Engine Heads and how to buy

Dontknowchit · Aug 16, 2025

I want to be sure to avoid PTV issues. I do not want to flycut pistons! Looking for performance gain in a aluminum head in the most bolt on package possible (assembled). Ok if I give up a little performance for convenience and good price.

I know the Trickflow 170 11Rs are great, but what about the AFR enforcers and the newer SVEs? They have springs that are ok with the factory or a mild cam like an alphabet? Am I limited to the 1.90s or can 2.02s still clear ok?

I know I still have to check before Installing but don't want to buy, ship, then have to try and return. Anyway to measure before ordering?

Bullitt347 · Aug 16, 2025

The camshaft is really going to dictate PTV clearance more so than cylinder head.
A stock cam would probably work with just about any cylinder head. The valves just are not open anywhere near the piston to worry about.
Most street camshafts, IE, designed for daily driver usage, will work fine with most cylinder heads.
You go over .550 lift or over 230+ duration (@ .050) then it is a whole different ballgame.
Keep lift/duration reasonable and PTV is pretty much a non issue.

nickyb · Aug 16, 2025

I'm sure if you call trick flow,afr,or lmr they can recommend a good head and cam
But you have to check p.t.v.clearance to be sure you have enough room.

Dontknowchit · Aug 16, 2025

Bullitt347 said:
The camshaft is really going to dictate PTV clearance more so than cylinder head.
A stock cam would probably work with just about any cylinder head. The valves just are not open anywhere near the piston to worry about.
Most street camshafts, IE, designed for daily driver usage, will work fine with most cylinder heads.
You go over .550 lift or over 230+ duration (@ .050) then it is a whole different ballgame.
Keep lift/duration reasonable and PTV is pretty much a non issue.

Oh that's awesome, I had no idea. Thanks!

AeroCoupe · Aug 16, 2025

If you look at the cylinder head data on the manufacturer's website they usually tell you what the maximum lift the springs (if buying assembled heads) are good to. They will also tell you what the seat pressure (when the valve is closed) and open pressure (when the valve is lifted to the maximum lift of the spring) are and these all need to be known when you are looking at a camshaft.

Really you need to know the cam and select the heads to work with it. There are other parts you need to consider like pedestal or stud mount rockers, will the heads dictate the need for different length pushrods other than stock, and if you buy assembled heads are the valves, keepers, retainers, springs, and valve spring seats ("washers" under the springs to keep them from eating into the aluminum).

Other thing you need to consider is the upper and lower intakes because if you cannot get air through them all the rest is for nothing.

Dontknowchit · Aug 16, 2025

AeroCoupe said:
If you look at the cylinder head data on the manufacturer's website they usually tell you what the maximum lift the springs (if buying assembled heads) are good to. They will also tell you what the seat pressure (when the valve is closed) and open pressure (when the valve is lifted to the maximum lift of the spring) are and these all need to be known when you are looking at a camshaft.

Really you need to know the cam and select the heads to work with it. There are other parts you need to consider like pedestal or stud mount rockers, will the heads dictate the need for different length pushrods other than stock, and if you buy assembled heads are the valves, keepers, retainers, springs, and valve spring seats ("washers" under the springs to keep them from eating into the aluminum).

Other thing you need to consider is the upper and lower intakes because if you cannot get air through them all the rest if for nothing.

Yeah, flow in and out has already been well handled. The plan right now is stock cam, rockers, and pushrods as needed. I've been looking at the 170 sve's this morning. Look like a good basic aluminum stock replacement.

Noobz347 · Aug 16, 2025

The best performing OEM cam for Fox/SN95:

1985–1992 5.0 HO Roller Camshaft Specs

Type: Hydraulic roller
Firing Order: 1-3-7-2-6-5-4-8 (351/HO order)
Advertised Duration: ~266° intake / 266° exhaust
Duration @ .050": 210° intake / 210° exhaust
Valve Lift w/1.6 rockers: .444" intake / .444" exhaust
Valve Lift w/1.7 rockers (Cobra-style): .472" intake / .472" exhaust
Lobe Separation Angle (LSA): 115°
Intake Centerline: 109° ATDC
Exhaust Centerline: 121° BTDC
Overlap @ .050": 0° (tight and emissions-friendly)
RPM Range (factory): Idle – 5,500 rpm

Notes: The Cobra and later SN95s used the same stick, so the “edge” was in the Fox GT/LX years where weight was lower and computer tuning was looser.

Rcdgl · Aug 22, 2025

Dont forget that valve size also matters. For instance, AFR 165 are supposed to fit, but 185s need bigger valve reliefs. I have the 185s and needed to cut the pistons. Later got a new shortblock with different pistons that cleared.

Dontknowchit · Aug 22, 2025

Rcdgl said:
Dont forget that valve size also matters. For instance, AFR 165 are supposed to fit, but 185s need bigger valve reliefs. I have the 185s and needed to cut the pistons. Later got a new shortblock with different pistons that cleared.

that is just what I ws getting at, previous posters said even 2.02 intake valves would most likley clear fine with a stock or stockish cam.

I don't want to buy a head that I have to try to return due to PTV. they are heavy and bulky. Was looking for rule of thumb for the SVE 170s or the enforcer 185s.

AeroCoupe · Aug 22, 2025

You can buy the fly cutters and do it yourself. They have stops and believe me if i can do it it’s super simple.

We took an old cast iron cylinder head and cut one of the middle cylinders out of it on a band saw. Made it easier to move from cylinder to cylinder.

