Let's talk about cams!

[ericjon262]

I've got a 2006 G6 3500 (LX9) that I'm swapping into a 1985 Fiero, I've decided I would want to put a cam in, as long as I don't have to pull the heads and have machine work done. what's the biggest cam I can run with an otherwise stock engine? the car is a five speed, and weighs somewhere around 2700-2800 pounds. I'm also fabbing up equal length long tube headers for the car. no emissions testing/ vehicle inspections here. the car will most likely be running an OBD2 ecm, and eventually, a couple of turbos.

[SappySE107]

None unless you pull the valve springs off and replace them. Then you can run whatever cam you want.

[ericjon262]

I'd be fine with changing valve springs, what cam would you recommend for a stock 3500 with headers in a 2800# car with a five speed?

[SappySE107]

Daily driver on the street? MPG matter or is this for fun only? Powerband? Strip cam is probably where its at. Longer pushrods are also needed for optimal performance. 26986 springs drop right in and support the cam.

[TGP37]

I would still pull the heads to swap the springs. I don't even know if it is possible with the heads on the block. I'm sure it could be done but you would need a compact spring compressor to release the valve, and not drop the valve into the combustion chamber.

Maybe you could get a nice pair of WOT MLS Head gaskets and reduce the thickness just enough to compensate for the extra distance needed for the pushrods. Could reduce the quench distance a little and increase compression ratio too, but I'de do what Sappy suggests first.


I'm planning to get a performance turbo street/strip cam next year. Along with arp head studs.....ahh I could go on but my budget is limited at times.

[SappySE107]

You can run .051" thick gaskets but that won't make up for the pushrod lengths. It would improve quench and increase compression slightly.

There is a tool to remove the springs while the heads are on the block. You have to make sure the valve doesn't fall, which can be done either by string in the chamber or compressed air.

[ericjon262]

Daily driver on the street? MPG matter or is this for fun only? Powerband? Strip cam is probably where its at. Longer pushrods are also needed for optimal performance. 26986 springs drop right in and support the cam.

it'll be a semi daily driver, I don't want anything that would require a compression bump, or kill ALL of the low end.

I would still pull the heads to swap the springs. I don't even know if it is possible with the heads on the block. I'm sure it could be done but you would need a compact spring compressor to release the valve, and not drop the valve into the combustion chamber.

Maybe you could get a nice pair of WOT MLS Head gaskets and reduce the thickness just enough to compensate for the extra distance needed for the pushrods. Could reduce the quench distance a little and increase compression ratio too, but I'de do what Sappy suggests first.

I'm planning to get a performance turbo street/strip cam next year. Along with arp head studs.....ahh I could go on but my budget is limited at times.

I'd like to do a turbo in the future, so bumping the compression up isn't really necessary, I don't want to have to pull the heads, becsause then that means new head gaskets and new head bolts, and if I have them off I'll want to port them and and and and.... my budget is pretty thin, so if I don't have to, I'd rather not... but we'll see.

[TGP37]

You can run .051" thick gaskets but that won't make up for the pushrod lengths. It would improve quench and increase compression slightly.

There is a tool to remove the springs while the heads are on the block. You have to make sure the valve doesn't fall, which can be done either by string in the chamber or compressed air.

But it would change the length of rods needed by using a thinner head gasket? As the heads/rockers are x amount closer to the block/cam. Or is the distance needed to compensate to great to make up in gasket thickness?

Just curious

I'd like to do a turbo in the future, so bumping the compression up isn't really necessary, I don't want to have to pull the heads, becsause then that means new head gaskets and new head bolts, and if I have them off I'll want to port them and and and and.... my budget is pretty thin, so if I don't have to, I'd rather not... but we'll see.

And ARP head studs, racing valves, 3 angle valve cut, I know the list grows fast....lol

[SappySE107]

If you milled .020" off the heads and .009" thinner head gasket, you could almost use stock pushrods on the strip cam. Technically you can anyway but I try to make it as close to optimal as possible. The Street cam would be fine with .020 off the heads and stock pushrods. You could run a race cam on stock pushrods and stock heads and the engine will run. It just won't be as good as possible.

[ericjon262]

If you milled .020" off the heads and .009" thinner head gasket, you could almost use stock pushrods on the strip cam. Technically you can anyway but I try to make it as close to optimal as possible. The Street cam would be fine with .020 off the heads and stock pushrods. You could run a race cam on stock pushrods and stock heads and the engine will run. It just won't be as good as possible.

gotcha, I'm starting to think that I'm gonna put a stock 3500 in for now. once the car is running, I'll buy another 3500, which would get heads cam, intake, and maybe some bottom end work. I'm very quickly getting on the slippery slope of "while I'm this deep I might as well..."

[Superdave]

I think you are making the right choice, start off with a stock engine that you know runs. Get used to tuning and work out all the bugs... then start adding fun stuff.


You'll be really surprised how fun a stock 3500 is.

[ericjon262]

I think you are making the right choice, start off with a stock engine that you know runs. Get used to tuning and work out all the bugs... then start adding fun stuff.


You'll be really surprised how fun a stock 3500 is.

it's become more of a money thing than anything else, I want to drive the car again, so I'm not going to change the LIM gaskets like I was going to either though, I figure by the time they go, I should have a new 3500 or a 3900 built, or when it's time for a clutch...

[TGP37]

Just like you, I want to drive my car again.

I started a manual swap a year ago...lmfao. On paper I could easily afford it and get it done in a month or two. But in real life, lol, it has taken far longer. In fact the manual swap is done, now I am wrestling with the clutch to properly disengage the flywheel.

AND, to top it all off, I had screwed up by using the wrong pigtail for my crank sensor. Took me weeks and hundreds before I finally figured it out.......new ignition system all around. New battery cables, connectors in the switch, ICM, plugs, cables, wires, alternator, crank/cam sensor, ugh it was painful.

If you milled .020" off the heads and .009" thinner head gasket, you could almost use stock pushrods on the strip cam. Technically you can anyway but I try to make it as close to optimal as possible. The Street cam would be fine with .020 off the heads and stock pushrods. You could run a race cam on stock pushrods and stock heads and the engine will run. It just won't be as good as possible.

I agree, perfection (or at least the aspiration of) is the key. And carving the heads down versus getting new pushrods is silly, lol. But if one needed to mill the heads then I can see it possibly working out well.

Thanks

[ForcedFirebird]

I would still pull the heads to swap the springs. I don't even know if it is possible with the heads on the block. I'm sure it could be done but you would need a compact spring compressor to release the valve, and not drop the valve into the combustion chamber.

I have done spring swaps several times without pulling heads. In fact all that would be needed is timing and valve covers to be pulled to change the cam/springs.

Take a long extension and put it in the spark plug hole and find BDC of the cylinder. Take some clothesline and stuff it in the spark plug hole until it's full. Rotate the crank a bit and the rope will push on the bottom of the valve. Then you can remove the spring easily and the valve won't drop. Then when done, rotate the engine back a bit and pull the rope back out.

You can also use a compression tester with an adapter to go to your air compressor hose, but the air will often move the piston down, thereby opening the valve, but if it's leaky or you need to take a break it's not so fun since the rope could sit overnight if you wanted.

[SappySE107]

Why does the timing cover have to be pulled?