Stingraye

Ok, I just G-Tech'ed my car last night and I was running an average of a 14.5 ET! But here's what I have, as you can see in my sig I have a 350 crate, edelbrock carb, just put a 700 Holley Double pumper on there, 3.23 gears with spohn torque arm. So why the heck am I still running a mid 14?? I just ran a 14.3 with the th350 before I swapped in the T5 and thought that was too slow, and expected to be FASTER with the T5, Especially now with the holley!! A friend of mine has nearly the same setup as me without the torque arm, edelbrock carb and 3.73 gears, and has 3" exhaust next to my 2½" and he runs a mid 13!! So why am I still so friggin slow!?! I really can't firgure this out and am pissed off at always being the slower one, anyone have any ideas???

dimented24x7

iTrader: (2)

im surprised the junk valve train takes the abuse of that cam. You REALLY need to ditch those 993 heads... They really block the engine from making any sort of power. Im in the process of junking them myself.

ME Leigh

You might be running into valve float problems, but i doubt it. There is nothing really wrong with those 993 heads (if they are) they are decent smog heads.

But i would say that you dynamic compression ratio (DCR) is probably really low ie >7:1 resulting in poor performance.

As for 14.5's that what you should expect from a replacement truck motor!

dimented24x7

iTrader: (2)

i think theyre trash... at least you really need to get good springs and screw in studs. those probably float around 4k with taht cam, and they arent built for any where near that lift. Even with the cam i have, the coils get pretty close to eachother. One of the things i eally hat eis the large chambers and the low CR of 8.5.

onebadwagon

lol, you all are acting like thats even near a big cam, you can get springs to keep it in check for about 50 bucks.


dude, seriously, if you arent dying for highway, get a set of 3.73s, that should pick you up quite a bit with traction.


adam

rezinn

Um what cam is that? The lift numbers tell me nothing. They're just about the least important part. Is your exhaust mandrel bent or crushed? That's one reason you're slower. Maybe you need to work on your launch as well, that's where real gains are made.

In my experience those G-techs are fairly accurate, but they're sensitive to level.

onebadwagon

im guessing the cam is about a 214 224 at .050 likely on a 112 or 114. just a little old torque cam.

adam

RB83L69

The lift numbers match a Comp XE274H. ????

The 993 heads are garbage. As long as that's what you have, it will never really run good.

What you have, if that is in fact a XE274, is valve springs designed to control valve motion on a cam with .390"/410" of lift, and very slow, lazy, gently sloped ramp, at up to 5000 RPM or so max. Now you have stuck a cam under them with enough lift to nearly coil-bind them, with super-aggressive, almost roller-like ramps. Your valves just get flung off into space every time they open, and the whole valve train probably isn't in complete contact with itself for more than 25% of the time at any RPM above 3500.

Seriously consider replacing the heads. They are trash, a copy of smoggers from the 70s, responsible for those magnificent 170 HP 350s we all used to have to drive. At the very least, put better valve springs in it.

2½" exhaust is too small. Put a real exhaust system on it. It's so small it chokes a 305.

Stingraye

yeah, the heads are the cast iron Vortec heads with the crate. And the exhaust is crushed, I plan to get random technology 3" soon, but not soon enough. I know my comp ration is 9.1:1 with those heads, but what heads or springs would you guys reccomend?? Heads is a lil too pricy for right now, but what about springs?? I also wanna get roller rockers soon too, so what do you think?? Thx.

SSC

If you have Vortec heads that isnt the problem but the springs are weak for anything over a mild RV cam. Sounds like you still have tunning issues to me. It usually takes me a few weeks to get all the tunning problems fixed with a new setup. 700cfm double pumper is a bit much carb reguardless what people say especially for your setup.

RB83L69

The "base" 350 does not come with Vortec heads.

The first thing you need to do is to figure out for certain what heads you have. All else depends on that.

There's no way you have a cam with that much lift under stock Vortec heads, unless you are one very lucky man. My bet is that if the engine didn't pitch parts through the valve covers the very first time you cranked it up with that combo, you don't have Vortec heads, you have 993s. The garbage.

If you do in fact have Vortec heads, then your car is a good 1½ seconds off the pace. There's something significantly wrong somewhere. But I doubt that. The "deluxe" 330 HP crate engine is the one with those. And of course, they have the same valve spring problem as any other replacement truck service part intended for fleet customers.

F-BIRD'88

There is nothing wrong with your motor. It is operating as designed. BUT If you want to go faster you'll have to put some
horsepower into it.
First replace the cylinder heads with small chamber 58/64cc
hi flow high performance heads.

