Ok I have a question. I am currently running th ePerformer intake and Holley TBI on my car. its a 92 model 355 with a stock LT1 cam in it. the car will only pull to about 4600-5000 max. The LT1 cam is good for more than that, and I am wanting to get a bigger cam as well. Is there any way to get this Holley to turn more RPM's?

 

What kind of heads are you running and what have you done to change the PROM. Even a moderately tuned 305 TBI with heads and LT1 cam will pull to 6200 rpm all day long.

 

Well the chip is done by PCMFORLESS, it will not go past 5000, but the heads are a sucky set of 72CC open chambers. I am planning a head and cam swap if I know for sure I can get more RPM's out of the unit.

 

Your limited RPM's are because of those heads. I would bet that your tune is only a rough geuss as well. Unless however you constantly sent them data logs to dial everything in. Just chaning those heads alone and adjusting the prom should make that motor pull to the moon. All TBI units are for the most part not RPM limited (to an extent) but instead power limited.

 

Ok, also who would be be teh best recomended to do a chip for me?

 

Any aftermarket place would be able to help you. As for TBI cars I would send series of data logs to Biran at www.tbichips.com . Lots of guys have great success with his stuff. However take all of this with a grain of salt. You will see your best gains by burning your own. Aftermarket chips (even with your data logs) are only a best geuss and leave a lot on the table. However, they are a great start to get your car to run while you learn how to burn your own.

 

thx for all you help man, I have a couple of guys here local that do their own chips, guess I need to hook up with them. So I should be able to get 62-6400 out of this intake and TB with a correct tune?

 

Deffinatley hook up with those guys that can burn their own stuff. You will owe them a brew or two when they make your car run awesome. For now your main restriction is the heads. I cannot judge the state of tune until you have someone look at some logs. Your buddies will help you out there. I just realized that you said you had a performer intake. is this the performer TBI or carb with adapter? If it is the TBI intake than you need to chamfer or bore the inlets bores to match the bores of the Holley 670. If not there will be a ridge that air has to go over before it enters into your intake. This will cause turbulent flow which is not good for filling the plenum of that intake.

 

It is for the TB, it is bored to match the 670, I had just heard that it wouldn't be good for that many R's.

 

I am glad that you boreed yours as well. I bored mine so that it will be ready whevever I go with a 2" TBI unit. Anyways, th eintake should be fine now. It is the same design as the carb one but with the top modified for TBI applications. Carb intakes will still flow a bit better but you should still be able to reach 6 grand. Any plans for what heads you are going with?

 

Looking for some 64CC 202 valve heads

 

I would keep the lookout for some L98 heads. With some port work these heads can flow awesome for any TBI application.

 

Hey Crack, if you are going to change the heads you should get a new intake as well. The tbi performer is only good to about 5000 to 5500 rpm on a 350. A good single plane would be better, say something like a Weiand X-Celerator. A set of World Products heads or a set of Vortec heads would also be a good starting point to build on. I also would look into a LT4 hot cam or cam kit depending on the set of heads you buy. Give me a ring sometime and we'll do some data logging.

Steve

 

72cc is like 8.0:1 compression man

 

The holley TBI will pull high rpms. Mine took me to around 6,400rpm, in which at that point, I think my tables in the chip ended and the injectors went static.

I was running a performer style intake with adapter plate on the 383. Swapped to the rpm airgap, and felt a huge difference, and better pull up high. Then I opened up the adapter plate and yielded even more. But, I am also running a higher comp. and different heads and cam.
Steve said it well. When you swap heads, you may want to think about a more aggressive cam depending on your goals, and a single plane intkake.
Check out the dyi prom board as well, and look into the prominator.

 

Thx for your input guys. I will be running the CC306 cam So I am going to be hoping to run upwards of 64-6500.

 

r90,

Have you put your engine and combo together yet?

Well, I have finally finished building my engine and am just waiting to get my truck up here over the next 2 weeks so that I can take my car off the road and start pulling and installing the new engine. So you guys definitely recommend Brian for a chip? I have no idea how to burn one but am slowly reading all the posts in the DYI.

Thanks

Bill

 

weberusn,

I am currently having the tranny rebuilt, and finally got a cherry picker, so the 383 should be out within a week or so to go in for a rebuild. I'm really satisfied with my previous setup, so I don't plan on changing too much. Depending what is wrong on the bottom end, I may go with a 4340 crank and stronger rods. I may or may not go with the 1.6rr-not sure yet. Hopefully, I get everything swapped into the '91 come july.

I definetely recommend brian at tbichips.com. Also keep the prominator in mind.

 

r90,

Make sure that you post your progress. I am really interested to see what happens with your car. Oh yeah did you say you spun a rod bearing on your combo before? I built up a 4 bolt main 383 with vortec heads also. I will snap some pics of the new engine and put them up here for you all to see. I just have to paint the motor first.

Have a good one,

Bill

 

Bill, I'd like to see some pics of your engine. What intake did you end up going with?

Progress on my build/rebuild is slow but steady. I am currently shooting for late june/early july to have my entire setup in. I have been working my but off (60-65hr weeks)as to hopefully afford everything to do things the right way the first time. I just ordered Spohn's subframes, and an a/c delete pulley. My tranny problem ended up being a blocker that had busted, and is currently being rebuilt with D&D Performance parts. Next on my list is a moser or strange 12 bolt w/ 3.42s. Still doing research on why it isn't a direct swap.....but so far I've come up with swaybar and panhard bars not working-and brakes.

 

R90,

Hey man. Yeah I will take some pics once I get the valve covers installed on there. Well, I ended up going with the RPM Air Gap. I really like what i have heard about it and what other people had to say about it. Plenty of people said they can notice a significant difference with this intake.

