[SlideNGlide]

Hello, new here and need some advice as I am clearly not an expert with engines. I am building a 350sbc for my 1951 Chevy Sport Coupe and need a little advice before I drop down a stack of money. This car will be a weekend cruiser with A/C, power steering, and power disc brakes front and rear. This engine must run on pump gas and not overheat in traffic.


Block: 350 sbc OE roller - 4 bolt main.
Heads: AFR 23 degree 195cc Street Heads
Compression: Would like to stay down around 9:1 (if possible? I hear less compression creates less heat? It gets hot in FL. )
Cam: Not yet purchased
Intake: AFR single plane air gap intake (match port to Street heads, I hear single plane plays better with EFI)
Headers: 1-5/8 mid-tube headers
Fuel: Not yet purchased (I am buying Holley Sniper EFI or FiTech EFI)

Transmission: 2004R
Torque Converter: Not yet purchased
R&P: 4.30
Wheel Height: 26in tall
Car weight: 3500lbs approx

So what cam and torque converter would you recommend with this setup? I was thinking about an XR264HR or maybe an XR270HR? But I am not sure about the vacuum and the power brakes situation? Any idea if these cams will still allow for power brakes? Does anything in this setup look horrendous? Should I change anything?

Thanks in advance for any advice you can spare.

 

[johnsongrass1]

Looks good from my house.
Either of cams are close enough. I’d go with the smaller one personally.

 

[bk2life]

Hello, new here and need some advice ……Block: 350 sbc OE roller - 4 bolt main
Thanks in advance for any advice you can spare.

Personally I wouldnt do any of that.. hat is your goal here? A nice cruiser with plenty of power, MPGs, drivability, ac/ps/pb..everything you are describing here I would use an LS based motor and have all that and still get 20+ mpgs. Shoot I have nearly 500hp and get 21 mpgs in my daily driver, with a 3600 stall.
And before I hear the, I want the old school look, take a look at his LS, it’s perfectly old school.

 

[75gmck25]

The XR264 will be fine with power brakes, and even the XR270 should have plenty of vacuum. With aluminum heads you should be able to run up to 9.5 compression on pump gas. Run your base timing relatively high (15-16 degrees), mechanical about 20, and check carefully for pinging.

You have a good combination of trans and rear end ratio, and a relatively light vehicle, so you don’t need as much help from the torque converter to get off the line. I would read through this article and see if you get a better idea of what you want. Torque Converter Basics: How To Choose Correctly? .

Bruce

 

[2001Blazer4x4]

Hello, new here and need some advice as I am clearly not an expert with engines. I am building a 350sbc for my 1951 Chevy Sport Coupe and need a little advice before I drop down a stack of money. This car will be a weekend cruiser with A/C, power steering, and power disc brakes front and rear. This engine must run on pump gas and not overheat in traffic.


Block: 350 sbc OE roller - 4 bolt main.
Heads: AFR 23 degree 195cc Street Heads
Compression: Would like to stay down around 9:1 (if possible? I hear less compression creates less heat? It gets hot in FL. )
Cam: Not yet purchased
Intake: AFR single plane air gap intake (match port to Street heads, I hear single plane plays better with EFI)
Headers: 1-5/8 mid-tube headers
Fuel: Not yet purchased (I am buying Holley Sniper EFI or FiTech EFI)

Transmission: 2004R
Torque Converter: Not yet purchased
R&P: 4.30
Wheel Height: 26in tall
Car weight: 3500lbs approx

So what cam and torque converter would you recommend with this setup? I was thinking about an XR264HR or maybe an XR270HR? But I am not sure about the vacuum and the power brakes situation? Any idea if these cams will still allow for power brakes? Does anything in this setup look horrendous? Should I change anything?

Thanks in advance for any advice you can spare.

I have the AFR 195 heads and I would recommend only 1 3/4" tube headers. Otherwise you are going to have a pretty good step down in size on the sides of the exhaust port where it enters the header flange. Also watch which flanges the headers use. The exhaust ports in the AFRs are pretty large and really match the Felpro gasket that AFR recommends (if you want to take a gasket along when shopping for headers).

On the intake side, know that Edelbrock makes a CNC ported version of the Vic Jr that matches the AFR recommended Fel Pro gasket for the 195's. Other than a slight difference of the radius in the corners of the port, this is an exact match. The AFR single plane is probably not matched and requires grinding - or it is already matched to ports in larger AFR heads. Check before buying. Also a good gasket to take when shopping for intakes.

The XR264HR would be a good choice. Should not be a problem with vacuum. This cam would work best at 9.8:1

 

[curtis73]

Compression alone doesn't make heat. Your compression ratio needs to match the cam... which needs to match the heads... which needs to match the intake, stall speed, trans/rear ratios... it all plays together.

But heat is the last reason to choose compression ratio. Heat is generally made by the hp you're making. More HP means more energy being released inside the engine, which means more heat to shed in the radiator.

Dual plane intakes will work fine with EFI, depending on the type of EFI. If it's a throttle-body EFI, the same basic carburetor-based rules apply because the air flowing through the intake contains fuel. If you have port EFI, a single plane makes sense for two reasons: 1) where the runners meet the ports at the head, the runners on a single plane are all at the same height which makes it easier to put all the injectors at the same height, and 2) since the air in the intake is not carrying the mass of the fuel along with it, the style of the intake has less importance on the qualities of how it flows air.

On AFR heads with their good chamber shape and aluminum construction, you have a good bit of flexibility with compression. I would say with either of those cams, 9.5:1 should be fine on 87 octane if you do your timing right. 10:1 with 92 you'll probably never get any ping no matter how hot things get. Heck, I run 9.5:1 on Vortec Iron heads with 87 and never have any problems.