[COPO9560]

Thinking about adding a set of modern heads to my L72. Currently in relatively stock form with 030 over pistons, 840 heads and old Ultradyne hydraulic cam. Hp unknown but easily goes to 6500 rpm.

Top of list so far is AFR 265 as cast with CNC chamber. Wanting to upgrade to roller cam and get to around 7000 rpm. Willing to go mechanical but hydraulic would be easier to deal with. (had mechanical flat tapper cams in past)

Going in 69 F body with manual trans and 4.56 gears. Street car that will get TKX tranny during makeover.

625 hp or above is goal with reliability to run power tour.

Thoughts or suggestions?

 

[68Chevele]

Those 265 AFR's will blow those old 840's away in performance. I for sure would run an Air Gap with a healthy 850 and 1 7/8" or smaller header, should make killer power.

 

[Harris Roc Malouda]

Thats gonna be fun..

good head choice.

Cam wise a hyd roller single pattern (or max 4° dur split) around 235-240 @.50 with around .600 lift would be my choice. LSA between 107-110.
If solid go a littler bigger.
Or you could use solid lifters on the hyd roller profile, those hybrid setups get more frequent recently..

Anyway: good roller rockers (with stud girdle because 7000 rpm?) and lifters are your ticket..

Scorpion rockers and Morel lifters for example..

 

[ekitch]

With the AFR's you are going to lose compression. You are going from a closed chamber head to an open. The stock L72 cast iron head has about a 105 cc chamber. Another head I would consider is Edelbrock. A 60499 Edelbrock head, out of the box, has a 100cc chamber, 2.19 and 1.88 valves, and flows 300 cfm @ 0.600 lift on the intake, and 218cfm @ 0.600 lift on the exhaust, with no work. With that small of a chamber, you will have to verify piston to head clearance. If you want to rev to 7000 rpm's with a hydraulic roller, that will require really good hydraulic roller lifters such as comp short travel, howards or morels and valve springs to go with it. Be ready to open up your wallet! I would not rule out a moderate sized solid street roller at this point. 625 HP on a 427 motor will not be easy. Just for kicks I built a 427 engine (433) on desktop dyno ver 5 with a 252/257 crane marine solid roller, 10:1 compression, and ported Edelbrock E street heads. Made 600 HP at 6500 rpm and 565 tq at 4500.

 

[cstraub]

Thinking about adding a set of modern heads to my L72. Currently in relatively stock form with 030 over pistons, 840 heads and old Ultradyne hydraulic cam. Hp unknown but easily goes to 6500 rpm.

Top of list so far is AFR 265 as cast with CNC chamber. Wanting to upgrade to roller cam and get to around 7000 rpm. Willing to go mechanical but hydraulic would be easier to deal with. (had mechanical flat tapper cams in past)

Going in 69 F body with manual trans and 4.56 gears. Street car that will get TKX tranny during makeover.

625 hp or above is goal with reliability to run power tour.

Thoughts or suggestions?

We have small square port BBC head to do what you want to do. This is a s 12.5 to 1 427 =.060 with the heads and a eddy dual plane intake along with a custom Straub Solid roller and Morel Black Mamba lifters. Goal was 700HP and I really didn't know if we could with the dual plane. 2 were build for vintage road racing.

View attachment 721987

 

[COPO9560]

Thanks to all so far. Maybe it’s time to consider breaking into the short block and upgrading pistons and rods as well.

Chris are you referring to the AFR 305 head? Honestly that’s smaller than what I have now. I’m flexible on intake selection as well. The mechanical engineer in me thinks the AFR have a lot more potential vs the Eddy head

 

[cstraub]

Thanks to all so far. Maybe it’s time to consider breaking into the short block and upgrading pistons and rods as well.

Chris are you referring to the AFR 305 head? Honestly that’s smaller than what I have now. I’m flexible on intake selection as well. The mechanical engineer in me thinks the AFR have a lot more potential vs the Eddy head

No. We use AFR porters castings that you can't stick you thumb down the intake runner. We develop and port in house. This head will be right at 288cc.

 

[Harris Roc Malouda]

No. We use AFR porters castings that you can't stick you thumb down the intake runner. We develop and port in house. This head will be right at 288cc.
View attachment 722004

looks like a dream factory ^^ congrats

 

[RickyHill]

The guy I deal with always asks 3 questions. Goal budget usage. From that he can help you down the correct path. He took my stock l88 put on a strip dominator intake with 215 oval port heads and stock zl1 cam and made 580 horsepower. He said he would try a 290 flotek or promaxx head with a strip dominator or rpm air gap. And to really help he would spend the 900 for jones or bam bushing solid roller with a custom cam to your specs. 625 horsepower is very easy to get. Heck johns own 30 over l72 with the 215 heads holley strip dominator and 630 solid flat tappet cam made 629 horsepower.

RH

 

[mrpaticular]

Maybe I missed this. IMO, 7000 rpm +, you need to make sure the valve train especially the valves can take that. Meaning lighter weight valves $$$$. A friend that visits here just popped the head off a valve. I did the same thing 25 years ago. Very costly and down time. I would keep rpm lower.

 

[ekitch]

This leads me to believe the old GM closed chamber heads are not that bad, if ported and reworked. They are heavy. I have the 290's on my 454 Chevelle and they kick ass if you ask me, make tons of torque. Aluminum heads allow a higher compression ratio and are significantly lighter and are way easier to port. Edelbrock and Brodix RR heads no problems with exhaust or brackets, like GM. AFR, Dart, World, and most others have raised exhaust ports. Just remember that. Pictured is a Brodix RR 312 head chamber, no cnc chamber but very easy to port and very nice work overall by Brodix for an as cast head. The next 2 pics is a World 3 head, hand ported. I put about 15-

20 hrs of porting on each World head.