350 engine
 

i have a l 31 350 block that i am redoing i am going to use a set of vortex heads{ new} i want to put a comp cam part #08-416-8 it has a lift of .488 /.495 but gm says that .475 lift is big as the heads will fit what do i have to do to use this cam thanks mike

Are you getting these heads new from GM complete with the springs? That may be all the lift the springs can take. You should get the Comp Cams spring set that is recommended to be used with that cam if that is the problem.

vortec heads don't give you much more flow with extra lift. they are, however designed for the roller lifters with quicker open-close ramps than flat-tappet cams can provide-at least with a realistic service life. ok, the L31 is a vortec engine with the roller cam and the same heads you are buying. anything wrong with the already paid-for set of heads?

To answer your question, the vortec heads are limited to the .48 inch lift or so because past that the spring retainer will contact the valve seal.

To fix this you can have the valve guide machined down some or you can buy some comp cams beehive springs. These with the proper retainer allows something like .54 inch (this is what i did). Max flow for these heads is just past .5 inch.

With heavier springs and higher lift you should go to screw in studs also. I would definetly stay roller and I would also consider the LT4 hot cam if you are going to buy another roller cam.

350 heads
 

mr maine do you have any part #'s for the bee hive springs and retainers would help.i did not get any heads just the short block, thanks mike

Comp cams part 26915 or 26918 for the springs. Differences are the spring rates. I think I have 26915 but its been a while.

retainers are comp cams 787

I would put together a full plan before you buy anything. For instance it may not be cost effective to buy brand new vortecs just to rip the studs out, throw away the brand new stock valve springs etc. For me I got a take out motor for 200 bucks, heads had just been to the machine shop for a cleanup.

Patriot performance has a vortec head setup with 2.02 valves, screw in studs, and hyrdraulic roller cam springs for like 750 and I have heard good things from guys that have actually run them.

Good luck, feel free to ask anything, and if I have experience there I will answer if not someone else will

yes, you will have to have the guides machined down, you can find heads from shops already done...

it might be worth your while to spend a liltle more and buy better heads - assuming you have a strong bottom end, the heads are what is goign to make your engine. a set of AFR's will put you in a whole different league power wise. add an off the shelf com cams xm series cam and you'll be over 400 horsepower easy., Just a thought...

350 lt4 cam
 

what kind of hp will the l 31 350 with the lt 4 cam make , and will it work with stock exhaust, thanks mike