I am looking for some opinions. I am going to have the heads off the motor (new head gaskets) and want to freshen them up. I am already putting new springs (crane kit) on for either an 847 or 306 (haven't decided which) and am looking for ideas of what else to do. Budget is very tight. My initial idea was to have them tanked to clean them up, and then reassemble them with the stock valves. Should i put in new valves? I was looking at the Manley Street Flo's with the under cut head. Is that worth it? Anyway, let me know what you guys think.

Thanks

 

Stock valves are fine for roller cam spring pressures, the factory valves are already back-cut so that's good too. You need to have your guide clearances checked, and the valve job should be re-freshed. The heads also need to be surfaced at the same time. You should be able to get a complete rebuild for $500 or so

 

IMO I wouldn't run that big of a cam on stock heads. I'd take a look at the 503, its about the biggest I'd run on unported heads.

 

and you have first hand experience?

why does everyone say that you can't run anything over a 220s duration cam on stock heads?

you can run a GM847/CC306 on stock heads fine. years ago thats what MOST people did. the GM847 is a proven performing cam time and time again. it has seen 11s with stock heads in a full weight car.


BTW, to the OP. I am doing a stock heads rebuild. stock bottom end but balanced with new rings, bearings, and ARP rod bolts. the heads have a slight mill, a good valve job, and gasket matching. I am going to be running a cam that is a little larger than a GM847. If you are going to be using a 2800 rpm stall and a 3.42 rear I would advise against running such a large cam. I am going to be running a yank PT4000 and a 4.10 rear. build the combination right and you'll fly. Anyone who says a smaller cam will walk a bigger cam either hasn't seen a properly set up big cam combination or they're just regurgitating what everyone says on the internet.

 

Yep, those days, and those guys have either moved on to other things or found a new hobby. I can still remember when there was NO springs breaking, lifters crashing, etc. Trouble is, today people want a 10 second DD that chops like heck, gets 30 miles to the gallon, bumps out 500+HP off the dyno, and makes two trips to the track a year. All that and NO broken parts. That's the trouble with the internet, too many people cut-n-paste what others say without much experience themselves. Too bad guys like Christian Millard, LJ Stevens. and Jordon Musser don't frequent the boards like they used to. Those guys were pioneers with the LT1 motor

 

No I don't cuz when I did my h/c I wanted it to perform as well as the numbers said it should so I did it right and got my heads ported.

I also didn't say you CAN'T, I said IN MY OPINION I WOULDN'T. see the difference.

Why make the sacrifice of drivability and fuel consumption when you aren't going to get the performance to go with it? Especially when your on a tight budget?

Now im not saying that the 847/306 have terrible drivability, my cam is bigger. but im comparing the drivability between the 503 and 306.

Then again this is just my opinion on the whole deal. So if you don't agree *cough*zigroid*cough* you can get lost.