Heres the setup...


4 bolt main 350 bored .020
Forged Pistons-Flat top 4 valve relief
Forged rods
Comp Cam 0.507/0.510
Holley 750 DP
Edelbrock performer intake

Unported Vortec heads
Comp springs

and the drivetrain if you care to make a 1/4 time estimate

700R4
shift kit
2400 stall
3.73 posi

 

Low 13s. Any work done to the heads besides the clearencing for lift?

 

not enough stall and that's the wrong intake completely. You need the rpm air-gap and 3500 stall easily. That cam is too large for a 2400 stall, so it's a mismatched combo.

 

I know the stall is too small. But I cant change it now, have no more money. Head are unported, no bowl clearing or anything. the intake was basically free, so I'ma use it for this season.

Is there anything that is going to hurt the driveability? I'm fine with not being able to get the maximun amount of power out of it now, but I just want it to be driveable.

 

you won't be able to stand on it from a stop, because the motor will be out of its powerband. if you ease it out of the hole it would be fine i'm guessing. No one really ports those heads, just a quick bowl cleaning but isn't worth much HP at all for the time involved. The intake and stall are wrong and will cost you at the track, but I'm sure I could tune the carb up quickly enough.

 

well first off, how big of a cam is it? lift doesnt tell much and that isnt much lift for a cam anyway, but big enough for vortecs. whats teh duration on it? hydro roller or not?

whats the compression ratio??

those are two big factors to look at


my buddies 83 shortbed chevy with 350 motor at estimated mid high 9's to 1 compression, 3500 stall, LT1 roller factory cam, RPM manifold with 750 DP went 13.58 at 99.

in my car it would have potential to go high 12's since i'm alot lighter than that truck. i'm doing 13.63 with stock L98 with exhaust with 2800 stall. he has bigger cam, better intake, more gear/stall and alot better heads than stock iron L98 heads. probly pushing near 350-360 on motor compared to my estimated 270ish

if your cam has some decent duration u'll be in the mid high 12's but you need a bigger stall for sure

 

Here is everything on the cam.



Brand: COMP Cams
Product Line: COMP Cams Xtreme Energy Cam and Lifter Kits
Part Type: Camshaft and Lifter Kits
Cam Style: Hydraulic flat tappet
Basic Operating RPM Range: 2,300-6,500 RPM
Intake Duration at 050 inch Lift: 240
Exhaust Duration at 050 inch Lift: 246
Duration at 050 inch Lift: 240 int./246 exh.
Advertised Intake Duration: 284
Advertised Exhaust Duration: 296
Advertised Duration: 284 int./296 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.507 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.510 in.
Valve Lift with Factory Rocker Arm Ratio: 0.507 int./0.510 exh. lift
Lobe Separation (degrees): 110
Intake Valve Lash: 0.000 in.
Exhaust Valve Lash: 0.000 in.
Grind Number: CS XE284H-10



and yes Steve, you can tune the carb, after all is was Jays. We can look forward to tuning it during TGF if I catch ya early enough and your not already trashed j/k

As for the Compression ratio. I have not figured that out yet. I know the reliefs are 7cc, but I'm not sure how it works or if that is all 4 reliefs. I believe Vortecs are 64 cc?

 

yes defiantly want a much bigger stall..thats a pretty stout cam for a flat tappet

 

Not going to be able to get a bigger stall this season. Just going to have to sacrifice some power

 

Quick work up estimate from Desktop Dyno2000 shows about 378hp.
Graph attached.

Al

 

Wow. Thanks for the Desktop Dyno sheet!

 

So what real problems can I expect with the small stall and bigger cam?

 

sluggish starts when dropping the hammer... the gears might help cover some of it but that stall will make if difficult to launch consistently. I have a vortec headed 355 w/ XE274 in my formula and the 3.27 + 2400 rpm stall isn't very fun trying to launch... though when moving along the car is great. in my monte i have a 3200 and it made a world of a difference in getting the car to move off the line and its way heavier than any third gen. plus flash stalling the car at the strip is nice.. its instantaneous 4000rpms off the line is great for jumping into the powerband.

 

I'm not going to be harming anything when hammering it though am I? Its just going to dog right?

 

I agree with the others here that you have a bit of a mis-match going on. However, I do not think at this point that your converter is a hugh problem. If you look at the Dyno2000 torque curve above at your stall speed of 2400 you have about 340 ft-lbs of torque. That along with your 3.73 gear should be more than enough for a good launch at least on street tires. From my experience a cammed vortec will seem like a dog on launch unless you get the timing right. Makes a hugh difference. I believe you are running a mech dizzy so you will probably end up in the area of 12-15 degrees initial timing and advance to about 30 degrees at 3600rpm. The higher base timing will be the key to getting it to lauch hard.

Now, I believe most of the mis-match is centered around the cam you have chosen. To me it is one or two steps too large for stock vortec heads. A smaller roller cam would have presented more torque and horsepower. However, since you already have the cam and no more money, here is what I would do in the future to better match the rest of your combo to the cam you have.

- To match your cam go to a single plane manifold
- Increase the exhaust valve size from 1.5" to 1.6" and/or port the exhaust side of the heads.
- Lastly, consider a higher stall after the above changes because now you will be making use of the rpm range your cam was designed for.

Al

 

I have the offer of a 3500 stall converter, 5,000 miles on it... Not bad o nthe price either, but I'm still not sure

 

Ok, maybe this will make it more clear. Here is a dyno2000 graph showing the future changes I suggested to match your cam. From this you will see you have less low end torque and the torque curve between 2400 and 3500 rpm is much steeper. So you will get much more benefit from the higher stall than in the previous graph I supplied.


Now, as a comparison here is a graph of my current setup, with a smaller roller cam, stock vortecs, and a dual plane manifold. Because it is a better matched combo it make more peak horsepower and torque than your current combo and take a look at the low end torque. Tire shredder with stock converter and still only running a 2.73 gear.


good luck
Al

 

Awesome. Thanks. We shall see where I am at after the machine shop does my heads. They should be taking about $500 of mine..