Buy a set of new complete Pro topline Iron lighting heads like Mark A. Shields did. Port match the intake to the heads.

www.proshaver.com
www.protopline.com

Upgrade your fuel system to a hi flow pump with 3/8" lines from tank to carb. Check the pickup in the tank.

Remove the whole exhaust system and and replace it with a
custom-made 2.5" to 3 " Y pipe and a minimum 3" high flow exhaust system. A 3.5" system would be even better.

Remove one valve cover and look for the casting number to see which heads you have.

Go to www.mortec.com and find your heads in the listings. They are likely low performance, large chamber, low compression heads.

Unless they are vortecs (I doubt it) find a garbage can and insert heads and close the lid tightly and walk them out to the curb.

If money is tight you could "home-port" a set of 305 heads with larger valves for less than you think. These Fully PORTED large valve 305 heads will raise the compression ratio and add lots of flow for more horsepower on a budget. Be prepared to supply the elbow grease and sweat thou.

onebadwagon

get aluminum heads, they are lighter, and fully repairable. unlike iron heads, i have edelbrock victor jrs and i love them,
dude, just save your money, quit buying the little junk, get heads, longtubes, victor jr, and a good catback. oh, and alot more cam too.


adam

Stingraye

Cast Iron 64cc Chamber Vortec Cylinder Heads with 1.94'' Intake and 1.50 Exhaust Valves

That's straight from the Jegs site on my engine, the Base 350, so I do have the vortec heads, not the 993's, that I'm certian of. So what kind of springs should I look into, or anything else?? And my friend is running a 495 510 cam on vortec heads and has been ok so far. I generally take the engine up to about 7000 rpm's between shifts, and everythign valvetrain holds up ok. So aside from exhaust what the heck am I missing here??

ME Leigh

If thats the motor you really have then that is not the base 350 crate motor that is the High Output (HO) motor. Its called "base" because it doesn't have intake, carb, distributor,WP, etc.

Stingraye

Yeah, I know that's what it is, it's the HO, but if you look it up in any book or site it's called the GM Base 350, compared to the Deluxe that has everything...

ME Leigh

Yes but confused everybody, I at least thought you were talking about the 260HP "base" 350 replacement engine. Not the 330HO.

Now that we know that you have a 330HO things are different. First get the recommend springs for the cam that you have. You will need to machine the valve guide- boss diameter down to about .630" for clearance.

RB83L69

Forget this monkey-spank about what the "base" is or what you're "certain of". Let's descend into the realm of pure fact here.

What is the casting number on the heads? That tells all. Without that, all we can do is guess and argue. With that, a concrete, workable plan can be devised.

Post the casting number.

8Mike9

Hmmn...."ran a TH350" and went slower than "switching to a T5"


My intuitive observation says now you have to learn how to drive, instead of "pointing it and aiming it".

Squeeks83

those heads, if your running stock exhaust, and that cam has the same spects as my cam, its a summit brand, part number sum-k1104 i think or sum-1104.

Stingraye

I'll admit I am still brushing up on my fine tune stick driving, but my friend who has an 84 TA with nearly the same setup runs a 13.7 in his car, and couldn't get anything better than a 14.5 out of mine. Only difference between the TH350 run and this one was the 350 had open exhaust. And I do know that my heads are the vortec's, but I can get the casting #'s probably tomorrow (granted it's more than 5 degrees outside) if you so desire.

Acidtalons

Chevy Hi-Performance article on modifiying Vortec heads.


http://www.chevyhiperformance.com/howto/97458/


"The guide is also machined at the top to mount a positive-style, 0.560-inch-diameter valve-guide seal. All of this conspires to limit total valve lift to a safe figure between 0.420 and 0.430 inch. The limitation is the clearance between the bottom of the retainer and the top of the valve-guide seal. "


Edit - P.S., might want to get some bigger gears, I have heard 3.73s can help as much as .4 sec.

Sitting Bull

I don't see how that engine could turn 7000 rpm, unless it was in the process of flying apart!

Sheesh!!!

Your valve springs and whatnot just won't keep up to that.

onebadwagon

valvesprings, cam, lifters EVERYTHING is not designed to be run to 7k, i bet if you shift it about 6k that will help you alot, just because you rev it higher, doesnt mean its going faster.

like i said before, get some gears, then learn to drive the dang thing.
drop a couple bucks and get it dynoed, i know down here in texas itll run you fourty or fifty bucks.

adam