PTV clearance help. AFR vs TFS

I'm trying to decide on the PTV clearance of each one.

The AFR 185's use 2.020 intake and 1.600 exhaust

The Twisted Wedge 170's ones use the same valve size as well.

This is going on a 347 block:

-6.55 Keith Black hyper pistons

Comp Cams Magnum 280H cam
Lift: .512
Dur: 280

I want to figure out which one will be the right fit before I buy a set of heads that are useless to me. Some people say the AFR's will touch. Some say they won't.

Then other people say the Twisted Wedge ones (from where the valve is at an angle) will hit if I don't have TW reliefs. Others say that from where the valve is at an angle, it won't hit.

Finally got the money saved up for some aluminum heads. I am just very confused and am building this first time motor. I just don't want to make a mistake because heads are expensive. I know it's best to test them with clay, and I will. I just don't want to buy a head set that will automatically have PTV issues out of the box when I could have bought a different one.

With that cam, what do you think?

What is everyone's experience with AFR to TFS clearance issues? Any help/situations/stories will help greatly.

 

The TW give more PTV clearance than std inline valve heads...

I used them with the TW Stage-1 cam on a 5.0 with flat top pistons(I mean smooth no reliefs) that were .003 out of the hole... No issues in nine years of street driving and approx 700 drag strip passes, gonna put them on a 331 one of these days...

 

That is what I was looking for. Some real life experiences. I have reliefs in my pistons, just not huge ones. What was the lift and duration on that cam? You had flat tops and they worked fine. So, I know mine will be alright then. Thanks!

 

Just curious as to why you are thinking about using the TW 170s and not TW 190s same valves just better flow numbers, 347s like to breathe

 

Mike's right. 170's will start running out of steam much past 6,000 compared to the larger variants. Plus you'll have more headroom for future growth without giving up much power below 2'500 or so with larger bowls.

And the manufacturers r the best ones to talk specs with. From all that I've heard and seen using either head choice.. much past .525 and 280 degrees gets tighter but is doable. Also keep in mind that the intake size has less impact that the exhaust duration does when it comes to PTV issûes due to later closing event on longer cams.

 

My cam has .499/.510 lift with 221*/225* duration @ .050 and is the "baby" of TFS cams... I'm going to use 1.7 rockers on the 331 so lift will increase to .530/.542...

TFS claims smooth idle but it is slightly rumpy(had knowledgeable Ford guys ask if I was running the B cam), the most I'd ever want to run on a regularly street driven vehicle... The fat girl T-Bird ran best of 13.11& 105.3 at 3760 Lb incl me... I ran 1 5/8 BBK headers & full 2.5" exhaust system also using Cobra or GT40 EFI intake... Stall was 2600 & 3.73 gears out back, with 3200-3500 converter it would have ran 12.8...

http://www.trickflow.com/media/pdfs/catalog_2014.pdf

Their catalog is here, Ford smallblock cams on page 41... They only offer roller...

 

Well, the main reason was I can't find any fast as cast 190's with a 58cc chamber. My stroker combo is based off 58cc to keep the compression to 10:5.

The lowest 190 I seen was a 62cc.

For mainly a street application, would the 170 to 190 be that big of a difference for me?

 

Yeah, I plan on calling Trick Flow tomorrow and talking with them.

 

Thanks for the info! I really like the better price of the TFS compared to AFR.

 

When my engine was built and I was talking to the builder about the heads being 62cc he told me that he took the deck height down so the piston was .003 out of the hole to bump up the compression to 10.3 the lift on my cam is 568 dont know duration as I was never provided a cam card.

 

Yeah that plus the fact they were the only performance heads I could use with the flat tops, definitely swayed my decision... I'd considered AFR but they weren't yet avail in '99(SBF heads were in their catalog)... The TFS cams had just came out, and they were yet to offer intakes or other components...

 

I'm running the AFR 185's, but also have pistons with valve reliefs. I don't have the duration on my cam in front of me, but I clayed the heads before I fired the engine and had enough clearence. Lift is .614 solid roller, but the duration will have more impact on PTV than lift will. Good luck on whichever you choose...I like the AFR's...but I have AFR's lol. When I was getting ready to get mine, I had some buddies that had the TFS, and they were convinced the AFR's were the thing to get (grass is greener thing probably ) Either are a good head, and it comes down to what you want. I've been completely satisfied with mine.

I personally went with the 185's because the ports were not raised any...my headers, scratch that, DRIVER's side header is a complete pain now!

 

My block is a '76. It was one of the taller ones. I had the shop zero it out.

 

Okay, sounds like a winner to me. I'm going to have to get back on the compression calculator and see how much the 62cc 190's will make a difference.

 

Well, I figure since this build is 80% street, I would be happy with the TW's. For the price of the AFRs, I can get the TW's and my rocker arms. Maybe even push rods too.