IgorT.455/406

Hey guys. I am going to yank my 350 soon and throw a 305 into the car for winter. I plan on working on the 350 while still maintaning the mobility of the car, so I can do mods to the car and the motor at the same time. I am going to a solid roller comp cam, 4.10 gears and slicks for next year. I was thinking about porting or having someone port my RPM heads. Right now, they are out of the box with about 30,000 miles on them. They still work very well, but I want more power! Anyone know how much or how well one can port the RPM heads and what improvment can be gained. This is the rest of the planned mods:

Custom Comp Solid Roller cam (for my LT1, but will run it in this motor instead). 242/248 duration, .580/.586 lift (w1.5 RR, I got bot 1.52 comps and 1.6 cranes) and 112 lsa. The block is a .040 over 4-bolt roller 1 pc. Endura X lifters, matching valvesprings. Crank scraper and maybe a larger oilpan.

Can I have the 2.08 intake valves cut in the RPM head and will it be worth the money/time.

Now the motor is a .040 over, small popup pistons, 70cc straight out of the box RPM heads, crane 1.6 RR, Crane 224/234, .496/.520 lift cam and 114 lsa hydraulic flat tappet. 10" converter and 3.27 gears and street tires (25.5" tall). With all my mods, 4.10s and slicks I want to gain a second or maybe 1.2 seconds, so I need help! I think gears/traction alone could gain me upto 1/2 second as the car sits. But like I said, I am looking for just over 1 second. Will I need a 385 stroker for that? Thanks a LOT!!! Right now at over 4000 feet altitude and bad air, car can do 13.6-13.7 at 104 mph. Corrected for the altitude and air that night came out to 13.1ish at 107-108 mph at sea level. I want low, low 12s at sea level on slicks. Thanks.

Lowend

THe most I have heard of anyone getting out of SBC RPM heads is ~260cfm intake (stock is ~230) . This will definatley help make some more power, but you have to ask yourself, is it worth it?
I don't know what guys are charging to port these now in days, but keep in mind you are going to be limited by the small 180cc intake runners.
If the porting is more than $500, I would recomend selling the heads and picking up a set of somthing a little larger.
The Edelbrock Vic Jr heads are a hell of a deal at less than $1000/pair bare with valves. They flow ~280cfm intake and have 215cc intake runners. Those not only will make more power out of the box, but also have the potential to flow a ton more than the RPM's due to their larger runners.
There are also of course the AFR 195's or 210's, but the budget goes up there.

IgorT.455/406

Then I would need srpings (need them anyways), retairner and keeper and valveseals. I would also need guideplates and screw-in studs I would imagine. Hmm, might be well worth looking into. I would like to keep the budget down as I still have to fix my '94 a bit too over the winter and I gotta have money for that.

cadjock

Hey Lowend ... What's your opinion on trying to get a little more hp out of my 383? I have the 64 cc Performer RPM heads/Cam/Intake combo with a flat top 383. It runs 105 mph now, but I'd like more. Would porting the heads do it, or am I only looking at a 2hp improvement?