Originally Posted by xeturbo
im new to this forum, and i am currently saving money to transfer my 302 to 351.
my 302 is very healthy and has only done 80,000 ks as it was rebuilt for full gas. my engine is now running optimax through a holley carby.
i am purchasing 351 rods+crank.
i am just wondering would i still be able to keep my 302 heads or will i have mega problems with pinging?
also i was wondering what type of cam you guys would reccomend for a lumpy idle so i can get some useable street power, say 5500 redline?
and also whats the point of view on cam gears?
thanks very much for you help, John.
You will want to clean the heads up using about a maximum of .006" milling to keep compression from climbing any more than necessary. Same with the block, just a clean-up of the deck. Aim for about a .020-.035" deck height for better results.
Pinging is very relative to everything installed in the engine and the work that the engine is doing for the given environmental conditions it faces.
Considering what you're trying to do with it, the best all-around camshaft for it won't be very lumpy, but will make very good performance across the entire useful engine RPM range. A lumpier cam can help reduce the potential for predetonation, but it will move the effective RPM range to a much more mid-range to upper RPM level, which you may not want especially for a daily driver.
I would also look for a thicker cylinder head gasket. Try to find one that will compress at about .046" or more as this will reduce your compression ratio a good bit, too.
My recommendation is to use a good Roll Master or similar timing gear and chain set. They are much less expensive and a better choice for a street engine. I run one in my 600+ HP drag engine and wouldn't run a floating idler gear drive. I've ran fixed idler gear drives and they are just noisey and expensive. I've ran gears/chain ever since.
Someone with more experience running the 302C head should have a better game plan than I can provide. They will know what works and what doesn't work for that cylinder head. I've ran the 4V closed chamber cousin of it on a number of engines, but I wasn't trying to keep from making compression with them. I've got a set now that I'm prepping.
I would focus my efforts on building up the cylinder heads and using a nice solid flat tappet camshaft with a Weiand X-celerator inlet manifold and push your RPM range up to about 2800-6100 (to as much as maybe 6500, depending on your head work and cam choice).
You would have all of the desired lumpity-lump that you want with good strong upper low RPM to very strong mid range to lower top end power that you could want in a daily driver. A camshaft with about 24-30 degrees of valve overlap (based on .050" lift) would put your cylinder pressure into a position where you could use the heads without any real "special considerations" for PULP.
I would use a good set of one-piece stainless steel valves at factory sizes of 2.07" x 1.65" as these are plenty big, IMO. I would machine the heads for screw-in studs and guide plates and run a good set of Crane Gold roller rocker arms or similar. You will need hardened pushrods for use with guide plates.
I would probably consider a camshaft with about 226* of inlet duration at .050" and about 230* of exhaust duration at .050" on a 112* LSA with lift at about .545" to .560" maximum. Crow makes a hydraulic flat tappet camshaft that is fairly close to these specs using part number: 211367 I would find someone who knows how to recondition the heads who also knows how to properly mildly port them. The money spent on the heads will be a good investment for performance. They won't need a lot of work to do fairly well, especially at engine RPMs below about 6000.
With a little bit of work you can make about 360-420+ HP from this sort of combination, depending on how mild or how wild you want to go with it.
If you're on a tighter budget, the Crow hydraulic camshaft above with a good set of roller tipped pedelstal-type rocker arms and reconditioning of your heads with some attention to cleaning up the port transitions (bowl work) would be a good choice along with a good timing gears/chain set, which in Australia are excellent quality parts that we here in the US import for our Clevelands.
My own preference in "engine sounds" is more focused on the right exhaust note than the whiney sound of a gear drive. A hard thumping exhaust that isn't too loud but isn't too quiet that speaks just the right amount of "you better watch your ass if the light changes" is, to me, a much better "announcement" than an electric drill running a metal holesaw through steel under the hood all of the time.
Of course, this same combination with a set of AFD 2V alloys will produce 500 HP if you have the cash. It will run much better on PULP, too. And it will take off about 25 kilos from the front of your car.