My 327 is on its way out so I need to put an engine together quick and cheap....thanks for any help. Looking to use this in my Build... L31 Short Block http://sdparts.com/details/gm-factory-replacement-parts/12556121 Was planing to use some 58cc aluminum heads and shim head gaskets to get the compression up to 10.5 ish. I have never built an engine before and am concerned about piston to valve clearance and my ability to measure it correctly. How large lift and duration of a solid flat tappet or hyd roller can I go on this engine before that becomes an issue? Which direction should I go with the cam? I know the solid has greater control at high rpms but the roller is better everywhere else. The heads will support 500 hp so I would like to go aggressive on the cam and be in the 500hp area. Any thoughts or recommendations?
The heads may support it but, Im not sure how realistic it is with that short block. Cast pistons and Cast crank not sure how long it would hold 500 hp if. Besides that its not just cam selection it is also rocker arm, 1.5 or 1.6, valve springs also, if the heads come ***embled what springs come on them, the springs can only support so much lift also. What Im saying is I would not get my hopes up for 500 hp. Also more info is needed to help out.
I haven't bought the rockers yet so I can use either. Probably go 1.5 for better geometry and just get a bigger cam. I will have the proper springs for the cam installed in the heads but i dont know what cam I am getting yet. I realize the bottom end is weak but its at least as strong as the late 60's 327's and 302's which spun over 7k rpms commonly. I am leaning towards a solid flat tappet unless this short block will not handle the rpms or added lift and duration available with a solid cam (PTV). My main concern is the PTV clearence. I want to go as big as possible with out having to worry about it. The heads are aluminum 210cc runner 2.02 1.60 valves with 58cc chambers. What other info would help you help me? I appreciate any advise.
Just off the top of my head I would not go over .500 lift. You also have to remeber that the 327 and 302 that you speak of turning 7000 rpm had fordged cranks and less rotating m*** than the 350.
You can get 7K from a 350 with a stock cam if the rest of the valve train is built correctly. It would not be recommended to spin it that high for long periods of time. Of course a balance and blueprint is part of the equation. There was speak of a roller cam verses a flat tappet cam. You can get just as much valve train control with a solid roller as a solid flat tappet cam shaft. Many of the fellas are going to roller cams because of oil concerns, initially there is a cost differential with the flat tappet cam being cheaper to set up but I think by the time you add in the price of oil and or additives to run your flat tappet cam over a very short period of time you will have eaten up the difference in cost. I probably would stay below .5 lift if I could especially with a shim gasket. If you are after building a high revving engine you are going to want to find a cam with tight lobe separtion like say below 112 degrees perhaps closer to 108 and long duration like say up aroud 285+ advertised. Most small block builders will tell you that 112 lobe separation and duration in the 170-175 range is optimum for a street engine buit with the wider lobe separation you can easily run 180+ on the street. I run 182 advertised with 112 on my 355 and have for about 130K miles no problems. Healthy idle and good top end. I don't have a lot of lift but I am running a '60s grind with good ramps. Not a modern cam shaft. There are fellas on here that are really good with camshaft numbers a lot better than I am. I justy know what works from years of fiddling with small blocks, if you want optimum numbers contact one of the fellas like falcon george or the like. They can actually come up with real numbers for you for a given application. I haven't been much help to you I am afraid but its a starting place. Luck on your build. Benno
i always have to ask, what are you putting the 350 in. how much will the vehicle weigh, and what are you using it for. sounds to me like your building a race only engine. steve pastorino
Power Secrets by Smokey Yunick. Own it, read it like it. It will aid you on your quest. Use modeling clay to verify piston to valve clearance before final ***y. I agree with limiting lift to under .500. You won't be able to crowd it much more.
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