Ok guys, Im going from stock 305 TBI 92 RS to a 79 Impala 350 with 305 heads, headers, and a cam *prolly 2000-5000 range computer cam*... Need to know whats recommended for a TBI unit. Was thinking of the holley 670 but will it be enough? WIll probably have 300+ HP Im thinking. What size injectors should I run with the setup? What intake manifold will work? WIll all sensors and linkage etc. hook up? Will my 14x3 open element air cleaner still fit? If not what size will I need. Any further experiences or info also appreciated, thanks.

 

I would first read the "all go here" stuf at the top of the page. Both the 454 and 670 TBI's have 2" bores. Your injector size will be determined by your overall engine set-up and what type of power it will make. It also depends on how you want to tune these injectors. You can have smaller ones run at high PSI or have large ones run at low PSI. If that motor has 305 heads on it it will be choked pretty good and could get by with 350TBI injectors. You are going to need a TBI intake that has 2" bores or use a carb intake with an adapter plate.

 

Neither. Just get the 2 inch bored stock unit on ebay and it will save you a lot of headaches in the future.

 

Not a bad idea as everything would link up easily... Is it going to be as good as the other 2? Happen to have a link to where they are selling one? Thanks.

 

It's on ebay. Actually I think it's better than the other 2 as they are supposed to flow 700 cfm. There was a recent thread about this. Try searching for "inch ebay" or some combo like that.

 

I bought one of the 2" throttle bodies off of ebay last week. I think it's a damn genious of an idea. He simply took a SBC TB and bored it out to 50mm. All of the sensors and linkage hook up just like stock, and he even throws in some injector pod spacers. Hell, he also puts in some specially made throttle blades that are shaved down.

I've also asked him about getting a hold of some 65# injectors so hopefully he'll be a source for that as well.

 

I almost went with the bored stock tbi, but then I got the 454 because for the same price I got 80 pph injectors. When I get home for spring break I'll do a tech article on swaping over.

 

Can anyone link me an auction with one of these bored out stock units? Really interested, can't seem to find anything like that on ebay. Or if there's a guy that does it and sells em on ebay, maybe his screen name so I know what to look for. Thanks.

 

Just so you know you'll need to do some chip tuning if you change the TB and the injectors. You might get away with out it if you use the stock injectors but you'll be leaving alot on the table.

 

I would like to ask why your using 305 heads on a 350. There are two things that you will need to address.

1. Compression will be raised considerably going from 72cc to 58cc combustiom chambers.

2. Valve size is to small to make decent power.

If you don't mind running premium gas and don't plan on any higher of a redline than the stock 305 has, it will be a low end torque monster. Why not run the stock 350 heads if there available?

Steve

 

Well I thought Id gain a good deal more power from the raised compression, since I can't really afford good heads. I can get almost new 305 heads from a friend for 50 bucks. Since every person on this board is saying Im crazy though Im beginning to wonder....I always thought it was a good way to raise power cheaply. Dont care about running 91 octane. I just want 300 HP as cheap as possible without taking apart the bottom end of the 350 Im buying, which has about 60k miles on it *aside from I will be doing a cam* Open to suggestions though...how much can I find a decent used set of heads for ? My friend will be doing a little work on em to. Oh and yes, the regular 350 heads are already on it, its in a running 79 trans am right now. The motor is from a 79 impala.

 

Did you ever get a chance to see how well the engine ran in the Trans Am?

There is a couple of cheap alternatives you could consider. Iron L98 or 350 tbi heads. The 305 heads would work and probably give you great bottom end torque and a decent mid range.

 

heres the link for the thread for those that watn to read it


https://www.thirdgen.org/techbb2/sho...+tbi+unit+ebay

 

Don't forget something here that i think you are overlooking. Yes the 305 heads will raise compression but they will reduce flow. Flwo will make much more power than raising the compression ratiom. I to would recomend the 350 TBI heads or evern better the L98 (350TPI) heads. Just call your local bone yards and see what you can get. You could get a set for around 100 or so and some port work will really make them shine. 300hp is not hard with the shortblock you have now. You just need a good cam, intake and head combo. You are using TBI right? If so, you are going to need a cam that is TBI friendly. That won't be so easy to do if you are using a non roller block and cam.

 

Can you reccomend any combos? Yes Im using TBI, and I dont relish the thought of the older non roller block. I'll take your word, I really dont know myself, this is all first time for me. Maybe I could find an engine from a 350 TPI camaro in a yard, would that be good? I do have to consider what I can find for prices, but I have a lot of mechanic friends who have friends in yards etc. Whatever heads I do get will be ported some.

 

A 350 short block would be a great start. You could use the ehads off of that, port them and have a great foundation. You can still use your TBI and stock valvtrain stuff. Plus, the L98 cam is pretty good in stock form and would have all the EFI friendly specs that will make it tunable. You will get a lot closer to your 300hp goal this way. It will also be a lot cheaper than taking that old block and having it converted to a roller set-up. What is your budjet if I may ask? You can still buy a brand new L98 shortblock (minus heads) for about 1300 or 1400 bucks. Not bad for a brand new piece that will accpet all of your current stuff on your car now. Either way you look at it you are going to be spending money. Because you are going to have to get a new fuel pump, possible larger than stock TBI unit, and last but not least, full exhaust and tuning stuff. Because of these costs it may behoove you to just go ahead and get a new L98 shortblock or get one out of a yard and have it cleaned up and checked out.

 

Well over the next few months I'll prolly have like 3000, but also need to get all this stuff installed. I've also been tossing around the idea of just buying a real z28 with all the stuff I want already done...seen a lot of em for like 5000 on ebay or local sometimes. Also, I could just save and buy a fully done 300 hp motor on ebay for like 2k. I can't go TO high in the hp in my car though, because then Im worried Id blow the transmission fast or rear end or something out, and if I spend all I've got then somethin goes Im screwed and with no car. So right now its a balancing act, but I know I have to do something soon. At idle my engine oil pressure is just above red right now, it's not gonna last forever. If time was an option I might wait longer, just trying to get the best overall car for a decent price within 3-5 months. If I could find a complete nice 300HP engine for like 1500 that'd prolly be cool, but its tougher to find one catered to a TBI. At least have to buy an intake manifold, engines made for computerless cars usually have cams that are to aggressive. ANyhow these are the thoughts goin through my head haha.

 

Myz, does you car smoke or burn oil? The low oil pressure could just be a bad sending unit. My oil pressue guage reads lower that it used to, a lot lower, but I know it's not reading correctly because it did it all at once.

Steve

 

I burn about a quart every 200 miles