1986 454, Square or Oval Port Head? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

toomanytoyz · 12-26-2008, 10:21 PM

Got a Chance to buy a Edelbrock Manifold for a BBC, Seller stated it's for a Square Port Head. What Head Type will my Stock 86 454 Engine Have & Does it Make a Difference???

Thanks, Rick

f.monroe · 12-26-2008, 10:31 PM

86 should have been peanut port head which is a small oval port head . The square port intake is for the early high performance heads that had square (rectangle) ports . I think that intake would do more harm than good on your truck .
Frank

Livrat · 12-26-2008, 10:39 PM

Your 86 should be oval port.. although some had the "peanut ports"..
The square port intake will work on yours as long as you use square port intake gaskets.. (otherwise you will have a big vacuum leak!!)
Using that intake wont hurt but you will not really gain anything other than having an aluminum intake.

toomanytoyz · 12-26-2008, 10:53 PM

Thanks for the Quick Responce, I was'nt sure which i had or if it would make any Difference................

Price is Really Good at $20.00, Just wanted to know if it was a worthwhile investment.

Thanks Again, Rick

grinch4om · 12-27-2008, 08:21 AM

buy it and peddle it

LONGHAIR · 12-27-2008, 10:36 AM

I would not even try to use it....It will definately hurt performance and throw your fuel economy in the toilet.
The huge runner volume if the rectangular port manifold will kill the velocity of the incoming air/fuel charge. This results in low vacuum signals to the carburetor...poor throttle response, bad mileage. Then the air/fuel runs into the nasty edge of the smaller port in the heads, this results in what is called "fuel dropout". Fuel dropout is exacly what is sounds like, the fuel drops out of the air, resulting in poor burning...loss of power, stumbling, etc.

Not good.

James McClure · 12-28-2008, 07:45 AM

Longhair forgot to mention oil dilution as also being a problem. You could get yourself a set of "open chamber heads" with 2.5" intake valves and 2" exhaust valves. Then you could use the intake, LOL. You'll hurt MPG though. I built one back in the 70's. All the goodies.600 horse at the rear wheels! Pick the front end of a 69 Chevelle 3 feet in the air w\14" wide slicks. Best track time was 9.9 sec at 148 MPH. Rear was a Brown spool and trans was a close ratio Muncie w\a vertigate shifter. A PITA to drive and really tough to get around corners, LOL. Wish I was that young and dumb again. Want a beasty? I'll build you one. jim

LONGHAIR · 12-28-2008, 11:08 AM

That's what the "etc." was for....LOL

Yes, you could swap the heads to match, but then you would need more compression to make that work too, then come the pistons...... So it's a whole new engine to go under that cheap intake...

BigBlocksRule · 12-28-2008, 11:12 AM

Buy it, sell it and buy the correct one for your heads. Pull a valve cover and get the 6 or 7 digit casting number and post it back here. I'm betting the casting numbers end in 236 which is peanut ports. The Edelbrock Performer intake will fit those. If you have 781 or 049 castings, the Performer RPM or air gap will work. I wouldn't even try the big square port intake on smaller heads for the above mentioned reasons. It's actually worth more than the small port intakes, you should be able to sell it for enough to buy the correct one.

12-26-2008, 10:21 PM	#1
toomanytoyz Luv the Crewcabs Join Date: Aug 2006 Location: Andrews, In. 46702 Posts: 4,097	1986 454, Square or Oval Port Head? Got a Chance to buy a Edelbrock Manifold for a BBC, Seller stated it's for a Square Port Head. What Head Type will my Stock 86 454 Engine Have & Does it Make a Difference??? Thanks, Rick __________________ 55 Nomad 52 Willys Truck 67 Stepper 67 Fleet 68 Wrecker 68 Suburban 76 Crewcab 79 Gmc Dumptruck 84 Blazer 86 Crewcab Stepside 87 Iroc 89 GMC Plow Truck 91 Camaro Vert 96 Z71 Stepsde

12-26-2008, 10:31 PM	#2
f.monroe Senior Member Join Date: May 2004 Location: Caldwell,Tx. Posts: 3,648	Re: 1986 454, Square or Oval Port Head? 86 should have been peanut port head which is a small oval port head . The square port intake is for the early high performance heads that had square (rectangle) ports . I think that intake would do more harm than good on your truck . Frank __________________ Born and proudly residing in a Red State !

