Hi everyone,

I was doing the ultimate TBI mods, and, like an idiot, I made the post the throttle plates bolt onto too thin. SNAP! doh!



Anyway, I guess its time to get a new TBI!!! A bit sooner than I was planning, but oh well. I've been looking at the Holly 670, but I was wondering if I should do the intake as well. The exhaust side is all set (headers & 3" catback) so I should be able to handle more incoming air. But, I don't want to do the cam and lifters at this point (for financial reasons).

My question is what intake manifold should I get OR should I pull off the stock one and machine it to 2" bores?

This is a L03 and I am running the stock heads. The only things I've done are the exhaust, an open element and a hypertech chip. I don't have access to PROM burning yet (but hopefully in the future).

Basically, if I get the Holley TBI and a new manifold, I want to get a combo that will work with as little "modding" as possible. I've read here that the EGR valve can cause a lot of problems with certain manifolds. Also, hood clearance can cause a problem (I have the stock hood with the cowl inductor). Should I go with a manifold for a carb and get the adapter plate? Should I delete EGR to avoid any hood clearance issues (no smog police round my parts)? What's involved in deleting EGR?

Can you guys post combos with a similar setup to mine that have worked and any crazy mods you had to do to get them to work? Any help would be appreciated! Thanks!

-Andrew

 

Welcome to the boards. I frequent Rochester myself a couple of times a year. Cool place. Anywhoo, to properly use the Holley 670 or to delete EGR you will have to get into chip burning. The stock TBI unit can go pretty far until it is maxed out. You will only have problems right now if you use it with the stock heads and cam. I would look for a unit out of a junk yard. They usually go for 20 bucks or less. As for what intake, that is tough. Take a look at the links in the "new to TBI" thread at the top of the page. There is a ton of info on which intakes are good for our cars. Since you have a cowl induction hood, your selection range is much higher. I would keep EGR until you can change it in the chip to dissable it. It is one of those things that is actually good for cars that are desinged to use it. If you want a true easy bolt on I would look at the performer TBI or the Holley TBI intakes.

 

Unless you are going to do some severe mods to you engine, the holley 670 is way to much. I would just find a TBI unit at a junkyard and rebuild it or just use the butterflies from the junkyard one. Turbp city also offers several modified stock TBIs.
WWW.TURBOCITY.COM

As far as shaving the butterfly shaft only do enough to reduce turbulance. anything more is overkill.

 

Good advice! Thanks guys!

I will look into finding something at a junk yard.

 

too large a Tb will kill your general drivability. i think my 2.00 TB's are a bit to big for 350 cid at crusing rpms. flows too much air too soon. needed more pumpshot to balance it out. too bad we dont have sequential secondaries!

 

Is there ever a time when its worthwhile to run a bigger TBI on a LO3? Maybe not a 670, but one from a 454?

For example, would an LT1 cam + a bigger TBI + new intake be a good combo, or will the stock TBI always be sufficient?

Thanks!

 

You woulkd need to add some heads and exhaust to complete the equation. The stock throttle body would be insuffient at that point. the throttle body you mention when modified will flow approx 540 cfm which is very ample for most small block performance applications.

 

it seems the consensus is that fueling is the issue when mods done. IOW TBI is mre fuellimited than air. maybe someone disagrees? seems we can flow air more easily than fuel. boring existing TB's may be a better choice than jumping to a 2.00 inch TB from holley or GM. they are both 2.00 inch. i would consider going larger but not 2.00 for a 305 cid.