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Old 03-02-2011, 03:25 AM
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327 sbc sportsman 2 heads

Hi all . Got a fully recoed 327 bottom end 40though up with steel crank , stock rods and releived cast pistons . Id like to fit a pair of world sportsman 2 heads i have that have been angle milled to 49cc chambers , 200cc runners and roller cam springs . Have crane 1.6 roller rockers , girdle and solid roller lifters . Have twin 4 edelbrock manifold and 600 carbs .Need help to select a roller cam to suit this combo . will run through powerglide and 4000 stall to a 3.55 diff . Pump gas .

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Old 03-02-2011, 07:06 AM
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How much of a dish are you running on your pistons, with a 4000 stall speed you may need some more gear.
Shane
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Old 03-02-2011, 08:11 AM
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Quote:
Originally Posted by theg
Hi all . Got a fully recoed 327 bottom end 40though up with steel crank , stock rods and releived cast pistons . Id like to fit a pair of world sportsman 2 heads i have that have been angle milled to 49cc chambers , 200cc runners and roller cam springs . Have crane 1.6 roller rockers , girdle and solid roller lifters . Have twin 4 edelbrock manifold and 600 carbs .Need help to select a roller cam to suit this combo . will run through powerglide and 4000 stall to a 3.55 diff . Pump gas .
I'm guessing this is a track car, or a limited use street/strip deal so why limit it to pump gas? This combo (200cc intake runners, especially) is screaming for a LOT of cam, which means a lot of compression, which means high octane fuel.

I'd rather see you staying flexible on pistons, rods and stall speed- or go smaller on the intake port volume. If you have 12cc dished pistons and a 0.040" squench, the CR will only be 10.75:1. And if the piston dish isn't "D" shaped, the quench/turbulence effect will be decreased.

FT pistons w/5cc reliefs will net you 11.85:1 CR- much better for a healthy solid roller. I would seriously consider forged pistons while you're at it.

The exact stall should be tailored to the cam, but you may be fine w/what you have, depending on a lot of variables. I would surely at least try it, but that will not be anywhere near enough gear, especially if the Glide has the stock low gear ratio.

The Crane rockers will need to be their top-shelf units (not castings) for the double springs the cam will need. You'll need a set of high quality, thick-walled pushrods, and in this case (high RPM, w/large OD springs and retainers) titanium retainers would be a good investment.

I would not trust stock rods- especially if they're small journal w/those puny 11/32" rod bolts. There are affordable rods w/good hardware out there these days that will be much more appropiate for a build like this.

Last edited by cobalt327; 03-02-2011 at 08:22 AM.
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Old 03-02-2011, 05:59 PM
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Comp Cams XR274R, XR280R, or the 280AR (or similar grinds from any company) based off what you posted and assuming 10.5-1 compression ratio and around 3200lb car.

I have no idea how piston to valve clearance is going to work out with the heads milled down that far, you will need to check this carefully.
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Old 03-03-2011, 01:17 AM
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good help so far thanks guys . I bought the heads fully race prepped by the previous owner for a speedway methanol car but never fitted after mods . They included all rocker gear and the solid rollers . Ill post some pics of this gear soon . The pistons currently fitted are stock alloy replacements 40though up . Is it essential to change these for dish top forgies or will they survive with revs to say 6000 - 6500 . Got good msd ignition and its a street car sundy driver only . Its to be fitted in an australian built rare 1968 muscle car . I can possibly set this up for methanol if necessary but would prefer pump gas for simplicity .
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Old 03-03-2011, 10:42 AM
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Quote:
Originally Posted by theg
I bought the heads fully race prepped by the previous owner for a speedway methanol car but never fitted after mods.
I would strongly suggest you CC these heads before assuming they're "only" 200cc. Alky SBC track engines use *large* port volumes in many cases. Even spec heads for restricted class racing have been known to be larger than what's in the rules.

If you have any choice in this, use a bigger displacement than what you can get w/a 3-1/4" crank.
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Old 03-04-2011, 01:05 AM
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will cc the intake runners to clarify . Is the problem with runners that are too large that fact the velocity is lost ? . How will performance be affected ? Still looking for feed back on a roller cam selection as I dont have one yet !
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Old 03-04-2011, 02:38 PM
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Quote:
Originally Posted by theg
Is the problem with runners that are too large that fact the velocity is lost ?
In a nutshell, yes.

