Cam Recomendation?

[49fastback]

I'm looking for some input for the cam on my engine build. The background of the engine will be a 65 truck block bored .070. Ross pistons with 1/16" ring package, eagle big block rods. The final compression ratio will be at 10: 1. Heads will be Edelbrock Performer RPM. I plan to fab a sheet metal single carb intake for it just to have something unique. I've built them for small blocks so it should not be that big a challenge. I have decided to go with a 4 speed and probably 4:10 to 4:56 gears. Getting back to the cam I'd like to use a mechanical grind to keep things simple. I'm no stranger to setting valves so I don't mind doing it. The RPM range of the engine I'm estimating at 3000 to 6700. Any recommends on a knarly street cam, duratiion, lift and brand would be appreciated. I haven't talked to any of the cam conpanys thinking you guys have been down this road before and can supply the needed help. Thanks in advance
JR

 

[BSL409]

I have a nice used Isky Z55 cam& lifters for a good price but it might be to small? 590lift

 

[49fastback]

What's the LSA and duration etc. on that? I did not check the Isky site for the numbers. Question; Why would you think its on the small side?

 

[jim_ss409]

Just to give you an idea of the rpm ranges. I had an engine similar to what you're building except that it had less compression. (9.5 to 1)
It had a solid roller cam with 250 @ .050 intake and 258 exhaust 110 LSA and .714 gross lift.
That engine peaked at about 6,000 rpm but continued to pull well beyond that.
That engine ran a best time of 10.36 in my 55 Chevy. (3400 lbs)

The engine in the car right now has a bigger cam, 265/270 @ .050 110 lsa, .737 gross lift.
It also has more compression, I'm guessing about 12 to 1
Anyway, that engine peaks at about 6,600 rpm and pulls through to 7,000 rpm.
It's run a best time of 10.10 in the same car.

The stroked 348 (437ci) I used to have in that car had the same cam except that it had a 108 degree LSA.
It peaked at 6,900 rpm.

On the street I wouldn't use anything much bigger than the 250/258 @.050 cam because the bigger cams are just a bit too much. (you won't need a ton of rpm with those cubic inches)
The lift on these cams is also a bit high for long term durability but I'd still shoot for something in the .600 range if your springs will allow it.
A solid roller cam is nice but Aubrey has some really good solid flat tappet cams that have lots of lift.
The one Jason, (Yellow Wagon) used in this engine worked really well. It's a totally different engine, stock stroke and ported truck heads but it made 473 hp.
http://www.348-409.com/forum/threads/yellow-wagons-409.18072/
It had one of Aubrey's flat tappet cams, 242/246 @.050 .595/.608 gross lift.
With your larger engine, you could step up a size bigger to get you in the 250 @ .050 range and get similar manners to what Jason gets.

I hope this helps give you some idea of the rpm range various cams will give you.
I think something like 250 @ .050 would fit your "knarly street cam" description. If it was ground with a 110 LSA it would be pretty knarly, and if it was ground on a 108 LSA it would be really knarly.
You'd certainly gain a little more top end power if you pushed the duration out to 260 or so but the loss of bottom end might start to outweigh the gains at the top end.

Hopefully others will chime in with their ideas.

 

[BSL409]

What's the LSA and duration etc. on that? I did not check the Isky site for the numbers. Question; Why would you think its on the small side?

338/590 lift duration 254 @50 110 LC

 

[4speedman]

I have a Isky 233 in my driver car .560 lift, 0.250 duration at .050, lobe separation 110.This is a 63 425 hp with ross 10 to 1 pistons and it sounds lopey and is enough for street use.The power range is 3000/7000.

 

[MRHP]

I have one of Aubreys in my 474. I think it is .628 .632 solid flat tappet. Nasty idle, and all the power you want with 12.0 compression. I can idle it down to 800-900 if need be. Next time I may step up a bit more.

 

[49fastback]

I should have mentioned in my earlier post that I am not using the 6.135 rod to increase the stroke. The compression height on the pin has been adjusted to allow the big block rod, so the engine has its original stroke. In the end I will end up with a .070 over 409 and by my calculations very close to 422 cubic inches, (not that big). It would seem that a 110 lobe separation is pretty common choice. It will be a street driven car so I'll go over the lift and duration numbers a bit along with the recommendations to what makes sense. To the guys that are running .700 + lift cams; Was any additional clearance cut into the piston? Although I didn't ask I'm guessing that most here are using the 2 x 4 for induction? Lots of questions I know but this is an engine that I have no experience with. Thanks for all the replies.

