Note: I am even more disappointed by my spelling!!! :rolleyes:

I finished installing my headers a couple of weeks ago and went to the track Saturday. My first impression was that the headers made absolutely NO difference! By the end of the day I will say horsepower is up, but not nearly as much as I had hoped. The most disappointing thing was I did not improve on my best time! But overall I can see that my mph is up, on a less than ideal day - temperatures were in the mid 80s. The good news is the car ran really well and seems to run cooler now.

Here is the "problem" - My best timeslip from Nov 2, 2002 (must have been cooler weather) is an outlyer. The typical pre-header timeslip before the headers is 100.5 to 101.5 mph

11/02/2002 rt=0.785 60ft=2.162 1/8mile=8.989 mph=82.28 1/4mile et=13.804 mph=103.45


Here are the 6 timeslips from Saturday:

0.524 2.361 9.539 78.69 14.465 101.41
0.446 2.283 9.279 80.64 14.106 103.17
0.652 2.372 9.312 80.61 14.166 102.74
0.646 2.299 9.194 80.78 14.036 102.7
0.719 2.249 9.208 79.54 14.08 102.23
0.675 2.27 9.269 80.33 14.106 103.08

I know, I know! Improve my 60ft and I will be in the 13s consistently :lol:

I am guessing I have added only about 20 hp? I was hoping for 40. MJ


[Modified by MNJack, 2:41 PM 7/1/2003]

 

You may have to richen you mixture to realize the benefit of a less restrictive exhaust.

 

Mark,
Your MPH is the horsepower indicator, the ET is more a function of driving skill. The fact that you added 2MPH in less than ideal wheather shows you have more HP. Your should check your plugs for carb richness as you could be lean with the new headers.
Ed

 

Look at it this way, the headers improved low end torque so much you're spinning more off the line. :reddevil

Seriously, what did you have before as compared to now. I agree with the other post, timing and carb adjustment may be needed. Even further, some header/cam combos work to hurt low end torque rather than help.

 

:iagree:

 

yeah 103 is indicative of mid 13's youll be there ,check your plugs.

 

Forgot to mention, I stepped up the primary jets from 72 to 74 after I installed the headers. (left the 45 rods alone). I think I may actually be too rich now - I am going to try 73. On Saturday I was launching very gently - no wheelspin at all. MJ

 

Are you headers hooked up to a stock 2 inch exhaust?

 

That is a good question, what are the rest of the mods on the car, especially exhaust related. Headers won't do much unless you have other things set up properly to match.

That means parts from the heads, exhaust pipes to the mufflers. If your heads have small exhaust valves are have crappy flow numbers then that is the restriction, next if the pipes aren't big enought or you still have the 2-1-2 setup then that is another big problem, cats are usually resrtrictive and last are the mufflers themselves which must be free flowing ( read loud ) :D

 

I have a 68 L36. Stock exhaust was 2 1/2 inches. I replaced it with a stock-type exhaust. 2 1/2" but the rear pipes are flattened. I have flowmaster 50s. I had to use flexhose to connect the headers to the rear exhaust pipes. A trip to the exhaust shop is in my future. Carb is Qjet (Edelbrock Qjet replacement 1901). Running stock style points, distributor. Not 100% sure but believe engine is internally stock, 68 L36 427, 390 hp.. MJ

 

The other posts are right on the money. If you have checked your jets and plugs, you may want to take a look at your ignition system. If you haven't already, consider having your distributor recurved. I hear Lars kits make a vast improvement It's also important to have good exhaust flow with a full 2 1/2 collector on the back side of your headers. Are you getting enough flow to the carb? Header installation should give you an average increase of 20 to 25 horse power..It's the fine tuning that really starts to add it up.
:D :steering:

 

You may also have to do some rejetting and make some timing changes. Your engine can now breathe better so other things have changed.....