SBC 420" and 8000 RPM

[BrazilianZ28Camaro]

Hello Gents

A good Friend just asked me what would be mandatory on a 420ci SBC to live at 8000 rpm on the strip.

You might know everything is danm expesive overhere in Brazil, so we have to get just the right parts for the job, not the best of the best,or overkill parts due costs.

I told he we had to have all forged internals,(3.875" crank) good rods, valve springs, steel main caps, good valvetrain, you know, all the basics.
I also believe a healty MFT cam will work, not as good as a MR cam but...

But now I'm wondering if the stock style wet sump , a good windage tray and bigger oil pan will work well or a dry sump is a must.

Another point : Are shaft rockers absolutelly necessary or a good set of rockers will take it (lets assume 350-370lbs open valve springs and 7mm light SS valves)?

So, I'd like to hear your real World experiences on this subject.What is really needed to this lil big block live.

Thanks

[Rowdy Yates]

This was told to me and used on the Lsx design no huge difference .. With 8500+ Rpm it's OK for short periods of time such as drag use. Dry sump is better but is great for extended high Rpm use aka road course. Good Mellings oil pump with a highly recommended vacuum pump - Canton oil accumulator for peace of mind . On the rocker arms if cost or what ever is a issue with shaft mounted rockers. I used Comp Cams stud mounted 1.8 rockers that used 8mm studs had the heads tapped for a larger stud and fitted the rocker arms for a new trunion with a larger stud hole. Had to weld up guide plates and used a rocker arm stud gridle. Person who showed me was running 8800 with a wet sump and 800 lift & stud mounted rockers arms with girdle.

Something like the Idea of you're thinking about.

[wjnielsen]

What is the piston weight? Lighter pistons should help the longevity of the crank and rods. I would expect a lot of moderate priced options would handle 8000 at the drag strip.

Also, a gentler cam lobe can make the difference between getting runs on a set of springs vs. seasons... and the difference between needing high $$$ shaft rockers, or stud mounted ones. What rocker ratio and spring pressures? Steel parts or titanium?

Edit: re-read your post. SS valves... But, the real question might be: "what is my budget, and how exotic of valvetrain parts can I (or am I willing) to afford?" Then, let that dictate how much the cam choice gets 'set on kill'.

The stuff that will live with a slower-acting cam lobe at the target RPM will certainly be less expensive than stuff that makes slightly more power...

[steve316]

To make your valve springs last is weight. ti. intake valves if in budget, also retainers, locks and the weight of the spring all come into play. Valves & retainers alone double the life of the spring.

[BrazilianZ28Camaro]

This was told to me and used on the Lsx design no huge difference .. With 8500+ Rpm it's OK for short periods of time such as drag use. Dry sump is better but is great for extended high Rpm use aka road course. Good Mellings oil pump with a highly recommended vacuum pump - Canton oil accumulator for peace of mind . On the rocker arms if cost or what ever is a issue with shaft mounted rockers. I used Comp Cams stud mounted 1.8 rockers that used 8mm studs had the heads tapped for a larger stud and fitted the rocker arms for a new trunion with a larger stud hole. Had to weld up guide plates and used a rocker arm stud gridle. Person who showed me was running 8800 with a wet sump and 800 lift & stud mounted rockers arms with girdle.

Something like the Idea of you're thinking about.

Wow 8800 with stud rockers and 1.8 RR!

We're planning to use 1.6 rockers to help valvetrain stability.
Vaccum pump and acumulator are good ideas for sure!

Thank you for the tips!

[BrazilianZ28Camaro]

What is the piston weight? Lighter pistons should help the longevity of the crank and rods. I would expect a lot of moderate priced options would handle 8000 at the drag strip.

Also, a gentler cam lobe can make the difference between getting runs on a set of springs vs. seasons... and the difference between needing high $$$ shaft rockers, or stud mounted ones. What rocker ratio and spring pressures? Steel parts or titanium?

Edit: re-read your post. SS valves... But, the real question might be: "what is my budget, and how exotic of valvetrain parts can I (or am I willing) to afford?" Then, let that dictate how much the cam choice gets 'set on kill'.

The stuff that will live with a slower-acting cam lobe at the target RPM will certainly be less expensive than stuff that makes slightly more power...

Pistons can be about 420g .

Good point about the valvetrain vs cam lobe intensity. I believe we can get Ti retainers, valves, I'm not sure .

Thanks for reply

[BrazilianZ28Camaro]

Valves & retainers alone double the life of the spring.

Wow! Thats a huge difference! Might be a better way in the long run!

Thank you for reply Steve!

[Rowdy Yates]

2.200 and under size valves just use hollow stems and save some cash.

[amc fan]

What size mains ? 350 mains have less crank pin overlap and will tend to flex more. Center counterweights will help let the crank live longer! Put the longest rod you can to keep the piston light. I built a 9.325' Iron Eagle with a 4" stroke,6.3 rods & 400 mains and it has a 1750 bob weight with flat tops and 1/16 rings and standard pins.

[MELWAY]

I turn my bracket engines 8800 with a mildon kicked out pan and a melling Std vol pump
Shaft rockers are highly recommended and like others have said use a cam with gental lobes to not beat on parts

A molnar crank and rods will get the job done

[BrazilianZ28Camaro]

2.200 and under size valves just use hollow stems and save some cash.

Cool ! Have you a brand to suggest me?

[BrazilianZ28Camaro]

What size mains ? 350 mains have less crank pin overlap and will tend to flex more. Center counterweights will help let the crank live longer! Put the longest rod you can to keep the piston light.

Mains will be 2.65" and internal balance.

I built a 9.325' Iron Eagle with a 4" stroke,6.3 rods & 400 mains and it has a 1750 bob weight with flat tops and 1/16 rings and standard pins.

Cool build! Can you share more info about it?

[BrazilianZ28Camaro]

I turn my bracket engines 8800 with a mildon kicked out pan and a melling Std vol pump
Shaft rockers are highly recommended and like others have said use a cam with gental lobes to not beat on parts

A molnar crank and rods will get the job done

thanks for the tips!

[Rowdy Yates]

Ferrea valves. Seen them tested against Manley and stock GM hollow stem valves on a Ls3 head 2.165 valve size. Degrees flows 6-8 more CFM with the same valve job for all tested. Sorry just got off.

[steve316]

The weight difference between ti. valves and hollow stem is a lot. Try to save a much weight as possible with in your budget. My valves in my sb2 weight 74 grams . same size stainless is 116. So you can see how this helps with spring life.