I put new Vortec heads with screw in studs, guide plates K-Motion K-700 springs Performer RPM Vortec intake and Edelbrock 1412 800 CFM carb. I've been to the track twice and the best time I can get is 14:149. Car hooks good. Wheels don't brake loose. Does seem to have slight bog after take off. Cam is an XE268H. Rest of mods in sig. Is my carb too big? That's all I can think of. My number on the timeslip is 4126.
Thanks.

Brad...

 

You need a converter. Maybe in the 2200-2500 stall range. You're 60' times are too slow.

 

I may hear some crap for this one, but i think you are over carb.
I have a 383 stroker bored .30 over and i am running a holley 600 on it and i was told from several machine shops that it should be good enough. I may up it to a 750 double pumper. That would be as high as i would go.

 

Agree with Steve. Need some converter. work on those 60'.

And does sound like too much carb. Put a Holley on it and see how it runs.

 

By judging from the 60 ft times he does need a converter proably around 2000-2400, and IMHO that carb is way too big, I would get somthing around 650-700 CFM.

 

My converter stalls around 2000. I'm gonna try some different springs and jets. I just bought that carb. Went to the store this morning parked the car in the garage. About an hour later I went out there and I had water all over the floor. Radiator took a crap on me. Good thing it didn't happen at the track. I would have been SOL. Best place to break down is in the garage. So I guess before I work on the carb I'll be buying a new rad. I want a new distributor too. If I don't get that carb to work for me I'll be looking for something else. I'm getting quite the parts stockpile here. Oh well. Thanks for the help. Also, on my carb, there is 3 holes on the power valve, (I think that's what it is) I have it on the top hole right now. Which hole gives it more gas. I don't know. I tried it on the bottom hole and it would just die trying to take off. The middle hole was ok but the top one seems to be the best. I would just like to know what those holes do. The book doesn't tell you much. Thanks.

Brad...

 

More gear would help along with a bigger converter. What has been done to the front and rear suspensions?

 

All thou a higher stall converter and more gear (with traction) will help, You've got a basic problem of low horsepower.
Your car should be going 102 to 105 mph in the Qtr easily
reguardless of these other factors.
Some things to check are ignition system and timing, 32 to 36 total/ 12 to16 initial. exhaust restriction. Air cleaner restriction, Carb jetting. fuel delivery. fuel octane
An engine that overheats will be down on power too.
My bet is ignition system and fuel system.
Check for any rubber hoses that are used in your system
for softness especially on the suction side (before the pump)
They can collapse shutting off the fuel.

 

Low horsepower? I have the same motor they've built up in Car Craft and hot rod and they were getting 400 HP out of it. I have no vacuum leaks. Just fixed all those last week to pass emissions.
I haven't done any front suspension mods but I have in the rear. LCA RLB's and boxed LCA's, PowerTrax locker and Summit heavyduty aluminum dif cover with the preload bolts for the bearings. The car was a V6 and I haven't changed any of the springs, front or back. Car hooks up good. I'm not spinning off the line. I have a line-loc and get the tires good and sticky. My rear tires are 265X50X15. They seem shorter than my old tires. These are only 24 1/2 inches tall. Would that make any difference? The engine setup I had before I put the Vortec heads and Performer RPM intake and carb was just some old stock heads and a performer intake with a Edelbrock 600 1406 carb and I was running 14:86. I figured my times would have gotten a lot better with the new heads and stuff. That was a lot of money for only a 7 tenth gain in the quarter mile. The elevation is only 300 feet at the track I race at. I know this car can do 13's. I got beat by a girl in a Z28 with TPI and she was running 13's. Thanks again.

Brad...

 

I've got the same problem. I don't have the Vortec specific intake, but I'm running mid high 14's. I'm going to get the heads ported and polished this summer. I have too much cam in the enginge and it bogs a little until 3000. I'm also going to put 1.6 rockers on after the heads are done and that should help out my low end more. Car Craft lies their a$$ off about HP. My friend had a 383 same as car craft built and was off about 70 HP. It's really hard to tune in that many ponies.