Why don't you just build up the 7.5 rear? I heard that they can take pretty good power with good axles, posi, gears, and rear end girdle. My buddy runs a 406 sbc with the stock rear, posi, and gears and has no problems. He says he put out over 500/500 at the flywheel. Also he runs nitrous and slicks at the track and has not had a problem yet. I mean maybe this is kind of unheard of, but he does it. I am still debating on whether or not to go with and after market rear. I guess I will just wait to see how this stocker holds up.

Keep me posted on your build up.

Bill

 

I really like the rpm airgap. The only drawbacks imo are the need for an aftermarket hood, limited adapter plates, and icing of the tbi in cold weather. But it did make for a drastic change over the standard performer intake. And an aftermarket hood not only looks sweet, it saves some weight. I only experianced icing at 40* and cooler, and that was with ram air. I think swapping back to the open element and sealing the cowl would have prevented that in cold weather.

I should have pics of my adapter later this week. The modding was worth it, but you will see what I am talking about it when I get the pics up.

As far as the rear goes, I am not taking any chances. My old setup consisted of a slip off posi and 3.73 Motive gears, new bearings and what not with the install kit. Needless to say, after a trip to the track with some cheapy 255's in the rear @ 28psi, the rear end started whining like a !@#$%. Maybe do to the harder hit of a manual tranny. My buddy literally shredded the teeth from his ring and pinion in his '91 z. The engine was a stock N/A L98 as well (a slew of other mods though). Needless to say, I don't want to take any chances, and though not a direct bolt-up, the 12 bolt will handle my power level, and save me some drivetrain loss and weight in comparison to the 9"

 

I agree about the air gap, its great, but cold weather is a problem, I kinda solved that but unbolting my cold air tubes.

I have just got my motor running good (after the winter tear-down) I spent alot of time opening up the plenum and adapter plate on my intake. And I polished every thing, the intake (a dull polish), my 454 tbi which I ported as far as I think one can with out going to bigger butterflys. I polished my heads alot too. With all that said, my engine runs great, lots off power, It caught me off gaurd the first time I floored it, I tached a little over 7000 by accident. To me my ported and polished induction, was the biggest power increase I've ever had.

The 670 holley should push a 383 to its redline with out too much trouble, as 90camarors proved.

 

R90,

Where is a good place to get an adaptor for the TBI to go on the intake? Did you make your own or have it made for you? I am looking to purchase one in the next few weeks so any info would be great.

Low1500,

Hey man does porting and polishing make a huge difference? I don't really know much about it or how to do it. Do most machine shops do port and polish work. Oh yeah I just got a truck like yours. It is a 1993 Chevy 1500 standard cab with a stepside. The motor that is in it I built but nothing special. Just a roller 350 with vortec heads. Pretty nice though I like it alot. Where do you get all of your aftermarket parts for interior and stuff like that?

Thanks guys,

Bill

 

I do think that porting and polishing made a huge differnce, Its not that hard, all you need is a good 1/4 rotary tool, a good book, and alot of time. I spend over 30hrs doing my heads and intake this winter. I don't have alot of interior mods, but my latest and greatest was captians chairs out of a 98 gm truck, there the absolute best truck seat ever, in my mind.

 

As far as the adaptor goes, I made my own, just because I didn't like holleys.

 

Low C1500,

Hey man. Can you reccommend any books on porting? I have a great rotary tool just need the no how. How did you make your own adaptor?

Bill

 

I went throught the process of making a plate in this thread.

https://www.thirdgen.org/techbb2/sho...ht=tbi+adapter

It was for a 350 tbi, and also before I had a carb spacer.

As far as porting, Standard abrasives has a good info on there site. I just used a rotary file bit, and wire wheels to polish. The abrasives seemed to expensive for me.

Also this has got some good threads for porting. It all depends on what kind of heas your porting. Too me porting was a great way to pass time this winter while the truck was on blocks.

 

low c1500,

Good post. I am going to find some metal and build one myself now. Thanks for the idea and the savings in money.

Bill

 

Weberusn,

I am using the Holley adapter plate, mainly because I haven't fabbed my own yet. Like Low C1500 mentioned, the holley adapter is not of the best design mainly because it has the tbi so far foward. The bores actually overlap the intake opening (check cheapy drawing of the way I have mine setup), which I would imagine disrupts airflow and atomization. I would really like to know what the holley engineers were thinking. I also had to grind the rear of the adapter plate a bit so my fuel lines would fit, because they are braided.

This drawing kinda gives you an idea of what it looks like after the adapter plate is opened up. Hopefully I'll have a digital camera this week, and take some real pics.

 

The only thing I can think of, is that holley made the adapter to keep the same linkage geometry for the 454 tbi engine, between the tbi and throttle bracket.

If the hood clearence is avaliable, I really recommend a carb spacer, this allowed me to blend the wider (side to side) tbi bores into the sqaure bore intake. Also where my adapter plate meets the spacer there is only about 3/16 wall thinkness on the spacer......so a gasket wouldn't really work.. I ended up using silicone for the gasket, and then putting a layer on the outside as well to prevent the silcone being sucked in the plenum. Not the best , but silver silicone doesn't show up to much. Also it worked very well. I had vacumm leaks last year, and nothing is worse for drivability.

 

Guys thanks for the info. It is good stuff. Hey should any metal fab shop sell that aluminum? Probably a stupid question.

Oh yeah do you think that the walbro 255 fuel pump is needed? I mean do you think that the 190 is sufficient?

Thanks

Bill