I'm starting to strongly consider biting the bullet and going retro-roller on my cam swap coming up instead of Flat Tappet. I've narrowed it down to Howard's due to the high quality and low price compared to others. Considering these two grinds, let me know your thoughts (and yes I like a rowdy cam, and won't go small lol)

And the Rattler (227/235) is what Howard's recommended I run.

1971 LT-1, 4 speed, 3.70 rear, no vacuum systems, and getting 64cc heads with 190/72cc ports that flow 230CFM @ .500 , 10:1 compression, LT-1 Winters intake, Doug's Side Pipes, and Holley HP 650 DP.

Rattler (118005-09) : 227/235 525/530 @ 109LSA 1800-5600 RPM

Big Momma Rattler: (118045-09) 235/243 530/530 @ 109 LSA 2000-6000



I don't like that the smaller one falls off around 5500, and like the larger cams power band of 2000-6000, and of course it's going to be rowdier in my side pipes


Any thoughts from experienced people that have ran similar roller cams? Something better you recommend? *keyboard mechanics, don't care about what you've read*

 

Sounds like a decent street combo, so my pick would be the smaller of the two you listed. Your compression and head flow better match the smaller choice.

 

Thanks for the input! What is the driver and results from them being a better match? More response and TQ?

 

Skip White Magic Cam 327s-383s Truly Magic

 

How's it drive? How's it perform? What's the characteristics?

 

I built a 357ci last year......and used this: Hydraulic Roller Camshaft & Lifter Kit; 1955 - 1998 Chevy 262-400 1600 to 5400 Howards Cams CL110245-10 | Howards Cams
Trick Flow DH175 heads and a EPS intake @ 10.5 to 1 compression.....2.5 outlet 65 SHP exhaust manifolds.......in front of a TKO 5 speed......650 Classic DP Holley......
This made great average power everywhere and sounded good......team it with 1.6 rockers for .536/.544 lift......this was an easy high 12 second car on street tires......69' with 3.36 gears.....pulled hard to 5800-5900 RPM......that's all it needed to rev to.....
I would stay away from the "Thumper" or "Rattler" grinds....they open the exhaust valve too early and compromise vacuum.....I am not really sure why these grinds exist as they do not do what they say they do......except make a choppy idle, and you can get that with a regular cam that is just larger.......
I also would not put a 190cc head on a 350.......a 175cc or 180cc is perfect...and builds better velocity......
You want vacuum and velocity.......the two are acquainted to each other and make for a crisp running engine that is easy to tune and has great response......idle vacuum and just off idle vacuum will get the boosters pulling fuel quickly and you have a 650 for even more velocity through the venturi.....which will signal the boosters even harder.....signal is power.......the Winters LT-1 intake is a surpising piece that was 30 years ahead of it's time (Unlike the **** cylinder heads).......
Do not get stuck on the manufactures RPM range....this is a very vague reference scaled on the conservative side......
Is your LT-1 running the stock domed pistons? If so....they measured 10.4 to 1 actual with the stock 64cc head......perfect for modern chambers......
Good luck to what you decide.......

Jebby

 

Jebby, thanks for this good advice ! How lopey/choppy was the idle on the above cam? (I want a nasty idle) lol I'm not sure which pistons are in my LT-1, and wont' know until I pull the engine. The Rattler doesn't have the super late exhaust like the Thumpr, and ready a lot of good reviews as opposed to the Thumpr - is the Rattler really that bad?

 

I think with heads that flow only 220 ish the rpms would be limited anyway and a 10 :1 compression engine would be a more broad band engine with the smaller cam. In my 406 I went with a 254@.050 solid and though the engine would rpm to the moon I found street driving was lacking low end most of the time. Yes I could row through the gears and shift at 7000 but mostly driving the low speed was lacking. The lc on my cam was 108 and it shook the fenders in my 406.

 

The idle was pretty lumpy but not a "fairgrounds cam"........
The cam may be well rated but I would just go to a larger cam to get what you want as you potentially can improve airflow and the sound is just a byproduct.....
In your case....the larger cam makes sense as you have a 3.70 gear....you may also have a close ratio trans with a 2.20 low.....so really a compromise......the 3.36 with a 2.56 low is a better street combo........more usable rpm range....do you know what you have? To get MPH from the 3.70 you really have to turn the engine.......I think if this were mine....I would put a smallish Solid Roller in it......something in the upper 230's for .050 duration.......if you want to spin it up......depends on how you drive it I guess......

Jebby

 

My specs don't even come close to yours, but as your looking at the various venders, watch your specs. Check them with the manufactures spec and part #. I found a couple different venders had errors on their sights. Lobe separation was wrong on two sights. 110 instead of 112. Not a big deal as long as you compare the manufacture parts number and specs to the vender sight. IMO I would call Howard if you haven't already, they seem to be the most helpful. I'm no cam expert either. Another forum mentions the various online compression calculators and if you already have a program for that more power to you.

