The CCC Installs AFR Heads
Thread Starter
Tech Contributor
Joined: Aug 1999
Posts: 14,382
Likes: 6,401
From: At my Bar drinking and wrenching in Lafayette Colorado
The CCC Installs AFR Heads
A few of the lunatics in the CCC (The Colorado Corvette Crazies - the Ultimate Corvette Tuning and Beer Drinking Fraternity) got together Saturday and installed a new set of 195 68cc AFR heads on Steve's ("brutal64") insanely quick 355 '64 Coupe.
Teardown to the shortblock was accomplished in 1 hour flat. Re-assembly took a little longer due to poor pre-planning on our part: We were short tools, parts and hardware, resulting in several unplanned trips to various stores during the work. We probably should have read the instructions prior to diving into the work and the beer drinking. In spite of this, the complete job was done in 7 hours from start to finish.
Steve's old heads were highly worked-over 2.02 "fuelie" heads that produced an outstanding level of performance. The change in performance by going to the AFRs was dramatic. Bottom-end and midrange actually smoothed out a bit, with an incredible level of torque - the car is VERY smooth to drive in power and overall "feel." On the top end, the engine now pulls brutally above 4000 rpm, and it doesn't quit through 6,000. It revs up to that point frighteningly quickly, and the desire is to leave it in gear and let it keep pulling beyond 6,000 since it's pulling so hard. Watching the tach is now mandatory, and shifting gears now results in a car that's all over the road in all 4 gears.
Very impressive. Check out the post over on C1/C2 for some pictures of the process. If you're thinking about doing this, drop one of us a line so we can tell you about the minor pitfalls and things to do before starting...
http://forums.corvetteforum.com/showthread.php?t=889261
Teardown to the shortblock was accomplished in 1 hour flat. Re-assembly took a little longer due to poor pre-planning on our part: We were short tools, parts and hardware, resulting in several unplanned trips to various stores during the work. We probably should have read the instructions prior to diving into the work and the beer drinking. In spite of this, the complete job was done in 7 hours from start to finish.
Steve's old heads were highly worked-over 2.02 "fuelie" heads that produced an outstanding level of performance. The change in performance by going to the AFRs was dramatic. Bottom-end and midrange actually smoothed out a bit, with an incredible level of torque - the car is VERY smooth to drive in power and overall "feel." On the top end, the engine now pulls brutally above 4000 rpm, and it doesn't quit through 6,000. It revs up to that point frighteningly quickly, and the desire is to leave it in gear and let it keep pulling beyond 6,000 since it's pulling so hard. Watching the tach is now mandatory, and shifting gears now results in a car that's all over the road in all 4 gears.
Very impressive. Check out the post over on C1/C2 for some pictures of the process. If you're thinking about doing this, drop one of us a line so we can tell you about the minor pitfalls and things to do before starting...
http://forums.corvetteforum.com/showthread.php?t=889261
Melting Slicks
Joined: Dec 2001
Posts: 2,025
Likes: 1
From: Billings MT
Sounds like all went well, that is certainly a thing to smile about! 
I'm assuming the heads were tore down and inspected prior to installation? I found that on mine the valve seat was cut non-concentric causing the valve not to seal (on a vacuum test).
Why i'm here (not meaning to hijack), but I have a question. Do you know where I can find a .073" idle air bleed? Also looking for idle feed restrictor jets. My Mighty Demon 750 is quite fat at idle. (Throttle plates set, correct PV, ect. - idle circuit only).
Thanks!
I'm assuming the heads were tore down and inspected prior to installation? I found that on mine the valve seat was cut non-concentric causing the valve not to seal (on a vacuum test).
Why i'm here (not meaning to hijack), but I have a question. Do you know where I can find a .073" idle air bleed? Also looking for idle feed restrictor jets. My Mighty Demon 750 is quite fat at idle. (Throttle plates set, correct PV, ect. - idle circuit only).
Thanks!
Thread Starter
Tech Contributor
Joined: Aug 1999
Posts: 14,382
Likes: 6,401
From: At my Bar drinking and wrenching in Lafayette Colorado
VETDRMS -
No, we slapped 'em on as received right out of the box after verifying that there was no debris in any of the runners - no problems.
Both Demon and Holley sell the air bleeds, although they're more expensive than main metering jets..! Demon also sells IFR plugs so you can drill them yourself.
WA -
Yes, the heads seem to be very well built, and the results are certainly quite impressive. Steve found the heads advertised by a distributor on eBay for one heck of a good price, making the swap almost mandatory..!
