I have run a 13.77@100.58 for my best et and 14.0@102.5 for my best mph (the 13.77 was with a 15mph headwind). Now I have a speed demon 650 with mechanical secondaries. I hope to hit 13.5 or 13.4 with it. Considering this, what do you guys think I can hit with the following modifications to my 350HO crate motor:

Professionally Ported and Polished Vortec heads, shooting for 250-260cfm @ .5 intake and 180-190cfm @ .5 on exhaust

Crower Solid Cam and lifters, specs are: 268/274 advertised,
238/244 @ .050, .523/.540 lift with 1.6 rockers, 107* LSA

Victor Jr. for vortec cylinder heads, or an RPM air gap with a 1" carb spacer.

Thin Fel Pro Head gaskets, shave vortecs 4cc to go from 9.1:1 to 10:1

Comp Pro Magnum Full Roller Rockers, 1.6 ratio

The Demon 650 Carb I just got


What do you guys think I will see in the 1/4 with these modifications? Thanks,

Seth

 

Why not just get Fast Burns? They'll do what you want basically out of the box, probably won't cost you much more if any than the mods you're talking about.

I think you'll want more carb.

 

Fast burns flow less than vortecs out of the box actually. The numbers everyone goes by for Fastburn heads are for the prototype head. The real things flow right around 220cfm @.5 on the intake side. I have a friend who bought these heads for his parents and was incredibly dissapointed to find that they flowed far less than he expected (220@.5, he was hoping 260-270@.5).

The reason I am sticking with my vortecs is that they came on my crate motor, and the guy who is doing my heads is a friend so he is doing them for practically nothing. You are right though, I will probably need more carb down the road. Anybody gonna venture a guess on my 1/4 times?

 

you could definately benefit from a bigger carb... all things said with it tuned right, i'm gonna say high 11's. IF it hooks up well

Eric

 

If i hit an 11.99999 I would be so excited lol. Any other guesses?

 

Scrap that cam, it's going to be an obnoxious SOB w/ poor streetability. You want a cam that size, yet pussed out when I tried to get you to go with 4.10's & a 28 inch tall tire.

 

LOL

 

I haven't looked through old copies, but as I recall at least one of the finalists in Popular Hot Rodding's Engine Masters Challenge last year used those heads out of the box (contest rules limited displacement to 366 cid small blocks, had to be factory or off-the-shelf hardware). Most of his fellow competitors spent most of their time/money modifying other heads.

I can appreciate that.

 

Supposively they are revising the fast burn heads to flow what they were originally intended to flow, so maybe he had a set of the newer prototype heads???

 

I have the Fastburns on my 406 and will be getting to the track in the next month or so. Then I will know if I am happy with them or not.

 

You need to check the specs of my old 383 on my web site when I was running high 11's with it.
With that much lift from the 1.6 rockers, are the valve springs and heads modified to accept that much? If not then there's damage just waiting to happen. Your duration is a little low to produce big torque numbers. You should have just installed a cam to give you that much lift with 1.5 rockers. Such a cam would have better duration numbers.

Your engine has potential but like everyone else says, get a bigger carb. A 750 would be a minimum but an 850 would be better. The 650 is a street carb. The rest of the engine package wants a bigger carb.

Low 12's or high 11's might be possible but traction will decide that. You're going to need slicks. It's also going to depend on how heavy the car is. It takes less hp to run 12.0 in a 3200 pound car than it does in a 3500 pound car. Removing weight is a cheap way to go faster. Total weight is with driver since that's the weight the engine needs to push down the track.

 

Right now I am at 3250 pounds with a steel hood. I am considering a larger cam now, so we'll see.

 

you don't need anywhere near that much headwork, or cam to turn high elevens, especially with a car that light.

get the compression up around 10.7, lil bowl work, vavle job. get the E/I ratio like 72-74% you'll only need about 222-8 on the intake side, and the exhaust the at the right percentage.

I'm running a hydrualic flat tappet comp XE cam 230/236 @ .487/.490 far less agressive than that hyd roller cam your wanting to run.

monkeying around on narrow cheater's it's been 12.06 @ 112.5
I've pulled the reigns back on it, so i can play cageless for a bit. since i've not the money to put it in

I agree with the other fella's that carb's gonna be too small.

 

3250 pounds with driver*