["QUICK-SILVER"]

I'd find out if the headers are going to work before I picked a cam.

The 704 would like headers and the 703 wouldn't care much either way.

Either cam is going to wake up fast in a 455. Got to decide if you want all hell to break loose sitting still or after you've rolled ten feet.

Clay

[1968GTO421]

Originally Posted by 1967Tempest

The second you hit the powerband the car instantly flys!!!

She kinda surges below 1500-1600 RPM. Once you broach past that hang on.

I can imagine, that the auto trans will make it easier to drive in traffic. All I can say about the 704 is this, This is the first engine combo that I have ever had of my own, that will boil off the tires from 55 MPH. Going 55 in 5th gear and downshifting into 3rd to do a pull and the tires spin. Truly fun to drive!!!!

I'm Sure part of my issue there is teenie tiny tires in the back. I have a driverside 1/4 panel issue that will be resolved when she gets restored..

Actually I think you've talked me into a 704 for my 428. Thanks.

[1967Tempest]

YES!!!!!!

Quick video of the idle. Ill take a new video soon..

https://youtu.be/aMi5XAQUYME

[455rebel]

Originally Posted by "QUICK-SILVER"

I'd find out if the headers are going to work before I picked a cam.

The 704 would like headers and the 703 wouldn't care much either way.

Either cam is going to wake up fast in a 455. Got to decide if you want all hell to break loose sitting still or after you've rolled ten feet.

Clay

You've got a good point, the 704 might actually be easier to launch, (hook),with street tires. By not pulling hard until 2k.
Ps-if I can't make the headers fit, what about the ram manifolds, the 704 would work with them?
My plan is, as the engine comes out for the build, to go ahead and fit the headers.

["QUICK-SILVER"]

Originally Posted by 455rebel

You've got a good point, the 704 might actually be easier to launch, (hook),with street tires. By not pulling hard until 2k.
Ps-if I can't make the headers fit, what about the ram manifolds, the 704 would work with them?
My plan is, as the engine comes out for the build, to go ahead and fit the headers.

The 704 has 60° overlap. Factory 068 cam has 63° overlap. That's getting in the range where you need better exhaust manifolds. The 71 455 HO engine was rated 8.4:1 CR. Came with 068 cam in stick shift and automatic cars.
With factory converters they would smoke the back tires if you kicked it from a stand still.

The 704's less overlap and less advertised duration will wake up faster than a 068 cammed 455.

All I'm seeing is tire smoke
Clay

And yes to the ram air manifolds if they'll fit

[1967Tempest]

Im running RARE Ram Air Manifolds. Love them. Ill never put headers in an A-body again! I had such fun cutting the old ones out with a sawzall!!!

[455rebel]

Do the ram manifolds exit in a similar spot as the logs?

[1968GTO421]

Originally Posted by 455rebel

Do the ram manifolds exit in a similar spot as the logs?

Not 100% sure but I believe that they do exit in a similar spot based on these photos of Pypes downpipes for both log and ram air manifolds.

https://pypesexhaust.com/c-946257-sh...downpipes.html

[PAUL K]

Originally Posted by steve25

You can replace the heavy 250 gram wrist pins in those Pistons with 194 gram pins from Butler

The big square balancing pad on the small end of each rod can be for the most part removed which will lighten things up even more and add life to the Rods!

Good advice but I think you got your numbers mixed up. 250 gram is the OLD TRW pins..... It's been 195 for many years and Butler sold a 150 gram pin that is no longer available.

I'd go with the 5700 rpm..ran tons of combinations like that with and without Nitrous and never a single issue. Also agree with the comments about meticulous rod prep.

[PAUL K]

Originally Posted by 455rebel

Do the ram manifolds exit in a similar spot as the logs?

No they don't

[b-man]

Originally Posted by 455rebel

Do the ram manifolds exit in a similar spot as the logs?

Depends on your definition of similar.

Not really close at all in my opinion. The RA manifolds exit much lower to the point where the bend after the flange doesn’t have any room for a straight section of piping, the bend must begin abruptly or you won’t have much ground clearance.

1967 RA manifolds with home built 2-1/2”’down pipes.



Log manifold with home built 2-1/2” down pipe.



PYPES 2-1/2” down pipes for log exhaust manifolds.

[68 461 Bird]

Originally Posted by 1967Tempest

YES!!!!!!

Quick video of the idle. Ill take a new video soon..

https://youtu.be/aMi5XAQUYME

Sounds great! What mufflers you running?

[455rebel]

Roughly, what's the power difference in the ram, vs, headers. The manifolds would go with my sleeper look better. Also Way less maintenance!
I'll try to post some pics of engine compartment, for advise on which might fit.

[1967Tempest]

Originally Posted by 68 461 Bird

Sounds great! What mufflers you running?

Some cheapo Thrush welded. I plan on getting the longest muffler I can safely fit when I redo the exhaust. I had to mangle the ELF out of them to fit the new 9" rear. I just keep telling myself itll be ugly till she gets restored..

[1967Tempest]

Originally Posted by 455rebel

Roughly, what's the power difference in the ram, vs, headers. The manifolds would go with my sleeper look better. Also Way less maintenance!
I'll try to post some pics of engine compartment, for advise on which might fit.

With the Ram Air header, youll gain some low end grunt but lose a bit on the top end. But the ease of install and the look, IMHO is in favor of the Ram Air header. One thing that I will do in the future is jet coat them.

Besides, if the car lives under 80 MPH for most of its life, RA all the way!!!

B-Man does bring up a good point about the abrupt turn. It isnt easy to get a socket in that area. I solved that by going to grade 8 Allen head bolts. Super easy to install with a ball head allen key.

[455rebel]

I'll do whatever it takes to get the headers or the RAmanifolds one on. So back to the 703 vs 704, with either ,from a 30mph roll, or less, a nail and all hell breaks loose? Would I be giving up more than 20hp with the 703? I learned long time back, a slightly small cam on street is way better than a slightly large one. Or maybe adv the 704 a tad?

[ponyakr]

"...Would I be giving up more than 20hp with the 703? I learned long time back, a slightly small cam on street is way better than a slightly large one..."


There's your choice. The bigger cam will make more horsepower. The smaller cams usually idle smoother, produce more vac, & have more low rpm torque.

In short, a smaller cam is usually more street friendly. But, LOTS of guys prefer a nasty idle and plenty of pull ABOVE 5000 rpm. So, it's your choice.

[i82much]

The 704 cam specs seem perfectly reasonable for a street 455 to me.

[JLMounce]

Originally Posted by i82much

The 704 cam specs seem perfectly reasonable for a street 455 to me.

Concur. Whatever cam you think you need in a 455, you can probably go bigger.

After about a week on my 462 I realized I under-cammed it and I've got a stick in there that's just a bit shy of the Old Faithful grind.

[many birds]

Not sure how pertinent this to your setup since you’re running a 455....I’m running the Voodoo 703 in 400 with #15 small chamber, small valve heads. I had the rocker studs changed for screw in, and new springs for the added lift. Everything else is stock. I also changed back to factory logs. It’s in 1969 firebird with stock converter, TH400, 3.55 rear and has no problems smoking the 27 inch tires. It gets about 12 to 14 inches of vacuum at idle in neutral and about 10 in drive. Requires premium fuel however. Drives fine, but could be a little smoother at idle.

Based on that, I would think the 455 would do fine with the larger cam.