No, we slapped 'em on as received right out of the box after verifying that there was no debris in any of the runners - no problems.
Both Demon and Holley sell the air bleeds, although they're more expensive than main metering jets..! Demon also sells IFR plugs so you can drill them yourself.
WA -
Yes, the heads seem to be very well built, and the results are certainly quite impressive. Steve found the heads advertised by a distributor on eBay for one heck of a good price, making the swap almost mandatory..!
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
What were the caveats? I had my valve seats cut even and the head milled straight.
I'll be doing this install next weekend... would be nice if I could get it done in 7 hours, but two days is fine by me!
I wonder how it'll do with a Crane 272 (216/216 .454/.454)...
-Steve
PS What push rod lengths did you ultimately go with?
I'll be doing this install next weekend... would be nice if I could get it done in 7 hours, but two days is fine by me!
I wonder how it'll do with a Crane 272 (216/216 .454/.454)...
-Steve
PS What push rod lengths did you ultimately go with?
Last edited by Pacin'California; Aug 22, 2004 at 06:47 PM.
Thread Starter
Tech Contributor
Joined: Aug 1999
Posts: 14,382
Likes: 6,401
From: At my Bar drinking and wrenching in Lafayette Colorado
Here are the things we ran into:
1. Make sure you have a thin-walled 12-point 5/8" socket - this makes removal of the stock head bolts much more trouble-free when the engine is installed in the car.
2. Get a set of small-head head bolts. You cannot use regular small block Chevy head bolts with the AFR heads because the heads on the bolts are too big (the 5/8" hex cannot be used with the AFR heads). You will need to use a set of ARP 12-points or a set of 9/16" hex heads. We used the 9/16" hex head bolts and installed them with a thin-walled 9/16 12-point socket. This just barely worked.
3. Make sure you install pipe plugs in the water temp holes in the AFR heads....
4. Check the pushrod guide plate alignment on the AFRs. Ours were out of adjustment and caused bind-up of the pushrods. They were not torqued to spec out of the box.
5. The stock length pushrods can be used, but if you want to optimize the valvetrain geometry for higher lift cams, use a set of .100" over pushrods (we did).
6. Get a set of good washers to put under the head bolts so you won't gall up the heads when you torque the bolts. Make sure the outer diameter of the washers is small enough to actually fit the counterbores in the heads.
7. Buy the right spark plugs as recommended for the heads - you cannot use your stock plugs.
8. Be aware that the AFR heads use a raised exhaust port configuration. This will raise the exhaust system and any accessories using the exhaust bolts about 1/4". We ran into a short alternator belt due to the higher mounting of our alternator bracket (1964 uses the exhaust bolts for the lower bracket mounting).
If we had accounted for these items, we would have had the entire job wrapped up in under 4 hours. We spent at least 3 hours driving around chasing down special parts on a Saturday afternnoon when everything was closed.
The Crane 272 really ought to scream with a set of these heads. Should be tons of fun!!
1. Make sure you have a thin-walled 12-point 5/8" socket - this makes removal of the stock head bolts much more trouble-free when the engine is installed in the car.
2. Get a set of small-head head bolts. You cannot use regular small block Chevy head bolts with the AFR heads because the heads on the bolts are too big (the 5/8" hex cannot be used with the AFR heads). You will need to use a set of ARP 12-points or a set of 9/16" hex heads. We used the 9/16" hex head bolts and installed them with a thin-walled 9/16 12-point socket. This just barely worked.
3. Make sure you install pipe plugs in the water temp holes in the AFR heads....
4. Check the pushrod guide plate alignment on the AFRs. Ours were out of adjustment and caused bind-up of the pushrods. They were not torqued to spec out of the box.
5. The stock length pushrods can be used, but if you want to optimize the valvetrain geometry for higher lift cams, use a set of .100" over pushrods (we did).
6. Get a set of good washers to put under the head bolts so you won't gall up the heads when you torque the bolts. Make sure the outer diameter of the washers is small enough to actually fit the counterbores in the heads.
7. Buy the right spark plugs as recommended for the heads - you cannot use your stock plugs.
8. Be aware that the AFR heads use a raised exhaust port configuration. This will raise the exhaust system and any accessories using the exhaust bolts about 1/4". We ran into a short alternator belt due to the higher mounting of our alternator bracket (1964 uses the exhaust bolts for the lower bracket mounting).
