A couple of years back I had 2.300 intake valves put in to increase the flow of my 440-1 heads. These are castings I bought back in 1998. They are cut to 62 CC chambers. I run an almost flat top piston, with a dome of about .060. The flow increase was fairly good for most of the lift numbers, averaging about 6 percent. There was a spot about .300 where the flow barely increased. I run a 283/296/110(edit;112 lobe sep) roller with .775 intake lift, .680 exhaust lift. The exhaust lobe is a mild rate of lift lobe. Induction is a 3X port matched with a Terminator injector running alky. 2 1/8 x 30 x 4 inch headers.
I tried going up in rpm, but going from 7100 to 7300 shifts didn't net me any ET gains.
One thought that came to mind is that the valves may be shrouded by the valve reliefs enough to offset the extra flow?
With 15/1 compression and plenty of exhaust duration, I figure the minor loss of flow on the exhaust shouldn't have hurt as much as the intake flow helped. The valvetrain is Jesel, 7/16 pushrods, Comp 347 springs. That should be getting the job done I would think. Any thoughts on this appreciated.

Just throwing this out there but if you have one set of heads flowing 375 and another set flowing 425 but the intake manifold will only handle 350cfm you may never see an increase. It may even cause turbulence. That's why I LOVE to bolt the manifold on and complete the whole system.

Alky is the problem

i was going to suggest more fuel. just because you increase air flow doesn't mean a direct increase in power. especially running alcohol i think you need more fuel.

More exhaust lobe. Faster and more lift.

You can't put more intake charge into the engine if the exhaust can't get it all out.

how tall is that 3X manifold

Not an expert on the subject, but have seen many people try alcohol on large cu.in engines and not have much luck. I am not a large fan of Ken at Indy
cylinder head,but he has told a few people I know that the same thing that everyone loves about alcohol is the thing that hurts large cu.in.engines.
The amount of alcohol to feed a large engine that keeps the temp. down lowers the cylinder head temp.
and prevents complete combustion,reduces ring seal.Does not show up with a blower or turbo because of induced heat and pressure.My friends switched to race gas and picked up.

If you're looking to make more power I'd start with the camshaft. Have you mapped your valve to piston clearance for both intake and exhaust? If so, you can provide that mapping to a cam vendor and see what they say.

What is the rocker ratio that you have now? If you have the budget, adding more ratio might be a good idea.

Having the 3X intake ported might also be a good investment. It costs about $1000 to have Wilson do a full competition port job but it is worth some power. It would be interesting to see what Wilson thinks of the 3X. The Super Victor makes more power than the 3X on my 514, but that is on race gas. The extra volume of the 3X should help with alky but who knows.

I have heard that alky can be less powerful than gas at some point. However with not having switched fuels, more air should equal more power, or at least you would think so despite the type of fuel. On the exhuast lobes, the motor ran virtually the same with less cam. I orginally had an Isky RR735 cam in it, which is 280/288/110 with a touch less lift of .761. My current rocker ratio is 1.55 and I would like to change at some point to a bit more aggressive ratio. With my present setup, I may be limited to about what I have due to installed height and pushrod clearance.
Andy, I haven't mapped the valve clearance. I do know I have about .150 on both valves though. What exactly does mapping the valve clearance tell the cam grinder?
I have thought that the possibilities for no gain may be related to either the valve/piston shrouding, or possibly a change in where the port flows, which may affect power enough to offset the gain in flow. Or maybe the same flow at .300 combined with the lower flow of the exhaust may be the culprit? There certainly are a lot of possibilities.

Mapping the VP would tell the cam grinder how aggressive you can get with rocker arm ratio, lobe design, duration, etc.

My guess is that the heads weren't the "cork", that the cam is. Therefore, adding more flow capacity didn't do much for you.

Buy a copy of PipeMax and load your engine details to see what it says. I bet it will tell you that to avoid choke you need at least 0.850 lift on the intake side. It might even tell you that you need 0.900 lift for max power. You'll have a hard time getting that much lift with 1.55 rocker arms so you'll most likely need to put 1.70 or bigger on the intake side. But before you start spending money, run PipeMax and study the numbers.

I would add more Cam if it was me... Also try 114-115 LSA.

The intake manifold is important, but less so with a terminator Alky injection as you are only moving air, no fuel down the plenum and into the runners.

Open the valves up to .900" after lash and look out!!!

Good luck,

Arnie

thanks for the input everyone. Musclemike, I will definitely keep your comments in mind.
EDIT- I incorrectly listed the LSA as 110 on the Comp cam. It is 112 LSA. Lobes are 1625b and 4247b

As others have said.........the camshaft is tiny. We ran that much camshaft 30 years ago in 440in super stock motors with stock heads. So it sure won't feed a 500+ motor with heads that flow 400cfm. Bottom line, the heads flow more air....BUT....the engine doesn't

Monte

Do you have a rough idea of how much power the engine is making? I think you'll be surprised how much power you could pick up with the right cam. (unless of course something else is also holding the combo back)

The motor dyno'd 847 hp at 7,000, 760 torque at 5700. The power seems to correlate well with the best ETs, 8.70s to 8.90s depending on tire type and DA, which on a good day is 1400 to 2000. The best on straight alky was 8.77 153 mph with radial 14.5 x 33 slicks. The big bias GoodYears helped traction and consistency, but cost a full .10 in ET. Changing from 5600 to 6500 stall actually picked up about .05 ET, but some of that may be related to the suspension not being optimized at the time. The car 60 fts better now, so maybe a tighter converter would improve ETs some.

For comparison. 572",-1 @380,14.7,Indy crossram on gas,2 Eddy 750, 285/292, 112, in at 108, .799 w/1.7 before lash,2 1/8" Hooker. This cam came from Mike.
1.33,9.25,147.6 @3340lbs. Just for comparison from Wallace
[Email]153.2@3000[/Email] = 886.57
[Email]147.6@3340[/Email] = 882.72
Not these #s are gospel but the comparison should be valid. I'm sure your intake and carb setup should be worth 20-30hp over mine. Granted my cu in is larger. I only turn it to 6900. Could it be the cam, fuel?
Doug

As Monte and others point out, most think I don't have enough cam. I have gotten info from elsewhere (Cammotion)that points in the same direction of faster exhaust lobes, and more at .200 on both sides. As far as fuel goes, I have fed this thing all it wants with the injector, and backed off to the best ET/MPH. I was surprised that it wanted so much more M5. I went from a .112 bypass to a .100. That is 12.1 percent more fuel.

Well I will join the more cam crowd...Also dont think that intake is helping it any.