 

Quote: "I have the same motor they've built up in Car Craft and hot rod and they were getting 400 HP out of it."

There are only 3 things that are the same on yours and their
motor (CC) 1 vortec heads, 2 performer rpm intake 3 compcams XE268 cam.
Your motor is not making as much power as theirs.
Other wise your MPH would be 102+++ regardless of
gear or traction. Your mph should be 105+.
Something is basicly holding your motor back.
Start with a compression test. should be 160psi+ in all cylinders
check timing should be 32 to 36 deg total @ high rpm
Can't help you with jetting cause I don't know that carb
Hook up a fuel pressure guage and observe the fuel pressure
at high rpm (through the traps) Should be no less than 4 psi.
Their cr was 10:1 , Is yours? Block /piston deck height, gasket thickness etc...
They made 400+ hp after pocket porting the heads.
You can bet they have a 3 angle valve job....
I agree that your car should be running at least 13.7@102
or better. But something is being overlooked.

 

I think that the pocket porting involved much more than a little grind on the combustion chamber. I think that those heads were gone over pretty good since they were grinding on them anyway. BTW Vortecs come with a really good three angle job on them already. 400 may have also been corrected power. I know I'm running less than 350 because I got beat by a LS1 TA the other day. I was rolling about 35 mph and saw him coming up so I shift into second, and hit it. I was pulling through third when he rolled past me. After all of this head work if I'm still not making enough power I'm going to the dark side and putting on a 100 shot plate.

 

OK. I've got the new radiator in. I have to work all this weekend. I'm gonna get a new distributor anyway. Gonna gap the plugs to .045. Any suggestions on distributor in the $200 range? I will do a compression check probably Tues. I also got some step-up springs I'm gonna try on that carb. Gonna go with a stiffer one and see what happens. I'll get a timing light when I get the distributor. I have checked it once with a light. At idle it was showing 20ish. I could have done something wrong. Not too good with a light. Never really used one. My car doesn't ping or knock. I usually tune it with the ear method then apply brakes and rev motor and see if it pings, if it does, then I'll retard it till it stops. Nitros is looking good to me to. This car is a serious money pit. I'm always broke.

Brad...

 

A chevy HEI in good condition with a MSD replacement coil
is all you really need to run fast.
One distributor I found to be worth every penny it costs
in terms of performance and durability is the MSD
billet Ready to run. It has a Hi performance inductive
spark amplifier,(built in) Vaccuum advance, an adjustable mechanical advance curve uses a stock type pre'74 chevy cap and rotor. and only requires 12v power source and a good coil
like MSD Blaster 2 to work great.
Total reliable unit.

No boxes or other stuff to let you down. good enough for 550+ hp and 8000 rpm.
The module in this distributor is the same one MSD sells to upgrade a stock HEI (with their coil) to racing spec.
You can't set ignition timing by ear, and expect even close to max performance. You will always over advance it.
Optimum timing is not even near {a little back from audibel knock)
optimum timing will be 32 to 36 deg @ high rpm. ( no vaccuum adv) Try 32 then 34 then 36. Watch your mph not your et.
The exact curve up to full advance will be car specific but I've had good luck with 12 to14 intial@ idle advancing to 34/36 total
@ 3500rpm. Usually I use one light spring and one medium spring
from an advance curve kit. If the kit includes weights and bushings try them too. This is critical to getting max power out of your car. We're talking +/- 50hp.
How's your exhaust system? Go to the track and try uncapping the exhaust. If that helps a lot you'll have to do something to
fix your system. You don't want to know what I did to mine.
But it works....
Work on getting Max MPH out of it. The ET and 60' times will follow....

 

Don't bother with the vacuum advance. Set the total timing at 36* at 3000 rpm and let the initial timing be whatever it is once you set the total. Remember that if you change the initial , you also effect the total. Use the lightest advance springs that come with the distributor if you do get an MSD one. Or if you go with a different distributor, get an advance spring kit for it. This should give you a good starting point to work with.

