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Discussion Starter · #1 ·
Hey guys,

Been awhile since I've posted. I was thinking of having my Brodix 270 rr ovals ported this past winter and never ended up going through with it. Many on this site didn't feel it was a worth while investment. Well, its nearing the end of car season here in Montreal and once again I'm thinking of ways to make my car better for next season. Not a race car at all. Street only

Ive seen that Mark cfmperformance, had some really strong gains on a customers 294 rr rectangular ports. Stock for stock they flow almost identical with the cnc options. Figured its a great benchmark for what I could possibly see from porting my 270s.

Curious as to how the experienced guys here feel the 270 with a great port job would compare to the stock 298 rr ovals?

$$ wise a great port job is much less than purchasing new high quality heads. probably $3k difference I assume. But then I could try to sell my used 270s and recap some of the money I guess

Going to a rectangular port heads also an option, but would require buying a new intake as well. And I've always liked the idea of having an oval port street motor. Feels like an underdog haha

As always, your guys thoughts are much welcomed!
 

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Given both heads and one is 270cc and the other is 294cc and if they both flow lets say 320cfm and the lower numbers are close to the same the 270cc head will be quicker and faster. Now I am sure the 294 head will be better and if this is a street car I would just port what you have.
 

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1971 Chevelle 406ci
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Hey guys,

Been awhile since I've posted. I was thinking of having my Brodix 270 rr ovals ported this past winter and never ended up going through with it. Many on this site didn't feel it was a worth while investment. Well, its nearing the end of car season here in Montreal and once again I'm thinking of ways to make my car better for next season. Not a race car at all. Street only

Ive seen that Mark cfmperformance, had some really strong gains on a customers 294 rr rectangular ports. Stock for stock they flow almost identical with the cnc options. Figured its a great benchmark for what I could possibly see from porting my 270s.

Curious as to how the experienced guys here feel the 270 with a great port job would compare to the stock 298 rr ovals?

$$ wise a great port job is much less than purchasing new high quality heads. probably $3k difference I assume. But then I could try to sell my used 270s and recap some of the money I guess

Going to a rectangular port heads also an option, but would require buying a new intake as well. And I've always liked the idea of having an oval port street motor. Feels like an underdog haha

As always, your guys thoughts are much welcomed!

It's a 540? Zero reason to use a restrictive 270cc port on an engine that big. All CFM is not equal. CSA matters at 67.5ci/cylinder. And these heads were only 303cc with the minor port work I did. I probably had more time in angle milling and porting the intake to fit under the stock 1970 SS hood than the heads themselves.
Maybe this will help demonstrate why.

Slope Rectangle Font Parallel Plot


Font Screenshot Rectangle Parallel Number


 

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Discussion Starter · #4 ·
Great of you to chime in right away

Yup its a 540. goal was to have something that's well mannered around 2200 rpm as its a stick car with a .68 overdrive and that's where I cruise at around 72mph.

Don't get me wrong, its been a great combo and exceeded my exceptions from when it was built. I've stuck with this car for a long time and have no intensions of ever selling it. I always to to make it a little better. removing the morel hydraulic roller litres in favour of the isky ez solid rollers was the best change to date. performance and sound wise. Also just dropped to a 3.55 gear out back to help with street traction and that helped in that aspect. just feel it could use some more power now. I ran door to door with a new hellcat redeye challenger 797hp but a heavy car, and was pleased at the time but I feel I need to keep our old big blocks ahead of the new showroom cars hahaha

Do you feel im past the point of the oval ports? Mike Lewis had quoted me a few options on heads and cam a year or so ago and favoured the AFR 315 and one of the Brodix 320ish heads and a more budget friendly AFR 325 but at a loss of hp comparatively. I have the utmost respect for Mike Lewis as I believe most guys do here. With exchange on the dollar these days, a $4k plus head cam package is like $6k to my door with exchange and taxes! I know it aint cheap to build a quality 540bbc. Was just wishful thinking I could get another 75hp+ for around $1500 all in
 

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What size cam and intended RPM range?
315's might be the ticket.

The 532 that Mike built for me has AFR 335's.
 

