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post #1 of (permalink) Old 03-15-2001, 12:31 PM
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Intake Manifolds

Do you have to have a four barrel intake manifold inorder to put a four barrel carb on?? Thanks

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post #2 of (permalink) Old 03-15-2001, 01:20 PM
 
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Re: Intake Manifolds

You *should* - you can get 4bbl --> 2bbl adapters if you want, but I'm told you're really cheating yourself of a lot of the benefits of the 4bbl.

If you just want more CFM.. I hafta ask why. A stock 304 or 345 doesn't really benefit from a big 4bbl. You might see better throttle response and better top-end by using a *small* 4bbl.. but a 2bbl is nearly as good and a lot cheaper.

-Tom

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post #3 of (permalink) Old 03-15-2001, 06:01 PM
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Re: Intake Manifolds

I would be putting it on a 392...If I can find one that is..

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post #4 of (permalink) Old 03-15-2001, 06:05 PM
 
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Re: Intake Manifolds

Ahh.. in that case, a 4bbl might be warranted.

I ran a 350cfm 2bbl on my 392 for a while.. ran fine (considering the condition the 392 was in)..

The 750cfm ThermoQuad on my current 392 is probably overkill.. but that's what it left the factory with, and at least it's a spread-bore.

The 4bbls are out there for the 345/392.. take your pick between cast-iron square-bore or cast-iron spread-bore.

If you find a 392, it should come with a 4bbl intake - to the best of my knowledge, the 392/2bbl was never offered (at least, not in a pickup or Travelall).

-Tom

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post #5 of (permalink) Old 03-15-2001, 08:03 PM
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Re: Intake Manifolds

Is there an advantage to either the spread bore or the square bore? I'm mainly doing four-wheeling....Maybe a little towing...I'm also trying to get more RPM out of it...I think I'm going to get some LS6 BBC springs...But what would be a good cam to get?? That would retain most of the IHC engine attributes? (i.e. torque)
post #6 of (permalink) Old 03-16-2001, 01:49 PM
 
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Re: Intake Manifolds

I think a spread-bore yields better low-end response than a square-bore - but square carbs seem easier to acquire (new)..

More important than the TYPE of intake is the carb you put on it. I can't help you too much on carb selection - I've run Holley 2bbls until recently with good resuilts - my Travelall's ThermoQuad hasn't caused me any grief yet, and I haven't wheeled my Holley square-bore 4bbl on the Scout yet.

I think if you want 6000rpm, the LS6. If you want 5000rpm, standard BBC springs might do.

I'm running the Isky 262/262 camshaft and I'm happy with it. But I also upped the compression a little and ported the heads. The compression made up any lost bottom end, and the ported heads/Isky cam let it run at 6000rpm and makes GOBS of torque in the mid-range (where I use it the most).

Really comes on after 1000rpm.

I bought the cam and springs from http://www.GryphinRacing.com after talking with John Comer about what I wanted the engine to do when I was done - he hasn't steered me wrong yet.

-Tom

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post #7 of (permalink) Old 03-17-2001, 01:00 AM
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Re: Intake Manifolds

What is porting the heads?? And you say you upped the compression? Did you just put 345 heads on? 'Cause I think that is what I am going to do...If I can find a 392....How much did it all cost? I've been to http://www.GryphinRacing.com but I could never find anything...Do you have to email?? Why doesn't he put the stuff on the net?? Thanks

post #8 of (permalink) Old 03-19-2001, 01:28 PM
 
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Building a motor

When I say "port the heads" I mean I used a die-grinder inside the "exhaust ports" (where the ex. manifold bolts up) to remove the large "hump" inside the exhaust port and clean 'em up for better flow.

I raised the compression by milling the deck of the block down and reducing the combustion chamber volume - NOT by swapping on different heads. I didn't want 9.5:1 from 345 heads on a 392 (and that's only if you use the "right" 345 heads on your 392).. and I was building a 345, not a 392 at the time. I shaved material from the "deck" of the block to get into the 8.5-8.75:1 range.

I sunk $2000 give or take into my 345. Over $4k into the 304 Gryphin Racing built for me - but the 304 will put my 345 to shame. ;-)

You have to email for the cam kits and valve springs n' such - he doesn't list everything on the website.

-Tom

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