Right now my combo is running really well for what it is. I'd imagine I might be able to sneak a mid 11 out of it as it sits. The camshaft I have now is a Clevite 246/246 @ .050. .53x/.53x INT/EXT. The lift numbers are with 1.6 rockers. It's a solid cam. I'd imagine the duration numbers would be higher as well with the 1.6 rockers but I'm not sure it'd make a difference. My question is, how much power am I leaving out there with a cam swap? Any suggestions?

See sig below for my combo.

Thanks,

You are leaving quite a bit on the table with a non-roller cam in your motor.

A roller will allow a much more aggressive lobe ramp and at the duration you are using, be at 0.600" or greater valve lift with 1.5 rockers. Your heads flow about 290cfm at .600" lift. enough for almost 600hp in the right motor.

Keep in mind that lift is typically a TQ builder, while duration determines HP peak RPM and can definitely affect TQ on the low end. So you may be able to use a roller cam with 10 to 15 degrees less duration to get a similar HP reading, yet add more power down low - area under the curve.

i think you're leaving more on the table with a performer rpm intake and a 650 carb than with a cam swap.

that combo needs a vic jr and a proper 750 (quickfuel, aed, etc.)

Whats the complete specs of the cam? Adv duration, lsa and installed angle?

I agree, port the intake or go single plane and more carb! Or efi

Matt, I am saving up for both items. Should have them installed when I get my taxes back. What do you think I'll see for a gain with the intake / carb swap?

Justin, I'll have to look when I get home. I know it has a 108 LSA. Have to double check the other specs.

20 or 30 maybe? about the same as a cam swap without all the work, lol. i bet it goes 118mph or faster

You think with a Vic Jr and a 750 DP it'll do 118-119? That would be right where I want to be for MPH. I'm not too worried about ET at this point.

Alright Matt, I just scored the intake manifold. I will continue to use the 650 DP until I save coin for the carb. How much of an improvement will I see with just the intake upgrade? 117 mphish?

You will need to retune for that intake and likely play with timing again, but it should help

Also while your at it, once air fuel seems to be in line, play with the lash settings. Open it up to see if it wants less cam, close it up to see if it wants more cam. Do intake first then exhaust, from there you can get a better idea of what next cam will be. I'd like to see more intake lift but it should still run good with what you have

The lash now is 0.030. I've never messed with valve lash before. Would I increase the lash for more cam???

Alittle excerpt from this article. I had it reversed, and will edit post

http://www.crankshaftcoalition.com/w..._solid_lifters

FWIW...those darts (same as mine) are a bit lazy on the exhaust side, if you could come up with a set of 1.65's for the exhaust you could help them out a bit as well.

For reference I am running a voodoo 60103 with 1.65's, 215 darts, HVH intake and 750 AED.

Also...the intake should be portmatched at least slightly to the heads/gaskets....and id say the 650 dp will handle it. I ran 10.1s @131mph with a 650.

Also...the cam is lacking, but there are other options...did you lock out the timing in the distributor? Have you done awah with power valves in carb?
All of these little things will help 60' and ultimately mph.

I read through your thread. I like it. Any numbers out of your combo? I want to see mid 11's out of the head / cam combo I have now.

When I do get the single plane intake I will slightly port the runners to match my gaskets. I wasn't sure if I would be giving up power down low going from the RPM to the Vic Jr. The timing curve I'm using is 24 degrees initial and 36 degrees in by 2500 RPM. I do drive it quite a bit on the back roads and on the street so I don't have it locked out. I think I still have the 65 power valve that came with the car. I didn't play with jetting yet as I am waiting for my buddy to come back from Nevada so we can tune with a wideband. That is a bad *** SBC you've got there BTW.

I think the Jr. might pick up some horsewpower, but you will lose enough low RPM that the car will probably go slower. Unless, of course, you are switching rear gears and winding that engine to 7000RPM or so. Based on the cam specs, I would assume that's about where it wants to be shifted.

Only been 1/8 mile so far with only 7 passes on it. Best so far 7.25 @ 92.8mph, 1.56 60' time.

Zach...i drove my old street car alot with the distributor locked..but you do what youre comfortable with. Power valves oopening and distributor springs are all time variables that affect the acceleration.

Im only giving ideas :-)

i feel like those effect consistency more than actual acceleration...at least in my experience.

but my experience was on a much slower combo...these things may have a larger effect on faster cars.

Leave the pv alone. Just jet up at track until mph stops improving. Of course you're on a street tire and a 10 bolt with a stick. So tuning won't be optimized

Also prefer to have a curve to the dist. to ea his own

IMO you need more gear like a 4.11/26 in tire something like that

Im a firm believer in giving some work to the intake too.
Not every car will benefit from it but in the right spots yours can
Got a nice solid roller just sitting here, too.


Wouldnt mind a little more carb also. 750 HP would be about right double pumper the way to go. Not saying you couldnt jet the 650 up you can but if you get into turning some rpm the 750 will give it upstairs.