Don Terrill’s Speed-Talk

Hi guy's, I was wondering peoples views on head choice out of the 2 sets I already own for the following 347 build...

347 ci
Mexican Block .060" bore
13:1 compression
- Crane F-272/400-2S-6, rpm range 4500-7900 with 347 cubes, @ .050" - 272/276, adv 308/312, LSA 106, lash .018 .018,
lift .640/.650

I have both AFR 205 heads and Victor Jr heads, the AFR heads only have a CSA of 2.165 so I am worried about potential sonic choking, and I could have the Victor Jr's ported, are the valves in these heads able to cope with the rpm? Has anyone run 205 heads @ 8000 on a 347 and had them choke the power off, who in Australia could port out the Victor heads? Steve

Im leaning toward having the Edelbrock heads ported, recommended springs, titanium retainer's (have), possibly new valves if they wont be up for trips to 8200.

Can anyone point me to someone with a cnc programme for the Victor Jr's in Australia

Sorry, can’t help with that specific question... as I live on the other end of the planet.

But I’ve used a set of vic jrs on a street/strip 347 for 10 years and just want to share some of the expeiences I have.
Home ported heads, valves from Edelbrock.
First 3 years running assembled heads hardwsre. Roller rockers and the studs got beaten up, up to 8000rpm. 7000 something regulary.
Switch to shafts, lighter, smaller springs and tit retainers.
Then calmed down with a rev limiter at 7200. 420+ according to wallace.

Ran for 5-6 more years and when tore down the valves were badly worn. Maybe the abuse at 8000rpm and less than ideal valvetrain. Maybe stem not properly surface hardened.... So, maybe you should invest in a set of valves? Hollow stem steel or tit? I sure hope you have shaft rockers....

Yeah, I have a new set of Crane 44808-1 Pro series Shaft rockers, thats another reason i'd like to stay with these heads. Would definitely run the titanium retainers as well. Hoping for 540 minimum

I'd go with the Vic jnr's, but ditch the eddy valves & use ferrea 6000, 5/16" stems have a decent weight advantage.

I can hand port them for you, but not cnc.
Imho hand porting can tailor the heads to your specific engine better than cookie cutter cnc, but more expensive due to labour time.

For romps up to 8200 I would take it a step further then the above and replace the Intake valves with Titainum.

What he said....

Knight; would a small stem 2.05’’ or larger valve at higer rpm have a shorter liespan then a 11/32’’ stem valve? Regarding valvejob/ maintanance...?

The small diameter stem give better flow- but are there any downsides?

I would have KnightEngines port & prep the vic junior heads; if race only and budget can handle titanium go with them, your spring life will increase enough over the life of the valves to pay for the difference in price.

Caprimaniac wrote: ↑Sat Mar 21, 2020 10:20 am What he said....

Knight; would a small stem 2.05’’ or larger valve at higer rpm have a shorter liespan then a 11/32’’ stem valve? Regarding valvejob/ maintanance...?

The small diameter stem give better flow- but are there any downsides?

No real downsides - provided the guides are done well.

Okay, thanks guy's, much appreciated.