 

My exhaust does kinda suck. It's pretty much stock with a cat. Had a muffler shop do it. The bends are ugly to say the least. Here is a pic of what I'm gonna be getting after I put in some overtime.

Will be picking up a distributor Tuesday. Not sure which.
Thanks.

Brad...

 

Yeah, that carb seems a bit too much.

 

That pic is of a 4th gen underbody, but a simular system can be
installed on a 3rd gen. Notching the flange on the trans crossmember where the exhaust passes under helps
to increase ground clearance. Thats going to be a loud system,
with a lot of noise inside the car.
Y not build a Y pipe off your long headers, into a big
3" main pipe with a high flow cat (carsound) that you can take out
3or4 bolt flanges. Use 3" mandrel bends to go over the axle
into an aftermarket muffler behind the axle 3" in and either a single 3" out on the drivers side or dual 2.5" outs.
Gives ya a cool sleeper look. "Hey that's no V6!!!"
Mine is long tube headers into 2 2.5" main pipes on the passenger side using twin mandral bends over the axle then has twin turbos ganged together in a staggered fashion behing the axle with 2.5" tail pipes into 3" chrome tips on the drivers side. The turbos have about 2hrs of internal surgery on each to improve flow.
Car runs the best Et's and MPH thru the exhaust.
Like I said it works. Quiet at idle and cruise but nice turbo sound when I stand on it. It's not an easy system to build,
next time I'm going with a custom built "Y pipe, 1 big main pipe system" as cars' seem to run just as fast with it.
Good Luck

 

edited: Don't want to "offend" anybody

 

I agree with everyone that sez you need to get a smaller carb and a higher stall TC.

One other thing that comes to mind is did you re-curve the distributor? What is the total timing and what's it all in by? I think maybe you need a more agressive advance rate.

You also need to get the 60's down. I ran 1.969 on bald XP2000Z's (245/50/16) with my low 14 second car

 

I'm hoping I can get the carb to work with new jets and what ever. I just bought that. If I have to I'll get another one. I'd rather not though. I'll be getting a new distributor Tuesday. And new wires. My distributor is pretty old. I'll check the timing with a light when I get the new distributor. If I can't get it right I'll try taking it to the dyno and see what they can do with it.
My exhaust won't be exactly like that, I have shorty headers, but I want it to dump like that. My car sits up a bit high anyway. Shouldn't be a problem with ground clearance. I hope.

Brad...

 

OK, I got the new distributor in. Did a compression check, and regapped the plugs. All cyl's were 140 psi except for #2 it was 135. Plugs are gapped at .045. Now the timing nightmare. I pulled the vac advance hose off and plugged it. Tried 12 deg and it knocked real bad. Tried 10 deg, still knocked. It's at 2 deg initial timing and doesn't knock at all. I'm also running 87 octane gas. That could be a problem. Only got a half tank of that in now. That'll be gone in a few days. I have a timing question. OK, I have the timing tape on my balancer, my tab goes to 16 degrees, or 14. Well anyway. How do I see what my full advance is at, at 3000 rpm's? Where do I look at on the tape and the tab? I won't get any track time till the 19th, maybe the 15th if I feel like driving that far. Testing and tuning on the street and freeway really sucks. My car died in traffice during my first test. That always sucks, when your sitting there looking like an azzhole holding up traffic. My distributor wasn't tight enough and retarded on me, making me look like a retard. Oh well. Just got out and advanced it.

 

