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Discussion Starter #1
Got my engine back from its second trip to a machine shop for a proper ballancing job and clean up.

Here are the details

466 cubic inches
~9.5:1 Compression
C8VE Heads
Mild porting on the exhaust
2.19 Intake Valves
1.76 Exhaust Valves
Performer Intake
750 Summit Racing Carburetor
Comp Cams
XE262H Cam, Lifter and Spring Kit
Duration @ .050 218/224 (I/E)
Lift .513/.520 (I/E)
Hooker Mustang Swap Headers 1.875" primarys to 3.5" collector
Comp Roller Tipped Rocker arms

Peak Numbers: 385 HP @ 4900 RPM & 485 ftlbs @ 3700 RPM

Do these numbers seem a little low? I know the cam isn't huge and my Performer intake is probably the choke point. Would an 850-870 CFM Carburetor help make some more power?
 

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Those numbers seem to be right on the money to me. All in before 5000rpm. I can't imagine a bigger carb helping you at all. The cam is very small and with that induction setup you can see it will be a nice street engine (torque number is good).

That is basically a nice street performance/stock rebuild and hopefully you got hardened exhaust seats so you can enjoy it for a long time.
 

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Discussion Starter #3
Thanks for the response. I was running the water pump and alternator off the flywheel as well, so I guess there are some losses there too. The torque was solid though, between 485 and 400 ftlbs all the way to 5000 RPM
 

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yes the numbers are good but the roller tip rockers are for chevy's and the geometry is wrong you are leaving a little cam lift on the table, and yes it will make more power with a bigger carb
 

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According to Summit's "CFM Calculator", about 750cfm is your engines limit for racing and may even be more responsive on the street with something around 650cfm. Your header size would be optimum around 1 3/4". We always tend to go too big on carbs and headers, myself included. :)

Colt
 

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Summit's "CFM Calculator",

thier calculator may say that but I guarantee you put a holley HP 850 on it and it will make more HP
 

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Summit's "CFM Calculator",

thier calculator may say that but I guarantee you put a holley HP 850 on it and it will make more HP
What do you base going bigger on. What information do you have on the OP's engine that you can "guarantee" more HP? Just ask'n?
 

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HP and TQ are about right for the combo as stated imo.

The modest lift on the cam, chevy geometry rockers and lack of port work to work with the larger valves are three stand out reasons I see.


We recently did a 9.75 to 1 466

Budget ported small valve heads 307/180 cfm @ .600" lift
Performer intake
219/227 voodoo cam .540" / .552" lift on a 111 lsa and l07 ICL
750 holley
Curved distributor with 34 total degrees timing. More did not make more power.


425 hp at 5000 rpm ''UNCORRECTED'' Multiply figures by 1.03 for STP gross HP
515 tq at 3300 rpm


Add rpm intake for 440 HP


This combo consistently makes these numbers on our local dyno which is the tightest one in the puget sound area.

This same combo with 10.3 to 1 static, Budget D3's, same voodoo cam and an rpm intake with 750 DP took a 3900 pound torino cobra to [email protected]


More port work with attention to the intake side !!!
proper roller rockers going to 1.8 ratio if the pistons have large valve reliefs and heads have dual springs.

Holley 750


You would pick up power no doubt.


Hope this helps.
 

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What do you base going bigger on. What information do you have on the OP's engine that you can "guarantee" more HP? Just ask'n?
he's BEEN THERE DONE THAT JUST LIKE ME,It needs more carb,and cam
 

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he's BEEN THERE DONE THAT JUST LIKE ME,It needs more carb,and cam

Now you are adding cam. See Mad Porter Post ^^^ All of that with 750cfm.

The OP's motor is mild lift, mild duration, no port work, 5000RPM's and 9.5 to 1. There won't be any air speed at all with the 850cfm. And then....Who know's? ,,but the ET Timer and Trap Speed Multiplier. :)
 

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Now you are adding cam. See Mad Porter Post ^^^ All of that with 750cfm.

The OP's motor is mild lift, mild duration, no port work, 5000RPM's and 9.5 to 1. There won't be any air speed at all with the 850cfm. And then....Who know's? ,,but the ET Timer and Trap Speed Multiplier. :)
A 750 is ok for street use. If he is after all he can get out of the combo he has a small cam and intake change with a 850 it will gain more power.
 

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Now you are adding cam. See Mad Porter Post ^^^ All of that with 750cfm.

The OP's motor is mild lift, mild duration, no port work, 5000RPM's and 9.5 to 1. There won't be any air speed at all with the 850cfm. And then....Who know's? ,,but the ET Timer and Trap Speed Multiplier. :)



yes, a cam would help.but if nothing else I'd add a larger carb
 

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What do you base going bigger on. What information do you have on the OP's engine that you can "guarantee" more HP? Just ask'n?
I don't care what Summit's carb calculator suggests (and it's a generic suggestion at best) These big Fords like lots of carb and cam. My little 466" in my boat is running a 290* .634" cam and 1,500 CFM of carb and it LOVES it! THAT doesn't follow their carb suggestions I'll bet.
Rob
 

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Scotty J makes good points and has been there and done that, but the OP asked if a bigger carb will make more power and the answer is YES it will, it may not be as efficient as a 750 but will make more HP ..........
 

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Discussion Starter #17
Thanks for all the responses. Didn't know about the difference in rocker arm geometry. I saw that most of the aftermarket ones were 1.73 so i thought 1.72 wouldn't be that big of a difference only about 5 thou less lift.

I think I'm gonna stay with the 750 for now and most likley the cam as well. This is an engine that will be going in a 1990 Mustang GT with a TKO-600 that will mainly be driven on the street, see maybe 1 or 2 drag strips a year and some local autocross. I'd like to have a car that breaks into the 11.5-12.5 second range in the 1/4 mile and keep up with newer mustangs and camaros.
 

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its not just the 1.72 to 1.73 its the angle of where the pushrod goes into the rocker to where the rocker pushes the valve stem its just different, (is there a sticky on the rocker arms?) anyone? so he can see what i'm talking about? anyway IMO all I would do to your combo to make a little more power is add 1.8 motorsport rockers (ford type) a performer RPM and a Holley 850 HP and it should make 450 ish HP, good luck with your build and have fun busting azz!!!!
 

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On the carb.....I'm in the bigger is better camp too.

For example, at a recent race I picked up 4 mph by switching from a 750DP to a 1050DP (850DP with Proform 1050 center section). This was on a 429 with a Performer intake, D3's, and a 224/234 cam running at ~9500 feet density altitude (probably moving the same amount of air as a 351). No calculator in the world will tell you that much carb is going to be beneficial, but it was. Interestingly, the 1050 drives better on the street too.


:cool:
 

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Thanks for all the responses. Didn't know about the difference in rocker arm geometry. I saw that most of the aftermarket ones were 1.73 so i thought 1.72 wouldn't be that big of a difference only about 5 thou less lift.

I think I'm gonna stay with the 750 for now and most likley the cam as well. This is an engine that will be going in a 1990 Mustang GT with a TKO-600 that will mainly be driven on the street, see maybe 1 or 2 drag strips a year and some local autocross. I'd like to have a car that breaks into the 11.5-12.5 second range in the 1/4 mile and keep up with newer mustangs and camaros.
Have you taken any weight out of your Mustang or do you know how much it weighs?

PS There are a lot of variables here, so this is just a guesstimate.

Your ET / MPH computed from your vehicle weight of 3000 pounds and HP of 385 is 11.55 seconds and MPH of 117.03 MPH.
 
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