Hi I am building a 383 stroker gen 1 and was wondering what would be the best mechanical or hydraulic flat tappet camshaft (don't want any kind of roller) for my application. It is going to be a street motor and rarely (probably 2-3 times a year) hit the strip. The powerband I want is 2000-6500 because of the intake and heads. It can be a few 100 rpms off but no more than 200. Unless you suggest a whole new different power band all together considering I haven't bought the intake or heads yet. I am wanting to make around 500 hp at the motor but know it will be under that # due to its need for street-ability. I am going to buy AFR 195cc heads and in the process of finishing the bottom end. It has 2 valve relief +4.00 flat top pistons, h beam 5.7" rods and is 0 decked. The AFR heads I want to go with have 65cc combustion chambers. The compression ratio should be right around 11:1.

I was thinking of Comp Cams XS274S. With 274/280 duration and .501/.510 lift. 110 LSA and 2000-6400.

Let me know what you guys think. Thanks

 

finding a cam with that kinda powerband on a flat tappet is gonna be tough bud but lunati makes lots of cams with close to that powerband heres a few lunatis LUN-10120703 isa 1800-6200 cam or the step up from that LUN-10120704 which is a 2200-6400 cam, and just so u know, those afrs will easily flow 6500 rpms, try a custom grind also tell them ur powerband and heads and such, and sometimes its a pain in the *** getting a custom grind because they tell u how they would build it not to your own personal liking often. ur best bet is a custom grind in a mechanical cam for making 500 horse in that sorta rpm range. my buddy was right at 500 horse with afr 195s with comp XR288HR which is a 2500 to 6500 rpm cam with 236/244 duration and .520/.540 lift. hope that helps you out i was gonna do a similar build but went cheaper with a 350 .60 over instead.

 

Thanks. To be honest I'm most likely going with the lunati 276/284 10120704LK. I am just wondering if I have a choice between 2 camshafts and they are the same duration but one has a higher lift which one is better for my application?

 

Go higher lift. Shouldnt have a problem getting 500 hp with those heads but .500" is not gonna make it. Run as much lift as you can to get the rpm range and flow required for 500 hp. Could go comp 284h or lunati's 705lk kit but its gonna idle abit rougher. 274-276 cams are abit more streetable and should get you where you want to be.

 

Don't be afraid to call or email cam manufacturer to get their recommendations. You will need to include other info (trans, convertor if auto, gears, tire size). It is my understanding when advertising the powerband, they rate it on a 350 ci. Using a larger ci (383) will lower the powerband.

 

I dont put much thought into advertised powerbands. Heads and intakes will influence that as well as tune. Most seem to be based on 350 cubes but they dont say anything else. As said cubes will lower the rpm range

 

yeh higher lift with the same duration is usually your best bet when choosing between 2 similar cams , especially for the street which your motor will see alot of, and try to stay 110 lsa for the street also, promotes better low end midrange than say a 108, 106 lsa cam, which would make your car nasty on the street, and not a good nasty.

 

and yeh a 383 will tax out that powerband faster than a 350, but a 383 builds much more torque naturally so theres no worries with the car producing enough power to launch if cammed correctly with those heads and correct converter is used also with a converter rated for a small block a 383 will be on the top of that number say its a 2200-2400 , the 383 will be at the tip of that, but if its rated small block/ big block, then u could find yourself right in the middle, being that big blocks create much more torque and other factorys such as gear ratio and vehicle weight also. so much goes into making a motor utilize a advertised powerband. so a custom grind might be your way to go to really match your car.

 

Y are you against a hyd roller? Esp if your using a roller block it should be a no brainer to use a roller.
If your going to drive it on the street a lot and track a few times a year, a hyd roller is the better choice by a long shot.

 

Thank you guys so much. I will go with the Lunati 276/284 cam then. It has 110 LSA. Would anyone know what length pushrods I would need with this cam?

 

Money. Only answer I got. I'm not going to half *** the engine (example is I'm using all arp hardware on the main components) but at the same time I can save a lot of money going the flat tappet route. Now in the future when I have the money to spend then yeah I love the idea of a roller. And aren't the old blocks (mine is a 1970 4 bolt main) flat tappet blocks?

 

Yes, if you have a 70 block, it'll be a flat tappet motor. Money is no doubt a big thing 4 all of us 4 sure.
Just becareful breaking in the cam. My friend just lost 2 cams in a row within 20 mins of run time. Yes, he used the break in oil, proper procedure and the zink. It just chewed up 2-3 diff lobes on each cam.
They just aren't made as well as they used to be..

 

Man that is scary. I will be extra cautious and thanks for the info

 

Yeah 87-02 blocks are possible rollers. Before that you have to spend alot more to retrofit a roller in. Worth it in my opinion if you are not skimping out on all other components. If you have a solid bottom end, big money heads and everything else, skimping for flat tappet with todays oils designed for rollers seems like a step backwards. It will work but much more potential in a roller.

 

Pull the inner springs out and drive it easy for 50-100 mi you should be fine
Some like to leave the springs and use 1.3 break in rockers crower sells them. Take your pick
Keep your rpm down...drive it normally just stay off the loud pedal
Youll have to use a checker tool to find pushrod length or should anyway
I still like the simplicity of flat tappets just hard to walk away from the power and increased driveability of rollers the difference is huge.
Long as it dont go flat youll have fun if it doesn you get a complete remachining job for free haha.

 

First of all thanks for letting me know all of that! So I should leave the break in rockers on while I drive for the first 100 miles? Should I bother setting a proper lash or just snug them tight and then after the break in I can change to my rockers and set the correct lash?

Second, if I had the money I would love to go with a roller cam. Honestly I just want to have a bit of fun on the street and maybe the strip for the hell of it with this motor and then when I have the money and am feeling bored I would get everything I needed to go with a roller setup. I have nothing against them and actually prefer them.

 

Here is another approach to spring break-in we have been doing for yrs.The article from Engine Builder mag is written far better than I could.

Safe Valve Spring Break-In
Most engine builders are well aware of the fact that high performance valve springs should be compressed to coil bind through several cycles before being installed. The problem with this procedure is that it can be time consuming, costly and even dangerous.
It is time consuming if each spring is compressed in a valve spring pressure tester and costly due to the fact that compressing many valve springs through several cycles accelerates wear and reduces the life span of the spring tester. Compressing springs in a vise or arbor press can be dangerous if the compressed spring escapes, thus becoming a projectile careening throughout the shop.
We have solved these problems by making a fixture which holds four valve springs and is compressed in our 20 ton shop press. The fixture is made of two 3˝ x 6˝ aluminum plates with spring seats machined into them. Each of the four spring seats has a .375˝ diameter steel rod through the center to retain the spring if one should become dislodged during the procedure. Each steel rod is attached to the bottom plate and has enough clearance to move through the top plate. A recess is also machined into the top plate to accommodate the shaft on the shop press.
Bill Riordan
Riordan Engineering
Twin Lake, MI

 

I am just going to buy a valve spring removal/install tool and take out the inner spring to save money and do it correctly.

 

I break my engines in fairly hard and quick. I dont drive lightly for 100-500 miles like some do. I do light throttle lower rpm pulls and let off, let engine brake down in gear. Builds vacuum in the cylinders and helps set rings. Do a few of those then start with medium throttle pulls to mid range rpms, let off in gear and engine brake down. Few of those then move up to wot and full rpms. Worked for me the last few motors. I was racing with less than 100 miles on them. Pure race motors dont have time to street drive softly and set up quick. No reason a street motor cant do the same.

Ofcourse for you after the initial 20-30 min cam run in, let cool down, change oil and then do your break in procedure.

 

I always wondered how pure race cars broke there motor in. Thanks for the info! I will probably do this and take it easy for 100 miles. It will be a little bit before the motor is built due to my lack of money. Thank you everyone for all of your help! I really appreciate it

 

FT topic aside same here.

Drove it normally for 50 mi got on the fwy did some progressive pulls then decel over and over.

Ran it to 5k, 5500 a few times, by 100 mi 6k..200 mi on it now run the pee out of it. Its either machined and assembled right or its not so babying if for 500 mi isnt going to make an iota of difference.
With the metals out today, finishes and tigher clearances things seat up pretty quick.

 

Broke my fresh 383 in on the 50 mile drive to the strip , then did 15 WOT passes

 

He guys quick question. I changed my mind from the 383 to buying a 355 short block with around 10:1 compression and slapping some 190cc aluminum heads (64cc) on with PBM Competition Undercut Stainless Steel Valves 2.02/1.60 and 1.46 diameter springs good up to a .550 lift and Comp Super 10 degree locks.

Now I am trying to make the choice between hydraulic flat tappets Lunati 276/284 .501/.525 or Comp Cams 284/296 .507/.510 with both 110 LSA and 106 ICL. What do you guys think is the better option for the most power? I am really looking for 450hp or a little higher. It is still going to be a weekend car and hit the drag strip probably like once or twice a year.

 

If you do the Comp with the 350 use their 274 grind youll like it much better.
Wasnt happy wiht the way the 284 ran in the 350.

 

Why is that? Is it cause it started making power at to high of a rpm? and if I do go with the 274 duration I'll go with the lunati since it's duration is about the same but has a higher lift. I was thinking I need to go with the 284/296 to achieve my 450 horsepower goal though and the 276/284 wasn't going to be enough. What do you guys think?

 

XE284 is a good sized cam for a 383, XE274 makes good power in a 350. I know a lot of people who have wiped lobes on the XE cams including myself so be careful.

 

If the heads are any good it should make 450 with a 274 cam. Thats a good bit of cam tho, get compression up in the mid 10's if you can.

 

What these two guys said.
The 284 was a pig in the 350 even with a littl more compression gear and a better head. Just too much duration for that little motor. And my XE flat tappets went flat too in under 1000 mi that was when they came out in the late?? 90s with the so called higher zinc oils which imo has almost nothing to do with failures.
Get the Lunati or some other brand.

 

Could very well be soft cam cores. Try another brand or ask comp for the core material and upgrades if possible

 

Agree Orr imo think thats the issue but Im no metallurgist lol .

I want my stuff made here and will pay for it-support the little guy while we still have some left!

Even have an XFI 280 roller that went flat in 15k.

 

Comp got a load of bad cores.Thing the ticked me off is they missed catching it in their Q.C.Then dealt with it one on one as the customer complaints came in.Didn't announce it for a recall.Basically tried to hide it.So who knows who's inventory is still bad............

 

What do you guys think the CC of these pistons are?

http://www.summitracing.com/parts/hpe-sp18

 

Never mind just found out. So yeah my compression should be at 10.23:1 Do you think that is ok to run a 276/284 cam? Or is it to low?

 

Thats on the money with aluminum heads