if i was to swap a lt1 cam into my 305, would i have to grind on the pistons to make clearance? ive heard of people having to do this with some cams and was wondering what the highest lift i can have without having to grind on the pistons? thanks for your help.

 

No. That would not be necessary. That's such a smalll cam, it's nowhere near any of that. It shouldn't be necessary to grind on anything.

Of course, that's a roller cam, and your 83 engine is not a factory roller, so you'd be looking at a significant chunk of change to put that in there since you'd have to buy the kind of roller lifters that all the rest of us had been using for decades before the factory mutilated the idea.

 

hmm whats the biggest hydrolic flat-tappet cam i could put in it WITHOUT having to remove the heads and grind on the pistons?

 

Stay below .650" of lift, you should be OK. You might be able to get away with a little more with shorter duration.

 

ive heard that people have had to grind on the pistons for clearance... i guess thats just for 1.94 intake valves instead of having 1.84... ok that makes sense...

 

No, not necessary with those either.

It's just not an issue with a typical street motor, especially not with some stock cam like any of the LT1 cams. Put it out of your mind.

 

so i can throw a comp xe262 cam in my stock engine, and not have to pull the heads now, until i get some vortech heads? sorry for being persistent, i just dont wanna screw up my engine because a valve smacked into a piston...

 

'83,

The limiting factor for gross valve lift in your case IS going to be the heads. The valve guides probably won't allow any lifts above about 0.485" without having the retainers crash into them. Your springs probably wouldn't survive it either.

Typically, the only times you need to be concerned with clearance on a replacement cam is above 0.580" with larger valves, adn if your valves are fitting into a 305 chamber, they aren;t that large.

The only other thing that could cause piston interference is an incorrectly timed camshaft installation. It happens, so degreeing the cam is always a good idea.

 

ok thank you very much for the infomation... im new to camshaft replacing and stuff... and am learning as i go, so you guys are very helpful. Thanks again...

 

Right.... the stock cast-iron guides are a massive blob of stuff, and stock retainers are pretty huge too; so the combination of the 2 doesn't allow the valve to open very far before they interfere.

The stock LT1 cams are all in the .450" range though; very tame. The XE262 has somewhat more than that but still not into the danger zone with stock heads. Stock springs, on the other hand, are totally inadequate for any of the XE cams. They accelerate the valves much too fast for those weak grocery-cart parts to have any chance at controlling the valve motion.

Any cam, even a mild stock one like a LT1 one, will benefit from improved valve motion control. Trash the entire factory spring apparatus, and replace it with Comp 981 springs and the retainers that go with them, or the equivalent (entry-level stock diameter) high-quality springs from one of the cam mfrs (not K-Motion or someone like that that doesn't make cams) such as Lunati, Crane, etc.

The valve reaches maximum lift when the piston is about halfway down the bore; an inch and a half or more from the deck, let alone the valve. The only time you end up with valve-to-piston problems with stock heads, is if you run large domes on the pistons, and a cam with lots and lots of duration. None of the cams you have asked about is even remotely close to this situation; and your pistons in your stock LU5 are flat-tops with valve reliefs, no domes.

Direct your concern elsewhere, in your build, that one issue will not exist.

 

This was due to the rotators on the exhaust valves. Like said, ditch these ASAP. They'll do nothing but hinder performance.

 

thank you thank you thank you

ive been afraid that id have to pop off my heads and grind crap ever since i read articles about people that have to grind on the pistons putting that cam and vortech heads on a 305... ok ill worry more about getting new heads now thanks again

 

They may be doing some grinding, but it's not on the pistons.... it's probably on the valve guides. Put the right springs on it, and with that cam, even with 1.6 rockers, you should be OK.