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Discussion Starter #1 (Edited)
Hi, I have a 521 bbf crate engine, all original with a powerglide in a 84 ford Thunderbird and Im running low 10´s and I want to get lower, around 9.70
I am going to send the engine for a refresh, it has around 200 runs, and they recommend me to change crank, rods and pistons, and maybe even cam and intake to make it a 557 but I think that it would be too expensive.
So I wanted to ask you if you think that it would be enough with a blueprint, porting heads and intake and maybe changing the cam? And do you think it would just as expensive as the first option or a lot cheaper?
 

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Hi, I have a 521 bbf crate engine, all original with a powerglide in a 84 ford Thunderbird and Im running low 10´s and I want to get lower, around 9.70
I am going to send the engine for a refresh, it has around 200 runs, and they recommend me to change crank, rods and pistons, and maybe even cam and intake but I think that it would be too expensive.
So I wanted to ask you if you think that it would be enough with a blueprint, porting heads and intake and maybe changing the cam? Do you think it would just as expensive as the first option or a lot cheaper?

Leave the bottom end alone, and bolt on AFR heads and intake.


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What heads and intake are already on the engine?
What pistons and connecting rods?
What cam?

More details about the 521 will help with more constructive comments.

There is probably alot of room for improvement with what you already have.


Suggesting AFR heads and intake - and pistons (with correct valve reliefs) etc.. will be spendy.
Of course there are a few AFR proponents here wanting to spend others money :)

Cheers
 

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Discussion Starter #4
thank you for your comments, here are more details of the engine:
-HP (SAE J607) 609 hp @ 5750 rpm
-Torque (SAE J607) 630 lb-ft of torque @ 4500 rpm
-HP (SAE 1349 Corrected) 580 hp @ 5750 rpm
-Torque (SAE 1349 Corrected) 600 lb-ft of torque @ 4500 rpm
-10.0:1 compression ratio Cast nodular iron crankshaft, M-6303-A514Victor single plane intake manifold M-9424-H429
-Ford Racing "Super Cobra Jet" aluminum cylinder heads. They flow significantly more than production 460 heads. Combustion chamber volume is 72cc (nominal)
-Ford Racing "Super Cobra Jet" valve train includes dual-valve springs, retainers, keepers, seals and premium stainless steel swirl polished valves. Intake valve diameter is 2.20" and exhaust valve diameter is 1.76"
-Ford Racing high-performance solid roller mechanical camshaft M-6250-A514 provides significant horsepower increases above 3500 RPM and good low-end torque. Valve lift is .640" intake and exhaust. Duration at .050" is 254 degrees intake and 258 degrees exhaust
-Ford Racing forged aluminum dished pistons, bore size 4.390"
 

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thank you for your comments, here are more details of the engine:
-HP (SAE J607) 609 hp @ 5750 rpm
-Torque (SAE J607) 630 lb-ft of torque @ 4500 rpm
-HP (SAE 1349 Corrected) 580 hp @ 5750 rpm
-Torque (SAE 1349 Corrected) 600 lb-ft of torque @ 4500 rpm
-10.0:1 compression ratio Cast nodular iron crankshaft, M-6303-A514Victor single plane intake manifold M-9424-H429
-Ford Racing "Super Cobra Jet" aluminum cylinder heads. They flow significantly more than production 460 heads. Combustion chamber volume is 72cc (nominal)
-Ford Racing "Super Cobra Jet" valve train includes dual-valve springs, retainers, keepers, seals and premium stainless steel swirl polished valves. Intake valve diameter is 2.20" and exhaust valve diameter is 1.76"
-Ford Racing high-performance solid roller mechanical camshaft M-6250-A514 provides significant horsepower increases above 3500 RPM and good low-end torque. Valve lift is .640" intake and exhaust. Duration at .050" is 254 degrees intake and 258 degrees exhaust
-Ford Racing forged aluminum dished pistons, bore size 4.390"
AFR heads and intake will bolt right up. No need to notch the pistons with that cam. Should be worth about 70HP. ~$2500.00 for heads and intake, sell the ones you have....$1000 out of pocket tops, with minimal headaches for 70+HP. No other changes are going to come close to that level of power increase per dollar. Change out the cam, and you could easily be looking at a 100+HP improvement.


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I believe Carl is right. Tear down the engine to check it over, check clearances. I’m sure it is ok, put new bearings, afr heads and intake, and cam. Your cheapest way to get what you want.

Having a shop build you a 557 is gonna cost a fortune. Just to balance the big strokers can get expensive sometimes. