I recently installed a LT1 cam (the specs are in my sig.). I can tell it definately has more horespower even though I'm still tuning for the new cam. The only problem is a noticable loss of torque right off of idle.

I have the ignition timing maxed out. I am wondering if there are any carb adjustments that might help make more torque off idle.

Before the cam swap I found that the 670 carb was a little big for the 305 so I had to use the biggest accelerator pump nozle and the green pump cam to keep it from stumbling with a quick stab of the throttle off idle. It gets the maximum amount of fuel in the shortest amount of time this way. It had real good throttle response at that time.

Is it possible that now with the new cam I get an overly rich condition when I stomp on the gas at a stop light?

Any feedback will be appreciated.

 

there are a few things you may work with there. you could try getting more advance in the curve earlier for the ignition timing along with changing when the secondaries open. that's a fairly healthy cam for a 305 with stock compression so a new converter would really be the fix.

 

I see. You're thinking that lighter springs in the distributor would bring the advance in sooner but the total advance would stay the same. I'll try that. I already advanced it till it pinged and then backed it off until it doesn't. But this way I can have more advance sooner but not add any in total so that It should keep it from pinging.

I'll see if that helps. Thanks.

Any other ideas out there?

 

Any time you stick a bigger cam in any motor, you are automatically trading off some low-end torque in favor of high-end torque (otherwise known as horsepower). To some degree your symptom is predictable. It's why Comp and the other cam mfrs always tend to err on the conservative side in their recommendations.

You already have a component mismatch, since you appear to have the swirl-port heads still on your motor (at least, at the level of detail in your sig, I'd expect to see some heads if they had been changed); you have too much gear for the torque curve that those heads will produce. You really should put some halfway decent heads on it. A set of 081s (TPI 305 or L69 from a Monte Carlo SS) would be the best choice.

Expect it to get a whole lot worse when you put that Air Gap manifold on it.

I don't think you'll be able to entirely tune it out by working on the motor. Try a looser converter.

 

Thanks. I understand that the LO3 heads suck. Do you think that the TPI heads would offer much of an improvement right off of idle?

I'm sure they would help make more power at higher rpm.

Where is the best place to get TPI heads and how much should I expect to pay for a decent set including shipping?

Also, which heads do you think would provide a better bang for the buck?

TPI heads - cost ?

or

Vortech Heads - cost $680 (includes cost of new intake)

I'm working on a tight budget because their are other mods I would like as well.

Thanks for the advice.

 

I see tons of auctions on ebay and lots of adds in hot rod magazines from machine shops selling reconditioned 081 TPI heads for around 350 bucks plus 50 bucks shipping.

You can probably find them used for around 50 bucks or less and get the work done ont them for a little less.

 

I don't think Vortec heads are the best way to go for a 305, not only because of the cost, but also because of the loss of compression. And those heads, as they come out of the box, are not a performance head; they're a replacement truck head. That means they have crap truck valve springs, the factory rotators and all that other extra dead weight on top of the valves, heavy truck valves, pull-out studs, valve guides so tall that the retainers will hit them at .480" of lift, etc.

Like I said above, the heads to look out for are 081s. They came on 87-up 305 TPI and MC SS L69. Watch the classifieds on this site, they show up all the time there.

 

I've got a line on a few sets of '416 heads (and a pair of '081s if you want the '87-later style) available in your area, if you're interested.

 

Vader, that would be awesome. Like I said earlier, I'm working on a tight budget. How much do you think the TPI head would go for? Where could I go to pick them up?

If the price on the vortecs are affordable enough I could maybee swing the extra money for the intake and the cost to have them milled down to maintian compression ratio.

Lance

 

I though some of you guys may like to know that with some tunning the car is really starting to come around after the LT1 cam swap.

I realized it was running really rich after the cam swap. I use an auto meter air fuel ratio gauge and highly reccomend them as a tunning tool.

Anyway, I leaned out the primary and seconday jets. I also stepped down a few sizes on the accel. pump nozzle. It also required a heavier vaccum secconndary spring.

It's got a lot better throttle response and I think I can improve it even more with a little additional tunning.

So far I've gained a little over 3 tenths and 3 MPH in the 1/4 Mi.

I think there is still more left in it.

Overall I think the price of the cam was the best $30 I've spent on it.