I posted in the TPI thread with no results....


I'm replacing the original injectors on my 85 305 TPI. I want to change the Camshaft and lifters too while I have it torn apart. Looking for a moderate change on the Camshaft. What suggestions would anyone have for a replacement cam and lifters? With the increase in cam size, should I increase from from the stock injectors?

This is my first TPI, I've several 2nd gen carbed engines, but new to the Fule Injectection.


All input is welcomed! Thanks

 

I'd first talk to the cam company, they'll ask you about your car (auto/stick, gears, ect), they can give you a couple of choices. Or follow someone elses build & talk to them.
If its a mild build you could probably get away w/ increasing your fuel pressure, by using an adjustable fuel press. regulator.

 

Not sure where you're going with this...

You can change the injectors in a matter of minutes. A few wires, a handful of screws, done.

It will take you an entire weekend, BARE MINIMUM, to do a cam swap; assuming you're experienced at cam swaps in general, and in TPI motors in particular (which somehow I'm suspecting is not the case). The entire intake tract including plenum and runners and base, distributor, valve covers, rockers, and THE WHOLE front of the motor including accessories, alternator, brackets (some of which involve the exhaust system), crank damper, and timing cover, must be removed. Additionally the cam will not clear the car chassis; the radiator, A/C condenser, and some of the brackets in front of that, will have to come out. This is .... not like a 2nd gen.

This is like asking, I have to change my oil this weekend, might as well put new rings and bearings in it while I'm at it, what rings should I use?

Then there's the matter of tuning... you have the slowest, crudest ECM in any TPI setup, the one-year-only 85 one. Any significant change you make to the engine will require effort in this area as well. Are you prepared for that?

I'd suggest, if your injectors are bad, change em out, and leave the rest alone, if it's not broke. The car you have is not a good candidate for a cam swap to begin with. I'd recommend not going back with the stock injectors; get a set of used Bosch 19-#ers off ebay, 2 sets maybe even just in case there's a bad one somewhere, and see where that takes you. They come in all manner of V8 Frod products and can be purchased all day long for $50 a set or less. At that time, if you haven't done a tune-up (plugs, cap & rotor, and O2 sensor), along with regular maintenance like fluid changes, catch up on all that.

You don't have 3.42 gears unless somebody has changed those out at some point. More likely, 2.73s. If you're basing your estimate on your "tach" (I use the word loosely) reading, you need some more research. While catching up on the overdue scheduled maintenance alluded to above, make a point of looking at the gears while you're changing the fluid.

 

I probably removed more than I needed to for the injector swap, but I'm looking at it as a chance to clean it up in the process. I did a top half rebuild (from the heads up to include cam, lifters, intake and carb) on my 76 350 many years ago. It sure was not as complicated as the TPI set up.

I don't mind the time and effort of the work it if would help performance. Would it be worth my time to upgrade the ECM? Or would there be additional items to replace/upgrade along with that change as well?

Would I be better just changing the injectors and any sensors, egr stuff, etc. while putting back together along with putting headers and new exhaust on it? Many of the other threads I have read seem to indicate that may be the best route for these 305 TPI models...

As for the rear end, I got the 3.42 ratio from the stamping on the rear-end housing. I will be changing the fluid in the near future and will have to confirm that with the actual gears I find in it. I have only had it for a year now, so there is no telling what has been done to it in the past 25+ years. However it does seem to be mostly stock and original.

I just want a good weekend cruiser with a little "bite" to the performance. I will save the radical changes for when I get another 2nd Gen with a 350!!

Thanks for the input, it's got me re-thinking the cam change.

 

He actually probably does have 3.42 gears. In 85 the only gears available were 3.23 and 3.42. No 2.73 gears in 85. And many did have the 3.42 gears.

 

Thanks for the input!

 

burnout88, I see you have a 305 TPI. Have you done any upgrades to the motor?

 

I guessing your car is higher mileage based on the age. I would not recommend a cam swap on a high mileage flat tappet cam motor. Also, the 85 TPI's have a decent camshaft in them already. It is actually the same spec cam as the 350 TPI car. Redlines at 5,500 rpm instead of the peaunt cam 5K in the 86 and later 305 TPI's.

Personally, since you have it apart I would just add a set of 1.6 roller rockers, and a high flow TPI base and runners. Rockers will give you .30 increase in lift which would be equivalent to a mild cam swap without the major surgery on the motor. Also, since you have the 3.42 gears and the factory hotter camshaft your motor will like a little more airflow on the top end (hence the base and runners).

The combo together should net you an easy 25 to 30 hp. You should also port your plenum like this http://www.corvetteplenum.com/Basic%...%20Service.htm

All of this will require no custom programing for the computer.

