a car that was put together with pizza delivery in mind and not ultimate performance ( which is why it had an even milder Crane cam at the time). I figured the short block was a throw away and the heads, cam, headers the important pieces. I do have the ARP bolts in my engine. It was a cheap insurance policy at the time and one of the few things I did to strengthen my 2 bolt cast crank short block.

I am curious about one thing with regards to your cam: What is the lobe separation angle listed on the cam card? The reason I ask is that the catalog listed the LSA on my cam as 110 degrees but when I got it, the card said 114 degrees. While I prefer the 114 to the 110 for the improvement in low end cylinder pressure, I am curious if Comp changed their other XE cams or just the XE262.

 

[8GPLE7]

Re: 350

wow, i watched that vid and i have heard before that xe cams are noisy in the valvetrain but you can totally hear that ticking!

Yeah it is loud 🙁
Some people claim they don't experience any noise while others say theirs is louder than mine :shock:

I want to check everything out first (pushrod length, lifters, lash etc) before I say it's normal. Just have to find the time.

By the way 85 Cutlass, my card says 110 lobe separation.


Cj

 

[megaladon6]

i have the xe274h flat tappet which also has the 110 LSA. it doesn't tap per se but it is producing a noticable sound, kind of like a chain or gear noise---checked everything, it's just the cam. the car spins the tires with 1/4 throttle--who cares about noise?

if the short block is on a stand you can flip it over and CAREFULLY rotate the crank, unbolt the rods and put in new bolts. you may want to have the head on with no lifters and no cam, just so the pistons can't slide out. also be careful that when you rebolt the rods on you have the bearing halves sitting correctly. and definately have moly-lube on hand for every possible wear surface.

degreeing the cam is not too difficult, just time consuming and you have to have the right tools. comp cams has a very good tutorial on their site. i have pics of when i degreed my cam in "pics of my 383ci build". it was my first engine build and my first cam degreeing. it took an hour or two but it's worth it, especially if you are having problems with timing.