Quote:
. How will performance be affected ?
Generally speaking, the powerband will be biased upward. The bigger the mismatch between displacement and intake volume there is, the bigger the bias upward will be.

Idle quality can be negatively affected as can drivability on the street. This is less a factor if the engine is being used in a race only setting, where gears, torque converter stall, etc. can be maximized to counter the effect of a loss of low end.

200cc intake runners would be the limit of what I would even consider using on a 327 on the street. That is the equivalent of a 215cc head on a street driven 355 SBC. BIG, in other words. 180cc would be better and even less can be used to good effect on a strong running street 327.
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Old 03-04-2011, 03:14 PM
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Quote:
Originally Posted by theg
will cc the intake runners to clarify . Is the problem with runners that are too large that fact the velocity is lost ? . How will performance be affected ? Still looking for feed back on a roller cam selection as I dont have one yet !

If the heads are ported properly and have good airflow the larger volume will not hurt you at all. Case and point is the newer gen IV engines, their runners are huge compared to the gen I sbc, but they work very well. Average port velocity is dependent on cross section AND AIRFLOW. In other words, if you have 10% more volume but 20% more flow then your velocity is higher.

Additionally 200cc's is about ideal for a 2.02" valve, maybe even a little undersized.


Your cam will need a good deal of lift and less duration than if you have a smaller runner. If you want goo help call a good cam grinder.
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Old 03-04-2011, 04:37 PM
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All that is fine- IF we were discussing the Gen 3/4 engines- which we're not. The valve inclination is different, the whole head is different. Totally un-comparable.

A poorly ported head- even if it was 160cc- is still a poorly ported head. But a poorly ported 200-plus cc head- like he is showing, not another completely different design- is going to be a disaster on a 327 cid SBC engine.

Flow is fine- but it doesn't work alone. If port volume didn't matter, there wouldn't be different volumes used for different RPM ranges/applications/CID.

A 200cc gen 1 SBC head will not have the same or greater low RPM port velocity of an equally prepared- but smaller port volume- head when used on a 327.
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Old 03-04-2011, 05:47 PM
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Why couldn't the 200cc head have a GREATER velocity?
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Old 03-04-2011, 06:00 PM
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Why are you asking- why don't you show evidence that shows this yourself instead of asking questions that only serve to flame instead of enlightening?

I'm done w/you, ap. In the past I've defended you- despite that being a decidedly unpopular position. No more. You offer nothing useful to me.

Good luck.
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Old 03-04-2011, 11:52 PM
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You mentioned that the heads have been prepped, so maybe this is not an issue, but World says that their Sportsman castings are not clearanced for 1.6 rockers --- the pushrods likely will rub. This was indeed the case on my set. If your prepping included lengthening the guide slots, there's no problem.
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Old 03-05-2011, 12:54 AM
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Sorry; forgot something. Your Sportsman heads sound pretty big for a 327, though with a solid roller maybe not. Velocity of the mixture is determined first by the speed with which the cylinder demands a unit volume of air, and that is fixed by its size and the referenced rpm. Only then does the cross-section where you measure velocity become relevant. You obviously want a lot of rpm potential, and of course a 327 @6400 demands a lot of air. But I would like to know how you get the beast to idle when you're done --- not so much because of the heads, but because you'll have 1200cfm of carburetion on top! The velocity through the huge 600cfm of primary venturis will be pretty slow at low rpm and fuel metering will likely be more than a bit erratic. Almost sounds more like a setup for tri-carbs But be careful of those setups... the old originals had specialized outboard carbs and calibrated linkages that are frequently not well duplicated in modern knockoffs.

Last edited by Leoman; 03-05-2011 at 01:16 AM.
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Old 03-05-2011, 01:05 AM
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no probs with the rockers . Ive got the ones supplied with the heads aswell as a pair of others . Both sets are crane 1.6 . The set that came with the heads are much thicker through the axis of the pin and much more material in them overall . They are a little shorter from the roller tip to pushrod locator but are 1.6 none the less . There has been a slight machining done on them aswell to give clearance for extra high lift .

Im pretty concerned about the port sizes after the previous comments and would appreciate as much input from everyone concerning this .

I dont want to do this fittment if its going to be a dog ! Im happy to run this as high reving engine ,hence 4000 stall and fuel econonmy is not a concern as its only a 20klm sunday driver . Its simply a hobby car .
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