hey guys,
i'm very new here and new to the v8 world in general. I just acquired a 91 RS with a 305 tbi. it's go a flowmaster exhaust(not sure if it's just the muffler) but everything else is pretty much stock.

now i've been reading a lot over the past week or two that i have had this car. I come to not want to fully develop this 305, but would like to do some things. new exhaust from the heads back...what hedders would you recommend and why? Long tubes? short tubes? another thing i don't want to do is change the heads. i may pull them if i put a LT1 cam. but will probably not. are the stock heads good enough for the LT1 cam? i was just gonna get a new intake mani...probably edelbrock. also...how hard is it to use a 454 TB? would a 454 TB be better than a 305 TB modded(unshrouded)?
i was going to also burn my own chips but have moates do the soldering and all that jazz. should i change the ECM? i don't want to do any re-pinning. i've had some experience tuning newer cars with a DHP Powertuner, and from some screen shots of some other adjusting programs for these cars....they have the same tables minus the MAF since mines don't have it.

so basically here's the full extent of the set up i want..

ultimate tbi modded tb or 454 tb(not modded)
edelbrock inake(which one should i get?)
hedders, to a new y pipe to a 3" exhaust
LT1 cam(i heard it's best to be installed 4 degrees retarded)
Custom tuned chips burned by me.
AFPR...does the stock regulator modified work just as well as a aftermarket AFPR?
and a walbro 255

i'm gonna keep this set up until i can afford a crate motor. which will more than likely be carbed. also keep in mind that that won't happen for like 5-10 years down the road. so i just need the car to be reliable.

what are your estimates on what kind of power this will make? i was hoping to run low 14's with that @ 100+ mph. but i know that's a little much to be askin a little 305 with that little mods to do.

thanks for reading...sorry about the long post

 

Sounds like you have a pretty good plan of attack, pretty common build.

I would get the chip burning stuff right now though and start tuning your engine as-is before you change the cam just so you can get your feet wet.

For headers, I'd say it depends on if you're keeping a cat or not. Do you need to stay emissions legal? If so, go with shorties. Same with the intake manifold, do you need to keep EGR?

With what you're doing, I would keep the stock TBI, and maybe do the ultimate mods to it. At least for now don't change it, all it does is throw in another wrench into the tuning process because the IAC is bigger on the 454 and coupled with the bigger plenum of an aftermarket intake you will have some troubles tuning.

AFPR, just make your stock one adjustable, that is explained how to do up in the stickies. That should give you enough room with the stock injectors assuming you have a new fuel pump.

LT1 cam should be a good choice, but I wouldn't retard the cam timing. You are keeping the stock heads which do not flow very well and won't make much power high in the RPM band. Retarding the cam will push the powerband of the cam upwards and you want to keep it low to take advantage of the better range the heads can support. I would just install it straight up.

Another thing is you are going to definitely need rear gears. Do you have an auto or manual trans? Get a set of rear gears and a posi carrier to go along with your cam swap. That's all I got for now, sounds like a lot, good luck.

 

thanks for the reply. that was very useful to me. i don't have to check emissions, but i will atleast try to keep the egr since i've heard that it actually cools the intake plus that's another thing that i don't need to "tune out" of the system. although i don't know if current hedders available has the egr attached.

so this is what i should do then according to your reply
stock TB, modded ultimate TBI mods style
intake manifold
hedders...was looking at summit racing and they have these flowtech ones...or hedman ones. i can't believe they are so cheap.
LT1 cam installed straight up
gears....how low? what brand? i have a manual
chip tuning
diy afpr

 

Sounds pretty good. I've got a manual too, I run 3.42 gears, make sure you get posi too. It's a matter of preference on gears, I like the 3.42's they made a big difference out of the hole and I can still cruise on the highway easily. Some like 3.73's, that's up to you to look at the pros and cons.

I would get an intake manifold. Lot's of choices there, I have the Holley 300-66, it's nice but I can't find an EGR valve that will fit so... Edelbrock Performer RPM is nice, not sure if any have EGR provisions though, I don't think so. Otherwise just an Edel Performer.

Headers: Flowtechs are cheap and small, don't bother. You want a 1 5/8" primary into a 3" collector. If looking through catalogs for exhaust, always buy the stuff listed for 305/350 TPI cars single cat. They will have the bigger pipes.

 

For gears on my '92 I went with stock take outs from a 4th gen. I stepped up from 2.73 to 3.23 and a posi. It cost me $140 off ebay and I've been very happy with it. I considered 3.42's but I drive quite a few highway miles and didn't want my milage to suffer too badly (I lost a couple mpg). I have a 700-r4 with 27" tall tires, which, combined with the gears puts me right at 2k at 70mph. One thing to watch out for on the gear swap is the vehicle speed sensor on the transmission. The problem I had may be unique to the automatic, but the speed sensor is different depending on the number of teeth on the driven gear in the tailshaft. Thankfully, I only needed to change the driven gear to correct the speedometer, but the additional side load placed on the speed sensor due to the increased diameter of the driven gear (more teeth necessitated the larger diameter) caused the shaft of the vehicle speed sensor to break after about 500 mi with the new gears. All I had to due was buy a new VSS that fit matched up with the number of teeth on the driven gear.

 

what about the ignition system. would going to a msd set up gain me any power? changing the ditsy?

 

I thought like that once. Changed some components to aftermarket parts. I had some ignition problems and tracked it down to be a bad ignition module so I swapped on a "high performance" Accel module, but still had the same problems. Tested and replaced many parts only to find that the Accel module was bad right out of the box. It tested worse than the stock one which was also bad. Replaced it with an AC Delco part and it all works perfect.

Long story short, tuneup the ignition with all AC Delco. I wouldn't use anything else anymore.

 

yeah i've been searching(more) and i think it's pretty much a concensous that these cars don't need a msd, unless you go carbed. Which i may do at some point....i don't know really what i totally want. that is also the reason i don't want to go into the heads. i was also reading a back article on the CHP mag and saw a third gen camaro with a q-jet. they go it to 13's but with nitrous. I was a bit disappointed that they couldn't even run a 14.9 with heads and cam. i thought that was pretty sad. granted that was with an auto and stock stall i believe. but the mph wasn't even that great.

 

There is some good reading on a couple of cars that comes to mind that are similar to your goals I think. Search the names and there is some good info on what you can do without doing much if anything to the engine. In other words mostly bolt on parts. The most recent is 91 RockS. His car is a good example of what you can do with the long block remaining stock. (Before his head change mod's)

Here is part of a post of his...........

[L03 timeslips, making progress...............
Went to the track last night to see if I’ve made any progress with the L03 305 over the winter/spring. Best time from last fall was a 15.561 sec with 2.371 sec 60’. Mods at that time were open element, headers, and 3” cat back with stock tune.

Mods since then include cat delete, air delete, underdrive pulleys, rear gear swap (3.08 open to 3.73 posi), and prom tuning. Goal for this spring was to break into the 14’s.

Results from last night . . . .

4th pass: 14.835 sec, 2.030 sec 60’ : Best of night. Great launch with little wheel spin. Good shifting.

Timeslips from passes 3 and 4 attached.

I know 14.8 is nothing to brag about, but considering this is on 305 TBI with a stock lower end, cam, intake, injectors, and throttle body, I'm pretty happy with these numbers. I think it's proof that a mostly stock, well tuned 305 can perform pretty well.]


So as you see gains can be made.....DM