BLK87Z

I have an 87 Z28 which I have built in the following way:

Engine: 350 4 bolt main, bored .030 to 355, 1977 model block, stock crank and rods, flat top pistons, ARP fasteners, Crane Cams Blueracer Cam with 445 intake lift (other measurements unknown lost cam card), stock Vortec heads with screw in studds and Magnum Roller Tip Self Aligning rocker arms, Compression ratio 9.6-1, Edelbrock Performer RPM Vortec manifold, Edelbrock 600cfm carb, Petronix HEI Flame Thrower Ignition.

Transmission: 700R-4 Raptor, built to withstand 600 horsepower, 2800 stall converter and Billet servo.

Rear-end: Stock 1987 Z28 10-bolt 7.5 Limited Slip with 2.73 gears, IROC wheels and stock rubber


But with that setup Im running 1/4 mile best of 15.6?? at only 89.?? miles an hour currently at Bristol Dragway, whats the deal?? I figured I would atleast be in the 14 possibly 13 with this setup? Any Tips would be appreciated!!!!Thank You!

'87FAKE-IROC-Z

You have the setup to run quicker, I'd say it's all tuning. Keep tuning and it will come down nicely.

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'88 RS (originally 2.8)
-350, .040 over, vette alum. L98s, stock tpi.
-305 injectors & chip
-TES headers & edelbrock cat back
-3.73 gears, 700r4.
Best with 2.8-17.4@77mph
Best with 305-15.0@93mph
Best with 356-13.7@101mph
on a 2.050 60 ft.
(Damn the 2.8!)

AlkyIROC

I'd say that's about right for your setup. You'll need to change a bunch of things if you want to run quicker.

Cam is very mild. Upgrade to one that will give you around .500 lift and install new valve springs.

Change the carb to a 750

A 700R4 tranny isn't designed for drag racing. It has more moving parts than you need (ie heavier and doesn't need OD) and the low first gear creates too far a gear spread between the 1-2 shift. For your current setup the torque converter is fine but if you bump up the HP with a cam swap then a 3200-3500 stall converter will be better

2.73 gears is really killing everything else. Those gears are designed to cruise down the highway at an idle not the drag strip. Put in some 3.42 or 3.73's to help out the rest of your current setup. The converter is going to waste waiting for the car to get up to speed with those highway gears.

Heads. A simple port and polish will help get more air into the engine. Larger valves will also help.

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Follow my racing progress on Stephen's racing page
and check out the race car

87 IROC-Z SuperPro ET Bracket Race Car
461 naturally aspirated Big Block

Best ET on a time slip: 11.242 altitude corrected to 10.89
Best MPH on a time slip: 121.52 altitude corrected to 125.89
Altitude corrected rear wheel HP: 497.9
Best 60 foot: 1.546

Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!
Member of the Calgary Drag Racing Association

87 IROC bracket car, 91 454SS daily driver, 95 Homebuilt Harley

[This message has been edited by Stephen 87 IROC (edited August 19, 2001).]

gremlinz28

You should be quicker than that. What was your 60 ft. times? Your 1/8 mile times? My best 1/8 mile run was 8.630 @ 83.37mph with a 2.03 60ft. Here is my setup:

350 4-bolt main bored .040 over. Stock crank, rods, flat-top pistons. Lunati "bracket Master 2" 290 .460 lift cam. Stock vortec heads w/ stock stamped steel rocker arms. Edelbrock Performer Vortec Manifold. Demon 625cfm Carb. MSD Pro billet Distributor, 6Al box and blaster 3 coil. 5-speed with a 3:23 limited slip rear-end. Damn near everything done to the stock suspension that can be done w/o major modifications. This was running on POS tires.

I would change the gear ratio to either 3.45 or 3.73. I have a set of 3.73's waiting to be put in myself.

Jason Gamlin
'86 Iroc
350 5-speed

[This message has been edited by gremlinz28 (edited August 20, 2001).]

ATOMonkey

I did the same thing. I went from an LG4 in my stock '87 with 2.77 gears to the engine in my sig and went from a best 15.9 to 15.2. It was very disapointing to say the least. I found out later that the swap meet special 650 spread bore wasn't enough for my engine, and the 2.77 gears where just killing me. My exhaust system was also very restrictive. I hope to do much better with this new setup.