You will not get any where with 87 octane gas. You will damage your motor if you continue to try to make power test runs on 87 octane gas. Detonation can destroy your motor in seconds.
Drain it or drive your car normally till it is all gone!!! and then fill up with 92+ octane gas. I use Sunoco Ultra 94. If you have that in your area, use it.
To set the total timing with a timing light and a balancer tape,
you sight up say 34 deg on the tape with 0 degrees TDC on the timing
tab. Your optimum timing may not be exactly 34 deg because
some balancers are off and some timing tabs on the timing cover are off. That's ok just start at 32 and try 34 then 36.
Till you get the best mph. Stop trying to power time the car by ear and feel. It doesn't work. Set it up at 32 deg at high rpm,
lock down the distributor and reconect the vaccum advance to
ported vaccuum. Till you can test it at the track. You may have to rev the motor to 5000rpm
while sighting the timing light to get full advance out of a stock distributor. Thats ok for now just do not over advance the timing.
You compression pressure reading is low. The motor may be tired (rings or valves) or the cam may be retarded, or the compression ratio isn't near as high as you think it is.
Did you open the throttle during the compression test?
Was the battery fully charged and the motor kicking over
at at least 500rpm during the test? All thses can affect the results of a compression test. Drop a teaspoon of oil in the sparkplug hole and repeat the test, if it then improves, the rings are worn.
Should be 150+, mine is 185psi.

 

I bought a new distributor. CSI 50,000 volts. When I did the compression test, I just pulled the plugs and put in the tester and cranked it over. Didn't have the throttle blades open either. I have new heads on that car, the cam is installed straight up.
And I have a new battery. Thanks for the timing tip. Friday I should be outta that gas and will put in the 92 or higher if I can find it. So basically, the more timing I can get the more power I'll make? Correct? I rebuilt my motor last year. I shouldn't be having a ring problem. I guess I could do a leak down test. Also when I took the plugs out, they all looked like new. I've got about 500 miles on them. The first plug I pulled I thought might not have been firing cause it looked like it came right out of the box, then they all looked like that. Now that I think about it, if I had bad rings I wouldn't have gotten such consistent compression numbers across all the cyl's. Right? Thanks for your help.

Brad...

 

"So basically, the more timing I can get the more power I'll make? Correct?"

No.... The engine will make max hp at a certain timing
point. It will be between 32 and 36 deg at full advance At high rpm.

Go beyond that optimum point and power decreases. This point is way before you will hear detonation knock.

More initial timing at idle and a faster advance curve will
help make more low end and midrange torque--- up to a point.
this will help your ET.-- to a point. too much will slow you down.

If you need more than 36 or 38 degrees timing to get the fastest
mph on a timeslip, your carb jetting is probabily lean or rich or your balancer/ timing tab is out a lot.

"Now that I think about it, if I had bad rings I wouldn't have gotten such consistent compression numbers across all the cyl's. Right?"
No all 8 cylinders could be bad "consistently".... There could be a lot of reasons for this, even on a "fresh rebuild"
Your compression test is low. You should redo it properly.
If it is low again you will have to fix the problem or you won't make the power you are expecting. reguardless of how much you spend on converters and smaller carbs and other exepensive stuff.

Just because you have new heads doesn't mean the valves are sealing. Just because you lined up the timing marks on the timing gears doesn't mean you cam is in time with your crank according
to the manufactures cam card timing specs. Just because you bored and honed the cylinder and installed new pistons and rings
doesn't mean you have good ring seal.
You can have a good leakdown or a bad leakdown test and
still get good or bad performance.
A compression test is the first and best way to see if your motor is healthy. It will save you a lot of money in the long run.

What altitude are you at? Higher altitude will result in a slightly lower compression test reading than you would get at sea level.
and horsepower. But unless you are on Mount Everest, your reading is low, so....

 

Hooked up fuel pressure gauge. It's between 3 and 4 psi at WOT. I was just out on the freeway doing a bit more testing. Air quality is good and I'm maybe a couple hundred feet above sea level. Car is running killer according to the seat of the pants dyno. Also trying to burn up that 87 octane. I work the next 2 nights so that should about kill that gas. As far as the compression goes. If there is a problem, I'm probably not gonna tear the motor back down. Might do another compression test the right way though just to see. I'm gonna borrow a 600 CFM carb from a friend this weekend and see what that does. Thanks F-bird. You've been most helpful.

Brad...

 

That fuel pressure is pretty low. I run 10 lbs with my carb'd motor and it doesn't drop more than 2 lbs during full run down track. Suggest you get a stronger pump that needs a regulator and set it to as high of pressure as the needle and seat will take up to 10 lbs.
As far as checking total advance; if you can get a timing light with a built in dial to set the advance on it you can set the timing light on 36 or whatever you want and set the mark on the balancer to 0 on the pointer. Also, all advance should be in by 3000 so there is no need to go higher with rev's than that.

