Bugman Jeff

I'm going to be swapping some Vortec heads onto my '73 L-48. I'm used to having to rejet carbs any time I do any engine work, but I'm not all that familiar with the Quadrajet. Will I need to rejet the stock carb after the swap? Thanks for the info.

Scottd

The carb should be fine, you may just have to fatten the mixture a bit....however....let me ask what you seek to gain with a vortec head swap. Are you keeping everything else stock? If you want to run anything other than a stock cam, you will need to get the valve guides machined. Also, you need a vortec specific intake manifold. By the time you are done with machine work, intake manifold and other assorted stuff.....a vortec head conversion will only cost about 200 bucks less than a much nicer set of racing heads (Dart, Brock, etc) that will yeild much better esults.

I did the vortec swap on my Camaro. I was happy with the results (but also did cam and carb upgrade) but wound up spending as much money and far more time than a set of aftermarket performance heads would have cost me.

Bugman Jeff

I will be adding a Summit 1103 cam a month or two down the road(paranoid about breaking in the cam on a whole new head/cam setup and the difference is really only a set of intake gaskets and a few minutes time), and I've got Hooker sidepipes already. The 1103 cam will work on stock heads with the springs/retainers I obtained. My goal is to gain some HP on the cheap, and I'll only have around $600 in the entire swap

scottyp99

I don't have any actual experience with the vortec heads, but from everything I have read about them, .465" of valve lift is coming awfully close to the limit, and the tools needed to do the "machine work" on them are really cheap and can be used with a power drill.


Scott

Vette5.5

For all the work you're doing, I'd definitely re-jet the carb. H-O Enterprises in CA can put together a custom kit for you. Also agree, since your going through all the trouble, it's aftermaket performance heads all the way. I have the H-O carb kit instructions. If interested, PM an e-mail and I'll get them out.

Bugman Jeff

Thanks for the input. I finally had a chance to check all my clearances with the parts I'm actually going to use. I've got .070" between the retainer and valve seal, and everything else checks out so I don't need any machine work. The total cost of my swap is only going to be around $500, $600-$700 less than if I'd bought aftermarket heads

Scottd

STOP! Vortecs will only run .465 without binding. Anything more and you WILL need machine work. There is a tool that lets you do the work from a drill press (70 bucks) ....but do you own a drill press that can support a 40 LB head? Have you added in the cost of the new Vortec specific intake (you CANNOT use a stock intake)....

I did the same thing you did. I was pumped that I only paid 125 for the heads...but after cleaning, surfacing, then realizing I needed the valve seats cut....it all adds up. My total cost of my vortec swap, including labor and parts was around 700 bucks. For 900 bucks I could have bought a set of bolt on heads and saved myself a lot of time and aggravation. Oh, dont forget the vortec specific valve covers you need to buy.....

Dont get me wrong....it was an awesome upgrade...but for the time and effort, a set of Patriot Performers will do the same thing with much less problems...

Bugman Jeff

I appreciate the input. As I said, I have physically assembled all my parts and have .070" clearance between the spring retainer and valve seal at max lift. .060" is the recomended "safe" clearance, and this isn't a high RPM machine. I've also checked the heads over, and the need no additional machine work beyond the $60 it cost to have them checked for cracks after I got them stripped down. Including the springs, retainers, seals and the crack check, I have a grand total of $280 in these heads, and they are ready to bolt on. ANY aftermarket head would at least double the cost of my head/cam swap, and on a stock L-48 short block the performance difference isn't worth the cost.

The cost of the intake is really a wash because any upgrade would include a new intake so I'd have bought one anyway reguardless of which heads I ultimatly went with

Scottd

Ok, I see that you are doing your homework. Did you get the heads resurfaced? If your deck is off by .005, its asking for a head gasket leak. Im crazy paranoid about head leaks...

Have you purchased a new set of head bolts? Vortecs use a torque to yield bolt that cannot be reused.....(again, Im crazy about head leaks)....seriously, dont reuse the old bolts...

Im not trying to talk you out of it, Im just telling you what was involved in my swap and how I learned the hard way....