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'89 Red Formula 350- 350 .060 over w/ forged pistons, 232* @ .050 cam, Performer RPM, Holley 750 DP, Vortec 1.94 1.50, Accel Coil and dist, Hedman shorty headers, Dual Exhaust w/ cutouts, WS6 suspension, 9 Bolt 3.27 Posi Edelbrock LCA's & Track bar subframe connectors, 700R4, A&A snorkel scoop Eclipse Head Unit, Delco Bose Speakers, 2 12" Pioneer subs w/ 400 watt/chanel amp

vortecfcar

those times are terrible! Im running 13 flats with that combo and am having traction problems. Whats timing at? where are you shifting? does the car seem to have power? give some more specifics

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91 RS W/carbed 350, Vortec heads, performer rpm, Comp cams Xtreme energy 224/230 duration and .477/.480 lift. BFG Drag radials. 3.42 posi,Corvette servoed 700r4, 3000rpm stall converter. Edelbrock TES, 3inch cat, flowmaster with single 2.5 inch exit.
Best time yet to come
13.0 @ 107- N/A
yet to come- Nitrous

This is a Pic of my car in race trim www.tbns.net/billyjay/camero.jpg

Yes I know how to spell camaro- so dont ask. I didnt make the link

BLK87Z

My timing is currently set at 12 degrees and 30 something?? advanced. Im shifting at 6000rpm's , and Im running the 1/8th in about 10 flat and the 330 in 6.6. This was on a mix of 93 and 110 octane.

Ray87Z

What was your sixty foot time? You'd need the worst launch I've ever seen to explain that time though...

That is like at least a second too slow even on a bad day, at bare *** minimum. Really should be no where near 15s...

All I can think is something is bad out of tune, bad plug/wire or something, cam is degreed off, etc, or something along those lines.

And on the bad track idea, what track are you running at? I suppose if you're in Colorado or something at like 5000 feet that would correct out to a more normal time for that setup. [Edit] Nevermind I see it's bristol. That's a fairly low altitude track right? What was the temp and humidity looking like? What was the car's engine temp? Even if all that was bad it still shouldn't be running that slow...

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Ray87Z
-Vortec headed 350.
86 IROC w/ a cammed 305 TPI.
Formerly Ray86IROC.
www.inter-scape.com/Ray

[This message has been edited by Ray87Z (edited August 21, 2001).]

BLK87Z

Guys this is my first time ever to a track so excuse the R/T's but here are my two fastest 1/4 runs Ill give the rundown of the whole timeslip because I finally went out and got them to get a better look at them:

R/T.......(.967).......(.682)
60'.......(2.341)......(2.308)
330'......(6.660)......(6.616)
1/8.......(10.142).....(10.084)
MPH.......(70.73)......(71.01)
1000......(13.130).....(13.058)
1/4.......(15.654).....(15.567)
MPH.......(89.02)......(89.59)

BLK87Z

Yes Bristol I would guess is a fairly low altitude track, the air temp was around 68-70F during these runs and was quite hummid. The track I was told was cold by a fellow racer. This is my first attempt at any type of drag racig but I did cut two decent lights a .589 and a .599 were my two best lights. These runs were made on Friday 17 2001, I made 9 runs the above two(in the above post) were the quickest ET wise, however I guess you have to remember Im running a peg leg 2.73 rear gear, and I have some POS Kelly tires on it, but it dosent seem to have any problems hooking at all. I wouldnt heat them up at all, I would just pull around the water box and stage up both beams then using my 2800 stall I would hit the brakes and let it sit at 2000, then launch on the third yellow light. The car however was getting pretty warm from statring and stopping continuosly in the staging lanes around 200-220 or so and I have a 160 thermostat in it. Please guys I have to get this thing faster the guys around with stock 5.0 Fords are cutting on me cause I have spent so much on mine and they are still quicker. I think the next thing we are gonna do to it is add a 4.10 or 4.11 gear. Any info is again appreciated!

gremlinz28

This is all hypothetical(sp?)

The gears are definetly hurting you. However you should have better times than that! I would go over everything that you could (Igition, plugs, plug wires, timing etc) Check your plugs to see if you are running lean or rich. Check for vacuum leaks. You total timing should be around 35 or 36 degrees (I run mine at 12 initial and 35 total). change your fuel filter, and if there is a way to do this on a carbed motor, check your fuel pressure. Are you running the stock maniolds, exhaust? This will really hurt top end performance!! You may also want to check to see if your throttle linkage on the carb is opening all the way when at WOT on the pedal (I have seen this happen too many times). I know this is a long list, but anything is possible to be causing your problems. Please ignore if you have already done all of this If you figure it out please post back!!

