490 SBC pumpgas 23* dyno results, need expert "power" advise

[67RS502]

Do those intake ports have any throat left in them?

Throats are 90-91%, I really didn't do much there.

[67RS502]

like your combo as is. Would be cool in a full size Chevy step bed street truck. Do you happen to have a picture of the block clearancing for the rods? This is the biggest sbc I have seen.

I may somewhere, but its a Iron eagle block with spread pan rails, so there really wasn't much clearancing with a small journal rod.

[67RS502]

More in progress pics, sorry for the poor quality, thought I had better pics of the ports.
Thought I had more of the bowls and intake ports, but I cant find any better.

I did a 438 sbf last year. Heads pretty much mirror yours in terms of flow. Cam was 266-276@050 and 728 lift. The difference i had was 13:5 comp and dual 1050's. Peak power was 703@6700 and 621 ftlb @ 5100. The exact same combo with one 1050 made 651 at exact same rpm. So with your lower compression but more cubes not sure if cam swap get you over hump. I think because you want streetable power you need a head thats a little bigger than what typically would be required. Or you cam and carb bigger and take a little hit in drivability department.I guess what im trying to say if you don't have higher compression and dual 1050's as option you have to get the extra power from somewhere. Heads that seem overkill on a 400" chevy likely not so big on 490"

So you picked up 50hp a T-ram and dual 1050s, that's a big gain.
Well these heads are about as big as they will get, there is a bit more room, but not much, when dealing with 23* heads.
The cross section is set up right on these for 490 cubes at 6500, but they are only 23* heads,
and may want even more more cross section because of all that stroke... not sure.

[Steve.k]

Yes 51 hp. Had a chi 3v 400 intake with single 1050. Put a ur19 edelbrock tunnel ram and dual 6464 1050's. Absolutely nothing else other than re ring and bearings.Horsepower peaked at 6700 on both which I thought wouldn't happen. The car is very heavy so did not want to change cam. Im not sure if those kind of cam specs work in your car. Mike would know if it would drive decent in big engine like yours?

[67RS502]

Heres the block clearance:

[67RS502]

[Carnut1]

It is a cool "street" engine no doubt. Did you use titanium retainers? I can't tell from the pics. I am also wondering about the closed and open spring load since this is a hydraulic roller. I have had good luck with hydraulic rollers in sbc and sbf's but I limited them to 7000rpm and valve train weight was important. I was thinking that the valve train might be having issues at 6000+ and holding it back. That is a decent sized intake valve, hollow stem? Thanks, Charlie

[n2omike]

A naturally aspirated 700 horsepower small block with a hydraulic roller cam and mild compression ratio is pretty damn awesome in my book! Plus, the fact that it doesn't even need to rev very hard to do so means it should have a long, easy, low maintenance service life! Hats off to a KILLER BUILD! Lots of quality work with what many would call outdated parts! Can't wait to see you on Larry Meaux's dyno, tweaking it to 700+ horsepower... still in relatively mild form!

Good Job, and mucho respect!

[RevTheory]

A naturally aspirated 700 horsepower small block with a hydraulic roller cam and mild compression ratio is pretty damn awesome in my book! Plus, the fact that doesn't even need to rev very hard to do it means it should have a long, easy, low maintenance service life! Hats off to a KILLER BUILD! Lots of quality work with what many would call outdated parts! Can't wait to see you on Larry Meaux's dyno, tweaking it to 700+ horsepower... still in relatively mild form!

Good Job, and mucho respect!

This is an underlying truth that often gets lost in our attempts to help find more power, rpm, whatever and is worth repeating.

[Orr89rocz]

Is a 4.42 stroke .985” piston really long life though? 1.4 rod stroke ratio? Curious how this all works out over time

[n2omike]

Is a 4.42 stroke .985” piston really long life though? 1.4 rod stroke ratio? Curious how this all works out over time

Stock 400 SBC has a rod/stroke ratio of 1.48... any many of those have lasted 200k miles.

Compare this 700 horsepower small block to 99.9% of the other 700 hp small blocks... and give me a realistic comparison regarding their expected service lives. Other 700 hp units will rev WAY higher, have a lot more compression, have solid vs. hydraulic lifters, etc, etc.

This is a low maintenance, long service life 700 hp small block. The fact that is was skillfully done with what most would call well outdated 23 degree equipment... instead of the latest, high dollar, CNC, billet, altered valve angle, etc part of the week is especially impressive!

Great build!

[Orr89rocz]

I wouldnt say a 427-440” would rev way higher. 6700-6800 isnt much higher and can be done but just curious on how a low compression height piston and low rod stroke would live over time compared to something more conventional. I never seen many pistons under an inch and rod ratios that low

It is a nice build and has more left in it

[67RS502]

It is a cool "street" engine no doubt. Did you use titanium retainers? I can't tell from the pics. I am also wondering about the closed and open spring load since this is a hydraulic roller. I have had good luck with hydraulic rollers in sbc and sbf's but I limited them to 7000rpm and valve train weight was important. I was thinking that the valve train might be having issues at 6000+ and holding it back. That is a decent sized intake valve, hollow stem? Thanks, Charlie

Thanks wanted to do something different.
Light weight steel retainers, no hollow stems, valves and Jesel came with heads.
Spring press is about 180/500
That's all I do is HR valve train, no sign of floating on the dyno
P-rods are .135" wall.
Should be good to 7000 I believe.

[treyrags]

Did Jimmy do the original work on those heads?

[67RS502]

A naturally aspirated 700 horsepower small block with a hydraulic roller cam and mild compression ratio is pretty damn awesome in my book! Plus, the fact that it doesn't even need to rev very hard to do so means it should have a long, easy, low maintenance service life! Hats off to a KILLER BUILD! Lots of quality work with what many would call outdated parts! Can't wait to see you on Larry Meaux's dyno, tweaking it to 700+ horsepower... still in relatively mild form!

Good Job, and mucho respect!

Yes, I'm happy overall, with a bit more time on the dyno it would have made 700 I believe.
I try to do all my stuff to be low maintenance, just not sure about this thing with the poor rod ratio.
90s technology
Yes, I will have to take Larry up on his gracious offer, with all his knowledge it should be a great learning experience... as it already is here on Speedtalk.

Things I consider changing before more dyno time:
1050 main body
try a dominator
more work to the intake
cam with 5-10 degrees more and as much lift as we can (but try to keep it streetable)
Possibly the Victor Ram I have, which will take new spacer plates since this is a tall deck block and RR heads.
I would also need to find some carbs to use for the dyno.

I thing these things should be worth some power.
Also whats acceptable as far as manifold vacuum for a street/strip engine? 1"