vetteguy112233

Tonight I decided to take her to the local midnight drags and here is what my 1978 SA, zz502 BBC (shifting at around 5000 rpm's), Hedman headers, 850 Speed Demon, MSD ignition module, stock Borg Warner 4 speed transmission, stock rear end (except gears which I think are 3.08's), ran.

Here are my exact times:

R/T ---- .423 (I know... I can do a lot better here)
60' ---- 1.980
330 ---- 5.573
1/8 ---- 8.512
MPH ---- 85.86
1000 ----11.058
1/4 ----- 13.193
MPH ---- 107.86

Corz

13.1 with a 502?

Thats a pretty impressive 60' but something just doesnt sound quite right about those numbers given the power your car should be making. Were you spinning badly in second gear or something?

litevette

I know you had fun, but you should be having a lot more fun with that monster motor. Did you have the whole family in the car or were you towing a camper? Not trying to rag on you at all. I just know you have a lot left in that thing. But even still, there are a lot of C6 guys that would like to run a 13.1 !!!

Jason Staley

Watch out you'll get addicted to it .

About what the others are saying .... yeah, your car should have alot left in it. But it will come with time - shifting and tuning can make a world of difference in a manual car.

Not bad times though, I just got into the 12's after several years of test and tuning and tuning and tuning ......

Little Mouse

Shifting at 5000 does a ZZ502 only pull to 4500 with power. Stop the
granny shifting.

Glensgages

..... since he has not mentioned what type of tires he is using, I'll assume that vetteguy112233 is traction-limited, and this is what is keeping his ETs in the 13-second range:
I've seen a box-stock ZZ502-equipped mid-'70s Corvette, with an automatic/10"-converter, 3.90s and 29" x 11" slicks click-off 12-flats @ 112, shifting at 5500 RPM.

vetteguy112233, for your own personal-information and comparison, my Z28 runs 8.22 @ 85 in 660', and 12.85 @ 105 in the quarter:
keep-up the good-work!

1Z87L8

look at his trap speed hes got to be loosing it in the first few hundered feet.

427Hotrod

Sounds like you had a great time!!

I have no doubt there were some traction issues and some easy going off the line to get it moving without scattering Vette rear end parts. You got a 1.98 60' and that ain't too bad on street tires with a stick.

The ZZ502 doesn't make much power past 5000...pretty much done at 5500 maybe 5700 tops. You could probably push shift points to that range and help a little.

You picked up 22 mph on the back side of the run which isn't too bad either. It was pulling pretty decent.

Quicker ET's are going to come from traction on the launch and on the shifts.

Where do you live? Any idea what altitude and what was weather like that day? It can make a big difference.

Keep it up and be careful not to break stuff. If you can keep similar launches, push shift points up a little and do some tuning, you also will be deep in the 12's with some decent weather conditions.

The point is to have fun and it sounds like you did! I even had fun reading about it!!

JIM

vetteguy112233

I am running street slicks for the tires, 295-65-15 BF Goodrich, so there was very little wheel spin. It shot out of the hole pretty good. I had very very little wheel hop, but then it hooked and took off. The reason I guessed 5000 rpm's is because my shift light and original tach do not match up. The shift light is 500 rpm's faster than the original tach for some reason, so to be on the safe side, I set the shift light at 4800 and figured by the time I reacted to the light, my shift would be right around 5000 per the light and if the light is wrong then it would be 5500 per the original tach. The max recommended rpm is 5800, will those 300 rpm's make a difference?

What do you guys think is more accurate, the original tach or the shift light?

I also forgot to mention that I live in SLC, UT and we are about 4000 feet above sea level, so the altitude isn't helping me at all.

Little Mouse

ZZ502 showes 502HP at 5200RPM oval port heads on a 500 cubic inch motor. no wonder they are keeping the engine at so low an RPM
level. I guess it has a low profile dual plane manifold to help choke it to death some more.

Fevre

Think your low end is all forged so you can spin that sucker to 7000, you need to shift above your max hp rpm's so when the next gear comes in you are higher in hp scale, seems a 6000 shift would pick you up a bunch of et.

vetteguy112233

Shifting at 6000 won't hurt anything?

Little Mouse

Vetteguy If its true that your engine is only making power to 5200 RPM I would try shifting it at 5600 RPM. Next time you take it to the track see if shifting it a little higher up helps the MPH and ET. Your lower end could withstand more RPM
but your valve springs with your hydraulic roller would be the reason MAX. RPM
is 5800.

Little Mouse

ttt

Glensgages

The big selling-point of the ZZ502 isn't 500+ HP, it is the 567 ft/lb of torque it makes on readily-available pump-gas, with 'matching' components and a very mild camshaft profile:
even-with 567 ft/lb of TQ, that Rat simply can't 'pull' those 3.08s out of the hole quickly-enough to show what it can REALLY do!


4.11s behind the 4-speed, with 28" slicks would put the car at 112+ MPH @ at a relatively safe 5500 trap-RPM, which is low-12s at WORST, and you could possibly run 11s in optimal conditions.

Glensgages

We put my '79 Z28 on an emission-machine years-ago, to check-out the tach, and it was within 15-20 RPM of what the 'scope' said at 5000 RPM (much to our surprise ), so I'm fairly-content with my tach, but I still use a shift-light for racing:
it is easier to use during competion, and it is idiot-proof
(if you knew the driver, you'd understand..... )


The shift-light 'SHOULD' be as-accurate, if-not MORE accurate, than your OEM tach.

Just my thoughts.....

Sayfoo

3.08 gears and 4000' elevation? Sounds pretty good to me.

vetteaddic

What kind of air cleaner?still running stock hood,could be your not getting air thru the air cleaner cause of hood clearance, if thats the case

Budman68

Sounds like you had a fun time. 13's in high alt. is great. A little practice and maybe a gear change and low 12's are in your future.

pef427

A nastier cam usually is the best first mod to a crate 502.