I have a 305 TBI that I am going to convert to a carburetor. I am looking for suggestions for a cam and an intake. The 3 cams that I am looking at right now are the LT1, ZZ4, and the LT4 hot cam. Will anyone one of these be significantly better than the others? Are there better cam options that don't cost twice as much? What will need to be done to the 059 heads to use a different camshaft?

I am also looking at replacing the Professional Products Vortec intake that I currently have. I am probably looking for a dual pattern, since I don't have a carb yet...and may go with a Q-Jet. I am not opposed to getting one that is square bore, if it is better than the others...that would also force me to make a decision on a carb. If you have any carb suggestions as well, I am more than happy to hear them. Thanks.

Cam

 

This intake http://www.summitracing.com/parts/PFS-52007/ will accommodate either a spreadbore or squarebore.

The LT1 is a good choice for install with just a change of valve springs.

 

Have these Vortecs been modified to work with the higher lift that a ZZ4 cam or HotCam requires? If not, LT1 cam with 1.5 rockers is about as far as you can go.

 

I think that is the intake that I have. I know that it is a Professional Products Vortec intake.

Cam

 

Nope, they sure haven't. What would have to be done to the heads to use the ZZ4 or the LT4 hot cam?

Cam

 

Stock Vortecs can only handle about .470" lift max before the bottoms of the retainers hit the guide seals. The ZZ4 cam is about .510" lift on the exhaust side with 1.5 rockers. The HotCam is .525" on both intake and exuast with the spec'ed 1.6 rockers (still ~.490" with lower ratio 1.5s).

Any machine shop can cut the guides down to open up this clearance well beyond what you're ever likely to need. Since they need to take the springs off to perform this machining operation it's an ideal time to upgrade the valve springs to a set better suited to work with a mild performance cam.

 

Would the performance gain be worth the cost involved to upgrade the heads to accept a ZZ4 or LT4 hot cam? I essentially want to get the most performance out of my 305...with the least amount of money invested! What would be an approximate price to have the heads modified to accept the higher lift cams?

Cam

 

Also interested in this info.

 

There are two choices for handling the higher lifts:

1) Have the top of the guides cut to accept positive-type stem seals - this shortens the top of the guide to give more valve travel. You can also have the OD of the guides cut so you can get better springs installed (the more common SBC performance springs), and even have the spring seats cut for 1.4" OD springs. There are cutters available that will do all three in a single pass. Obviously, the heads have to be off to do this, and it is best left to an experienced machine shop.

2) Beehive springs and their smaller retainers. Allows more valve travel before the retainer hits the top of the guide. Of course, you have to use stock-type stem seals since you won't be cutting the top of the guide.

Well, I guess there is Door #2:

3) Cut the top of the guides and use beehive springs & retainers.

 

Do you have any idea what kind of cost would be involved with these modifications to the heads.

Cam

 

Also, how much performance gain would there be by using the ZZ4 or LT4 hot cam over the LT1?

Cam

 

Anyone?

Cam