darkstar575

Hey there I'm rebuilding a 95' 350 w/ stock aluminum heads(if there are any other heads that I don't know of that would be an upgrade let me know other than edelbrocks etc..., or how much of an improvement I could be looking at with some porting), lt4 hotcam, and headers. I may run some nitrous, I'm rebuilding it with forged pistons and an eagle crank. Other than that it's a stock spec motor, except for the carb swap.I wanted to know which carb would be ideal. What cfm should I be running I'm about to buy either a 650cfm holley dp, or an edelbrock 650? Any comments on those carbs would be great. Also, I'm junking the opti spark distributor and using a Mallory hei distributor. Don't really wanto be paying 180 for an opti-cap... Also if anyones looking for some stock 88 Iroc rims with 4 month old falken tires on them let me know. We could strike a deal.

Klortho

to be perfectly honest.....keep the FI setup, you will kill alot of the torque and hp that the motor makes by swapping over to a carb. Why waste an LT1 on a carb swap when you can take a Gen 1 350, do the same thing to it. IMHO these motors were ment to be run FI with the opti and PCM to take the best advantage of the 10.5:1 compression and still be able to run it on mid grade gas, getting 260-28mph in the process.

Best place to find out more about the carb swap if that's what you have your heart set on is camaroz28.com

Coach Hawk

NONE of the aftermarket LT1 heads are a true upgrade, as the stockers are very very well designed. the ONLY advantage that the aftermarkets have is that they have more "meat" for porting.

Look into Loyd Elliot and Advanced Induction for head porting. Their head/cam packages can make well over 400 HP on a stock shortblock)a friend using AI heads/cam on his STOCK 70,000 mile bottom end is running 12.6 1/4 miles in a 4400 LB Caprice)

Also, I only paid $190 for an ENTIRE new Opti, even though my 100K origional is still going strong. I wanted to have a spare "just in case"

darkstar575

I noticed there are alot of mixed feeling about the opti, is it really that bad? It looks like either you have your original in good shape or you have to keep changing them. My buddy has a 96 and the opti goes about every year...Another thing is that he's getting an average of like 13-16 mpg with the lt1 fi...It only get's worst with carb... What et's should I be running or are you guys running with lt1 swaps, and with what mods?

Klortho

I'm on the second opti, and it came with the motor I have, apparently it was a rebuilt GM unit and is going very strong with it. On my trip to Atlanta for G10 I got 22mpg with no tune, running pig rich and 3.70 gears but I do have a 6-speed in the car as well. I haven't taken mine to the track yet, but I saw a time slip from ssean92 that he ran like 13.6 in the 1/4 with a stock motor, 6-speed and 3.73's spinning through 1st and 2nd. The buddy of mine who knows LT1's inside and out said in my GTA, with it hooking up should be seeing low 8's in the 1/8th.

Coach Hawk

The biggest drawback to the Opti is it's a PITA to service. Because of this, it's often neglected(how many people go 100K+ with their factory HEI C&Rs?). The pre-95 F and Y body unvented optis had trouble with moisture because they were not propely vented. 95+(94+ b-body) got an updated vented opti. The electronics almost never fail, it's usually the cap and rotor(rotors tend to explode with repeated use above 6500 RPM). When the electronics do fail, it's do to improper venting, usually from a plugged vent line(a new vent harness should ALWAYS be put in with a new opti).

MSD recently introduced their Pro-Billet Opti that has a very much improved cap and rotor. They also have a cap and rotor retrofit avalible for stock opti's that's much more than the factory set.

Darkstar, what type of opti failure is your does your friend with the '96 usually have? Does he replace his vent harness with his opti's? Is his vent harness plumbed into the intake before the TB like it should be?

Also, I'm running mid to high 13's with my stock open diff 2.73's. as soon as I get a new trans(one that doesn't slip massivly between 1-2), I'll take it to teh track with some nice weather and see what happens.

darkstar575

I have no idea if he switches the harness along with the opti. It does make alot of sense though. I mean we live in Miami maybe improper ventilation and high humidity hinders the optis life I guess. Hopefully i'll be seein some low 13's...with a t56, and slicks...

darkstar575

Ok so lets say I stay fuel injected... is there anyway to use an hei distributor? If I get it modified anywhere?

Klortho

Why?

The Opti puts out a hotter spark than the HEI does. As long as you take care of the opti and service it like it should be it will last you for a long time. I have run the fool out of mine, hit the rev limiter several times at 5800 and have not had a problem one with it. It seems to be that way, either you get a good one or you get a crappy one. The changing of the cap/rotor is why the units keep failing, because nobody wants to change it out in an 4th gen since it's such a pain. But in a 3rd gen, you have more room in the front to service it.