Hi all,


First time post here, although I have done plenty of reading.


I have had my '90 Camaro for a couple of years now. It is a LO3, T5 manual, T-Top, cruise control electric windows, AC (before the previous own ripped most of it out as they could not be bothered to trouble shoot the gas leak...not bitter at all) car and I have slowly been working through various mods to get it where I want it. It currently has (not that it particularly matters); headers, smog/cat delete, open element filter, exhaust, wonder bar, Eibach springs, adjustable panhard bar, KYB's front and rear and subframe connectors I need to find the time to weld in.


Onto my question. I am based in the UK with no support for the factory TBI tuning wise so the plan has always been to switch to a Holley Sniper at some point (on the LO3) which would then basically allow me to build a 350 (possibly a home-brew 327 as that would suit our roads/the driving I do better) to anything inside of 500-600hp for not an unreasonable cost financially (I am undecided between the quadrajet and the normal sniper as, like the 327 idea, the quadrajet style is possible more optimized for use over here but both are more expensive than the more run of the mill route). Just


On to my question:

We are saving to buy a house currently (not a small matter over here with house prices as some of you may be aware) so the Holley EFI/engine build is probably not going to happen certainly this year and maybe next which means I am getting itchy feet and want/need(?) more power! Everything that has been done so far can be carried over to the new engine so far and I want to carry on with that theme (i.e. the headers, exhaust, smog delete, air filter etc).


What I am wondering; is whether the stock TBI is 'clever' enough to run correctly with a simple 1.6 rocker arm swap on the stock cam presumably with a couple of extra degrees of timing? Obviously, in the ideal world you would want to get a chip made to get everything optimized fully but will it run well enough without being touched? I would love to do a cam swap for similar money (by the time all the small bits and pieces are together) for more noticeable gains but from my reading that is never going to end particularly well without access to to a TBI tuner...


I am just trying to do what I can to the 305 without getting in over my head with no TBI support and be cost effective in that I can swap the bits to the new engine when the time comes. If anyone has any ideas for cost effective upgrades that fall into this category whilst I have parts in my summit basket they would be open to consideration. It is far from the end of the world if the TBI will not support the rocker arms; it is just something I thought of whilst building a bit of a bulk list in my summit basket as it is more cost effective with shipping duties etc to the UK to order as many parts in one go as possible.


Thanks for taking your time to help!

 

I think you can get away with quite a bit of modifications before the (quite dumb by modern standards)ECM is bothered-main thing is idle manifold vacume should be decently close to stock -much of the rest of the tuning can be done by tweaking fuel pressure,timing,using different injectors,and the like.I don't think the 1.6 rockers will bother anything.If you install a 350,you can use the injectors and ECM prom from a 350 equipped TBI vehicle of same eraickup trucks,etc.

 

On the 350 TBI I had in my G20 van back in the day, I put 1.6 full roller rockers, swapped to an edelbrock performer rpm with a TBI adapter, 454 TBI unit with stock 350 injectors, added tri-y headers and already had a decent catless exhaust. Ran very well on the stock 350 van chip. I played with the timing and fuel pressure to get it to make the most power at WOT and let the ECM remove the fuel it did not need at part-throttle.

 

A 327 would be a major improvement over a 305. Damn near anything would be an improvement over a 305. A Chevy 307 would be better than a 305. The 305 is crippled by it's tiny bore, which then means small valves and ****-poor breathing.

Of course, a 327 implies a two-piece rear main seal, which then requires a different flywheel/flexplate.

1.6 rocker arms will be fine on the stock tune. This assumes that everything else is up to spec--cranking compression, timing chain slack, distributor wear, cam and lifter wear, etc.

Beware the T5 transmission. You put any power to it, it'll shatter. They're best installed with wing-nuts so you can change 'em without tools when they break. Like Doritos, crunch all you want, they'll sell you more.

 

As others have said, bolt on upgrades (air cleaner, headers/3”exhaust, 1.6 rockers) and advance the base timing 4-6 degrees will run fine on the stock chip. Stock they run rich at wide open throttle anyway, so the mods will bring the a/f ratio closer to optimal. You could also add an adjustable fuel pressure regulator for some fine tuning of the a/f ratio.

 

Running a lil more fuel pressure doesn't hurt an L03 either. I ran a 14lb spring on mine with 6deg base timing and it seemed to give it some power. I did have a custom chip burned also but not at first when I made these changes. Car ran great.

 

Thanks for the feedback all. I will grab some with my next Summit order then.

The car only has 60k miles on it and 49k when I go it two years ago so we should be all good regarding wear and tear. The lifters I changed the lifters and one cried enough pretty quickly when I got it and started using it daily. It sat for 16 years until 2016 and then the previous owner brought it and put 2.5k on it in 3 years so there were some bugs to work out. The one that is still outstanding (I have the parts) is the valve stem oil seals which I should probably do, but having deteriorated rapidly once it started being used they seem to be in a slow process of self healing going by the much less regular plumes of blue smoke out of the exhaust on hot starts when the oil is thin especially.

Regarding the T5, it is hanging on in there although both it and the rear end are definitely not 100% happy. Fortunately the only Tremec dealer in the country is only about 10 doors down from where I work so it will get a T56 when the T5 lets go! Still on the 2.73's and it is a daily with UK fuel prices; so the plan would be to get a close ratio 4th gen style T56 magnum as first is exactly the same ration as the T5 and 6th is exactly the same as fifth so the cruising manners will be identical same just with closer more evenly spaced gears in between (no huge chasm between 4th and 5th as with the T5). The very long term idea would be then to fit some steeper rear gears (3.27 or something mild-ish) and swapping the 5th and 6th cluster for the Ford ratios if possible so 1sth through 4th would be much more sporty and suited to our roads but then 6th would be even better for cruising especially for European trips with speed limits higher than the 70mph we have here. Almost no chance of this happening though. That said, my Grandpa lives in Mallorca so the dream is drive it down through France and Spain and get the ferry across. The only problem is that you can get there and back by plane for £100 or less and he has a car there that we use so it is hard to justify at minimum of 6 times that (probably closer to 10) or more just in ferries and getting across the channel before you even consider accommodation on the way down and fuel. One day though!