[Bandit400]

Hello, about 10 years ago I built my engine for my 70 Bird, and hopefully did it right. However, I am now second guessing my cam selection. Am I leaving power on the table with the cam I chose? I chose it based on advice I had received, but it seems to run out of breath around 5k RPM or so. Not hitting a wall, just doesn't pull as hard as in the midrange. Reading about the Old Faithful and Road Pavers make me wonder if I would benefit from a swap. I can also call SD to get their advice too I guess. Combo is as follows:

70 Firebird
3.42 gear
TH400
3000 Stall Edge Racing Converter

Engine 462 Stroker
1974 400 Block
Butler Roatating Assembly
Eagle Crank/Rods
SRP Pistons
KRE 72CCs, out of the box

Holley Sniper EFI

Cam specs-Hydraulic Roller
230/242
.361 Lobe lift, .613 total lift with 1.7 Rockers
112 LSA

Can you all take a look and let me know if I made a mistake on this cam power wise? I'm not looking to spend more money, but would like to get the power I paid for with those heads, as well as take advantage of the technology afforded by the HR cams. Thank you!

[ponyakr]

I think it just makes sense that an increase in duration will move your power band up in the rpm range. That seems to be what you want.

I think Cliff has mentioned that 230° @ .050 is a minimum, for 455 & larger engines. So, with that in mind, you have what some might consider a smaller cam, for your engine size.

You'd probably notice some difference from no more than a 6° @ .050 increase. But there are probably some here who would recommend at least 240° @ .050.

There are sometimes not a lot of HFT cam comparison testing. But, I assume there has been lots of roller cam testing. So, some of these guys should be able to give some links to some test results that will provide the info you need.

[TCSGTO]

Yes, you will make a few more horsepower and be able to wind up higher with 5-7 more degrees of intake duration but you have to decide if it’s really worth it.

With the cam, gaskets, oil you’ll have $500 or more in a cam change not to mention your time. You might gain 20-25 Hp. Is it worth the investment? Only you can make that call.

Your current cam is not bad. If you were running something smaller than that a cam change would be a no brainer.

[shaker455]

Originally Posted by Bandit400

Hello, about 10 years ago I built my engine for my 70 Bird, and hopefully did it right. However, I am now second guessing my cam selection. Am I leaving power on the table with the cam I chose? I chose it based on advice I had received, but it seems to run out of breath around 5k RPM or so. Not hitting a wall, just doesn't pull as hard as in the midrange. Reading about the Old Faithful and Road Pavers make me wonder if I would benefit from a swap. I can also call SD to get their advice too I guess. Combo is as follows:

70 Firebird
3.42 gear
TH400
3000 Stall Edge Racing Converter

Engine 462 Stroker
1974 400 Block
Butler Roatating Assembly
Eagle Crank/Rods
SRP Pistons
KRE 72CCs, out of the box

Holley Sniper EFI

Cam specs-Hydraulic Roller
230/242
.361 Lobe lift, .613 total lift with 1.7 Rockers
112 LSA

Can you all take a look and let me know if I made a mistake on this cam power wise? I'm not looking to spend more money, but would like to get the power I paid for with those heads, as well as take advantage of the technology afforded by the HR cams. Thank you!

What brand cam & do you have part number?

[pastry_chef]

What intake manifold?

I'd have the heads ported, 310 to 320 range, the intake could probably benefit from work. Then pickup a cam better suited.

https://headsandmanifolds.wordpress....-head-porting/

[TCSGTO]

Originally Posted by pastry_chef

What intake manifold?

I'd have the heads ported, 310 to 320 range, the intake could probably benefit from work. Then pickup a cam better suited.

https://headsandmanifolds.wordpress....-head-porting/

In real world dollars those changes would cost $2500+ all in,that's at the low end. The OP said he doesn't want to spend alot of money.

[Bandit400]

Sorry, forgot to mention the intake. It is a Holley Street Dominator single plane.

[carcrazy]

Not a cam expert by any means but I don't think you should be running out of breath at 5000 with that cam....maybe some other issues.

[Skip Fix]

Checking valve springs to be sure they are up to the job.
Higher ratio rockers might buy a little more power rpm but are the heads machined for them. On my 455 we got a 5-8hp bump each ratio bump I did 1.5, 1.65, 1.8.

[grivera]

Was cam degreed-in, if so where? Is your fuel system up to task? What is 1/4 mile performance or is low power band assessment seat of pants?

[TCSGTO]

Check fuel delivery and valve springs first like others here mentioned. For a single plane the SD intake isn’t known to make real good top end power without porting, that’s why they made the Tomahawk which is based off Dave Bishops’ ported Street Dominator.

You could pick up a Torker II and put a 1” spacer under it if you want to wind up it up to 55-5700.

[pastry_chef]

Originally Posted by TCSGTO

The OP said he doesn't want to spend alot of money.

Sure..
OP wants / engine wants.

[ta man]

Is there a baseline for performance? Dyno, or dragstrip or you want to beat your buddys Hellcat?
Everyone in this street section is leaving power on the table somehow..but that is a choice for street manners or cost.
That is why you need a baseline for what you have to determine if the current setup has issues and to figure out what needs to be done and at what cost.

[firechicken]

What are you running for an exhaust system?

[Skip Fix]

Everyone in this street section is leaving power on the table somehow..but that is a choice for street manners or cost.

For sure-look at what track times the NHRA Stockers run! But I guarantee they are not streetable even with adding mufflers.

[PAUL K]

That cam will definitely pull past 5k....something else is holding it back. A lot of good suggestions above start eliminating the suggestions one at a time.

[tom s]

Make sure you have 150-160 on the seats if you want some RPMs.Tom

[Steve C.]

Comp XFI lobes 3016B and 3038B
Custom ground with a 112 lobe separation

Good chance if Comp was involved with making the valve spring decision it could be the infamous 995 spring ! If they are and installed at 1.700" they do not have enough spring pressure. But this is pure speculation on my part !

Similar situation if they were Crower 68405 springs at 1.700" with 110 lbs.


.

[amcmike]

Originally Posted by carcrazy

Not a cam expert by any means but I don't think you should be running out of breath at 5000 with that cam....maybe some other issues.

First thing that sprang to my mind. If everything is setup and matched properly, the cam should be good for a bit more rom than that.

[tom s]

As said,start with the springs,if they are not up to the task everything you change might not mean a thing.Tom