 

1. Edelbrock specificly recommends 6psi max @ idle or their carb will flood by forcing the needle off the seat.
As long as your pressure gage reads 3psi + @ WOT and high rpm
you have enough. Edelbrock has various sizes of inlet needle/seat pairs to adjust for more fuel flow @ 3+psi @ high rpm.
Way more than enough to serve this motor. More pressure will only cause more problems.

2. A stock distributor is set up with a slow advance curve.
It may not fully advance till 4500/5000rpm. If you only rev to 3000 will setting the timing, it will then be over advanced at high rpm on this distributor. Therefore you would have to rev
till the distributor is fully advanced to set total timing.
Until such time as you can re-curve your distributor you may need to do this to accuratly set "total timing".
The first order of business in maximizing perormance is to establish what the motor wants in total timing deg's@ full advance. Once this is found you can work on optimizing the inital timing and advance curve rate. Finding optimum total timing for your motor will get you to 95%, setting the curve will get you the last 5%.

 

That is what I am thinking. It is a automatic right? Do you brake torque the car, you want a litlle wheel spin, but not excessive, obviuosly.

 

The slow factory advance curve is exactly the reason I earlier recommended to get a spring kit. Slow curves promote slow acceleration, going with the lightest springs in the kit will give full advance by 3000 rpm. As far as fuel pressure goes; more pressure is better. If 6 lbs is all that carb can handle, then increase the pressure to that. The whole key is to get the motor up on the torque curve as quickly as possible. Sluggish timing curves, etc will only serve to slow down the car's acceleration and as a result slow down the 60 ft times.

 

Unless I missed it no one has mentioned the possibility that the cam timing is off. Just lining up the dots is kinda like playing pin the tail on the donkey...

Sometimes you hit, sometimes not.

I have setup a few motors and it seems half of them are not "straight up" when the dots are lined up and this needs to be corrected with bushings on the cam gear dowel.

You can be sure that 400 HP motor had the cam degreed.

Not flaming you at all, I just wanted to bring up what I feel is a key point to making power.

Thanks,
Ernie

 

Unless I missed it no one has mentioned the possibility that the cam timing is off. Just lining up the dots is kinda like playing pin the tail on the donkey...

Sometimes you hit, sometimes not.

I have setup a few motors and it seems half of them are not "straight up" when the dots are lined up and this needs to be corrected with bushings on the cam gear dowel.

You can be sure that 400 HP motor had the cam degreed.

Not flaming you at all, I just wanted to bring up what I feel is a key point to making power.

Thanks,
Ernie

 

Well right now I don't have a degree wheel. I did buy a new AFTER MARKET distributor. It's a CSI billet aluminum with a 50,000 volt coil. Gapped my plugs to .045. I just put in 10 gallons of 92 octane propower 76 gas to see if I can get some more timing and see if it's any better than the 87 I was running. I put the Orange Spring in my carb. Seems to be running better. Not bogging. I'm gonna go play with the timing right now and test it out and see what the diff is. I also have a 2000 stall converter on it. Thanks.

Brad...

 

Carb is set fine. I read the HEI tech article and realized I had the vacuum advance on the wrong vacuum port on the carb and also figured out how to see what my full advance is and where after reading the article about 50 times. I didn't realize that the distributor has 20 degrees advance built in so I had to add 20 + 6 to get my advance number which is 26 obviously and it came in as schedualed. I was hoping I didn't have to change the springs on that hot motor. But now I have a serious tranny problem. Fluid is getting forced out through my dipstick when I come to a stop and smoking on my headers. I have no idea why. Well anyway, my car is undrivable now till I get that figured out. But the motor is running killer. It really seems to like that 92 octane. With the other heads I had on it, it ran like crap. 76cc heads. Was gonna go to the track today, was getting all ready, but I took it for a test thrash and my tranny started acting up. Now I gotta fix that.
Damn.

Brad...