Jason Gamlin
'86 Iroc
350 5-speed

[This message has been edited by gremlinz28 (edited August 22, 2001).]

mss

you should at least be in the 14s with that setup

ATOMonkey

After I put my new Holley mech. 750 dp on my engine the car went a 14.7 according to the little G-Tech meter, so add about .1-.2 to take into account the road might not be flat. My exhaust was real restrictive. You could hear the engine just dieing at about 5000-5500. It sounded like it was going to come apart. I never got to run on open headers, but I'm guessing at least a half second better which would put me down into the 14's solid on 2.77 gears and the transmission shifting like crap. With this new setup as soon as I can get it running, I'm hoping for high 13's low 14's.

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'89 Red Formula 350- 350 .060 over w/ forged pistons, 232* @ .050 cam, Performer RPM, Holley 750 DP, Vortec 1.94 1.50, Accel Coil and dist, Hedman shorty headers, Dual Exhaust w/ cutouts, WS6 suspension, 9 Bolt 3.27 Posi Edelbrock LCA's & Track bar subframe connectors, 700R4, A&A snorkel scoop Eclipse Head Unit, Delco Bose Speakers, 2 12" Pioneer subs w/ 400 watt/chanel amp

Ray87Z

Yeah, wait a minute what exhaust setup do you have? I see there is no mention of it in your post. I just jumped to the conclusion that you had a decent header/aftermarket cat/cat-back exhaust for some reason... Depending on what you have that could be alot of the problem. If you do have a decent setup then I'm drawing a blank again, it'd just about have to be tuning related then...

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Ray87Z
-Vortec headed 350.
86 IROC w/ a cammed 305 TPI.
Formerly Ray86IROC.
www.inter-scape.com/Ray

[This message has been edited by Ray87Z (edited August 23, 2001).]

84zeddd

A plugged catalytic converter might cause
this.You should be running with stock 5.7
cars I would think.

BLK87Z

Guy for an exhaust system Im running Headman Shorty Headers, a custom made 2 1/2 inch y-pipe and from the y-pipe a single 2 1/2 inch custom bent tube back to a crossflow 80 series Flowmaster with dual tips. Id say this is choking the car down quite a bit, as probably is the stock 305 aircleaner and single snorkle with a K&N replacement filter in it.

BLK87Z

Also for spark plug wires Im running Accel Super Stockers or something, and the plugs themselves are Bosch Platinum Series made with a longer shank for the Vortec heads (got them for a 1997 Silverado Vortec). I found ot what may be a small problem one or two of the plug boots is gooy as if its gotten hot and melted a bit when I changed plugs the last time so it may be arching to the header or something but it seems to run really strong with no misses at all. Im very dissapointed in its performance for all the $'s I and my Dad have put into it for it to run this way. I also have not catalytic convertor for the above post!

Ski89Z28

Boy I know how you feel cause I had problems with my car when I did the cam and head replacement and did a 14.12. My problem was a vacuum leak, bad one. Everyone told me is was the gears, 2.77, but it wasn't them. However if I would go to 3.23's I would be much faster.

But as for your problem I think your system becomes air starved in the upper rpms. I think this cause your 60' times indicate that your spinning ... alot! But your mph show your not getting anywhere or no HP at the top end, hence air starved.
I agree with Stephen that a 750 carb would help and porting the heads and larger valves would help too.
If you don't want to replace the cam you can try putting on 1.6 RR if you don't have them on already. This will help with air to the heads too. But a better cam and knowing what you for duration and lift would be nice to know.
Bottom line is that with a 355 motor and the right parts (induction and exhaust) you should still be able to do a mid 13 with 2.73 gears. I can get a 13.8X with a stock intake(TPI) and just a cam and head change and 2.77 gears and I think I can do a little better.
I hope it works out for you, Good Luck!

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89 IROC 350 Auto
MSD 6AL
Custom DUAL Exhaust
Edelbrock Performer 6085 Aluminum Heads
ZZ9 Cam
TPIS Level 5 Chip
And Free mods.
(stock intake, runners and suspension)

13.879 @ 98.90 mph (with 2.77 gears!)


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