I picked up my 180cc street heads from my machinist to get them milled down to 64cc. The chambers were measured just shy of 70cc. They were actually milled to 63.5 cc.

Is it normal for the AFR's to be that off as compared to advertised? Just curious.

SBC 350 +.020
AFR 180 SH
Holley 300-36
Holley 670 Street Avenger
Pertronix HEI
Lunati 401A6 on 112 lsa
9.6 compression
2500 stall
3.73 12 bolt posi
85 GMC short bed

[QUOTE=wildman926]I picked up my 180cc street heads from my machinist to get them milled down to 64cc. The chambers were measured just shy of 70cc. They were actually milled to 63.5 cc.

Is it normal for the AFR's to be that off as compared to advertised? Just curious.[End Quote]

My favorite subject, with a very "familiar" mfr. Of course it's not "normal", but it happens to be very "true". But in staying "fair" here, they ALL (all brands) have to be "double-checked" no matter who makes 'em! One more note, you MUST use the identical valves used by the head mfr. or you will get different numbers. In our case they made the change out there and never changed the tape.

The problem on our specific pieces, at is it appears to us, is they didn't take into account a last minute valve substitution on these exhausts. The CNC tapes are wrong (as-is)! If we change the valves and re-cc them, the numbers are there! The "large" head of the substituted valve subtracted about 4 cc's. You may want to factor that into your equation, because it does have a direct effect on the cc's.

We always prefer to have the chambers WAY under if possible, it ends up being less work for us and ALWAYS give the customer a better finished unit!
It's not a problem for us when we do this everyday, but for the individual
who relies on the correct numbers, it's nothing more than grief. Thanks, Gary in N.Y.

P.S. I have 2 very irate customers I'm dealing with at this present time over 16 pistons that were ordered ahead of time based on the (quote) "CNC'd-121 cc numbers" (unquote)! One set we're finishing now, the other is already
"hogged-out". I tried to explain to the customer it turned out to be an advantage in his favor, our "main-man" (head porter) was able to make some additional improvements in the end numbers. Neither minded the fact that it would all be "right" in the end, they were simply "disappointed" in the add'l costs incurred. One more, one of these customers checked his chamber volumes long before I ever got the heads to prepare. He asked me to "double-check" his numbers fearing he measured wrong. However, he was correct, 117 cc's.

I picked up my 180cc street heads from my machinist to get them milled down to 64cc. The chambers were measured just shy of 70cc. They were actually milled to 63.5 cc.

Is it normal for the AFR's to be that off as compared to advertised? Just curious.

SBC 350 +.020
AFR 180 SH
Holley 300-36
Holley 670 Street Avenger
Pertronix HEI
Lunati 401A6 on 112 lsa
9.6 compression
2500 stall
3.73 12 bolt posi
85 GMC short bed
=
Which head?
There is a 68 & 74cc head.
2cc's in a production environment is not unusual, in fact in my experience less is somewhat unusual.

That said, in the last couple of years I have personally measured 5 sets of BB AFR heads & 4 sets of small block ones I have records for without wandering out to the shop,,
Every one was within 1cc of advertised with the BB ones running 120 on two, 121 & 122 on the others & 116 on a set I ordered as such.
These were all with the Tulip exhaust valve.

On another, I just finished doing, I cut .023" off of & they cc'd at 116. They came at a tick over 120 from AFR.

On the small blocks, they ran between 73 & 75cc's on 195's & 76cc's on the 210's
Advertised is 74 & 76cc's respectively.

I have one set of ford's that are advertised at 58 & cc'd at 60 so they are 2cc's off.

I just finished two sets of RHS/Protopline whatever cast iron heads they were advertised at 64cc's. They were 69 with Ferrea valves
One set of Edelbrock's advertised at 110. They were 113 with the valves supplied
A set of Dart "Platinum" advertised at 64. They were 67 again with Ferrea
As was stated, you have to use the valve the chamber was "designed" with to get a meaningful measurement.

With regards to AFR I have just not found the "issues" some seem to have had & I have had a "few" sets pass through over the years :D

If you order them with a different valve it would of course be wise to check them as any valve change can make a big difference but this is not the fault of the supplier except they should probably inform you of the difference,,,, probably would if you asked,, :rolleyes:
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I have no clue what the "tape that is wrong" is referred to in the above post as CNC machines do not use tapes, they use computer programs but I can gurarentee you AFR or any other company for that matter is not going to change the standard CNC chamber program to accomidate a valve change unless it is a running change in producton.
AFR uses three valves in the exhaust of the BB heads, the "nail head", Tulip & Inconel, all being Ferrea.

I gotta say, darn, you guys are good!!

pdq67

Sorry to not give enough info, but they are part number 0916, 180cc Street Heads, Straight Plug w/heat riser, 68cc, standard configuration as delivered from AFR. The heads were measured with the valves that came with the heads, and my spark plug, before and after. The machine shop is G & G Performance, well known here for there work.

Regardless, I am very happy with them and looking forward to getting them on.

Do you guys think that I have too much cam, and should go smaller?

Are you going to race that truck at all? I'm very curious to see how your combo does on the drag strip.

I would not mind taking it down to the track to see how it does once I get everything done. I only drive it to work on Mondays, to home on Fridays, and just put around my general area on the weekends due to having a company truck.

The only thing that I am worried about is the cam. After measuring everything, my static is 9.6, dynamic comp is 7.7, which should be perfect for pump gas, and since it is ground on 112 lsa, it should be ok for street manners as well.