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Flow numbers for double hump heads

 
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aharris05
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Joined: 07 Sep 2011
Posts: 34

1444.66 points


1968 Chevrolet Camaro

PostPosted: Tue Jun 17, 2014 1:08 pm    Post subject: Flow numbers for double hump heads Reply with quote

Guys, can anyone tell me the approximate runner size and flow numbers for a set of 186 "fuelie" double hump heads? I think I got a great deal on these, and I hope they will be worth the investment. These have 2.02 intakes, and appear to have been worked a little on the intake side. I am curious how they might compare to a modern aftermarket set, or if I should sell them off and buy something better. Everyone tells me that the factory heads don't come close to aftermarket pieces that are now available. I have 2 options for the block - its a .030 4 bolt, and I have the stock GM crank (355) or an Eagle stroker 383 to put in it. Gonna be a Street/Strip motor I hope to get at least 400 HP out of.
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aharris05
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Joined: 07 Sep 2011
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1968 Chevrolet Camaro

PostPosted: Tue Jun 17, 2014 3:24 pm    Post subject: Reply with quote

That IS alot of info! So to my untrained eye, the numbers for these "186 FUELIES" don't compare very well to most anything similar on this list. It looks like the Vortecs are significantly better too. I think I am going to see how much I can sell them for...
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af2
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1933 Willys Coupe

PostPosted: Tue Jun 17, 2014 5:31 pm    Post subject: Reply with quote

That is why I posted the link. Some people swear the 186 is the best head ever made and that is not even close to the truth. EQ makes the aftermarket Vortec that will accept the early intake pattern but you have to use the Performer RPM or equivalent intake with the taller ports.


E-Bay those 186's. people building matching #'s cars will pay good money for them.
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clay
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1972 Chevrolet Nova

PostPosted: Tue Jun 17, 2014 11:20 pm    Post subject: Reply with quote

I'm with af2 - ditch those heads. Only major downside to factory Vortech's is the valve lift limit. If you are going with a flat tappet you might be fine. I can't remember what the exact limit is (high 0.400's come to mind) but you can easily search and find that out. Since you have the crank for a 383 I'd build that in a heartbeat. Only cost at this point over building a 350 is clearancing the block if you have to pay someone to do it. You can use whatever rods you want in either setup as pistons are readily available for 5.7 or 6 inch rods in a 350 or 383. 5.7" rods will keep the wrist pin out of the oil ring groove on the 383. You need to do the math for compression ratio - might have to run a dish piston on the 383 with the Vortech head and pump gas. Clay
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Big Dave
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PostPosted: Wed Jun 18, 2014 11:37 am    Post subject: Reply with quote

IF you use the old heads you will be limited to the old stock horsepower numbers. Modern heads are the reason everyone on the internet has a 500+ horsepower motor under their hood.

I do not believe that having the piston pin in the ring pack is a problem. I come to that conclusion because nearly every motor I build is using the longest rod that will fit in the block and with the longest stroke that will clear the cam (aftermarket blocks raise the cam for that reason).

Clay raises a very good point. The longer the stroke the higher the static compression you will build in the chamber. I do not like having the combustion chamber in the piston as it raises the piston's weight (I grew up with 409 big blocks). Rather than going with a dished piston I would select a head with a slightly larger chamber (say 72-74 cc).

With aftermarket heads you can relieve the valve shrouding on a 64 cc chamber; or by grind on the spark plug flame break under the plug and lay back the walls a little if you choose to use Vortec heads. Aftermarket heads have much more material in the deck and combustion chamber walls than factory heads so they will support grinding material without weakening the head. On factory heads you can not grind much unless you "look" first to see how thick the material is by using a sonic probe.

You build your motor as large as you can afford to make it last longer by building more power in the lower RPM range.

Big Dave
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af2
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Location: grassvalley, ca
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1933 Willys Coupe

PostPosted: Wed Jun 18, 2014 1:17 pm    Post subject: Reply with quote

Why no link?

I thought it wouldn't interfere with this site.
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SMOKEmUP
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Joined: 30 May 2002
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1979 Chevrolet Camaro

PostPosted: Wed Jun 18, 2014 2:40 pm    Post subject: Reply with quote

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Big Dave
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PostPosted: Wed Jun 25, 2014 5:10 pm    Post subject: Reply with quote

You can also go to the car mags technical pages and read the information on those sites where they compare the latest and greatest car part against the defacto standard; or the Chevy part if there is no other.

Just keep in mind that car mags make their money advertising the latest and greatest car parts, so they do not tell the whole story in their articles. They don't lie out right, as the data they publish is factual and scienticically reproducible; they just don't tell the whole truth if it would adversely affect how you would look at the advertised product.

So if you keep an open mind and wonder about what they are not telling you they can be a great source of information.

Big Dave
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