My hill climb car was powered by a 13:1 c.r. 333 cid sbc that dynoed just over 550 hp with #77599 Victor Jr. Aluminum heads. According to Edelbrock these heads are good for 580 hp out of the box. I have built a new 14:1 c.r. 412 cid short block in order to improve low end grunt.

My problem is that I do not believe these heads will support the new engine's top end potential, which should be between 650 and 660 hp. I'm trying to get at least 375 ft-lbs @ 3000 rpm while having a rev range up to 7300.

Has anyone experience porting these heads to get them up over the 600 hp+ mark? I'm also not happy with valve spring quality as the valves were badly marked from bouncing in less than 3 hours of racing. This is with Edelbrock's super 1.55" OD roller cam springs.

Suggestions?

Many thanks,

McKee  

I rather think that these heads are probably a bit small for a 400 plus inch engine and 7300 RPM. I haven't ported any of these but starting with a 215 cc factory ported head a little caressing with a die grinder ought to get 230 240 ccs which would be closer to what you need.

As far as bouncing valves are concerned with the Edlebrock springs causes a couple thoughts. First, I'm sure Edlebrock doesn't put in springs that can cover the contingency of every cam, lifter, and rocker combination that can be put into an engine, I think you're better off to go with springs from the cam manufacturer after careful coordination with them on all the details of the valve train and how the engine gets used. Second, high RPMs and stiff springs cause all sorts of problems that can look like the springs aren't doing their job. The damage you're seeing can also be the result of rocker and or pushrod flexing. You could include rocker stud flexing, even with a girdle, if you're not running rockers and a bolt down shaft.

This is obviously a full up race engine, and weird stuff happens when these motors are worked for prolonged periods of time. This is different than the odd blast from stoplight to stoplight in that the engine is hanging out for long periods of time at max output and probably being over-reved during the process. Most pro level drag race engines don't live 3 hours, the typical front of the pack competitive engine is pretty shot after 500 miles, so you just have to expect that this motor of yours is going to get beat up in the process.

bogie  

imho,those heads are a tad small for your combo.you will need a head with at least 220-230cc intake port with a larger minimal cross sectional area.Brodix has  their 227 cnc ported track 1 head that produces great results.if your not limited to a 23 degree head,ever think of trying an 18 degree head? as for your valve springs,mass produced heads usually have cheapo springs.first thing i do if i get a head complete is change the springs to match the cam,especially roller springs.hope this helps,good luck