Ok you guys, looking for a little advice here...actually a lot. About 6 months ago I bought a 92 305 TBI, and have slowly been accumulating parts for a build-up. I was wondering if the parts I have now will overwhelming for the 305, what I will need to go with (Bigger Throttle body, etc.), and I KNOW I will need some custom PROM burning and tuning...but I know absolutley nothing about that...so I was looking for some guidance. I know the Bottom End is fine, because the previous owner, who happened to be the original owner, was not aware of the tach being off progressively, and he says that it was like that from the factory...so as far as anyone (beside's me of course!) goes...the car has red-lined at 3 Grand throughout its entire exsistince! lol...I did a Comp. check last week and all cylinder's are within 3% of each other after 130000...can't get much better than that!...The drive train is basically all stock for the moment...Here's what I have done to the motor so far...
-K&N open element with Edlebrock Housing
-Removed EGR
-March Pulley's
-Ultimate TBI Mods
-Low temp Thermostat and Fan Switch
-Accell Cap, Rotor, High-V Coil, etc.

And here's what I have in my room waiting to be put on....
-081 casting heads, Oven baked, Steel shot blasted, Magnfluxed, New valve guides, Cut for positive valve seals, flame hardened exhaust seats, CBN Resurfaced (.010), 3 angle Serdi valve job, New enlarged 1.94 intake...stock size 1.5 exhaust valves, New .525 lift valve springs, New seals, and New hardened valve locks. They are not yet ported, but I will be working on that soon or I have a feeling it will kill my cam...
-Comp Cams Xtreme Energy Hydralic Roller, 264 Grind, .488 intake lift, .495 exhaust lift. @108 intake centerline and .050 lift 212 intake and 218 exhaust duration, with 112 degrees of lobe separation...
-New Hydralic roller lifters
-double roller timing chain
-All Hardware and gaskets needed

Basically I need some Advice...what are my options on intakes, what are the best options as far as headers go, and I do NOT need to be smog legal as I live in the great state of Texas. I was wondering if the stock TBI will be sufficient...I know it will be pushed to its absolute Limits...but I'm getting short on cash for the moment. And I was wanting to know ANYTHING anyone can offer as far as PROM burning goes...because I don't have the slightest knowledge of where to even start, but I know it will be a MUST after the heads/cam swap. Any other advice of Recomondations are ENCURAGED! Pretend it was your car...go WILD!!!!

 

Chevy High Performance is doing a build up of your same engine in the current issue. The next part will be in the September issue.

They went with Vortec heads and a new Edelbrock TBI manifold for those heads. However, your 081 heads (ported and polished properly) should be able to produce similar power. That is where I would start on the manifold issue. See what Edelbrock and others have as a stock replacement. Some folks really like a single plane replacement for the stock TBI unit, the Victor Jr. for instance. Lots of those in the want ads for a reasonable price. But if you're low on coin, keep the stocker until you're a little more flush.

CHP is already pushing 300 hp using the stock TBI. They are going for a Holley 4 barrel TBI replacement in hope of more power.

Interestingly, they are also using a healthy sized roller cam. Pick up the issue and check it out. They have a place burning a custom chip for them, also. That might be a good source for your chip.

If you need some help in the head porting department, follow the link at the end of my sig.

Good luck

PS The guys on the TBI forum can and will help you out lots. A good bunch.

 

I've got a 305 tbi too, I'm at 115,000 miles so I just did a tune up. I was pleased to find out my compression is great, all 8 cylinders running at either 200 or 195... well I was wanting to install some new heads, cam, headers, the works... but after talking with two separate mechanics and even my Dad (I'm34 btw) that if I were to add heads to my engine I could potentially 'blow the bottom end out' or make my top end 'too effcient' and end up creating an oil burner instead this happened to an old ford work truck of ours years ago... but I was thinking since my motor is still in such great shape I could get away with it...

I've never seen that concern expressed here... maybe I haven't been around long enough? either way I'm depressed, guess I'll have to wait untill I can just transplant.

Maybe that's something to think about tho 92? I'm no mechanic, maybe there are precautions you can take without having to entirely rebuild?

 

vp,

I think that is an old wive's tale. I have rebuilt heads on my high mileage 305 and it runs a LOT faster than it used to--and doesn't burn oil as a result.

I say go for it.

 

Definatley not a wive's tale. If you have a high milage engine with borderline worn bores/rings, then rebuilding the heads could put it over the brink and the engine can start to smoke after that.

But - so long as the bottom end is OK, you shouldn't have any problems.

 

I HAVE heard of that old wives tale....and although I havn't heard of it happening to anyone I know, well, I've considered it. I could go in and re-ring/bearing the bottom end, and have the block Hot-Tanked to clean the oil-galley's etc. but the cylinder walls still have visible cross-hatch, so therefore minimum wear...and I have More than adequate Oil PSI and next to no Sludge in engine...so I think I'm gonna go for the build without this...and if it starts to smoke...well....S*it....

Thanks alot Bull...I will be getting a copy of CHP today...is this the first issure where they address the 305 build, or is it a continuing series...? I decided against the vortec heads simply because I could get the 081 heads so much cheaper, even after all the machining, etc. and fully assembled they were still cheaper...but of course I'm not ALL about cutting corners...you can't be with these cars...so keep the recs. coming yall! Thanks alot

 

Yes, this is the first of the articles on building a TBI 305.

 

Ive seen engines blow apart after head and cam upgrades as well but you need to consider the fact the added hp also tends to add a extra weight to your foot as well. If the rings are in good condition you usually wont have a problem with higher cylinder pressure due to smaller chamber heads.

This 305 build looks good but with all the time and money your putting into it you should at least rebuild the bottem end. Why chance anything?