BB help-oval or rect heads
Thread Starter
Le Mans Master
Joined: Oct 2000
Posts: 6,209
Likes: 33
From: Texas-out west
BB help-oval or rect heads
Here is my basic plan: 70 coupe that will be weekend cruiser, maybe drag strip 1 a year, more racing buddies than anything else. Plan to have tremmec tko, 3.36-3.55 rear gear, 2" headers, 66 vette 427 holley intake, 850DP, closed chamber L-88 12.5 pistons with open chamber head to get around 11-11.5 compression hopefully. Cam will be something similar to comp cams 292 solid if not that cam. Now what HEADS do you all suggest, oval or rectangle and brand you would go with and reasons. Thanks :party:
Safety Car
Joined: Aug 2000
Posts: 3,909
Likes: 26
From: Clymer PA
Re: BB help-oval or rect heads (LT1driver)
LT1driver:
I believe you mean the 294S...which is the Comp Cams Magnum solid flat tappet. I'm running this cam, and while it's a nice modest cam I wish I had gone larger.
You will get mixed opinions on the Oval Port vs. Rectangle Port debate. Jim (427hotrod) ran some worked over O-Port heads on his 427 motor. His setup ran 11.20s, the only thing that kept him from 10s was the fact that if he launched any harder his rear end and componants wouldn't be able to take it. I'm running worked over O-Ports on my 468 and am turning trap speeds of 116mph....with some tuning should be up around 118mph. That's more than capable of mid 11s. The nice thing about O-Ports is the increase port velocity. If you went with a 325cc intake runner R-Port head, you will not really see the benefits of it until around 4000-5000RPMs. It's going to lack bottomend. I'm really happy with how my O-Ports perform. So I would say for a street car, worked over O-Ports are the way to go. For a full on drag car, R-Ports wouldn't be a bad choice.
I believe you mean the 294S...which is the Comp Cams Magnum solid flat tappet. I'm running this cam, and while it's a nice modest cam I wish I had gone larger.
You will get mixed opinions on the Oval Port vs. Rectangle Port debate. Jim (427hotrod) ran some worked over O-Port heads on his 427 motor. His setup ran 11.20s, the only thing that kept him from 10s was the fact that if he launched any harder his rear end and componants wouldn't be able to take it. I'm running worked over O-Ports on my 468 and am turning trap speeds of 116mph....with some tuning should be up around 118mph. That's more than capable of mid 11s. The nice thing about O-Ports is the increase port velocity. If you went with a 325cc intake runner R-Port head, you will not really see the benefits of it until around 4000-5000RPMs. It's going to lack bottomend. I'm really happy with how my O-Ports perform. So I would say for a street car, worked over O-Ports are the way to go. For a full on drag car, R-Ports wouldn't be a bad choice.
Team Owner
Joined: Feb 1999
Posts: 34,454
Likes: 665
From: Republic of Texas
Re: BB help-oval or rect heads (bence13_33)
< So I would say for a street car, worked over O-Ports are the way to go. For a full on drag car, R-Ports wouldn't be a bad choice.
Burning Brakes
Joined: Aug 2001
Posts: 1,002
Likes: 0
From: Bay City MI.
Re: BB help-oval or rect heads (LT1driver)
LT1driver, I have heard many times that oval ports are the best for the street, but in my setup I am running Merlin R-ports 310cc intake runners and 119cc combustion chambers. I have a Crane hydraulic 296-2 cam and it makes tons of power with not too much off the bottom end. These heads are probably overkill for me, but when it hits about 3500 rpms you best being going straight! I have my MSD 6al set at 6500rpms and it seems like there is way more power on tap. Good luck with the project, and my vote would be for Merlin heads.
Safety Car
Joined: Aug 2001
Posts: 3,892
Likes: 13
From: Pettis Performance 565 with two stages of Nitrous Supply nitrous 1.082, 4.61 at 155, 7.17 at 192
Re: BB help-oval or rect heads (LT1driver)
I agree with Bence, for your combo go with ovals. I like ovals for less than 650 hp. The increase in velocity is a big benifit on a street motor, not saying rec ports won't work, but in my opinion ovals are usualy the way to go.
Just for a comparrison here is my current build up:
454 +.030
10.5 JE
850 DP flowed to 920
Ported Edelbrock ovals
Ported Edelbrock Victor Jr.
Solid roller 255 / 262 at .050 .651 lift.
I should be in the 625 ish HP range with this combo.
Just for a comparrison here is my current build up:
454 +.030
10.5 JE
850 DP flowed to 920
Ported Edelbrock ovals
Ported Edelbrock Victor Jr.
Solid roller 255 / 262 at .050 .651 lift.
I should be in the 625 ish HP range with this combo.
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
Re: BB help-oval or rect heads (69 N.O.X. RATT)
I also agree with Bence and 69NOX.RATT. Oval ports will match rectangular ports up to at least 6000 or 6500. I ran a set of ported 325 rectangular ports and they were a dog on the street. Run them to 7500 and they really came alive but I didn't go there often. Most of the driving is in the 2-3000 range.
Go oval ports. Rectangular ports can be down as much as 50FT lbs in the lower rpm.
Go oval ports. Rectangular ports can be down as much as 50FT lbs in the lower rpm.
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Thread Starter
Le Mans Master
Joined: Oct 2000
Posts: 6,209
Likes: 33
From: Texas-out west
Re: BB help-oval or rect heads (norvalwilhelm)
Thanks guys for imputs, ovals seem like choice below 6500, Bence you are write, my typo, 294s was cam I meant. I like turning 7+ but like my motor to stay together more. Like has been said how often do you really turn 7+ on street. Thanks again. :cheers: