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To cam a 383

1K views 16 replies 4 participants last post by  Bruce1968 
#1 ·
Hey guys this is my first post on here so be forgiving with me:ROFLMAO:. I've got a freshly swapped 383 stroker in my camaro P/N (12498772) all the internals are stock, it has a brawler 750 carb, performer RPM intake, aluminum fastburn heads, and MSD 6Al ignition system. i want a cam combo that makes strong low to mid range power and with a stout lope to it. I'm currently in highschool so driveability is not a huge concern but nothing completely insane. I am very experienced working on cars, but engine building is new to me.
 
#2 ·
A couple questions that might help you get better answers
  1. What's your compression ratio?
  2. Manual or Automatic and if auto what the stall converter RPM?
  3. Rear end gear ratio?
  4. Do you need to run things like power brakes, power steering and AC?
  5. Which heads specifically do you have?
  6. Is this a newer model block with a one piece main seal that originally came with a roller cam or the older style that had flat tappet?
Beyond specifics on a cam grind, CompCams makes a Thumpr searies of cams that are specifically designed to have a nice lopey sound. Also, I think most major cam companies will help you with your decision if you give them a call but they will ask stuff like what I did above and probably also the weight of the car.
 
#3 ·
I would recommend calling a cam company. I used Comp Camo on my current engine. You need none information like tire size, gear ratio, transmission, vacuum brakes, as well as all of the information you already listed. Picking a cam is more than just noise. A truck guy at Comp, or at Straub can help you decide. You also need to make a decision on roller or flat tappet. Roller is considerably more expensive with spring changes, lifters, fuel pump push rod and cam button, distributer gear changes, but more user friendly. Then you need to decide on rocker arm length ,1.5 or 1 6 , or a combination of both. Don't forget measuring for correct push rod length. If you have guide plates you will need Moly rods. Hope this doy deter you. A decent Roller set up will cost you about $1500.00 when the smoke clears. Good luck with your build and welcome. Pictures of your car will be nice for the site. First gen?
 
#4 ·
265255
That’s my bad I didn’t even think to go into that much detail on the car. I’ll be calling comp once I get a chance, is the 1500 dollar price point worth the power gain from a mostly stock spec cam? That is a pretty scary price for myself. Thank you guys such much for the quick replies aswell
 
#5 ·
To go more in depth on the car it is 9.7:1 compression, a manual 5 speed transmission, the rear gear is a 3.73, Power brakes and power steering, no A/C, one piece main with hydraulic roller, the intake/exhaust on the head is 2.00”/1.55”, and the chamber is 62cc, 22in tires, and the car weighs around 3300-3500pounds I’m guessing
 
#6 ·
Since you already have a roller cam, you'll want to stick with it. Putting in a new cam in an engine already running a roller will not cost you $1500. That's a pretty high estimate even when coming from an older block that is not ready for a roller. Your existing springs are likely fine and as long as you keep the lift within their limits. If your heads came assembled with springs, the manufacturer should be able to tell you how much lift they can support. You're only going to need the change springs if you want to more lift than they can handle or rev the engine above their limits to control the valves. I am doubtful that's the direction you want to head for your daily driver. And the same for your rockers. Stock 1.5:1 rockers are fine for most use cases. Roller rockers are nice and will reduce valve stem wear but should not be considered a requirement. A 1.6:1 rocker will give you more lift but you'd need to make sure you stay within the limits of your springs and, less likely with 9.7:1 compression, don't cause valve to piston interference. My advice is stick with a came that works with your springs and keep the rockers you already have. Also, I think you can reuse your existing roller lifters which is something you definitely can't do with a flat tappet.

A roller cam can open and close the valves more aggressively which improves power over a flat tappet. Also, you can expect them to be more reliable with today's oils that lack the zinc and other things a flat tappet cam needs to stay healthy.

Are you sure the diameter of your rear tires being 22"? That's pretty small. From your pic, I'd say closer to 25"

I'm thinking about running those wheels on my 68 as well. What size wheels and tires do you have front and rear?
 
