[Johnny406]

My oldest son and I just started building a 428 Pontiac I recently picked up for the 1980 Formula Firebird to replace the 350 Pontiac currently in it.

The purpose is a true street/strip build for street driving and racing the High School Drags series next year.

With that said and trying to the best of my abilities to only use stuff I already own as much as possible, I dug up this old Schneider HFT cam that's been sitting around for years. Attached is the cam card, how well do you gentlemen think it will work in a 428 with a set of long valve milled .060 6X-8 heads that should be about 9.0:1 compression? The car has 3.42 gears and a 2800 Redneck converter from back in the day. Exhaust is a set of old Hedman 3 tube headers that will be uncapped when racing.

I'd spring for a set of Rhoads V-Max lifters too if that would tame it on the streets.

[25stevem]

Being it’s a single pattern cam and your compression will only be 9 to 1, if your still running the stock 1.66” exh valves I would opt for 4 tube headers if it’s in the budget.

Other then that the Cam will work for you, and yes I would use the Rhoad’s lifters to build bottom end and improve launch.

Also note that the stock 1.586” spring installed height of those 6X heads will need to be modified to work with that Cams .518” lift.

Also do not cut corners and run stock valves as they loose there heads all too often!

[Johnny406]

Originally Posted by 25stevem

Being it’s a single pattern cam and your compression will only be 9 to 1, if your still running the stock 1.66” exh valves I would opt for 4 tube headers if it’s in the budget.

Other then that the Cam will work for you, and yes I would use the Rhoad’s lifters to build bottom end and improve launch.

Also note that the stock 1.586” spring installed height of those 6X heads will need to be modified to work with that Cams .518” lift.

Also do not cut corners and run stock valves as they loose there heads all too often!

Thank you, I should've mentioned that they have long 1 piece RA IV valves in them.

[b-man]

Summit 2802 or equivalent.

[25stevem]

A Tulip back RA4 intake valve chokes off the flow in a D port head, especially a low comp D port head with there lesser short turn height!

Please replace them if the wallet can handle it.

If your talking about just a RA4 length valve then disregard what I said here.

[HWYSTR455]

It's hard to beat the 2802 cam in that type of setup, but it looks to be on backorder.

Another good choice would be the crower 60919, but it's like $60 more than the summit.

I've never been happy with single pattern cams in a Pontiac, and you should use a dual pattern. The one you have 'will work', but think even a smaller, dual pattern cam would crush it in the performance dept.

There's really no good way to make a single pattern cam work well with pontiac iron heads, getting the intake to exhaust ratio needed to make it effective would take porting and a low restriction exhaust.

Using the cam you have would probably not be a favorable street experience either.

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[Skip Fix]

Throwing 1.77 exhausts and just some port clean up in some 6X will get the E/I OK for a single pattern., look at Jim Hand's old numbers on his he published even. A lot of aftermarket RAIV length are not as "tuliped'" as factory valves. Heck you have it use it, maybe play with ratio on rockers. heck and old Cam dynamics 228/228 on my stock 78 400 picked it up enough to start having fuel delivery problems at the top of second!

Heck my RAIV 400 picked up with a reverse pattern cam!

[Jay S]

I don’t know much about their cams, but being a HFT cam, it has a lot of lift for the .050” durations.

I have my doubts a set of Vmax’s would add much performance off the line with that 2800 stall and that cam. The 112 LSA is fairly wide using a single pattern cam, it should have pretty good street manors as it is with stock type lifters. For a 9:1 428 operating in higher elevations I would give it more advance than the cam card says. Probably 106-108, I think it would be noticeably quicker.

[b-man]

Put the right cam in it.

It might be the one you already have and it might not.

Being the heart of the engine it’s worth spending a little extra to make it the best it can be.

[Tom Vaught]

I would never personally run a factory RA-IV intake valve in anything.

Not after I saw the 1 piece RA-IV INTAKE Valve magically turn into a 2 piece valve after the head came off the valve in Wisconsin at Broadway Bob's track there.

Jim Brady had just performed a tire cleaning prior to approaching the starting line.
He was idling towards the line and the head came off the valve and the engine stopped, locked up.
He took it home and the engine was fine with neither the piston or the head hurt.

If the valve is not a one piece valve I will never use it.

JUST SAYING

Tom V.

[Jay S]

A RA 4 valve is getting really long on a 6X head. If you have never done that you might want to check the rocker arm geometry, it is going to set the tip pretty far to the edge of the stem.

I assume your building the car for your son for CO tracks and driving? Last I remember you are in CO???

If the car is going to be raced and street driven in the CO area, which often has DA in the 6000+ range (I know the DA can be much worse that that, over 8000 IRC). With those things in mind that particular single pattern cam likely won’t be to far off the mark of what the car wants, and will be very livable on the street. The combination of the compression and higher altitude was the main reason why I suggested in the other post that the Schneider cam should be advanced from were the cam card said.

