RB Cam Performing Right?

[Road Grabber]

My current cam has 48 degrees overlap and runs about the same or a bit better than the previous cam with 54 degrees overlap.


Andy F. made 550 hp with that cam with manifolds on his 470. Pretty small cam. Probably 0.500” net lift. Probably 230 -232 degrees duration at 0.050” when considering the 0.028” lash.


View attachment 1968850View attachment 1968854View attachment 1968855
500 cu. In.
600 hp -ish
Manifolds
15” idle vacuum
Used a stock stall converter for years
3.23 gear
2 1/2” exhaust
15 years old
Drive it to work. Drove it to both Carlisle and Mopar Nats this year, with track time at both.

Probably not a 50,000 mile motor. With a couple changes, could be. But ask yourself this how: many miles do you really drive your car? You’ve had your car for 30 years. How many miles did you put on it? What does your next 30 years of driving look like?

All that said, based on your comments in this discussion, keep the cam, put headers on it, put it in the car, close the hood and forget about it. It won’t matter if I it makes 450 or 550 hp. You, nor anyone else will know.

If you want to stick with manifolds an explore a better cam, contact someone that has experience and does it for a living. Like PRH

Who is PRH?

The lack of much difference installing the more efficient heads and bigger cam was the reason for inquiring and higher expectations.

Time will tell after the new dyno runs without bent pushrods.

Thanks for replies.

 

[496 polara]

Who is PRH?

The lack of much difference installing the more efficient heads and bigger cam was the reason for inquiring and higher expectations.

Time will tell after the new dyno runs without bent pushrods.

Thanks for replies.

See post #24

 

[Road Grabber]

See post #24

thanks

 

[BSB67]

See post #24

This.

PRHeads - Dwayne Porter, Porter Racing Heads

 

[PRHeads]

Like I stated, I don't subscribe to the proportional relationship. Nor does the Desk-Top dyno, albeit a fairly crude tool. As an example, your analysis would be analogous to saying that if you took all the key components from a 273 that made 1.0 hp/cuin and put them on a 500 cuin engine it too would make 1.0 hp/cuin. This would include valve size and head flow.

Actually, I look at it as taking the top end off a 360 making 400hp, and putting it on a 273 and making 300hp.
(Taking the top end from the bigger engine making more power than is expected out of the smaller engine, and using it on the smaller engine)

I have DD2000.
I gave up on that years ago.

I built a pair of BBM’s, and dyno tested them.
Nearly twins except for the ci.
493 vs 446.
Both were 10:1, and got bowl ported rpm heads, sd/850, 2” headers, SFT cams with 1.5 rockers.
Same lobe family(254/254-110 for the 446, 250/254-112 for the 493).
I don’t recall the exact numbers, but the DD predicted the 446 to make noticeably more Hp than the 493.
DD doesn’t like combos with what it feels are undersized heads.
The real dyno results were quite different, with the 493 making about 45 more hp than the 446.

The actual hp/ci was pretty similar between the two.
446- 1.16
493- 1.14

At that point I figured any program that predicted the opposite of what was really going to happen was something I wasn’t going to spend any more time messing with.

 

[Road Grabber]

Actually, I look at it as taking the top end off a 360 making 400hp, and putting it on a 273 and making 300hp.
(Taking the top end from the bigger engine making more power than is expected out of the smaller engine, and using it on the smaller engine)

I have DD2000.
I gave up on that years ago.

I built a pair of bum’s, and dyno tested them.
Nearly twins except for the ci.
493 vs 446.
Both were 10:1, and got bowl ported rpm heads, sd/850, 2” headers, SFT cams with 1.5 rockers.
Same lobe family(254/254-110 for the 446, 250/254-112 for the 493).
I don’t recall the exact numbers, but the DD predicted the 446 to make noticeably more Hp than the 493.
DD doesn’t like combos with what it feels are undersized heads.
The real dyno results were quite different, with the 493 making about 45 more hp than the 446.

At the point I figured any program that predicted the opposite of what was really going to happen was something I wasn’t going to spend any more time messing with.

I guess you can't argue with cubic inches.

 

[PRHeads]

I don’t ever recall building an engine and after dyno testing it thinking to myself, “I should have made it smaller”.

