lil305gta

Which cam would be the best for my current engine and mods, I also have runners on order and a set of underdrive pulley's. I like the build up of Blue Thunder in GM High-Tech on the sleeper 305. Witht the addition of the cam that should put me at about 300 flywheel hp. Correct me if i'm wrong. But they made about 283 with runners, headers, exhaust, cold air, pulley's, and an air foil. I will have the same plus the cam. What do you guys think?

Duke

283??? From a 305 with just those mods? If their using stock heads and cam, then I'm very much impressed.

lil305gta

I was shocked as well, it was an 89 Formula 5 speed. All they had was bolt ons and you figure 236.9 hp and 303.8 tq on the dyno. You figure 20 % and get about 283, if you figure 15% cause of the manual tranny you get about 272. Still damn good for an lb9 with bolt ons. Add heads, cam and weight reduction, ported plenum, custom chip and you got a 13 sec NA 305. That is what i'm looking for. with my modded tranny I may be able to get more than they did. To date the best et was like 14.29.

irocz8957

go with the lt4 cam!

IrocManiac

Is the LT4 cam gonna be too much for the TPI runners/intake? I haven't ever read about swapping in an LT4 cam...

lil305gta

Here are the specs on each cam:

LT1- 201/208 @.050 Lift .447/.459 LSA 114

LT4- 203/210 @.050 Lift .476/.480 LSA 115

Will I run into vaccum or lopey idle with either of these cams? Other mods will be pulley's, afpr and intake runners.

lil305gta

So from the above specs listed, which one would be the best to go with and not have to worry about breaking the engine and my pocket.

Makaveli

you should be fine with the LT4 cam, it really isnt much bigger than the LT1 cam. it does have some more lift though, and id look into new valve springs and such, might need some sort of head machining to get that higher lift to work right with the valve guides and all, but i might be wrong. someone can help as far as valve springs and such.

but since its on a wide stock style lobe separation at 115, and lowish duration numbers, you wont run into crazy vacuum shortages and lopey idles. i wouldnt really imagine it acting different than an LT1 cam, but someone else can probably comment more on that. throw in a CC306 in a 305 then you might have a few vacuum problems...

good luck!

Dirt Reynolds

The 1988-89 L98 350 (and the '88-'89 305 TPI 5-speed) got the largest production cam of that era; even larger than the LT4 cam:

1988-89 TPI 350/TPI 305 5-speed cam:

PN 10066049

Dur. @ 0.050": 207/213 int/exh.

Lift: .415"/.430" int/exh.

Lobe seperation angle: 117 degrees

Playdough

You shouldnt have any probelms running either cam with your setup. New springs might not be a bad idea, but other wise it should be just fine. You will notice a little bit of an idle change but nothing drastic.

Now the cam I plan on, may have some issues. CC304, 210/220 .500/.510 on 114 LSA.....

Jim85IROC

The only thing "larger" about it is the duration, and just barely. The LT4 cam has a MILE more lift (assuming the spec is with 1.5 rockers and not the 1.6 that the LT4 motors came with), and a narrower LSA for more overlap. In most cases the LT4 cam would be considered the "bigger" cam.

But... the LT cams were designed to work best with the LT1 intake manifold. The cam is not optimized for a TPI setup. Whether or not it will work better than an L98 cam, I don't know. I suspect that the LT1 cam won't work as well as an L98 cam, but due to the lift, the LT4 cam might show an improvement assuming the heads don't restrict the flow too much at high valve lift.

Chuck!

I went LT1, shoulda went bigger so I bought a crane 2050 for lt1. .498 .498 214 214 115 lsa.

I should add this is on a tbi motor which makes power to about 5700, but I want to be about 5900-6000. Running a Performer RPM manifold, though.

Kevin91Z

Those LT4 cam lift numbers are with 1.6 rockers. The LT1 cam is shown with 1.5 rockers.

And a TBI setup that makes power up to 5700 RPMs? You have dyno proof of that?

Sitting Bull

No, I think the LT4 numbers are with 1.5 rockers. With 1.6 rockers they are usually around .50x or higher.

For a 305 I'd stick with the LT1 cam, if you want to drive it everyday. If it is just for the track then go crazy. But that LT4 cam is doubtless going to require having the heads machined to handle its greater lift. And that costs $$$ and time

axoid

Not for a LT4 cam but for an LT1 with a performer intake and Torquer 305 heads.