I'm getting all the pieces together for my 355 build and the cam is one of the last parts. I would like good performance and that sweet cammed sound would be nice too! I'm looking at the lt4 hotcam or the comp XR270. My question is what would be best for my build? The price is about $85 between the two here locally so I don't want to spend more money for the same performance. Here's the two cams

Hotcam: 218 int./228 exh. @50, 0.492 int./0.492 exh., 112 LSA
XR270: 218 int./224 exh, 0.495 int./0.502 exh, 110 LSA

My 355 will be 10:1 compression, 1.6 RR's, headers with full exhaust, worked vortec heads (studs, milled, bigger valves, lift good till .585) RPM intake, stock 700r4, and 3.73's out back. any suggestions or help is appreciated!

 

XR270 for sure! Hot Cam's have slow ramp speeds. Faster ramp speeds such as the Comp will make more power under the curve. Just make sure you setup the valve springs accordingly. Good luck!

 

I agree with Orr89's comments in this thread:
https://www.thirdgen.org/forums/tech...70-vs-lt4.html

To make it an apples to apples comparison, you should run the LT4 Hotcam with 1.6 rockers like it was designed to use, and degree it to a 106 or 107 ICL, not the "drop-in" 109 ICL that the roadracers prefer.
There shouldn't be more than a 10-15 hp difference between the two cams then.
As the other thread mentioned, consider a used CC503 cam too if you're budget shopping.

 

I had the XR270 in my 355.. it had a moderate idle, not too wild and put down 230WHP/320WTQ. (About 290 HP/400 TQ)

Combo: '79 350, .030 over. ~9.5:1 SCR, '882 heads, Torker 1 intake/750 carb, longtubes and a TH400/3.23 gears.

With your better heads and higher compression it should do great.


I've probably got a video if it running if you want to hear.. it had TD's with FM40's, sounded mean.

 

sure a video would be great!

 

I have to agree with David. Chances are, the ramp rates probably are better on the Comp cam. Also, as stated above, if you want to go a bit more radical, shop around for a cheap 503 (Comp XR-276) cam. That one would probably give more power than either of the 2 you listed. With the heads, intake and rearend gears you're using, the 503 would work real nice. Btw, I'm running the Comp 502 grind, which is very similar to that 270 cam. About the only difference is it's 112 LSA instead of 110. Mine is a 355 with AFR 190 heads and a Super Ram intake. The 502 works real well with my setup, but I'm considering going to the 503 one of these days. I think it'd give it a bit more oomph.

 

thanks for the info Pat. So I would need a big stall with that 276 right? Or can I keep the stock one for a few weeks while I save up for one. I'd like to get my 350 in asap because the 305 burns through a quart of oil in a few days

 

While you can probably hold off on the stall converter for a short time, it'll definitely work better once you get one in there. I'd recommend a lockup style converter that's somewhere between 2800-3200 stall speed. That oughta do it. Btw, a Vette servo would be another nice addition to the trans.

 

well once the engine is in along with a few suspension pieces i'll be doing a t56 swap. So I don't want to put too much money into the 700 that i'll probably break anyway. Also is there part numbers on the nose of the comp cams or something? So I would know what cam it is if buying used

 

Numbers should be etched on back end. Should have the grind number of 08-422-8 for the XR270 cam. If no number or has been removed, I wouldn't buy.

 

alright thanks. Well I forgot that I am actually getting a tax return this year haha. So I think i'll put that towards a converter and try and find an XR276. I'm pretty sure my car still has a 27 spline converter because it was made in early 1984. This is what i'm thinking about http://www.summitracing.com/parts/hup-21-25 Does anyone have experience with these? I unfortunately do not have the cash for a $450 converter

 

Very short clip but you can get the idea.

http://www.youtube.com/watch?v=BG2uN...ature=youtu.be


The 276 should be quite a bit meaner, before i sold the car i was thinking about going with that one as well.

 

My suggestion for a "cheap" converter that works really well is one from Roadrunner Converters in Phoenix. I bought a 2600 stall, 30 spline one from them for a paltry $150 shipped to my door, and I'm amazed at how well it works considering the price! Not sure if they have a 27 spline unit, but more than likely they'll have it. http://www.roadrunnerconverters.com/gm.htm I didn't see a 27 spline converter on their website, but you could call them and see if they can get you one. I've actually got a Vigilante converter sitting in a box that I'm gonna put in one of these days, but so far I've been pretty impressed with my cheap Roadrunner unit!

 

You can spend the money now or later depending on how well you want the car to perform. A good converter is a key component to applying that engine power to the back! I'd do it once and be done. Vigilante, Yank, Circle D... Some really good ones! They are usually worth .5-.7 tenths over stock units depending on the setup. Thats bang for you buck if you look at it... $750 bucks for that kind of a gain is worth every penny! Just be sure to have good sticky tires at the track when you do! lol

 

At 10 to 1 comp and wanting some cammed sound, go next size up. 276hr or 503, only diff is the lsa