12-26-2008, 10:39 PM	#3
Livrat Member #1049 Join Date: Jun 2000 Location: Troy Montana Posts: 3,940	Re: 1986 454, Square or Oval Port Head? Your 86 should be oval port.. although some had the "peanut ports".. The square port intake will work on yours as long as you use square port intake gaskets.. (otherwise you will have a big vacuum leak!!) Using that intake wont hurt but you will not really gain anything other than having an aluminum intake. Last edited by Livrat; 12-26-2008 at 10:39 PM.

12-26-2008, 10:53 PM	#4
toomanytoyz Luv the Crewcabs Join Date: Aug 2006 Location: Andrews, In. 46702 Posts: 4,097	Re: 1986 454, Square or Oval Port Head? Thanks for the Quick Responce, I was'nt sure which i had or if it would make any Difference................ Price is Really Good at $20.00, Just wanted to know if it was a worthwhile investment. Thanks Again, Rick __________________ 55 Nomad 52 Willys Truck 67 Stepper 67 Fleet 68 Wrecker 68 Suburban 76 Crewcab 79 Gmc Dumptruck 84 Blazer 86 Crewcab Stepside 87 Iroc 89 GMC Plow Truck 91 Camaro Vert 96 Z71 Stepsde

12-27-2008, 08:21 AM	#5
grinch4om dang its hot Join Date: Nov 2006 Location: frankfort kentucky Posts: 1,349	Re: 1986 454, Square or Oval Port Head? buy it and peddle it

12-27-2008, 10:36 AM	#6
LONGHAIR just can't cover up my redneck Join Date: May 2004 Location: Columbus OH Posts: 11,414	Re: 1986 454, Square or Oval Port Head? I would not even try to use it....It will definately hurt performance and throw your fuel economy in the toilet. The huge runner volume if the rectangular port manifold will kill the velocity of the incoming air/fuel charge. This results in low vacuum signals to the carburetor...poor throttle response, bad mileage. Then the air/fuel runs into the nasty edge of the smaller port in the heads, this results in what is called "fuel dropout". Fuel dropout is exacly what is sounds like, the fuel drops out of the air, resulting in poor burning...loss of power, stumbling, etc. Not good.

12-28-2008, 07:45 AM	#7
James McClure One shot, one kill. Join Date: Dec 2007 Location: Saratoga Springs NY Posts: 859	Re: 1986 454, Square or Oval Port Head? Longhair forgot to mention oil dilution as also being a problem. You could get yourself a set of "open chamber heads" with 2.5" intake valves and 2" exhaust valves. Then you could use the intake, LOL. You'll hurt MPG though. I built one back in the 70's. All the goodies.600 horse at the rear wheels! Pick the front end of a 69 Chevelle 3 feet in the air w\14" wide slicks. Best track time was 9.9 sec at 148 MPH. Rear was a Brown spool and trans was a close ratio Muncie w\a vertigate shifter. A PITA to drive and really tough to get around corners, LOL. Wish I was that young and dumb again. Want a beasty? I'll build you one. jim __________________ 1984 K20 350M engine with 465,000 miles. Well, it's finally done!! Almost 2 years of work, but it was really worth the effort. Little stuff left to do is mount winch, wet sand & buff out and build belly pan\running boards. Body work takes lots and LOTS of beer!!!! God, Guts and Guns made America and God, Guts and Guns will preserve it! The worst thing you could do is get into my sights, but that don't matter, you'll never know it, cause you'll never hear the shotJim or Paladin whichever you choose.

12-28-2008, 11:08 AM	#8
LONGHAIR just can't cover up my redneck Join Date: May 2004 Location: Columbus OH Posts: 11,414	Re: 1986 454, Square or Oval Port Head? That's what the "etc." was for....LOL Yes, you could swap the heads to match, but then you would need more compression to make that work too, then come the pistons...... So it's a whole new engine to go under that cheap intake...

12-28-2008, 11:12 AM	#9
BigBlocksRule Registered User Join Date: Jun 2008 Location: Lubbock, TX Posts: 2,047	Re: 1986 454, Square or Oval Port Head? Buy it, sell it and buy the correct one for your heads. Pull a valve cover and get the 6 or 7 digit casting number and post it back here. I'm betting the casting numbers end in 236 which is peanut ports. The Edelbrock Performer intake will fit those. If you have 781 or 049 castings, the Performer RPM or air gap will work. I wouldn't even try the big square port intake on smaller heads for the above mentioned reasons. It's actually worth more than the small port intakes, you should be able to sell it for enough to buy the correct one.



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