If we had accounted for these items, we would have had the entire job wrapped up in under 4 hours. We spent at least 3 hours driving around chasing down special parts on a Saturday afternnoon when everything was closed.
The Crane 272 really ought to scream with a set of these heads. Should be tons of fun!!
Safety Car
Joined: May 2001
Posts: 3,758
Likes: 3
From: Surrey
Lars,
I'm in imminent danger of buying a set of 180's so this info is excellent
What alternator belt did you end up going with? I've fitted some M/T valve covers & had to move the alternator up to clear by changing from a 15540 belt to a 15555 belt.
I make that 2 pints I owe you now
I'm in imminent danger of buying a set of 180's so this info is excellent
What alternator belt did you end up going with? I've fitted some M/T valve covers & had to move the alternator up to clear by changing from a 15540 belt to a 15555 belt.
I make that 2 pints I owe you now
Last edited by UKPaul; Aug 24, 2004 at 09:54 AM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Safety Car
Joined: May 2001
Posts: 3,758
Likes: 3
From: Surrey
Originally Posted by lars
Paul -
We went with an alternator belt that was about one thumb width longer than whatever belt was on there before...
We went with an alternator belt that was about one thumb width longer than whatever belt was on there before...
Thanks.Hi Page,
Hope all is well? So far, so good with AFR. They've recommended the 180's over the 195's for my setup & what I want for the future (big flat torque curve between 2000-5000rpm, lots of midrange grunt & good street "manners" with some sort of half-hearted attempt to retain the good fuel economy I'm currently getting). Now waiting for an email in response to a few more questions (like do they do 50% discount for foreigners?
).A couple of kegs sounds right up my street, but if I'm buying a set of AFR heads (+ all the peripheral gubbins) a couple of pints is all I'll be able to afford!
Thread Starter
Tech Contributor
Joined: Aug 1999
Posts: 14,382
Likes: 6,401
From: At my Bar drinking and wrenching in Lafayette Colorado
Matt -
On our 195 heads with the large diameter valvesprings it is not physically possible to insert the stock head bolts into the 2 end locations under the valvecovers: The bolt heads actually interfere with the spring seat and cannot be inserted into the counterbores. We could have used a big prybar and pushed the springs over to the side in excellent Bubba fashion, but we would not have been able to use a socket on the bolts since the hex on the bolt would actually touch the walls of the counterbore. So we used a set of Manley 9/16" hex head bolts with a thin-walled socket, and this worked perfectly.
UKPaul -
If you want to arrange some sneaky ordering and shipping to avoid customs, drop me a note. I'll be glad to help out getting you a nice setup. I can also "kit" all the other parts you need to complete the swap if you'd like. We got an excellent deal on the heads through an eBay dealer (roughly $1200), and we could duplicate the deal for you.
On our 195 heads with the large diameter valvesprings it is not physically possible to insert the stock head bolts into the 2 end locations under the valvecovers: The bolt heads actually interfere with the spring seat and cannot be inserted into the counterbores. We could have used a big prybar and pushed the springs over to the side in excellent Bubba fashion, but we would not have been able to use a socket on the bolts since the hex on the bolt would actually touch the walls of the counterbore. So we used a set of Manley 9/16" hex head bolts with a thin-walled socket, and this worked perfectly.
UKPaul -
If you want to arrange some sneaky ordering and shipping to avoid customs, drop me a note. I'll be glad to help out getting you a nice setup. I can also "kit" all the other parts you need to complete the swap if you'd like. We got an excellent deal on the heads through an eBay dealer (roughly $1200), and we could duplicate the deal for you.
Last edited by lars; Aug 24, 2004 at 11:39 AM.
Melting Slicks
Joined: May 2001
Posts: 2,131
Likes: 4
From: May help you? You can sure as hell try!
Originally Posted by lars
Teardown to the shortblock was accomplished in 1 hour flat. Re-assembly took a little longer due to poor pre-planning on our part: We were short tools, parts and hardware, resulting in several unplanned trips to various stores during the work. We probably should have read the instructions prior to diving into the work and the beer drinking. In spite of this, the complete job was done in 7 hours from start to finish.
Thread Starter
Tech Contributor
Joined: Aug 1999
Posts: 14,382
Likes: 6,401
From: At my Bar drinking and wrenching in Lafayette Colorado
LeMans -
Let me assure you that the CCC has NEVER run out of beer during a tech session...! We've sent people out on emergency re-supply runs just prior to beer exhaustion, but we have NEVER actually run dry of beverages. I'm not sure what would happen if we did, but it wouldn't be pretty....