Noobz347 · Aug 22, 2025

Or pick up a set of TFS Twisted Wedge heads.

Dontknowchit · Aug 22, 2025

AeroCoupe said:
You can buy the fly cutters and do it yourself. They have stops and believe me if i can do it it’s super simple.

We took an old cast iron cylinder head and cut one of the middle cylinders out of it on a band saw. Made it easier to move from cylinder to cylinder.

Yeah, having those metal shavings in the cylinder just seems like a job I'd rather not do in the car, and if this engine is coming out, it becomes a stroker. Plan was cheap heads and no cam on this. Get to about 400rwhp (has a vortech already), and build a 347 slowly on the side while still enjoying the car.

Dontknowchit · Aug 22, 2025

Noobz347 said:
Or pick up a set of TFS Twisted Wedge heads.

I'd love to but plan is to go more cheaply on this motor, enjoy the car while I build a stroker slowly on the side. The difference is $1500, and I'll likely want a different head for the 347 or 408, not decided yet. That's a long term plan.

I've only ever done gt40 head swaps with a buddy, never bought them new from a retailer, hence the questions.

AeroCoupe · Aug 22, 2025

Getting the shavings out is easy. Watch some videos.

I get what you are trying to do so if you are not worried about changing the cam then just get a 1.90 intake valve head especially with the blower.

rednotch · Aug 22, 2025

Afr has the enforcer 185 available with the 1.90 valve option now. If budget isn't an issue I would do TFS's 11rs though.

Noobz347 · Aug 22, 2025

Dontknowchit said:
I'd love to but plan is to go more cheaply on this motor, enjoy the car while I build a stroker slowly on the side. The difference is $1500, and I'll likely want a different head for the 347 or 408, not decided yet. That's a long term plan.

I've only ever done gt40 head swaps with a buddy, never bought them new from a retailer, hence the questions.

I must have missed something because I'm not sure what this means.

The TFS TW, I'm referring to are these: https://www.trickflow.com/parts/tfs-51410004-m61#overview

It will work well on [either] of your combos (current or stroker). Boost would be the icing on the cake.

The deal with the Twisted Wedge is the valve angle. You can run these over the top of 86 flat-tops, even (been there, done that, used my 86 cam and short block, slapped a Kenne Bell on the top).

View: https://www.youtube.com/watch?v=YdglgCkXkiA

He has the combo in the description.

Dontknowchit · Aug 22, 2025

Noobz347 said:
I must have missed something because I'm not sure what this means.

The TFS TW, I'm referring to are these: https://www.trickflow.com/parts/tfs-51410004-m61#overview

It will work well on [either] of your combos (current or stroker). Boost would be the icing on the cake.

The deal with the Twisted Wedge is the valve angle. You can run these over the top of 86 flat-tops, even (been there, done that, used my 86 cam and short block, slapped a Kenne Bell on the top).

View: https://www.youtube.com/watch?v=YdglgCkXkiA

He has the combo in the description.

Thanks for the link, those are WAY WAY! cheaper than I thought they were. I must have been looking at something else where the TFS TW 170s were like 2800 a pair! Well in thais case I think these would totally be the ticket! I knew about the design basically eliminating the PTV worries but just thought they were much more. If I did a n/a stroker boosting compression would be good, with the vortech, its not as good as it means less timing. Still undecided on what flavor stroker I would do. Thanks a ton for this!

gkomo · Aug 22, 2025

I think I paid $1,700ish including tax for my TFS TW 170’s from LMR.

Noobz347 · Aug 22, 2025

Dontknowchit said:
Thanks for the link, those are WAY WAY! cheaper than I thought they were. I must have been looking at something else where the TFS TW 170s were like 2800 a pair! Well in thais case I think these would totally be the ticket! I knew about the design basically eliminating the PTV worries but just thought they were much more. If I did a n/a stroker boosting compression would be good, with the vortech, its not as good as it means less timing. Still undecided on what flavor stroker I would do. Thanks a ton for this!

Just for reference:

CR vs. gasket thickness (61 cc heads)

0.027" → 9.36:1
0.036" → 9.14:1
0.041" → 9.03:1
0.045" → 8.94:1
0.049" → 8.85:1 ⟵ ~½ point down from 0.027"
0.051" → 8.81:1
0.055" → 8.73:1
0.060" → 8.62:1

This would be on a stock 302. Obviously, it would be different for your stroker but then, you will pick the pistons that you [want] for that build.

Dontknowchit · Aug 22, 2025

"you will pick the pistons that you [want] for that build."

Exactly that would be green field except for the block. the "garage's engine" as my wife will undboutly call it will, will have a curated parts list.
if ultimatley I decide to go full 427, the block would be aftermarket also.

Engine Heads and how to buy

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I have been doing it wrong this whole time

I gotta say i never painted my nuts, Never Ever

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lube between the nut and the face. I know my lubes

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Stangnet Facilities Maint Tech... Er... Janitor

1985–1992 5.0 HO Roller Camshaft Specs​

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lube between the nut and the face. I know my lubes

Stangnet Facilities Maint Tech... Er... Janitor

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lube between the nut and the face. I know my lubes

I'd like to remain having one chocolate starfish

Stangnet Facilities Maint Tech... Er... Janitor

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now i can hopefully expect to receive the shaft

Stangnet Facilities Maint Tech... Er... Janitor

CR vs. gasket thickness (61 cc heads)​

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