alot of people are either using or suggest using a LT1 cam in their TPI engines. now, i always thought that this cam doesnt have a distributor gear because of the LT1s opti-spark ignition. does GM make this cam with a gear in place? or are you guys talking about pulling one from a LT1 motor and swapping it in? if so, how does that work? please help, this has me confused.

 

The only difference in the LT1 and L98 cams is the LT1 has a pin sticking out of the front of it to drive the Opti.

Using a stock LT1 cam in a L98 is supposed to give you 25-30 hp from what I've heard. Anyone wanna clarify this more for us?

 

I put a 96 LT1 cam in my L98,but it's hard to tell what I gained because I also installed 1.6 roller tips,bumped the compression up,SLP headers,fully ported my L98 heads and installed a Hughes 2500 stall converter. Now I need slicks.

 

Vette 89,

While factory LT1 camshafts may lack a fuel pump lobe, they have the same distributor drive gear. However, instead of driving a distributor, they are used to drive a stub shaft that operates the oil pump.

 

so if i take a cam out of a LT1 engine, it wouldnt be a direct swap because the cam lacks a fuel pump lobe. this is what i am looking to do (put a LT1 cam into my L98, i heard gains from 20-30 hp are common), im watching a few LT1 cams on ebay, but if it doesnt work, then its pointless.

 

I sincerely doubt you'll see 20-30 hp just by swapping to an LT1 cam from an L98 cam. The duration is near identical, the LT1's only advantage is it's lift. In other words, it's like adding 1.6 rockers to an L98 cam. In practice you don't see 20-30 hp from that either.
IMO a cam swap is WAY too much work to do just to swap another anemic stock bumpstick in. I'm sure you'd see twice the gain by swapping to a nice aftermarket piece. If you're trying to stay cheap, the ZZ4 cam is a decent and worthwhile upgrade and can usually be had for near $50 used. Even new it's relatively cheap through GM.

 

Well an L98 cam is only .403/.415, .430/.442 w/1.6 while an LT1 is .447/.459, .476/.490 w/1.6. So there is a fairly significant increase in lift, you'd definately see some power, but the wimpy 203/208 duration and 117 LSA would give up lots of power to the ZZ4-208/221,112 .474/.510.
Moral of the story, if it isn't free, don't do it, all that work deserves a worthy stick! And the ZZ4 works great in TPIs!
DO NOT use the stock valve springs with either one!

 

You don't need a fuel pump lobe because you have an electric pump (in-tank or otherwise).

 

So all you would have to do is replace the stock valvesprings and then you can use either cam no problems?

 

ive got some new GM LT1 valve springs on order. would these work with the ZZ4 cam? what else do i have to change to swap cams? i heard you can reuse the roller lifters, but do the pushrods and cam bearings have to be replaced? thanks

 

I certainly wouldn't use LT1 valve springs with that ZZ4 cam. You need springs that will handle over .500 lift, LT1 springs will be marginal at best , the LT4 Hot cam uses specific valve springs and it has .525 lift, the ZZ4 is .510 on exhaust, so I'd order those if your stuck on ordering GM springs. If you go 1.6 on the ZZ4 cam, the LT1 springs will definately be useless.
Use the wrong spring and you'll be sorry, be sure to check all your valvetrain clearances! Good valve springs are too cheap to risk having valvetrain bind and no power.

 

How good of a cam is the LT1, for a 305 with Vortec heads. I'm going to be going to ported and milled Vortec heads and I'm trying to decide what cam I want to go with. I can get a used LT1 cam for free. Does anyone have experince with a 305 with an LT1 cam? TIA.

 

well, im not planning on going to a larger rocker ratio, and for now im kinda stuck on ordering the LT1 springs (i have a bid on ebay, and have yet to be outbid). so i need a camshaft that will work with those variables. it sounds like the LT4 hot cam, and the ZZ4 are out of spec for what ill be running (ie: too much lift). and some of you say a cam swap is pointless if i want to use a LT1 cam. what about a LT4 cam? is this any better than a LT1 cam? im going to be porting my lower intake soon, while i have the manifold off, i figured id swap in a cam (dont feel like ripping off the manifold assembly twice if i dont have to). so, any suggestions on a cam choice?