ok, im looking at the LT4 Hot Cam from GM performance, what i need to know is if its goin to work with my LG4's stock heads, and will all the valuves and stuff work, or am i gonna have to get something less??
218/228 .050 lift... you can go to summit racing and check them out if you want more info.. thats all i kno... thanks

 

I believe that cam is too big for those springs, you will most likely snap one and do some damage. I was considering it for my L98 heads and those springs wouldnt have held up to that cam, which is why I am getting a set of aluminum Brodix IK200's =)

 

so your tellin me that even with the kit i couldnt do it? the kit comes with the new springs... i think ive been told i have 416's or something like that for heads...but why cant i? explain further would you

 

With new springs that are in the kit you would be ok. I think that he was thinking that you were going to be re-using your old stock springs.

 

cause the only worry i have is the springs wont fit right and i'll have to get the worked....

 

Exactly, you didnt mention the KIT, just the CAM. However, I think you are going to need some head work done to get the springs in there. Not to mention that high lift might be too much, and you might risk smacking a valve on the piston. What is your head CC and your Compression ratio? This is important to look into.

 

should i look in my haynes manual for that? or google it up?

 

it's that a roller cam? flat tappet block?

 

hydralic roller

 

....going into you'r 84 flat tappet block? does this kit come with retrofit roller lifters? Or else I can see one major problem with it fitting

what is the lift? something like .510" right? You may need offset locks to give you a bit of room for the excess lift. Assuming it fits.

 

gosh darn it, i want this cause urbanhunter says with this upgrade should have my car near 270-290 hp... or thats a estimate.. and that would be great, just for the cam, headers, ignition, and removal of two belts.. ac and ummm smog ha ha

 

When matched with the intended 1.6:1 ratio rockers, the LT4 hot cam has .525" lift.

This much lift will require that you have the valve guide bosses shortened.
Or the retainer will contact the vave guide boss/ seal and destroy it.
You want to shorten it by .200". The tool that does this also reduces the stock valve guide top diameter to allow nice positive valve stem seals to be fitted. The LT4 springs are 1.32" in dameter. they may/or may not sit in the stock 416 heads spring seats. may require machining the spring seats larger.
A alternative spring is Cranes 99846 stock diameter H-11 drop in racing spring.
No machining is required to fit this spring to 416's. (other than shortening the guide tops)

In order to use the intended 1.6:1 roller rockers you will have to replace the rocker studs with screw in "poly lock" style rocker studs and elongate the pushrod slot in the head. this involves pulling out the old studs and drilling and tapping for new ones. (Comp, ARP) 416's have deep exhaust spring seat pockets. When you eliminate the stock exhaust valve rotators you must shim up the exhaust spring seat (about .105") .030+.060+.015 shims to make up the difference.

The hot cam would work good on a 305 if you fully port your 416's and change to larger 1.94" intake valves. You could shave the heads a bit to raise the compression ratio too. (.040 to .050) You'll need a high stall torque converter (auto) and higher rear end gearing. 3.73++

 

speak dumb terms for me, when you start talkin bout valve terrain you loose me, pistons, cranks, rods, bolt ons cool i understand...
but heads, they are a whole new world for me to learn

 

hey f-bird, what is a polylock style rocker? just a rocker with a machined top surface?


'84, f-bird gave you a lot of good advice there, now's a good time to learn
First of all, you can't use a roller cam in a flat tappet block, unless you use retrofit hydraulic roller lifters. Those are pricey. I'd recommend just getting a good flat tappet cam.

doing some work to your stock heads will help you achieve that 270-300HP goal much more easily.

 

SD1007 springs are stock dimeter and good for 570 lift. 350lbs@1.2 and 120@ 1.8" installed height

 

i am still confused tho, about what i have to do to the heads.. thats what i want put into stupid terms...

 

that cam may be too large. What happens is, your rocker tip, while pushing down the spring, may push your retainer, into your valve guide boss, or your positive valve seal. If you take off your valve covers, you can look at what i'm talking about.

Your pushrod, is pushed by the cam. the rocker is pushed by the pushrod, and rocks, and pushes down on the valve. If that rocker pushes too far down (high lift cam), then the rocker tip, the part pushing on the valve stem, goes down too far, and pushes your retainer into the boss. Best to go out and look to see what's up.

 

If you're serious about installing the LT4 hot cam in your 305 just take this thread, your cylinderheads and wad of cash to your local automotive machinist.

Personally I would not bother with a Hyd roller for this motor.
Crane cams # H-272-2 is about equal in "size" to the hot cam but in a flat tappet hyd profile. Much cheaper. Will work without machining the heads but I recomend using crane # 99848 replacement valve springs.
Specs are 272-284 advertized duration 216-228 @.050 112LSA .454"-.480" lift w 1.5 rockers .484"-.512" w/ 1.6 rockers. I would use 1.6's on the intake side only 1.5's are fine on the exhaust side.
Although the hot cam is ultimately a little more powerfull than this flat tappetcam , it will have the same operating characteristics and close to the same power.
10-15hp difference. Combine it with the head porting mods and some gear and a high stall and you'll have a good combo.
the crane part number is 113941 Don;t expect miracles from th cam swap itself. A cam is just one part of a package. But if your willing to do the head work outlined above, combined with this cam it will work well in a 305.
Will ant a high stall and lots of rear gearing 3.73-4.10