i still say stock l98 350 tpi motors are capable of consistant 14.1-14.2 runs without timing adjustments b/c thats what my car ran stock

It really depends who you talk to. It all depends on track prep, condition of tires, and suspension condition. I believe that GM claims that a stock L98 runs like a 14.4. Don't forget that I did mention that I was running on bald @$$ street tires too. Maybe I could run like 14.1 without timing adjustment, but at that time, the adjustment helped me out.
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Also, If you look at my times and my trap speed, they are pretty good. Even without the timing advance. so I believe it was a factor with traction in my case.

13’s are definitely possible. I ran a 13.59@100 in my formula 350 with the only major hard parts changes being an SLP intake and cat back.

As far as adjustable fpr’s… I just made my stock one adjustable:

Hey crossfire, How did you go about making your stock fpr adjustable. I am really curious as how to do it. Does it function well? Please let me know.

Took the stock housing, pounded the top contour flat to give the washer somepace to go, drilled it, added a T-nut (here’s a back side showing it with it’s broken off tabs and epoxied in):

The rest is like what’s in that picture.

Works great. Eventually I replaced it with a Holley unit which so far ahs failed and replaced 2x…

Raptor, you only got about a tenth of a second when you went from 2.77 gears to a 3.73??????? I thought there would be more of a difference.......

me too but she wants 4th at about 1000' .I just found the mod to shift into 4th at wot and will be doing it asap .will post new times in drag race forum when i have them .

crossfire : cool idea i may try that 1 also.

83 crossfire, does the same thing about increasing fuel pressure apply to TBI motors???? Thanks, Tom
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Ok, cool I look forward to hearing what happens....How hard was it to make it shift into 4th at WOT..........

Why didn't you put your modded FPR back in instead of buying more Holleys?

TBI engines are supposed to run at 9-12psi, but usually run best at 12-14psi. TBI fuel pressure regulators are pretty much adjustable from the factory, they just have a cap pushed into the hole over the screw or a drop of braze dropped in there, just disassemble and remove whatever is in the way. I’ve taken the end of the adjuster screw, bored a hole in it, threaded it and added an allen head to make it easier to turn, but that’s not necessary.

Here’s the adjuster screw assembly and the plate that the spring rides on inside the housing in a TBI one (it’s sitting in a hole in the top of a workmate type table), cut and threaded for the allen head sitting next to it:


And here’s the assembled deal


If you can’t tell, I can’t leave anything well enough alone…

Well, I got the holly because I liked the pretty machined **** on the top rather then taking a ½” wrench with me to the track and thought “hey, this thing has to be better than some cobbled piece of crap that I made…” (usually the same thought I have before I get pissed off at assorted aftermarket manufacturers), and I was getting free warranty replacements on the holley till I decided that I’m going to do something totally different with the car. FWIW, with the wrench I could adjust my setup on the fly, the holley deal you really have to pull the vacuum lines to adjust. In retrospect I should have never wasted my time and money.

Thanks, Crossfire......Nice pics......

Yeah, thanks Crossfire. Those pics and descriptions helped out alot. I think I may end up fabbing my stock one as well.... But I might use another aftermarket one instead....Will bumping up my Fuel pressure help me out in the 1/4? just curious.....

I found my crossfire (TBI) car ran best at 14psi, my L05 truck at 13-14psi.

My tpi Formula 350 ran _fastest_ at ~54psi, but also left some black soot on the back bumper at that pressure, so I would assume that it was rich somewhere at cruise or part throttle.

So yea, I know at least in those cases it helped, but of course I actually tested it with back to back track runs in all 3 cases.

Is 54psi too much for the street? Just curious since my car is a daily driver.

I never saw any difference in gas mileage or issues other then that I started seeing some carbon/soot on the bumper above the tailpipe. The car passed emissions that way also. My $.02, try it and run it where it runs the best. I think mine started at around 42 or 43psi stock, and I gave it 2 more psi and ran faster, kept giving it a little more pressure till it slowed down and then backed off a little.

Damn, that is crazy with that gear...........How much does that car weigh?????? Mine ran 15.3....Im jelous....must have a 3.73.................Is that a 305, or a 350???????

It says he has 3.73s i think. that is a pretty decent time.... also says he has a 350

Check out my sig, I'm running rather decent with minimal mods too! I believe my barely modded 5.7 car would run mid- high 13's with some ecm tuning and stickier tires. But I'm about to install a 75 shot NOS kit and UMI subframes, lower control arms, and the adjustable panhard rod next week. Hopefully I can break 12's!!! I won't be doing any tuning or tire upgrades, but I'm gonna see how she runs anyways. I'll keep You all updated with my times. Later On

Awesome Rik! Keep us updated!!!