Hey guys,

Long story short, would like to put a 5.3 Vortec in to an FC RX7. I lack the space for the car so I'm starting with the engine. Plan is to have a nice, fun and easily drivable car while trying to keep it low budget. Something I can drive around all summer without issue. So no super big power numbers or super lumpy cams that sound awesome. Might be asking for too much but I don't think it's too lofty of a goal with patience.

I have a low mileage, running 5.3 Vortec LM7 from a 03 Silverado with engine harness and ecu I've found. I have a buddy in Oregon who can sort out the harness issue in trade for some parts but I'm currently researching a nice and drivable setup for the cam but am struggling with a lot of conflicting info.

I would prefer a torquey setup but would prefer something with a better powerband then the factory setup from the truck and my research has led me to using a Corvette LS1 camshaft.

What I'd like to do is pull the heads, redo the valve stem seals and get a fresh head gasket and toss it back in, as for the bottom end I'd like to just replace the oil pump/water pump/timing chain with the camshaft and all the necessary bits for install in the RX7(Accessories, intake, etc).

Now my question is, with attempting to keep this low budget what other modifications should I do? I think I would require teh matching pushrods/retainers/springs for the camshaft and retain my heads and have a good flowing motor but opinions seem to differ about the "flowing" bit.

I've also heard I should swap in LS7 valve springs, but is that a relevant/necessary mod for what I'm planning? Down the road I will be going aluminum block but while I'm messing around with my first LS stuff I don't want to run the budget up too high.

I apologize if this is in the wrong forum, I believe it to be in the right one and if it is not please direct me to where I should go.

Thanks in advance.

 

I wouldn't use the LS7 springs if I were you. I don't remember the specs on them exactly, but they don't support much lift when you swap them on a non-LS7 head with a .200" shorter installed height. Some relatively inexpensive beehives from PAC or Comp should work fine, depending on the cam.

As far as a cam goes, there's hundreds, maybe thousands of threads where someone asks what cam they should buy. 90% of the time the responses are "call so and so to spec you a cam", 5% of the time someone actually suggests a cam or two, and the last 5% are usually smart asses like me that will ask something like "well what color is your car?" The reason for that is because to really nail down a good cam, a lot of different things need to be considered, from the intake to the mufflers, and even the trans and rear gears. Several sponsors are willing to help you either by phone or by filling out a questionnaire to specify some of the important factors and recommend a cam to suit your needs. Personally, I suggest Patrick Guerra aka PatG.

 

Nothing beats a custom cam. But if you want to go cheap, I have the whole setup from a 2000 Corvette LS1. That's the "biggest" LS1 stock cam as they varied over the years. $60 shipped.

**Edit - Doh. We already discussed this via PM. Thought you were someone else. Hopefully you can get some feedback from the rest of the guys re: LS1 cam. I am interested as if it doesn't sell, I'll still put it in the LM7 before I sell it. I also think a 2" intake valve and milling of the heads would be cheap and get you the most out of a cam swap.

 

@KCS, I'm fairly sold on the Corvette LS1 cam due to the ease of drivability aspect of it as I did research cams and found that I was in too early of a build process to commit to a proper aftermarket camshaft. Down the road I will do exactly what you recommend and contact a vendor for a cam but as it stands I'm just looking for any complimenting or necessary mods for a 5.3 with an LS1 Cam swap.

And @Mercier, I'm pretty much 90% sold on grabbing that Camshaft from you, just trying to track down any necessary/complimenting mods from research and forum posts instead of harassing you over PM haha.

 

10/4. Good luck with your hunt.

 

If it's a low mileage motor, why are you going to replace perfectly good components?

 

Sort of a "if the engines out why not?" and if I'm gonna change the timing chain and head gaskets, might as well pop in a better cam eh? At best it drives better, at worst I learned a bit more and got some more experience messing around with these engines.

 

The answer is wasting money buying parts that don't need replacing. You don't have to pull the heads to change the cam. Timing chain, yes by all means change that. Cam, hell yeah. I just wouldn't touch anything that works fine unless it won't work in your car.

 

That is correct that you don't have to remove heads to change cams. This is the norm actually. The important bit that some folks miss is after the rockers and pushrods are removed, and before you start removing the cam, rotate the cam at least 360 degrees to push the lifters up. The trays should hold them up long enough for you to swap the cams. If a lifter falls, you will likely then be pulling the head. Valve springs can also fairly easily be changed without removing heads as long as you are careful and use something (air usually) to hold the valves up.

 

You can use dowels in the oil galley to hold the lifters up "just in case".

 

I was actually mainly pulling the heads to do valve stem seals as well as wanting to change the head gaskets. Its the kind of thing thay I'd hate to have to replace once the engine is in. Gives me a chance to inspect the engine better too. Mostly just for my piece of mind which I don't think is too unreasonable.

 

I do appreciate your advice, it's just something I'd like to do to help give me that extra piece of mind and it won't break the bank replacing those parts.

 

Absolutely if you have any doubts, get it done now. It's worth a hundred bucks and a few hours of time to know what you're dealing with.

Keep in mind that the head bolts are torque-to-yield so you have to buy new bolts every time you pull the heads. If you plan on keeping that block for a good while you can invest in studs. A little more expensive but reusable should you change heads or gaskets in the future. The bolts can be had at most parts stores.

I bought some non-ARP studs for about $90. The head bolts might cost you about $40-$50 anyway for both sides last I priced them. I wouldn't run a million pounds of boost or 300 shot of Nitrous without getting the good ARP studs but the ones I got are pretty stout pieces and I think good to pretty ridiculous power levels. PM me if you want to know where.