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Discussion Starter · #6 ·
current cam is something like 250/239 .638/.604 108lsa. and is actually now a little smaller due to converting to solid rollers

as stated it needs to be well mannered at 2100-2200 rpm for cruising
 

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Discussion Starter · #8 ·
From what I gathered from this over the years is it’s not possible to make it well mannered down low and have it make big power on top end but……

possibly have it well mannered down low and peak around 6000 but able to maintain until around 6500?

Not sure if that possible or not.

Car Land vehicle Wheel Vehicle Tire
 

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Great of you to chime in right away

Yup its a 540. goal was to have something that's well mannered around 2200 rpm as its a stick car with a .68 overdrive and that's where I cruise at around 72mph.

Don't get me wrong, its been a great combo and exceeded my exceptions from when it was built. I've stuck with this car for a long time and have no intensions of ever selling it. I always to to make it a little better. removing the morel hydraulic roller litres in favour of the isky ez solid rollers was the best change to date. performance and sound wise. Also just dropped to a 3.55 gear out back to help with street traction and that helped in that aspect. just feel it could use some more power now. I ran door to door with a new hellcat redeye challenger 797hp but a heavy car, and was pleased at the time but I feel I need to keep our old big blocks ahead of the new showroom cars hahaha

Do you feel im past the point of the oval ports? Mike Lewis had quoted me a few options on heads and cam a year or so ago and favoured the AFR 315 and one of the Brodix 320ish heads and a more budget friendly AFR 325 but at a loss of hp comparatively. I have the utmost respect for Mike Lewis as I believe most guys do here. With exchange on the dollar these days, a $4k plus head cam package is like $6k to my door with exchange and taxes! I know it aint cheap to build a quality 540bbc. Was just wishful thinking I could get another 75hp+ for around $1500 all in
The 540 I did is in a full weight 1970 Chevelle with 3.73/.82 OD with 275/60-15's and I'm told has excellent low speed manners by the lady that owns it and her brother in law who has driven it. IIRC it made 13-14" vac at idle, and the car builder even commented how mild mannered it was to move around.
IMO you were past the point of a 270cc oval port a long time ago, my 489/496 builds get the RR294s with a RPM AG, the main reason I used them on this 540 was for the stock port locations and low valve cover rail to keep it simple for install.
Mike won't steer you wrong, and any option he offers is because he knows how well it works. Cam timing has to do with your low speed manners, the larger port head will let that mild cam perform better with RPM. The 540 example above would have made more power with a limited travel or solid roller lifter, but it will never see any track duty or 6k+ rpm, so a Street Series Morel suited the application just fine.
Killer looking Camaro!
 

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That is one beautiful 68 Camaro
FWIW, I'd leave it alone and enjoy the engine as is. But that's me.
The OP is not racing....so he's not chasing tenths of seconds or trying to hit a certain MPH.
I assume he's very traction limited from a dead stop with this combo.
Sometimes, you just have to enjoy your well thought out and well put together street combo.
IMHO, the juice ain't worth the squeeze on a head swap for this street car that never sees the track.
 

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Cool ride for sure, think of a 540 with 270 heads like a giant peanut port engine, may not make a ton of power above 6K but who cares when you can make 750 pound feet of raw torque.
 

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Discussion Starter · #14 ·
Mr 4 speed

thanks for the kind words. Its an original L78 4 speed car. I have the original drivetrain sitting on a shelf. I try to keep it stock/sleeper looking.

The car does run well. And she holds her ground pretty good on the street. I don’t street race from a dig very often, if anything a roll race really. I just know that when I did do a few runswith the red eye challenger I was door to door and happy with that , but I would’ve been much happier if I was slowly pulling on him hahaha.

Was hoping a $1500 head and intake job could bump me up that extra 75hp to be able to pull away without doing a new head cam package and hoping it keeps its street manners

when you live where I do and have all this time off in the winter and can’t actually drive the car, working and playing on it is the next best thing
 

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1968 Malibu sport coupe, 489 ci. 590 hp 600 tq, RV T-400 Freakshow 3200 stall, 3.73 12 bolt posi
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Beautifull Camaro (y) (y) my 1st car was a 67 327 3 spd then 4 spd'ed it, Butternut & Blk vinyl top & int., no console and no spoiler, would a gear change help?
 

