I just put Vortec heads on my low milage 305. I installed a LT1 cam that has about .450 lift, 18 psi spring on the pressure regulator, summit intake with a TBI adapter, headers and free flowing exhaust. I have not started it yet because I am waiting on a few odds and ends, does anyone have a chip they can sell that can get this in the ball park and make it drivable? The Camaro is automatic with 3.73 gears.

 

With the stock chip, it should start and run decent and you should be able to get it to be driveable with air/fuel in the ballpark by adjusting the fuel pressure. I would leave the base timing at 0 BTDC for now, which would act like 6-8 degrees advanced with the faster burn of the Vortec heads.

Once it is up and running, then you can do custom tuning based on your specific combination of parts.

Sounds like a nice setup.

 

You put Vortec 305 heads or the 350 heads/ Did you have 350 heads milled down?

 

Thanks. I have read that you should set base timing at 6-8 advance for base timing with Vortec heads, especially if the cam is bigger than stock for a better vacuum signal with the stock tune. I don't know how true this is.

Also, do you know from experience that it will run with a stock tune?

 

They are the Vortec heads from summit, the chamber is bigger so it should put me in the mid to low 8s. Not ideal but better than rebuilding the stock crap and I plan to put a 383 in the car next year.

 

No, I haven’t done this particular combo on a stock tune, but I have swapped cams, heads, exhaust on stock chips so I have a good idea of what will work. In your case, the LT1 cam is pretty mild (very similar to an L98 cam), smooth idle and should pull almost as much vacuum at idle as the stock L03 cam. The cam selection makes the biggest difference on the map sensor reading and subsequent fuel/spark tables. The next thing are the heads. The Vortec heads and the swirl port heads (stock L03) like a similar amount of ignition timing (about 6 degrees less than an L98 or LB9 head. So, leaving the base timing at stock 0 degrees would be where I would start.

Certainly custom tuning would optimize the setup to get the best performance and driveability, but the stock tune will be close enough to run safely.

 

Thanks! nice to hear from someone who has done something similar. I do not want to invest in tunning software. If I am going to drop $400 I would rather put that towards an aftermarket fuel injection system that is easier to tune, faster processor and easier to use.

 

That’s a bit of a mismatch, but it should run. Those heads are for a 4” bore, so your compression is low and the narrower cylinder will impede flow around the valves a bit.

 

You will be able to tune it good enough with just fuel pressure and base timing. Since you plan to swap the motor in the near future, I would not spend the money on a custom tune now.

 

Good, I rebuilt the throttle body and put an 18psi spring in it, is that the right direction? Too much, too little?

 

I don’t know if 18psi is the right number. Every combination is a little different and could be higher or lower. An adjustable pressure regulator is the better way to go. I would use a wideband 02 sensor to monitor air fuel ratio while under WOT and adjust accordingly.

 

In my experience Vortec heads like alot more timing than the stock swirl ports. The swirl ports make peak power in the 26-30° range and often have 20-24° total in factory form. I find Vortecs to run best at 6-10° advance. The TPIs generally run 30-32° total in stock form.

 

hey fast355,i just swapped a set of stock "350" vortec heads(did the ls1 springs,comp retainers,new seals) on my LG4 as well as an L-82 cam i had sitting around for years (out of a 290/350 crate someone pulled out new)
i installed an edlebrock rpm intake and a holley 650 dp. and hooker 2460 headers....i know the compression isn't ideal but i because i plan on using these heads on a 350 build and didn't want to mess with them(or mill off 0.045")
and figured i would run them on this turd as it was ungodly slow with the peanut cam

any recommendations,ideas,suggestions? i know you seemed to like this cam in a 305 you used to have.