Let me assure you that the CCC has NEVER run out of beer during a tech session...! We've sent people out on emergency re-supply runs just prior to beer exhaustion, but we have NEVER actually run dry of beverages. I'm not sure what would happen if we did, but it wouldn't be pretty....
Burning Brakes
Joined: Mar 2001
Posts: 1,171
Likes: 0
From: Thornton Co
Originally Posted by LemansBlue68
For a minute there I thought you were going to say that the beer supply ran out.:shocked:
That's the funniest thing I've heard in a while. Lars has done a great job of documenting the AFR install and the performance improvements. All I can say is anyone thinking of an AFR upgrade you won't be disappointed.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Pacin'California
Your getting the wrong Crane 272 cam. This is the one I recommended and used for years with 1.6 roller tips and @125 lb springs so I would not have valve float to well over 7000 rpm
Part Number: 113941 Grind Number: H-268-2 (REPLACES H-272-2)
Engine Identification:
Start Yr. End Yr. Make Cyl Description
1957 1987 CHEVROLET 8 GOOD IDLE, FOR 350+ CU. IN. MODIFIED ENGINES WITH FREE-FLOWING ABOVE WATER EXHAUST SYSTEMS FOR PERFORMANCE APPLICATIONS IN LIGHT PLEASURE AND SKI BOATS, INCLUDING JET BOATS, 8.75 TO 10.75 COMPRESSION RATIO ADVISED (C.A.R.B. E.O. D-225-18). BASIC RPM 2000-5000
Engine Size Configuration
262-400 C.I. V
Valve Setting: Intake .000 Exhaust .000 HOT
Lift: Intake @Cam 306 @Valve 459 All Lifts are based
on zero lash and theoretical rocker arm ratios.
Exhaust @ Cam 324 @Valve 486
Rocker Arm Ratio 1.50
Cam Timing: TAPPET @.004
Lift: Opens Closes ADV Duration
Intake 25.0 BTDC 63.0 ABDC 268.0 °
Exhaust 75.0 BBDC 25.0 ATDC 280.0 °
Spring Requirements: Triple Dual Outer Inner
Part Number 99848
Loads Closed 105 LBS @ 1.700 or 1 45/64
Open 280 LBS @ 1.240
Recommended RPM range with matching components
Minimum RPM 2000
Maximum RPM 5000
Valve Float 6500
Cam Timing: TAPPET @.050
Lift: Opens Closes Max Lift Duration
Intake 2.0 BTDC 36.0 ABDC 107 218.0 °
Exhaust 52.0 BBDC (2.0) BTDC 117 230.0 °
Part Number: 113941 Grind Number: H-268-2 (REPLACES H-272-2)
Engine Identification:
Start Yr. End Yr. Make Cyl Description
1957 1987 CHEVROLET 8 GOOD IDLE, FOR 350+ CU. IN. MODIFIED ENGINES WITH FREE-FLOWING ABOVE WATER EXHAUST SYSTEMS FOR PERFORMANCE APPLICATIONS IN LIGHT PLEASURE AND SKI BOATS, INCLUDING JET BOATS, 8.75 TO 10.75 COMPRESSION RATIO ADVISED (C.A.R.B. E.O. D-225-18). BASIC RPM 2000-5000
Engine Size Configuration
262-400 C.I. V
Valve Setting: Intake .000 Exhaust .000 HOT
Lift: Intake @Cam 306 @Valve 459 All Lifts are based
on zero lash and theoretical rocker arm ratios.
Exhaust @ Cam 324 @Valve 486
Rocker Arm Ratio 1.50
Cam Timing: TAPPET @.004
Lift: Opens Closes ADV Duration
Intake 25.0 BTDC 63.0 ABDC 268.0 °
Exhaust 75.0 BBDC 25.0 ATDC 280.0 °
Spring Requirements: Triple Dual Outer Inner
Part Number 99848
Loads Closed 105 LBS @ 1.700 or 1 45/64
Open 280 LBS @ 1.240
Recommended RPM range with matching components
Minimum RPM 2000
Maximum RPM 5000
Valve Float 6500
Cam Timing: TAPPET @.050
Lift: Opens Closes Max Lift Duration
Intake 2.0 BTDC 36.0 ABDC 107 218.0 °
Exhaust 52.0 BBDC (2.0) BTDC 117 230.0 °