Hello I must start out by saying that this is the best sight I have found about TBI, Ive searched the archives,and found a lot of usefull information, tips and trick, I cannot tell you guys how much of a relief it was to find a board about TBI's...

Ok let me start out with my motor.Its a 350 .030over, out of an 88 chevy p/u, Im not sure of the head castings( I forgot), I installed a hydraulic roller cam 0.431" / 0.451, 1.5 Roller rockers, Holley 2"TBI with the holley manifold.Jet stage 2 chip, headers,.700r4 with a 9" with 3.70 gears. Runs great, but my 1/4 mile times were crappy, 15.22 was the best I got.kept spinning off the line..The motor acts like a rev limiter is kicking in around 6000, I messed up and didnt put new springs on with my cam.either that or its my fuel pump(its still stock)..still with me??

Ok this winter I plan to install a either a comp XR258HR or the XR264HR with the matching springs of corse.IF i go with the 258 I was maybe thinking about 1.6 rockers. not sure. I also plan on installing a H/p fuel pump. I found the CFM one, but I also read in the archives about one out of an 85 vette, Has anybody had any luck with these cams??? Or the fuel pumps????

Any Ideas??? suggestions???comments??? anything would be greatly appreciated..Thanks for bearing with me...

 

Sounds like you need fuel, tuning and proper valve springs. A typical TBI system does not like 6000 RPM's and makes most of its power down low. In addition to that, that cam is very similar to an LT1 cam and will run out of steam at 5300 rpm's. I bet you are running very lean up top. You really need to ditch the stock TBI fuel pump once you add any heads/cam set-up. Look into a walbro high volume one. You also want to find out what kind of heads you have and if they can accept the cam you want to run. You will probably need to have the seats machine to accept anything over .480" lift. Also I would SERIOUSLY look into a custom chip for your car. those Jet chips aren't worth a dang and your car will come alive with a custom one and run the way it is supposed to. Other than that it sounds like you are on the right path and have a nice set-up there. You will need some suspension to get that power to the ground.

 

First off 15.2 for your setup is pretty good. That cam is probably only rate to 5000rpm. The stock heads suck for high rpm revs cause they stop swirling the airflow after about 4000rpm (just a guess), so above that the swirl port is a restriction.

And the stock spings will probably float @ 5500rpm.

As far as cams, I really like mine, its the 268, 276 comp computer cam on a 114 lsa. Still lots of tourque. Stay away from anything with less than 114 lsa, cause it gets hard to tune, and you'll lose tourque.

You want more power well....you'll need about 24 lbs at those holley injectors for your setup.

Fuel pump: theres only really one pump to go with for my money. Thats the walbro 255.
http://www.autoperformanceengineering.com/

 

I once contacted a chip reprogrammer and he told me that I wouldnt see no benefits over a custom chip verses my JET.

.Who and where would you guys reccomend to reprogram my chip,?? I dont really want to spend 300 bucks on a custom one...

With the walbro 255 will I need a regulator?, or will the holley TBI take care of it via the return line????

I plan on doing the head machineing work, for the cam...I also have a 1" spacer I need to install also..

How would I get 25lbs at the injectors with the pressure regulator on the holley??
I really appreciate all the help and info you guys have givven me and I need more...Thanks

Matt

 

Above all other mods and parts , I recomend getting the stuff to burn a custom chip.

The holley regulator should have an adjustment screw.

 

That is pure BS. Your car will be a whole new car with a custom chip. The Jet chip is so close to stock it is rediculous.

 

yes, the best bet is to spend $200 and get all the equipment to do your own chip. that is where you will see real improvements.

 

Where Do I get the equipment to do this???

 

Quote:

Where Do I get the equipment to do this???

Check out this article from the tech articles page https://www.thirdgen.org/newdesign/tech/promintro.shtml . It will tell you where to get the stuff as well the basics of prom burning. Read the article and start doing as much research as possible. I agree with the others that a custom chip is what you need to get the most out of your mods which, seems like a good setup once you get the heads, springs and fuel pump worked out. Good Luck!