Been offered a cheap 401. Comes with a new cam, lifters etc new in the box. im mostly interested in the cam as im after one for my main 401 and the whole setup is cheaper than buying just a cam. Just im utter crap with cam specs. Dosnt matter how many youtube vids I watch it just dosnt seem to sink in. I think its i just dont know the ranges a Nailhead likes. the cam in questions specs read as below: The 401 has is .060 over, ported, decked, polished, Eleco 2x4 intake with two 650s. currently have stock cam. running hyraboost brakes so vacuum isn't a issue. after a bit more of a rougher idle and streetability. I had been thinking a mild cam like a TA-25 or a Comp Cams Thumpr 279TH7. links below. http://www.taperformance.com/proddetail.asp?prod=TA_25 http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1515&sb=2 So advice please. how would the above work with a Nailhead. cheers Alex
whats the advertise duration. your lobe separation is 108.5 which is good. with that duration and lope separation you will have a rough idle
That cam is a little on the big side.. You'll lose some low end punch and gain some high rpm power. What car is it in and what rear gears are you running? Any idea what your true compression ratio is? Most replacement pistons only produce 9.5 or less. Add some thick head gaskets and you lose some more CR. It's in the neighborhood of a Comp Magnum 280H or Olds W-30 cam. Would be fun it you like to rev it up a little. If you want more low end power, the TA 25 would be a good choice. gsgtx (posted above) probably tried more different cams than any of us!... he's speaking from experience.
Thanks for getting back so fast guys. unsure of the advertised duration. all i got is the above image. Engine is in a step down Hudson. 3.50 Moser rear end. 28inch tires on 15rims Worked 700R4 Trans. 1650 converter (realize I will need to get 2000 or larger) Unsure of compression at the moment. Bored .060 Decked .020 to compensate for modern head gaskets New cast pistons cant remember make at the moment. New Hastings moly rings Balanced Rods resized w/ ARP rod bolts Crank turned .010/.010 and polished Oil galley plugs converted to screw in New Melling oil pump, lifters, valve springs, cam Heads rebuilt w/ new valves, new iron guides, cut for Teflon oil seals, milled .010 Updated to modern silicon front/rear oil seals Heads Ported & polished Adjustable pushrods. new timeing chain, water pump, frost plugs etc castings all cleaned up etc. Cam I currently have in it specs read as: Exh Duration: 284deg intake Duration: 284 deg exaust Duration at .050 lift 207deg exhaust valve lift .430in intake duration at .050 lift 207deg intake valve lift .430in thanks for all this great feedback guys keep it coming. cheers Alex
Do the heads have any porting done to them? If so do you have flow numbers for them? IIRC the Nailhead heads flow under 70% intake to exhaust so it would be of benefit to have a dual pattern cam that has a bit more exhaust duration to get the spent gasses out. Yeah, just looked it up and the intake to exhaust flow un-ported looks like the ex. flow is around 59% of the intake flow from looking up the unported flow numbers from this website; http://www.users.interport.net/s/r/srweiss/tablehdc.htm To run a single pattern cam you want around a 70% ex. to in. flow ratio or the exhaust will have a hard time exiting and hurt performance. Of coarse headers and an X or H pipe exhaust system would help, but if only exhaust manifolds and simple duals then a dual pattern cam should really be considered. Will this car have headers? The 700R4 with the 3.50:1 rear gear will make up for any low end lost from the cam being on the beginning of the larger size but only @ 229* at .050" is still on the mild side for a performance cam for 413 cubes. If your unknown pistons are Egge cast pistons then your compression is probably on the lower side even with the .020" removed from the deck? If you do have the Egge pistons which I suspect you may have because not to many piston companies make N/H pistons, then your compression ratio is probably around if your lucky 8:1 so the cam with the more duration @ .050" is going to be even more sluggish down low than the one that's in there already. With unported heads the RPM will be limited to the lack of flow of the heads because there isn't enough air flow to make power in the higher RPM range especially without the compression the engine would want to have with the bigger cam. To really know what cam will run good for your N/H, the true measured compression ratio is needed. Flow numbers would also be very helpful if there has be port work done to the heads.(if not, the website above has the unported numbers)
