Hey there people, Im a freshy to this forum and wanting to get
some feedback as to the HP Im trying to get from my 351C.
Im aiming for around the 500HP mark and the bits I have to do
this with are as follows-
2 bolt block
eagle H beam 5.7 rods
will have oil restrictors
Wiseco forged .30 over pistons
Comp ratio around 10.5-1
4V closed chamber heads with ferrea stainless valves
Yella Terra rockers
Offenhauser 360 divided plenum intake
Motorsport solid cam
Int dura 310
Ex dura 321
Int lift 580
ex lift 606
The defect being, not having enough oil in the sump for high speed operation. Why on earth would you want to restrict the amount of oil going to your engine? Remember, oil cools the engine as well as lubricates. Ever heard of rocker gear wearing out prematurely because of a lack of lubrication?
I don,t know too much about the offy,is it single or dual plane.I personally think a double pump inthe vicinity of 750 800 cfm is going to shit on a vac sec.I had a 750 v/sec on my 4v 351 on top of a torker intake and wanted to see if an 850 dp would make any difference.Suffice to say i settled on a 800 dp and lost the v/sec.Wiseco make nice pistons but a cam of that size (im assuming 250@ 50) really should have more than 10.5 to 1.Oil restrictors are a matter of conjecture between clevophiles.there are many pro's and con's .Whilst limiting oil to the top end of the engine can have benefits buy keeping the oil in the sump one must remember that valvesprings need a supply of oil to cool them down.Use a good oversize pan that holds plenty of oil and a standard volume oil pump.using a hi volume pump and standard pan should be avoided.If the oiling thing is an issue with you you can run an external feed line directly to your mains to give them priority oiling.
My cam is Ford Motorsport, same lift as you but just a tad less on the duration you quoted. But me reckons the duration figures you quoted not for 1.73 rocker ratio, because I'm sure my cam grind is the biggest solid Ford Motorsport pruduce.
Either way agree with russ don't waste your time on a vac secondary, 750DP bare minium, 800DP better or even 850DP if the Offie manifold is a high rise type ie funnelweb style.
Also agree 10.5:1 not enough to make best use of those heads and cam, sure it will run on premium unleaded but expect a motor with a lazy/soggy bottom end response at 10.5:1.
Um you cant be serious paull? YOu use a restrictor cos it doesnt need or require that amount of oil going to the top of the engine (SPECIALLY AT HIGHER RPM) in most cases not only can it hurt bearings not using an oil restrictor you can also fill your rockercovers full of oil hence where the (not enough oil in the sump) saying came from. It pumps to much to the top end and cant return it fast enough. I used to drill a little whole in the cam bearing and use that as the cam restrictor and use a little screw in grup screw with a whole in it in the rear of the engine.
Works a treat and im sure u wont find a serious engine runnig a solid or roller cam anywhere that doesnt use one.
U can run higher comp than 10.5 in most cases if the engine is set up right. Use of a vac sec carb on any engine other than stock is pointless unless u have stad gears and no convertor. GO the DP anyday
P.S how much iol do u think your engine puts into the top end with a restictor kit...its AMPLE for the engine to keep valve springs cool ect.
The offy isn't a high rise, is dual plain tho,
will look for 850DP.
What comp ratio should I be looking at 11-1, 11.5-1?
Engine is going in a ute with toploader and nine inch running
3.0 gears, I should be looking for 3.5's or so?
With all this is the 500HP mark achievable?
Is it going to be 100% street driven? If so then you will just get by on 11:1 nicely with BP 98 / Shell Optimax plus maybe a bit of octane booster. But 500HP 351's don't come cheap and I would suggest you need atleast 11.5:1 more likely 12.1 to achieve that realistically and then you would need a mix of Avgas or racing fuel - not cheap.
Flick the Offy, go Funnel Web or Weiand single plane. Even really good dual planes start to lay flat at about 5500 and your cam is good for 6500-7000, maybe more. 3.0 gears will make it a prick to get out of the hole, but great if you live in the outback and do highway driving. But seriously, all depends on end purpose. Optimum 1/4 mile times you would need 4.11's or higher, but 3.5's with a manual would be a reasonable compromise.
Thought about stroking it? Bit easier and cost effective to reach 500HP.
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