Hi there folks LOL i have A 87yr. Camaro it has a 305 tpi (I think thats LB9 motor) I just recently bought A used 87 350 4bolt-main block. My budget is a little tight but im am willining to purchase the needed parts to make my conversion work!!. If theres any1 out there plz help me with my confusion, im using the same 305 heads for now,which is A stock set up.Can i use the same injectors (19lb) and the same ecm and prom.Will I be able to run this set up for now and have a drivable car

Plz HELP Thakz
P.S. I have A new knock sensor(for A 350) and a adjustable fuel pressure regulator

 

It probably will run with the 305 injectors, and eprom, but not well. The 305 heads are only 58cc, so your compression is gonna be high too.

Really, you should get some 22lb injectors, a 350 eprom, and some 350 heads before you do this build. Some junkyard l98 heads are probably your best bet if you are trying to keep costs down (they should have the same intake bolt pattern as your 305 heads too).

How bad shape is the 305 in? If it still runs strong, I would suggest saving and getting some nicer things to start with. (Better heads, 24lb injectors, eprom burning equipment... yada yada yada) But it really depends on what you want out of this build.

 

Thanks!!! My 305 pistons are sezied in the block.So the car wouldnt be able to run at all?,with the 305 top setup, Can it at least be drivale untile I upgrade the heads?.And can vortech heads fit on my block with out any machining? Thanks for your time all advice is good advice LOL

 

Just want to get it running for now,but i have intension on going all-out later on down the line.I do plan on running a twin turbo setup later on it( I know first my forged bottom end, Hi flow heads, and turbo cam in lifter setup,But I just want to pull the car out of the damn graveyard(87 T-top Camaro)but what are some pointers you have for an inspiring young Gear-Head, that wants to kill those pesky rice rockets
Thanks for your input

 

on my 92 ive got a built 355 but the valve seals went out so i put back on my 305 heads and it runs fine also i upgraded to a 350 computer but have a 305 hypertech chip on it and it does fine for now so you should have no problem for now it should be driveable jus fine it also ran fine with the 305 computer

 

I recently bought an 88 IROC in which the previous owner had started a swap from a 305 TPI to a 350. He told me that the block, heads, etc came from a 91 C1500 pickup. He ran out of time, money or know-how (probably all three!) and I got the car at a realy good price. I finished the install using the original induction setup, injectors, etc., from the trashed 305. I also used the original wiring harness and ECM and re-used mano of the original sensors. I'm still trying to get things dialed in correctly but overall the engine runs well. THe point of all this is that, at least for the short term, your project is feasible!! Good luck.

 

The 305's heads can be really great heads since they already have good flow numbers. So, unless you buy some new heads off of ebay that come in a kit with roller rockers and choice of either 1.5 or 1.6 ratio and strengthend rods.. for about $450+.. you should otherwise take those 305 heads to a local machine shop and have; a three angle cut and bowl job, ported, 2.02/160 size valves installed, new seals and springs. You'll have really good heads and you'll know that everything will bolt up. Getting new heads with larger valves will develop more power as a rule of thumb than stock 305's when you shop. Even if the flow numbers vary. I researched flow numbers on those heads and found what difference it was just with larger valves vs hp.

On the swap. Get a tuned 350 prom to work with your setup. 19lbs injectors will run just fine until you decide to upgrade. 24lbs injectors will require the prom to get modded further, otherwise if not expressed the prom will be tuned for a hot 350 running 22lbs since they are standard those years. You said you have the proper knock sensor for the swap... you also need to get a Electronic Spark Control module for a 350.

 

if you need to purchase injectors...save 10% using discount code: TG11 at checkout

www.southbayfuelinjectors.com

 

Hey all, looks like I’m resurrecting a 10 year old thread.

looking for some input, 2 years ago I bought a 87 GTA that was originally a LB9/MM5. The car sat for 15 years, before I got it running again. Someone back in the 90s did some serious mods to it, and I’m looking for some fuel pressure help.

the car was modified in the following
L98 short block
running the original 305 heads (I’m assuming they got bigger valves)
non-adjustable regulator
19lb injectors
SLP tri-y headers and CAI
Smog system gutted and removed
Based on the lope I assume it has an aftermarket cam also LT4 hot cam?
dual cooling fan conversion

since I bought the car I put a ported base plate on and an adjustable regulator.

I never measured the original fuel pressure and I don’t know if the pump is stock or not.

I have the fuel pressure adjusted to 49 psi right now.

My question is is that a good pressure for high compression heads, or should I dial it back to 45 psi.

 

Stock is about 43psi. Adjusting fuel pressure is a crutch for combating short comings like too small injectors, or trying to compensate for mods without tuning the ECM. It's pretty much a hack with limited usefulness. A relic from the days of "computers are scary! give me those underdrive pulleys, a 160-degree POWERSTAT, some 12.5mm plug wires, and a Hypertech airfoil!" Seriously it's pretty much a joke in 2019.

 

Drew, understood. I’m not trying to modify the car without doing a tune or using a hyperchip or all of that nonsense. This car was already tuned with a custom tune and the PROM was burned (no MOATS chip) way back when. The last time it was driven before I got it was 2002, and these mods had already been done. The car is already mean, and makes plenty of power for what I need. Remember I said it is a 5 speed car, so the 305 chip was already modified for the bigger cam, 350 displacement, etc. The car was tuned with the 19lb injectors, my question was more directed to the guys that were tuning these cars before the vortec heads we’re readily available and guys were putting the 081 heads with bigger valves on a 350 short block to take advantage of the higher compression, and high exhaust velocities and better scavenging properties of the 081 head on a 350.

i just put an adjustable fuel pressure regulator in and a ported baseplate when I was getting it running again.

i wanted to know if perhaps there was a heavier spring that may have been put in the fuel pressure regulator to boost pressure. If nothing else, I’ll monitor my plugs to see how it is burning the fuel, and see if it’s running rich with 49 psi.

 

Higher pressure wont necessarily make it richer, the A/F ratio is managed by the ECM and the O2 sensor. Putting a big injector on it won't change that, changing the size of the injector allows the engine to see the correct A/F ratio if the O2 sensor calls for it.... If your engine is not modified, you won't need a bigger injector, the correct pressure ensures that the injector can deliver if it is asked to....

 

That's only true of closed loop operation..... so cruise and idle. WOT operation is a lot more muddy. If you increase fuel pressure, when the ECM reverts to open loop fueling (such as in WOT operation) then pre-calculated table values are used and increasing fuel pressure will directly affect the AFR. Some BIN's will hold over rich fuel trim (BLM) data and use it when it transitions to WOT, but not lean fuel trim data..... what the ECM does is somewhat unpredictable unless you know the proclivities of your particular BIN file.

But the short answer is - DO NOT change the fuel pressure unless you have made arrangements with management across the street at ECM central or the results will be unpredictable and universally bad.

GD