 

Idles at 500 very nice sound. Drive's great pulls hard down low. make's very good power to 6200 in 327 and 5600 in my 383.

dyno 383 with cheap Chinese heads. And I know the date is wrong

 

Jebby, What other streetable larger grinds would you recommend? My LT-1 has an aftermarket Borg Warner Super T-10 in it (I don't know the story why) , and I don't know the ratios.. I have confirmed the 3.70 (cruise at 3200RPM at 70MPH)

I small solid roller would be cool in my opinion, because it pays homage to the solid FT that came in the LT-1. How are the manners of a 230ish solid roller? I like to rev my engine (I have a C4 ZR-1 too, and used to revving high lol) But I don't need to get my LT-1 to 7K, i'm good with 6K on a street car.

 

Wow! That's some impressive numbers!

 

Actually, side pipes at best are a free-flowing exhaust. Like an untuned dual exhaust.

The second thing is: factory cam rpm ratings are listed for run of the mill 350. adding cfm of head flow, better intake, and ,,,, can extend the upper rpm range. The deficit to these cams IMO is the 109 LSA. Which makes a narrower power band, but being H-roller you have an rpm limit of sub 6500 rpm. For that matter You have to have forged and balanced internals to be exceeding 6500 rpm on a regular basis.

I was also around solid and solid rollers before H-rollers were even made. So I'm not really an H-roller heavy lifter fan. So my first attempts at hot rodding my little l-82 were intake, exhaust headers, heads, and cam. Much like what you are doing.

Do those 190 cc heads have bigger intake ports than the Lt1 intake? That is a big no no. I went straight to the lowest rpm single plane made to port match to my heads. Weiand Team G. Single planes require less carb than a dual plane, so your 650 is great. Heads can be used on future motor products so don't ever go low cfm. I didn't want to go overboard on my first 383 so I only put on competition ported 227 cc. Your 230 cfm at .500 isn't very good. You can pull up online charts of potential HP vs CFM.

 

I know these heads are mild, but I got a super deal on them for $600 new in the box! Story is, the seller bought them from Corvettes at Carlisle from a vendor, and bought two seconds. The second set didn't get used, and I bought them from him. The specs I have are according to the seller, but these appear to be nicely worked foreign AFR copies. I'm not sure if the ports match the Winters intake, haven't pulled it off yet.

It's an LT-1 so it should be a forged assembly, but I'm not trying to keep the engine over 6500 RPM regardless. . With what you're saying on these heads, where should I focus on cam duration?

 

Did you get a full list of flow numbers or just what you posted? I personally like to look at the Exhaust / Intake flow ratios. You want to most duration split if it is below 75% and less split if it is above 75%.

 

I am not sure if I missed it, what is the car going to be used for? Racing, cruising or daily driver? That would dictate my choice. I see you have a 4 speed Tranny and 3.70 rear gears. I am no expert but my gut tells me that on the highway and on 4th gear, your car is going to annoy the hell out of you at 60 to 70 mph. In the city no big deal. Let me clarify, the sound will be a little unbearable(High RPMs). You would need a tranny with overdrive.

 

My car is used for spirited driving (beat on it down the back roads), and around town/cruise ins. It may see a track once a year, if it does. I don't do long interstate cruising with it (for more than an hour) , but oh yeah she makes some noise with the side pipes and 3200RPM at 70MPH. I'd love a 5-speed, but it's not worth the expense for me - I don't have a problem humming the engine down the highway when I do. And I have a C4 ZR-1 that's built with a 6-speed for when I want to do Corvette road trips.

 

I have the XR276Hr Retro roller cam with a 4 speed. Which is a 224/230, a step below your choice and she gets a little noisy at 75 mph, and I have 3.08 gears. I also insulated my doors, floor, back area and I am even contemplating above my mufflers. However that might look a little tacky, so I probably won't. I will tell you this, at idle my car does sound pretty good, but you might have to add Headers, straight exhaust with an H-pipe, and chambered mufflers. My bad you might just need some headers with your sidepipes.

 

Was going to chime in that what you're describing is pretty much what to expect. I'm running a 238/246@.050, 114 lobe separation, solid flat tappet cam in a 427 and it's just about perfect. Idles at 800 w 13 inches of vacuum, will spin the tires from about 2000 in 1st w 3.36 gears just mashing the gas and pulls to about 6200.

Figure about 10 degrees less at .050 for hydraulic will get the same response as a solid. That would put a good hydraulic at 228/236@.050. A roller will be a bit better idle and low end for the same .050 duration bc the ramps are much faster. Or add 5 degrees @.050 for the roller vs the flat tappet. That is, unless the cam grinder insists on punching the lobe separation angle. Just that by itself hurts vacuum and low end response, even if it boosts peak power.

First cam in this car was Comp 292 Magnum hydraulic, 245/245 @ .050, 110 LSA. It was, In a word, crap.

Use those numbers as a guide, keeping in mind you need to drop the duration to account for smaller displacement.