#9 ·
Since you already have a roller cam, you'll want to stick with it. Putting in a new cam in an engine already running a roller will not cost you $1500. That's a pretty high estimate even when coming from an older block that is not ready for a roller. Your existing springs are likely fine and as long as you keep the lift within their limits. If your heads came assembled with springs, the manufacturer should be able to tell you how much lift they can support. You're only going to need the change springs if you want to more lift than they can handle or rev the engine above their limits to control the valves. I am doubtful that's the direction you want to head for your daily driver. And the same for your rockers. Stock 1.5:1 rockers are fine for most use cases. Roller rockers are nice and will reduce valve stem wear but should not be considered a requirement. A 1.6:1 rocker will give you more lift but you'd need to make sure you stay within the limits of your springs and, less likely with 9.7:1 compression, don't cause valve to piston interference. My advice is stick with a came that works with your springs and keep the rockers you already have. Also, I think you can reuse your existing roller lifters which is something you definitely can't do with a flat tappet.

A roller cam can open and close the valves more aggressively which improves power over a flat tappet. Also, you can expect them to be more reliable with today's oils that lack the zinc and other things a flat tappet cam needs to stay healthy.

Are you sure the diameter of your rear tires being 22"? That's pretty small. From your pic, I'd say closer to 25"

I'm thinking about running those wheels on my 68 as well. What size wheels and tires do you have front and rear?
That is super helpful, I am trying to go fairly radical with the cam so I was thinking about going to the 1.6 rockers, as for the wheels they are US mags u111 17x9.5 in the front on a 245 tire and the rear is a 18x10.5 on a 275 tire, Im trying to build it as an aggressive pro touring car also as for the tire diameter I’m not sure at the moment I’m out of town, but overall the wheel combo is something I fell in love with about the car. Some of the older guys in the car community don’t seem to like them though, I guess because they weren’t in their high school parking lot like that
 
#7 ·
Already having a roller in it will definitely make it quite a bit cheaper. You will need to know the spring seat limits for a bigger camshaft before going too crazy. My $1500.00 estimate was for a retro roller kit. You dodged a bullet on that one. Nice looking car .
 
#8 ·
Based on the information available for the GM 12498772 engine, the fast burn heads that came on this engine have a max lift limit of .530" , something to consider when looking for a replacement roller cam.
Below are the cam specs for the cam that was originally installed in this engine.
265261

Below are a couple links detailing engine and head specs.
Engine
Heads
 
#10 ·
So I know what the lift of the cam means and determines but could you explain how much of a difference I’d be getting if I came close to the lift limit of .530”? I guess what I’m trying to get at is .530” considered a large amount of lift or is that “girly” as my dad would say, if I’m doing a cam swap I want to do it right and not have to go back for more power later, on this motor I plan to keep it N/A and push it at most 650 flywheel HP and in the neighborhood of 6500 rpm
 
#12 ·
Sounds like you have a decent combo now. If you're going a little bit more cam, definitely think about the springs. You don't have much more to play with there. The cam I went with is not much bigger than yours. I'm not really concerned about sound. You really need to sit down and figure what you realistically want out of the car. Call Chris Straub , or Comp Cams and talk to someone who does cams every day. They will help you the most.
 
#13 ·
Well, I think to hit 650 and rev to 6500 your going to need more than a cam. Your heads have 210cc intake runners which helps but the valves are on the small side for your goal. Keep in mind that cam shaft lift is measured at the valve so regardless of the rocker arm ratio you can’t open the valve more than .530”. If you want to run right to the limit, you better actually check to make sure you can go that high without getting into coil bind on the valve springs. Advertised cam is usually stated with 1.5 rockers. If you want to know the lift with 1.6s, divide the advertised lift by 1.5 then multiple the result by 1.6. And, there more to it than lift. Duration matters as well and yours is on the tame side I believe but that’s to make it very street able and have enough vacuum to support power brakes. You could increase it by 10 degrees or so but then those power brakes might not work so good anymore.

I was going to run a 235 in front with an 8” wheel. Are you rubbing anywhere in the front with that setup. If you get a chance to share the complete tire sizes that would be great.
 
#14 ·
Another very large thing I never thought of was how it would affect my brakes... definitely going to need to give comp a call to find a happy medium, I truly do appreciate everyone that has responded. You guys have taught me a lot In just a few hours. As for scrubbing the wheels I’m on coil overs and the car is fairly low considering it is on the stock frame and all. I do have an issue scrubbing while taking tight turns in parking lots but driving down the road I have no issues. If you want to run that 275 or larger in the rear you’ll want pretty stiff rear suspension or large bumps at speed will cause the tires to rub. Also I can get you the actual specs of the wheels and tires later this week
 
#17 ·
You might want to Google on some create 383s and see what kind of power they are making with certain cam/head/intake combinations. Like I said before, I don't think you'll see 650 with just a cam change. A 500hp 383 is a pretty stout engine.
 
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