AFR 227 and SRP piston to valve clearance

[ProStreet71]

Hey guys, im thinkin about getting a set of the AFR 227 heads for my 406 but am worried about the 60/40 split valves and piston to valve clearance. I guess my question is, do you have to run a special piston to run this type head? Since the valve is rotated slightly i wonder if the valve releif in the piston will have enough clearance with my current piston? I have the standard SRP line of pistons with -5cc reliefs. I always check p/v clearance with assembly but i dont want to shell out 2 grand for heads that wont work for my setup and have to spend another 600 or so for another set of pistons. This is already a running engine but i want to upgrade my Motown 220's. Thanks

[Marv D]

There a 2.08" (or at the 227's a 2.1" ) valve as I remember, radial clearance in the pocket is ALWAYS something to check. There is no way to say,, 'go' or 'no go' as there are just too many possibilities. SRP has a pretty wide intake valve pocket, but,,,, only ONE way to find out. Besides,, as a very wise engine builder once taught me,,, if your not whacking on pistons for valve clearance,,,, your not trying hard enough

[68 C-10 KID]

I have the AFR 227's w/ 6" rods with the SRP flat tops, Also running a .642 lift Isky cam. I have plenty of clearance. I had about 90 for int & exh.
Those heads rock. So nice you want to put them under glass.

[djracer]

I had to massage the pockets on my last pistons because of a 2degree rolled valve angle. It didn't cost that much to have them cut.

[ProStreet71]

Thanks guys. I am goin to order a set of the comp ported version. I talked to a few of the guys over at speedtalk and said they had no issues with the SRP slugs as also 68c10kid had none with those either.

[ProStreet71]

Hey 68c10kid, those are impressive numbers you have on that engine. We have almost identical builds. Hope i get numbers like that! What kind of times do you get in the 1/8? Im trying to get low 7's with all motor. Also how street friendly are those heads? Alot of folks say they are not to street freindly, but i think that just depends on your definition of "streetable". I dont think they could be any worse than my 220cc runner head that i am running now. After all they are only 7cc bigger and should give quite a bit more power. Thanks

[Marv D]

Before you place that order, do be aware the 227's require a offset shaft rocker system to get valve train geometry anywhere near correct. A Crower 60/40 offset shaft rocker package in 1.5:1 ratio will be right around a grand,,,, $1100 or there abouts for T&D, and Jesel will be maybe $100 more with their good packages.

[ProStreet71]

Thanks Marv. Yes I am aware about the rockers. Thanks for making sure though.

[68 C-10 KID]

Originally Posted by ProStreet71

Hey 68c10kid, those are impressive numbers you have on that engine. We have almost identical builds. Hope i get numbers like that! What kind of times do you get in the 1/8? Im trying to get low 7's with all motor. Also how street friendly are those heads? Alot of folks say they are not to street freindly, but i think that just depends on your definition of "streetable". I dont think they could be any worse than my 220cc runner head that i am running now. After all they are only 7cc bigger and should give quite a bit more power. Thanks

My ET numbers are not correct. My trans was going out when I put the 406 in. I do not have the time slip's with me. I believe it was around 7.5's in the 1/8 and 12.0's in the 1/4. I drive my truck all over, to the track to the coast and all over town. On the freeway it actually gets 9.5 mpg's. That's no joke. I'm running a 950 Hp. I do not recommend locking the distributor out. I run advance for street ability. I have a lot of time vested in vacuum gauge tuning. So my vote is yes, very street able.

[ProStreet71]

Im not nockin your carb but most of the guys over on the speedtalk forum say the 950 is basicly just a 750. Not sure just exactly what it is but sumthing like its just an 850 with a 750 baseplate but dont quote me on that. I will try to do a search over there on that forum and see. Joe Sherman says you get more power out of the 850. Just thought you might like to know. Thanks

[ProStreet71]

Did a search and i had it backwards. It is a 750 body with a 850 base. Joe Sherman says he has flowed them and the 950 flows 65 cfm less than the 850. Made 25 HP less on the dyno also.

[68 C-10 KID]

I do believe your right something to do with the butter fly size and venturi sizing. I have had the 950 on since end of last year when I made the attempt to get the trans in the night before last day of race season, just for it to rain. I have the 850 also that's normally on it. I'm wanting to do some track testing w/ both carb's.

[68 C-10 KID]

Originally Posted by ProStreet71

Did a search and i had it backwards. It is a 750 body with a 850 base. Joe Sherman says he has flowed them and the 950 flows 65 cfm less than the 850. Made 25 HP less on the dyno also.

Looks like a have a big toilet bowl on it then. LOL What the hell are they good for?

[nxtruck]

ProStreet71,
To answer your original question; as a few others have said, there's not a yes or no answer to this. You will have to check clearance to make sure that you're ok. I've built 2 different short blocks in the past 6 years and used these same heads on both motors. A dome piston 421 and a dish piston 434. I had plenty of clearance with both. I used 2 completely different cams, as well, one of which was right at .700 lift and 292 @ .050 duration. I'd guess that you'll probably be ok, but there's only one way to know for sure.

[oldno7]

We'll I havn't been to this sight for a while. I'm glad you all started this section. You guys are a little above me though. I have a 72 long fleet with just a mild 350 afr195 comp 262cam Yeah I know. It runs 8.60's in the 1/8 though. TCI 400 tranny with 4.56 posi. It sure needs more power! It falls on it's face at about 400ft. It's all fun though oldno7

[Super73]

Total lift is not the issue for any set up. Where problems araise is Intake valve opening and Exhaust closing points. Since the IVO point is typically BTC and the EVC is ATD those are the critical points to check.

Only way to know for sure is put it together and check it with clay or put a degree wheel on it and drop a valve every 1-2 degrees to check for total clearence (assuming you are using a solid lifter).

But if you do run in to P2V issues Moving the cam with an adjustable timing set can gain you a little clearence but obviously it will effect the power band do to changing the valve events.

[nxtruck]

I agree with everything you stated. I mentioned the specs on one of my old cams just to give the original poster an idea of how rowdy a cam I had used with these heads and didn't have to cut the pistons. Generally, the smaller the cam, lift and duration-wise, the less the chance of having to cut the pistons. Like you said, your clearance problems don't happen at max lift; they'll happen during the intake-opening and exhaust closing.
I just thought that I'd reply with this as to not mislead the original poster into thinking that max lift and duration figures are all that need to be taken into consideration.

[Super73]

Theoretically you could have piston to valve clearence issues with a cam that has 224* duration at .050 if the intake centerline was low enough.

[ProStreet71]

Thanks for all the replies guys. I just got my heads. These things are a work of art. I hate to put them on the motor they look so good. But looks dont get you down the track any faster, so i cant wait to see how they perform.

[68 C-10 KID]

Originally Posted by ProStreet71

Thanks for all the replies guys. I just got my heads. These things are a work of art. I hate to put them on the motor they look so good. But looks dont get you down the track any faster, so i cant wait to see how they perform.

Just a little memo.
Make sure your push sticks are not hitting the top side of the rail and the valve cover.

I also drilled mine for the steam relief for all my street diving needs.

[slednD1]

trick flow made pistons for thier twisted wedge heads to correct this problem,call thier tech support and act as if you intend to buy thier heads and see what piston info they give you.sounds like a great project keep us posted!