 

[CDNpontiac409guy]

Ah yes, stock stroke... RPM is easy this way. Huge cam is not required.
The factory manifolds for these engines, appear to be by far, the very worst manifolds ever made for engines.
ANYTHING else, should be better. If you like the 2X4, then the Edelbrock will help. If a good single 4 bbl is what you're after, then you could make one.... or wait for about another 6 weeks.
Here's your cam:

MS-250618D

10.5 - 11.5:1

6600

R

280/284

250/254

.618/.630

on a 108 lobe sep.
You'll need about .150" deep valve pockets.... no more than that.
Use 1.7 rockers, after lash, net lift at valve is about .580" / .592".
With stock diameter exhaust valves, there should be no need for cutting a little "brow" for clearance.
When boring the block, be sure to NOT permit your machine shop to re-machine the "counter-bore" at the top of the cylinder. .070" will give you a completely finished cylinder, with no "step" at the beginning of the combustion chamber.

 

[49fastback]

A question on the lash. Why 1.7 vs. 1.75? Concerning the intake I'm not a huge fan of 2 x 4 and will go with a single carb setup and consider those options later. I only entertain the idea of doing a sheet metal version as it will be a unique piece. As for the machining, the boring has been completed and we won't be putting that nasty counter bore back in as that was the reason we decided to go +.070 the first place but thanks for the heads up on that. I'm also going to be using studs vs. bolts on the mains so I can incorporate a windage screen. I know this is subjective but what type of HP numbers are realistic / possible with this setup.

 

[CDNpontiac409guy]

It's the over .600" net lift, that starts taxing the valve train pretty hard, and I know clearance to the combustion chamber wall is right there. Not to mention.... WAY WAY WAY better choice for rocker arms, using 7/16" studs.
Put an 800 Holley on there, with good headers.... HHMM.... I can see 500-525

 

[jim_ss409]

I don't know where I got the idea that you had a stroker motor.
Anyway, the cam Aubrey mentioned sounds really good.

 

[49fastback]

"It's the over .600" net lift, that starts taxing the valve train pretty hard, and I know clearance to the combustion chamber wall is right there. Not to mention.... WAY WAY WAY better choice for rocker arms, using 7/16" studs.
Put an 800 Holley on there, with good headers.... HHMM.... I can see 500-525"
Ok fair enough. the cam you spec'd above....is a mechanical flat tappet (non roller) right? One more question; Do the Edelbrock heads have enough spring pressure for that grind or will I have to change them up? My past experience has taught me that a little too much spring is far better than just enough.

 

[Bernie]

I used a comp cam with (installed specs) Intake 242 exhaust 246 @.050. Lobe separation is 110. The card says gross lift of intake .595 and .605 exhaust duration @ .020 tappet
lift 272 intake and 276 exhaust. valve timing is open at 11 degrees Btdc and closes at 51 degrees Abdc. for intake. Exhaust opens 53 degrees Bbdc and closes 13 degrees Atdc. valve
lash is .018 on both.
My builder says my engine has about 540 ft. lbs of torgue. and 520 hp on his computer program. I wanted a torgue engine because my car weights 3600 with me in it. I hope
I got this right and helps a little. (I shift it @ 5000 rpm.) The block is a 65 truck 348 bored and stroke to 440.

 

[CDNpontiac409guy]

That cam sounds familiar, Bernie... though I KNOW it makes good power to 5600 +

On the Edelbrock heads, it's more about the springs not handling the lift. You need about 135-145 seat / 290 - 310 open.

 

[jim_ss409]

I'd think that Aubrey's 242/246 cam would also work great.
The bigger 250/254 cam would certainly make more power from the mid range on up but that "smaller" cam is what Yellow Wagon used in his engine and it made 473 hp with truck heads, so if you wanted to be a little more conservative, the smaller cam could also work.

 

[boxerdog]

I happen to like that cam also...stock stroke 409, I try to shift at 6900 give or take.

 

[CDNpontiac409guy]

That cam in my stock bore/stroke 409 with small port heads and Speed Port 6000 intake, shift at about 6700 ( 466 HP ).
It's a good cam... even pretty good on fuel

 

[boxerdog]

C'mon Aubrey, that's laying it on pretty thick!! Economaster...not really.

It's a great cam but mine sucks fuel like it was free!! Stock carbs and intake....slightly heavy foot sometimes.

 

[jim_ss409]

slightly heavy foot sometimes.

Yep, that'll burn ya some fuel.