Most of the time when we go west, from eastern Nebraska toward tracks at higher elevations toward CO we just change the tune on the carb, and leave the rest of the engine the same. But if the engine was going to spend it’s whole life up at the higher elevations, and we were trying to get the most out of it, we have found that some of the things we do that maximize power at lower elevations are not helping much in terms of power at the higher elevations. At those higher DA numbers, your NA engine can’t make as much power, your car will be quicker backing off from the bigger duration on the exhaust, and changing things like bigger rockers ratios on the intake side only. You’ll likely find you can even get away with a fairly poor E/I split on heads, and make the same power. When we go west to higher elevations, and are having trouble making an index, on solid cams we tighten the intake side lash, and loosen the exhaust lash, and always pick up E/T. When we bring the car back to our normal track we have to change the lash back, or we go slower. The engine wants something different on the cam as the DA of the air changes several 1000 feet.

The 4 tube header are probably always better, but my hunch is the 3 tubes probably won’t hurt it much at a high altitude track either. If you have them already, I’d run them.

[Johnny406]

I had these heads initially done by Lanier's Speed Shop (Race port) back around 1997 with Bosnia deployment money. I bought the valves, springs (since replaced), locks and retainers from RRE way back then. I was able to use stock length pushrods. For whatever reason, the longer valves compensated for the heads being milled .060. I ran them on the old 406 for about three years until I built the current 455. At that time I went with my Merrick ported 6X-4 heads (now on the old 406 in the street car). Jack Ferris, my friend and all around great guy redid the heads and more/better ported them. They have since been waiting for this day to come out of hibernation.

[i82much]

Originally Posted by Johnny406

I had these heads initially done by Lanier's Speed Shop (Race port) back around 1997 with Bosnia deployment money. I bought the valves, springs (since replaced), locks and retainers from RRE way back then. I was able to use stock length pushrods. For whatever reason, the longer valves compensated for the heads being milled .060. I ran them on the old 406 for about three years until I built the current 455. At that time I went with my Merrick ported 6X-4 heads (now on the old 406 in the street car). Jack Ferris, my friend and all around great guy redid the heads and more/better ported them. They have since been waiting for this day to come out of hibernation.

camp mcgovern here, june-oct 1998. don't have any car parts left from it though!

[Johnny406]

Originally Posted by i82much

camp mcgovern here, june-oct 1998. don't have any car parts left from it though!

LA Lisa on the Serbian side of the ZOS near Vlasenica Dec-Nov 1996.

[Jay S]

Sounds like a good set of high flowing iron heads. They would work well with bigger rocker ratios than 1.5s on that cam.

I am curious what what you had for rocker arms on that with the nearly .25” longer valves. Sometimes it is surprising how much you can alter the factory valve geometry and still make things line up.

[Johnny406]

Originally Posted by Jay S

Sounds like a good set of high flowing iron heads. They would work well with bigger rocker ratios than 1.5s on that cam.

I am curious what what you had for rocker arms on that with the nearly .25” longer valves. Sometimes it is surprising how much you can alter the factory valve geometry and still make things line up.

Back then (still have them) I had Harland-Sharp 1.5's on it. Years ago I bought a Spotts eye pushrod hole enlarger guide for that very reason/idea.

[25stevem]

The actual way higher then 1.5 ratio of the Sharps along with the mill of the heads is why a stock length push rod worked out for you, and as Jay noted so will that Cam up in the Clouds like you are.

Put the money you might have been thinking about using for another Cam into something else on the motor, like maybe a crank scraper.

[Jay S]

Here an old rocker arm tech video interviewing Ralph Johnson at crane cams (he was well know for his engineering work, and worked with Smokey Yunick.

https://m.youtube.com/watch?v=RjaosX63DkM

It shows what happens when you mess with the rocker geometry via pushrod length. The longer valves have the same effect if you keep the pushrods the same length. My guess is those 1.5 HS rocker arms were running 1.6 to 1.65 the way those head were set up with the stock length pushrods. If you made that long valve HS combo work before, this 428 build with that Schneider cam is probably a good place for those parts yet.

[grivera]

Originally Posted by 25stevem

The actual way higher then 1.5 ratio of the Sharps…

Can you elaborate?

[Steve C.]

Not 1.5 ratio here, but will be of interest....

Curiosity led us to bench-test 20 different 38-inch stud-mount rocker arms on a small-block Chevy.
All of them were advertised as having a 1.6:1 ratio—and exactly one of them multiplied the lobe lift of the cam to the valve accordingly.

Rocker-Arm Comparo
What’s in a Number? More Than You Think

https://www.motortrend.com/how-to/hr...r-arm-comparo/


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