Well I did my cam swap back two weeks ago and I ran at the season opener at my local track. The numbers were a little depressing but I had alot against me. Here in VA we has a freak 75 degree day with high humidity I thought it would be nice and cold but at race time it was 68 degrees and 72% humidity...so that was kinda going against me from the start. I posted a best of 15.022 @ 92.87 mph. I ran an average of 15.075 with 60 ft. times aroung 2.15. So from my fastest ever I gained 3 tenths and approx 3-4f mph. But my fastest ever was in 45 degree weather with low humidity...so it was actually more of a change. So you guys thinking about a complete LT1 swap can expect 4-5 tenths and 3-4 mph in good conditions with the right tuning. BUT...

I think I was running lean and maybe too much timing. It seemed to fall off near 5000 especially in the 2nd to 3rd shift. It also seemed to stumble some and sound a little funny after 4500 in 2nd. My shift points that yeilded the fastest times were 5500 1st-2nd, and 5000 from 2nd-3rd. Some of you fuel pressure guys (a.k.a. Mr JPrevost) could enlighten me as to around what psi I should be runing or a way to increase fuel delivery that would be great. I checked today and I am running 11 psi right now. Also I'm running 8 degrees advanced right now and I'm affraid it might be a bit too much...any thoughts? And what should my total advance be?

Thanks again for the help!

Matt

 

U know with some 3:42's or 3:73's u would knock a good 4 tenths off that time? GET DEM GEARS AND POSI IN!

 

you are not likely to run too much timing, if the car is idling smooth and drives good aroudn town and has good throttle response you have the timing in teh right general area. the bigger cam will actually require a lot more timign than the stock chip is prepared to give the car, so if anything you are running out of timing.
iwoudl say you have to go to at least 12.5psi in the fuel pressure, this is the most liekly cause of the car falling off after 4500 rpm.
teh trick for now is going to be to play with both a little to see what makes the car happiest. for now tune it for your aroudn town driving adn cruising. once you have that so it is all good and feels solid from start up to full temp you will want to do the aldl jumper when you are at the track for a little extra enrichment adn see how it runs.
you coudl definately use soem more traction from the looks of your et and mph. that mph is good enough to go into teh 14.5 range if you hook.
when you aere looking to track the power gain from a particular mod, watch the mph, not the et, mph is the measure of power, et is the measure of hook and gearing.

congrats:lala:

later
tim

 

p.s. on teh traction part of things, you have enough power to pull a 1.8xx 60ft. work on that and the rest of the et will drop like a rock adn your mph will sky rocket.
you only need to get to about 97mph to get into teh 13's, you are most of the way there already.

later
tim

 

I have a question about the springs u got. Did u get the KMO-K-7420 retainers and 7 degree locks or KMO-K-7500 retainers and 10 degree locks? It is recommend by the site that I get these. Do I really need them?

 

Thanks for the imput guys!! I know I need some better gearing and I'm looking for a good canidate for a swap now. I was really happy with the mph increase and I know my 60ft times are a little slow. I hope the gears will help solve a lot of these problems.

91bird305...

You don't need any special retainers...I just reused my old ones. I used K-Motion's K-700 springs and they work great! I also changed out the valve stem seals and O-rings while I had the springs off...might as well.

 

I have bought the same springs, and I'm looking to do the swap soon. I'd like to replace as much as possible on the top end (mostly because my car has 245,000 kilometers), and I'd like to know where you got your stem seals and o-rings.
Is there anything else I should replace on the head/valvetrain area on such a high mileage engine? Other than what I've already got planned (timing chain, valve springs, cam), that is. Thanks.

 

I got my valve stem seals at Auto Zone. About $30 bucks will easily get you the high temp seals and O-rings. I would replace the pushrods (about $40-$60 dependinf on what you get) and I know I wish I had saved a bit more money and got new 1.6 ratio full roller rockers. I would say now that it would have been better for me to have waited until I got the roller rockers because you have to take everything off to change the cam...so you might as well put all new high performance stuff back on.

 

The LT1 cam doesn't breath well past 5000 anyways. My friend's 94 Trans Am sputters past 5000.

 

this is soemthing that i have heard too on a lot fo the boards. i have been told that it is the result of a very poor exhale on teh part of the LT1 heads and exhaust. most guys seem to be able to get the power to carry up to about 5400 once they add a good set of headers.

later
tim

 

I have headers and an exhaust cut out and I can hear the car sputter at 5500. That was the sift point that yeilded the best results. I guess with headers and an open exhaust the LT1 can make power over 5000. I just need to get her running right so I can make a mid to upper 14 pass...then come the gears




burning them both :rockon:

 

That's why I'm going with the LT4 hot cam.
Because of its size, I'm going to skip the 1.6 rollers. Thanks for the suggestion, I'll look into Autozone.

 

on a 305?

 

I would run it in a second

course youll never get it to work unless you have some serious track tuning time with an eprom burner and the knowledge to know what and why to change
or the assistance of a WB o2 sensor would really simplify things

course a matched system is integral aswell

 

I upped my psi to 12.5 yesterday and it seems to run a bit beter when I get into it. The idle is little shaky but that's no big deal...btw I have noticed that ever since the cam swap my mpg has sucked! Either I developed a worse case of lead foot syndrome or the cam dropped my mpg considerably...oh well gotta lose somewhere for more power

 

Hmmm, maybe I'll just wuss out, and switch to carb.
Hahaha! Just kidding, Pablo.
I know I'm kind of diving into this head first, but something tells me that the L03 can take more cam (with a matched system, like Pablo says), than we give it credit for. I'm obviously not going to run that cam with the stock fuel pressure, stock intake, stock TB, stock heads, stock cat-back, etc.

How much is a wide band O2?

 

i plan on wussing out and going carb then in the summer a ZZ4 cam

 

Don't forget that the Lt1 cam has a huge lobe seperation. The more seperation the more "self EGRing" it does to help make power up high without needing to pull out timing. You'll also notice that if you don't degree a cam installation that you'll also find some running stronger off idle and some running better up top. There is more to a cam than just the profile and duration.
You might be asking why have such a high lobe seperation if it hurts high end hp...well without it your computer would go crazy and you'd hate each other. The more seperation the more vacuum and the better emissions.
I can't wait to go to a roller cam. Either zz4, Lt4 or Lt4 hot cam unless I can find an awesome deal on an aftermarket piece.

 

tbi has far more potential than carb

but lets face it, for regular folk like myself, a carb is waaaaaay more convenient


ill come back to TBI in the future (like february of 2002 because im taking a little trip in july for 6 months)
things will be different