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Discussion Starter · #16 ·
Nice, very similar to mine then

I just did a gear swap to 3.55 to help with traction on the street and 3rd gear pulls long and hard now too. It was ok with the 3:73 before too. Even had 4.10s at first when it was a 502bbc and needed some help to get up and go. But once the 540 was in the 4.10 had to go haha
 

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Nice, very similar to mine then

I just did a gear swap to 3.55 to help with traction on the street and 3rd gear pulls long and hard now too. It was ok with the 3:73 before too. Even had 4.10s at first when it was a 502bbc and needed some help to get up and go. But once the 540 was in the 4.10 had to go haha
I bet that big engine would pull super with a 2.73 tall gear. Sure would be fun on the highway, I have 3.55's in my street car with a T-56. Super fun to drive now, but I only have a tiny 350 Vortec egine.
 

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It's a 540? Zero reason to use a restrictive 270cc port on an engine that big. All CFM is not equal. CSA matters at 67.5ci/cylinder. And these heads were only 303cc with the minor port work I did. I probably had more time in angle milling and porting the intake to fit under the stock 1970 SS hood than the heads themselves.
Maybe this will help demonstrate why.

View attachment 749782

View attachment 749783

hats off.
somehow you and mark jones are the guys achieving the best lbft/cui numbers (1.33+) which also come in already mid 4000s, all the time.
Thats one of my personal indicators of good work.
Especially when talking street hyd roller engines..

One question though:
In what way can a head supporting lets say 350 cfm at .600 lift, be too small for a street 540 with lets say a goal of 650hp?
I am talking about AFR 265s for example or any other head with small CSA (below 270) and good flow (350+).
I dont understand.
How can more demand (e.g. 540 vs 496) be a bad thing, if head is able to supply up to 700 hp (2x 350cfm) within hyd.roller rpm range (up to 6500)?
I know you can overcharge a chamber, but doesnt that only apply when going high rpm?
Isnt demand THE way to increase low end torque for street engines?

For example i run a MJ496, 049 heads on 496 cui with a 238 hyd roller cam and dual plane.
It makes 670hp at 6k but also drives like a granny car, so willingly accepting throttle inputs at 1500 rpm and up. Its almost like a stock car to me.
And i think not only the short cam and the dual plane, but also the "small" CSA 049 heads play their part there..
 

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Discussion Starter · #19 ·
Your 496 seems very similar to my 540. I would say your probably making the same horsepower as me. I haven’t been in a dyno yet but I’d expect mine to be in that 650-670hp range as is

I’m running a strip dominator single plane with a pro systems 950 carb and solid rollers

CPMotorworks your 540 with the 294 rr might be peaking early but doesn’t fall on its face after 6000rpm either. And it’s making probably close to 75hp+ than mine in the same rpm range

wouldn’t that setup be exactly what one would want in a real street car?
 

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Hey guys,

Been awhile since I've posted. I was thinking of having my Brodix 270 rr ovals ported this past winter and never ended up going through with it. Many on this site didn't feel it was a worth while investment. Well, its nearing the end of car season here in Montreal and once again I'm thinking of ways to make my car better for next season. Not a race car at all. Street only

Ive seen that Mark cfmperformance, had some really strong gains on a customers 294 rr rectangular ports. Stock for stock they flow almost identical with the cnc options. Figured its a great benchmark for what I could possibly see from porting my 270s.

Curious as to how the experienced guys here feel the 270 with a great port job would compare to the stock 298 rr ovals?

$$ wise a great port job is much less than purchasing new high quality heads. probably $3k difference I assume. But then I could try to sell my used 270s and recap some of the money I guess

Going to a rectangular port heads also an option, but would require buying a new intake as well. And I've always liked the idea of having an oval port street motor. Feels like an underdog haha

As always, your guys thoughts are much welcomed!
How much power are you after? The 270's with a good valve job can make 700HP out of the box....
 
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