And bring some facts into the light.....

OK, I got my 383 shortblock blueprinted and put together for final assembly. I got the good ole' L31 Vortecs from GMPP. The cam Im runnin is gonna be pushing .490" lift w/ 1.5RRs, which Im usin for the time being. Now, I understand that for final clearance checks, I need to check the retainer to seal height. However, I happened to get some ants in my pants and decided to see how much I got from retainer to guide boss. If im readin my mic correctly, Ive got .680"!! From the top of the guide boss to the bottom (inside) of the retainer. hell, even if if my seal was .150" from guide to top of seal, I could get .500" lift with good clearance. (dont bash yet, I dont know how thick seals really are ). Does this sound right? I bought the vortecs used, so maybe there was some machine work done??

But, lets say that Im like most novice engine builders and Im missing a variable somewhere. I noticed that the stock Vortec retainers seem to have a shorter "stem" than the ones that came with my cam kit (see link at bottom of post). Perhaps i could gain more clearance by using stock retainers? The motor will redline at just over 6k, low end torque monster is what im shootin for.

And, as I said, I am a novice, and like most startin out Im hard headed. I ported out the exhaust on my Vortecs (not the intake, dont wanna mess around with atomization. Porting exhaust might help me with nitrous burning). In doing so, I hit an air pocket and subsequently ended up with a hole going into the water jacket. Easy fix, just another $60 that could have been spent elsewhere, but a good lesson learned.

So, having said all that, had anyone else ever measured their L31s from guide boss to retainer? That number seems to deviate from what Ive read about stock L31s

retainer pic ----> http://www.angelfire.com/freak3/spills1969/car_stuff/

 

It's not the guide boss to retainer distance that you necessarially need to look at, it is the spring. You need to completely assemble your head, seals and all, then measure your total valve lift. You do not want to compress your spring all the way down to get a reading either.

For your application, you should stay with what the specs on the heads say. If you want to get more lift, I would suggest different springs. I do know that Crane makes a spring, that is a direct drop in and will net over .500 lift. Give them a call and they can give you the specs. Make sure it is the direct replacement ones and not the ones you have to machine the head for.

 

well, i got the comp xe274H cam and kit. came with lifters, cam, springs, retainers and locks. So Im guessin, and from what I remember, the springs should hold up to what the cam is pushin out.

 

Those springs will not fit in Vortec heads without machine work. That is the biggest down fall for these heads. You can not use the standard valve springs unless you spend more money.

 

what do u mean they wont fit? like they wont fit in the spring seat?

 

The spring seat is extra thick at the bottom. This will have to be machined away to use standard valve springs. Comp cams make a beehive style valve spring to get around the extra machining. However, to accomodate more lift, you will still have to have the valve guides machined down to allow more lift than the max .480".

 

I've heard from several sources that the retainer to seal/boss clearance varies alot on Vortecs, and is usually artifically small (clearance wise) due to the seals not being seated as far down on the boss as they can be. Several people have claimed to run over .500" lift without modding the heads after using a appropriately sized deep well socket and hammer to gently seat the seals fully...

Never got around to checking mine before the car was totalled...

Crane also makes a spring/retainer set that fits in the stock spring seats and has a retainer designed to allow for extra clearance, runs like $150 for the set I think. I believe 10309-1 is the part number, they're sold as listed specifically for the iron LT1 heads that are very similar to the Vortecs...

 

From the pics on his site it looks like they might already be machined. Do you have a description of the heads when you bought them? How about a better pic of the valve stem area?

 

ill ask the guy at work a lil more about em. He said he pretty much took his longblock to the machine shop and sad "make it run". So there might have been some machine work done to em, he said he was runnin about .480" lift on it.

As far as the springs go, The one that came with the cam kit fit perfectly, ID and OD. So, again, maybe another reason to believe that they could have already been machined. Im at home for lunch now, so when I go back Ill ask the guy. Ill also try and get some more pics uploaded tonight.

 

That pic is a guide that has not been machined. Mine brand new looked exactly like that. I have been told by other who have modified there vortecs for more lift had to machine the guides down a bit to accept it. Check out this article
on the proccess.

Here is a pic of the valve seat and the unmachined valve seat.

 

Aftermarket springs that have the second coil inside will not fit unless the seat has been machined.

 

I dont get what u guys are saying about the springs not fittin in the spring seats. mine fit just fine, unless you mean theres only supposed to be a certain amount of clearance between the OD of the spring seat and the OD of the springs, and vice versa for the ID. Even with the stock ID if the seat, my springs fit just fine. They just single coil with dampner. I guess I just dont understand what exactly you guys mean by "not fitting", either not fitting in the seat at all, or not having the right clearances.

 

If you have single coil springs they will work with out machining the seat. Standard springs and aftermarket springs don't work because of the second coil inside. It will not clear the bottom of the guide. Look at the last picture I attached. The guide on the left has been machined, The guide on the right has not. Even if a standard type spring with the 2 coils fit on the guide on the right. It would bind like crazy when compressed. That is why you have to have them machined down. Your heads may already have this done. If yours look like the guide on the left, it has been machined down. Check out that article and it will explain why and how that has to be done.

Stock vortec valves springs look just like these but the inner coil is not there. Spring like these would not clear the bottom of the guide when compressed if they will even fit at all

 

These are made to fit stock vortec heads. Not inner spring coil.

The bottom is wider than the top. Hence, beehive style

 

okay, okay. I see what ur sayin now. I, for some reason, consider springs with dampner to be "2 coil" springs. Cool, well mine will work since I got single coil springs .

Only thing Im worried about now is retainer to seal clearance. Ima get some seals sometime tomorrow and check it. Granted I only check one I and 1 E valve, but even on those, .680" frmo retainer to boss sounds good to me . Again, I WILL check all valves once I get the seals. But as Ray said, it might vary frmo head to head on clearance issues. The guy that had em before me said he was runnin .487" lift qith no problems. I even inspected the old seals a while back when I first got the heads, and I didnt see any sign of the retainer smacking the seal. Wait and see I guess.