My mods are listed in my sig. Now get to it!!! And post your progress.

 

Thanks burnout, sounds like some great options!!

 

Does anyone happen to know the numbers on the stock Cam in the 85 305 TPI?? Just curious now that it seems it's the same as the 350 TPI Cam.

 

Found the answer to my own question...

https://www.thirdgen.org/forums/tpi/...cs-85-tpi.html

 

The info is also listed on the main page here. With a lot of other general tech info on your car.

https://www.thirdgen.org/1985-chevy-camaro

 

Thanks, this was actually the page that came up when I first started looking stuff up last year after bringing mine home. Been stuck on ThirdGen ever since!!

I'm glad I researched this before buying a cam, sounds like a have a good one and can spend that money on the rockers!

Never ending source of information on here, Thanks for the input!!

 

Another mod that you may want to consider is a high performance torque convertor. Anything from a 2400 rpm stall and up will net you some solid times in the quarter mile and 0 to 60. Up to a half second in the quarter mile.

You with an intake, rockers, torque convertor, and other misc small mods you could probably drop over a full second in the quarter mile times. The torque convertor is a lot of bang for the buck.

 

I think the Torque converter has been upgraded along with a shift kit (it will scratch 2nd with little effort), I will have to go through the paperwork the guy gave me when I bought it. I remember seeing some trans work done.

I'm looking into Rockers now and gonna try to find someone local to port and polish the plenum.

This will be my project for the next month or 2... I'll keep ya'll posted!

 

Another question to through out there...

Want to change the timing chain while I have it apart too. I see many options from just a chain, to chain sets and I also see gear sets (eliminating the chain all together).

What is everyones expierences with these options? Good, bad and ugly.

 

Best option is a good quality chain, of the "true" roller (as opposed to the genuine faux roller) variety. If it costs less than about $30, it's NOT a roller; instead, it has bushings, and it will "stretch" (wear) worse than a stock Link-Belt style. The Comp 3100 or the Cloyes one are the best cheepest options; aound $45 for either.

You MUST replace the chain and sprockets together AS A SET. Weird inscrutable things happen when you mix parts, but one thing is for sure, you won't like any of them.

Avoid gear drives. They offer no benefit whatsoever for s street car, and make a ridiculous amount of poseur noise. Kind of like taking a 90 HP chick econobox commuter recycled beer can and putting a 6" diameter non-muffler on it and driving it around in 2nd gear all the time... it'll make people think you only just did graduate in the last couple of months from a skateboard to something with an engine, and it sounds like you're a little past that point in life.

The plenum isn't the restriction. Messing with it is worthless, only good for convincing yourself you've accomplished something, and only works if you're real gullible. It only matters after LOTS of other restrictions have already been addressed.

Best bolt-on you can do, is headers. GOOD ones. Not just the cheeeeeeepest thing that the law will allow to have "headers" printed on the box. After that, a good 3" cat-back.

 

Thanks for the timing chain input. As for the plenum, my plan is to just clean the heck out of it before putting it back together. The only mod I plan on adding to the intake system is an airfoil.

As for headers, I am looking to replace them along with a 3" cat back system. I have noticed that headers have quite a gange in price (as low a 125 a set up to 700+).

When you say "GOOD" ones, what are some reccomendations?? Obviously I don't want to cheap out, but I am on a budget. Hoping to spend no more than 300-350 on headers.

 

OK, looking to order the injectors this week. Since I am not changing anything in the intake system I will be staying with the stock 19 lb injectors. I was looking at the Bosch III (which require an adapter to fit). Then I came accroos a deal on some standard Bosch that are a direct fit (both remanufactured). The standard Bosch are half the price and have a 1 year warranty. (the only performace upgrade I'm doing with this current project will be headers and a 3" cat back exhaust)

My question is, is there any performance advantage/disadvantage between the 2 models??

Here is the link to the standard ones I found on ebay;
http://www.ebay.com/itm/180733357620...84.m1423.l2649

What ya'll think??

 

Here are the Bosch III injector I found;

http://www.southbayfuelinjectors.com...o_305_TPi.html

 

Any input on the Bosch injectors. Model II's vs Model III"s

 

The IIIs have a better fuel atomization pattern.

Not sure how much difference it really makes; maybe a bit of driveability and/or economy, I doubt it amounts to much in the way of power though, but in general, as small as the difference in price is, I'd go with the best I could get.

I have IIIs in just about every FI vehicle I own. 3 out of 4.

 

I can't seem to edit this...

THe "adapter" thing is because the IIIs are slightly shorter, maybe .100" or so. IIRC you can grind the boss where the fuel rails go to let them go down into the hole in the base farhter.