https://www.thirdgen.org/forums/sout...at-do-you.html

This is my progress I have been tracking at the 1/8th mile track with my bolt on auto 91 305 TPI. Through the various posts, I have updated what has been done to my car and the improvements it has made.

I have gotten tips from people in the southern california section but now Im wondering what everyone else here thinks.

 

Your comparing current summer times to winter times. You've added gears which have made up the difference in winter to summer temps. 1/4 times will be at least .5 slower than winter times. Run it again in cold temps with nothing changed from today, and you will see some nice improvements. Does that make sense?

 

That makes perfect sense, but Irwindale is open from 5:00pm-10:00pm. Every time I've raced its been pretty cool out but I understand what you are saying. Even though its cool, temps are still warmer in the summer time.

 

Yes, DA or density altitude can play a big factor. If you are comparing improvements to the car you have to take the DA into account on the days you are running.

 

One thing I have been thinking about are the valve springs. The car has 189,xxx miles on it and I bet it still has the original valve springs. When I got the car it only had 143,xxx miles on it, so I doubt the previous owners ever changed them. (I am the third owner of the car) Plus the power curve on the dyno didnt look solid. Regardless of performance do you guys think it would be a good idea to change them for reliability issues?

 

I think you'd be completely wasting your time going in there to change springs, especially with a stock cam. How new are the plugs/wires/etc? Check the condition of the plugs, and run the car in a dark area at night and look for a light show.

 

Even with the high miles on the car, you think it wouldn't be worth it? Well the cap, rotor, and the wires are about three years old. I got them with the Jegs tune up kit so the wires are the MSD 8.5mm. The plugs are Accel u grooves that I put in last summer.

The funny thing about the light show is a buddy of mine were looking under the hood a couple weeks back around 10:00 at night and we noticed the porcelain glows when the spark goes off. I didn’t know you could see that. And if that is not a good thing please let me know. Lol

 

I might as well list everything I have done to the car in this thread too.

-K&N filters for air lid
-180 thermostat
-Air Foil
-SLP Runners (port matched)
-Edelbrock Baseplate
-SLP 1-5/8 shorties
-converted to hi-flow magnaflow duel cats
-Magnaflow 3 inch catback
-March underdrive pullies

-Black poly bushings throughout the whole car
-TDS Wonderbar
-TDS sub-frame connectors
-Tubular control arms
-adjustable panhard bar
-fourthgen 10 bolt with 3.42 gears
-LS1 aluminum driveshaft
-Zr1 wheels
-Nitto drag radials

 

There is usually a glow, just make sure you dont have any stray sparks. Check the grounds from the battery to the block to the body, make sure they're clean and tight.
As far as the springs, they dont usually just wear out. I see a lot of talk about it, but unless you go through the time of actually testing each spring before and after there is not really a lot of substance to that argument. They do kind of suck though, but if the power output is really as rough as that dyno sheet shows it looks like a misfire.

 

I changed the springs on a high mileage 305 once and the only thing that changed was the engine seemed slightly smoother at high rpms.

 

Thats a reason I thought changing them could help my at the track.

For the sparkplugs I pulled the #1 plug and it looked like their was some reddish film on it. Just a little. I realize now I need a new socket. Since I have the headers the pipes get in the way.

 

Absolutly, I'll bet those springs don't even have 80# on them.
While you're at it, new seals would be in order.

 

So Don, what springs and seals do you recommend?

 

Manley, contact Kevin (e-mail)

 

With a stock cam, and typical 5500 rpm operation, I dont know if new springs would help all that much but certainly wouldnt hurt. You dont need much spring for a stock cam. Comp 981's would drop in and be plenty with just 100 lbs on the seat. Hard to say how much pressure stock springs have lost over 189K miles, but I dont think it takes much pressure to control a stock LB9/L98 type cam over a 0-5500 rpm range.

If you dont mind doing the work it would be nice to replace the springs/seals to have fresh heads.

 

I was also going to use this opportunity as an excuse to put in 1.6 rockers. I know I would definitely need new springs if I did that. lol

 

I would do the cam, not just the roller rockers if it were me. I think an XE256 or XE262 would do the trick. Also, some swear by a srock Lt1 cam if your roller. This would no doubt put you in the solid 13's with valvesprings. Your what 14.25 now? Comp Cams CamQuest show's a TPI 305 with an XE256 cam to be a nice driver, with power up everywhere. It also shows the XFI260 to have the most power, but I have never seen anyone with that cam.

 

I’ve thought about a cam but it’s a high mileage engine (189,xxx). I have always been told not to put a cam in a high mileage engine. According to this site http://www.wallaceracing.com/8th-quarter.php I'm about a 14.5 in the quarter. I’ve also read on here that putting 1.6 rockers on is almost the same as putting in a LT1 cam.

 

Do a compression and leakdown test, if both are in spec, go for it. Whats left of the valve guides is going to be gone anyway with just the 1.6 rocker arm swap. Go for broke!

 

Cams are fine to swap in at any mileage as long as the the engine is in good shape. I have put one in a 170,000 mile 305 with success.