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I am finally getting my heads but don't know which ones to get. Edelbrock is telling me one thing and World Products is telling me another, They both recommend rect. port heads but Edelbrock said the World Merlin heads intake runners are to big at 320 for my car but world said that the Edelbrock intake runners are to small at 290 for my car so please help me make my decsion here is my combo 69 Chevelle 454 30 over, 11 to 1 compression, 595 solid lift cam duration at .050 is 248 intake and exhaust lobe separation is 110, 825cfm race demon, full MSD ignition, 2 inch headman headers, 150 shot of NOS, Edelbrock victor intake, turbo 400 trans with 4000 stall, 410 gears, 28x15x12.5 mickeythompson tires. The heads that are on the car right know are LS7 rect. port heads with a mild port job. A few people I have talked to said I should just keep these heads and get a good port and polish job on them. so please help me if you can any comments would be greatly appreciated. I almost forgot I think I am going to change the intake the Edelbrock victor I have know is really old it is a tarantula style so help me find a intake also that will wook good with my combo. The car will be A track car so I am not worried about how it drives on the street.I will be shifting around 5800 to 6200 RPMs. I want to get the car in the 11s on motor. Thanks

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69 chevelle ss 1bad454
 

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Mark, if you want rectangular port heads than those who have told you to stay with what you have are giving you good advice. However if you really want the best heads for your heavy street/strip Chevelle you should be swapping to oval ports.

Many will/have disagreed with that statement, except those who are really in the know.

Unless you must have aluminum heads, cast iron should be your choice and a direct swap for those open chamber LS7 heads would be GM 049 or 781 open chamber oval port heads.

If it's an aluminum head you must have the best oval port aluminum for the money is the Dart. They like all aftermarket heads can be purchased fully assembled which I do not recommend. They are also available ported or full CNC ported. Stick with the Super Mod porting rather than the full CNC porting. These heads have a 265cc intake port out of the box that will grow to 275cc with the porting mentioned.

Most rectangular port heads whether "stock" or aftermarket have too large an intake runner for low to moderate RPM operation. This combine with the actual shape of the port and what you have is a lazy port that does anything but promote high velocity and good torque. Both of which are what's required to get your Chevelle to launch better than average and therefore ET better than average.

Regardless of what you read in the magazines and what the salesmen tell you, it's a oval port head you want for a heavy street/strip car without a lot of gear and not wanting to turn 7000+ RPM to ET.

Surely a rectangular port headed motor can be built that will run ET's similar to that of a oval port headed motor in identical cars. But the penalty is that the large ports require more of everything to do so. More compression, cam, converter, carb, gear and RPM. All of which will lead to poor driveability, diminshed reliabilty and engine life. The higher you RPM your motor the shorter the life of engine components. FACT!

Much server space has been devoted to this topic here at TC. Do a search on my user name for more info and links to other discussions and articles demonstrating their(the oval ports)worth.

If after reading thru these previous discussions and their links you would like to further discuss the merits of an oval port headed motor feel free to email me.

BTW, the smallest rectangular port intake runner head comes from Brodix in their BB-1 aluminum head. This head has a 280cc intake port out of the box.

Regardless of which style head you choose, the heads should be milled to achieve the smallest chamber volume necessary to maintain the compression ratio you chose to have. Why only 11:1 CR if this is really going to be a track car only?






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racer's '68

[email protected] n/a
1.41 60 foot (new best)
3900 lbs.

[This message has been edited by racer1320 (edited 06-08-2001).]
 

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racer1320 Wow! I just checked out your 68, that must be a sweet ride. My son has a 70, we are putting a 475hp+/454 in this car. My goal is to make this car safe for Daniel. I know he is going to launch this thing and when he does I want everything to go straight. can you give me advice on setting his car up similar to yours? Also not sure what carb to use on his engine. I'm thinking of the Holley Street Avenger 770 vac sec he will be driving this car on the street more than the track.

the car currently has

new stock springs, these will change for BB.
rear air bags
no sway bar in rear
12 bolt rear end. gears Unk
kyb shocks
275 50 15 on rear 15/8 rally
255 50 15 frnt 15/7 rally

engine:

049 oval port ported and polished heads
polished trw 30 over pistons
not sure what cam not to wild though
balanced
heat treated ten over forged crank
heavy duty rod bolts.
roller rockers

we don't have carb, headers or 400 tranny yet.
Thanks for your help, it's nice to know I have good heads, specially when I don't have a clue what I'm doing.



[This message has been edited by driverk (edited 06-13-2001).]
 
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