 

[gtxrt]

what rpm did you shift at with your 484 cam ? when was peak HP and TQ coming in at with this last build.

 

[Road Grabber]

It was never on a dyno but I can tell you I could shift at 6000 if I wanted to. The engine could keep going. I never liked to going above 6500. I followed the older yellow Direct Connection book guidelines for engine performance designated for engines with a six pack giving racing times and HP. It was a perfect fit with even the jetting and outboard metering plate hole revisions. I'd look it up but some low life stole my yellow Direction Connection Book. I miss that book. It had proven tested engine results and gave you the components for back then. I'm not sure if Chrysler has a revised edition for today.

The rods have been fitted with resized six pack rods using ARP rod bolts and the balancing has been redone because I did have the block bored .040 with 10.5 to 1 notched forged pistons.
Stock replacement 6 pack pistons and of course the new Trickflow 240 heads are closed chambered bringing that up a bit. The block decked raising a bit too.

.040 cometic gasket.

 

[496 polara]

I think some headers would really surprise you in a good way. If you do a Dyno test with them do ask what size headers they are going to run. Typical Dyno headers may be 2" and while it will make more power they are too large for your combo IMO.Your peaks would be moved higher but the midrange numbers would likely be down.

1 3/4 or 1 7/8 would be ideal (heck both would be a GOOD test).

 

[Road Grabber]

I think some headers would really surprise you in a good way. If you do a Dyno test with them do ask what size headers they are going to run. Typical Dyno headers may be 2" and while it will make more power they are too large for your combo IMO.Your peaks would be moved higher but the midrange numbers would likely be down.

1 3/4 or 1 7/8 would be ideal (heck both would be a GOOD test).

Thanks
I will ask what size they are

 

[PRHeads]

I’m assuming the valve to piston clearance(depth and radial) was checked.
The reason I ask is the TF heads have big enough intake valves where the radial clearance might be tight with the 6bbl pistons.

 

[Road Grabber]

I was told that was checked with .200 clearance.

Thanks

 

[PRHeads]

My concern was more about the radial clearance than the depth(how close the valve is to the “side” of the pocket).
The TF intake valve is .110” bigger diameter than the stock intake valve, which is what the 6bbl piston notch was designed for.

 

[Road Grabber]

My concern was more about the radial clearance than the depth(how close the valve is to the “side” of the pocket).
The TF intake valve is .110” bigger diameter than the stock intake valve, which is what the 6bbl piston notch was designed for.

I will mention that for sure. I know he is removing the heads and I would think that visible damage or hits could be seen on the pistons.
I’m not reading favorable comments on Howard’s lifters at or above 5500. I am not on location and can’t remember which lifters I bought. Paperwork is elsewhere. I knew Johnson lifters were good but I don’t remember which lifters I bought.

Thanks for your help. I will give him a call.

 

[Road Grabber]

I found my order. Turns out I did purchase the Howard’s lifters. I’ve seen a few dynos now mention problems with them at above 5500.

Have you had any experience with them?

 

[PRHeads]

The “max effort” Mopar lifters from Howard’s were Gaterman at one point, but I don’t know if they were when you bought those.
I haven’t personally used those, but I had several customers who bought them and I don’t recall hearing any problems.

The street series 91767 are morels.
We have had a few of those act up when pushed above 5700rpm…….. so engines using those generally only get pulled to 5600.

My experience with Hyd lifter woes are that it typically happens like a light switch.
They’re good right up until they’re not…….. and then they’re really not good.

 

[Road Grabber]

The “max effort” Mopar lifters from Howard’s were Gaterman at one point, but I don’t know if they were when you bought those.
I haven’t personally used those, but I had several customers who bought them and I don’t recall hearing any problems.

The street series 91767 are morels.
We have had a few of those act up when pushed above 5700rpm…….. so engines using those generally only get pulled to 5600.

My experience with Hyd lifter woes are that it typically happens like a light switch.
They’re good right up until they’re not…….. and then they’re really not good.

So these are a different animal..

I’ll do a bit more research. I’m trying to prevent another issue. If it turns out that the dyno test shows a problem it means changing lifters which means disassembly of the intake. More time. More cost…..

Over four years now