Which heads would you buy?

Cobra912 · Sep 29, 2010

Sold my heads, want to change things up a bit. Thinking about the RPM heads for use with my Performer II with 2.02 valves, or the TFS heads (track heats or whatever?) but I'm worried about the TFS piston to valve clearance. My pistons are SRP's notched for reliefs, but I understand the TFS heads are a little touchy. Cam is comp cams NX264HR, only .512 lift but may switch to a XE274HR before it goes back together, this time with head studs stil running 10lbs of boost. I would also like to lower my compression ratio so input would be greatly appreciated along with head gasket thickness and selection.

THANKS

lancec2c30 · Sep 29, 2010

If you get your valve clearance figured out, Power-adder solutions over on the corral quoted me $1100 shipped for TFS twisted wedge heads assembled. I thought it was a decent price.

Cobra912 · Sep 29, 2010

that is, thanks

Shaolin Crane · Sep 30, 2010

I second some trick flow heads fast as cast make great power, but if you can, go CNC and dont look back

Jaym14 · Sep 30, 2010

I have the trickflow 185 Cnc's... Really fantasic heads

NIKwoaC · Sep 30, 2010

Jaym14 said:
I have the trickflow 185 Cnc's... Really fantasic heads

Yea, and don't let the number fool you, Trick Flow 185s are much more head than AFR 185s, or pretty much any other "in line" 185 head. Trick Flow 185s are actually closer to an AFR 205 in terms of flow.

BTW, if you go to "bigger" heads, you can typically get away with "less" cam. In other words, going to a cam with more duration at the same time you move to better flowing cylinder heads is not necessary. The bigger cylinder heads will flow more air while the valve is open, so you can get away with keeping the valve open for a shorter time frame, which also reduces overlap, and ultimately increases low speed drivability. The big heads/small cam is the science behind the Chevy LS engines, and is what makes them great performers.

So, if you're hell bent on changing the cam, maybe go with something that has similar (or even less) duration, and more lift. Like, .550+. Maybe look into a custom cam...?

This may all be a moot point, though, aren't you already on the ragged edge of stock block durability?

Cobra912 · Sep 30, 2010

NikwoaC said:
Yea, and don't let the number fool you, Trick Flow 185s are much more head than AFR 185s, or pretty much any other "in line" 185 head. Trick Flow 185s are actually closer to an AFR 205 in terms of flow.

BTW, if you go to "bigger" heads, you can typically get away with "less" cam. In other words, going to a cam with more duration at the same time you move to better flowing cylinder heads is not necessary. The bigger cylinder heads will flow more air while the valve is open, so you can get away with keeping the valve open for a shorter time frame, which also reduces overlap, and ultimately increases low speed drivability. The big heads/small cam is the science behind the Chevy LS engines, and is what makes them great performers.

So, if you're hell bent on changing the cam, maybe go with something that has similar (or even less) duration, and more lift. Like, .550+. Maybe look into a custom cam...?

This may all be a moot point, though, aren't you already on the ragged edge of stock block durability?

Very good points, thanks

Yes I think I'll go till I blow

Well I'm ashamed, I picked up some brand new RPM's with 2.02 valves instead of the 1.90's, got em brand new for under a grand. I was motivated by price and didn't wanna have to sort out any TFS to piston issues. At least they are fresh and I'm gonna spring for a different cam. Maybe another NX cam around the .550 range that will work with a .575 spring. The cost of a custom cam scares me......even though I have a lot of money in my car, it's pretty darn budget compared to others running mid 10's in a non-gutted street car. But I know there is a lot to be gained with a custom cam and convertor. I'd be happy with 500 to the wheels, want a 10.30 ET next year!

Hi-Po · Oct 2, 2010

Cobra912 said:
I picked up some brand new RPM's with 2.02 valves instead of the 1.90's, got em brand new for under a grand. I was motivated by price and didn't wanna have to sort out any TFS to piston issues.

I don't get this - my understanding is that TFS heads with 2.02 valves will clear stock pistons (I am running those heads myself, no clearance problems) whereas RPM's or any other head with 2.02 valves will not clear stock pistons without notching?
Why would you have less ptv problems with 2.02 valves RPM heads compared to TFS heads?

Edit: sorry didnt notice you already have notched SRP pistons - but still surprised to hear that TFS heads may have clearance issues. TFS heads will clear stock pistons with upto .600 lift.

90lxcoupe · Oct 2, 2010

If you have the money go with the 205cnc'd trick flow, if your trying to save some bucks go with the fast as cast, the FAC heads flow close to what a 185 cnc does out of the box. The fast as cast head was modeled after the 185 cnc, and there like 1500 bucks

NIKwoaC · Oct 2, 2010

Hi-Po said:
I don't get this - my understanding is that TFS heads with 2.02 valves will clear stock pistons (I am running those heads myself, no clearance problems) whereas RPM's or any other head with 2.02 valves will not clear stock pistons without notching?
Why would you have less ptv problems with 2.02 valves RPM heads compared to TFS heads?

Edit: sorry didnt notice you already have notched SRP pistons - but still surprised to hear that TFS heads may have clearance issues. TFS heads will clear stock pistons with upto .600 lift.

Trick Flow "Twisted Wedge" valves are arranged differently and angled differently than most any other head on the market. Their placement makes the heads perform better than traditional placement and also helps them avoid PTV issues to an extent. Traditional "in line" aftermarket heads, like AFRs, Edelbrocks, RHS, etc have valves in roughly the same place as stock heads.

Lastly, valve lift has NOTHING to do with PTV clearance, that is just one of those age-old myths. PTV is affected by valve opening/closing events; basically duration and overlap. You could theoretically have an intake valve with 2" lift, but if it didn't open until ATDC, it would never hit the piston. Same with exhaust valve, if it closed BTDC, no worries. Of course, IVs open BTDC and EVs close ATDC, thus the (usual) need for valve notches.

Which heads would you buy?

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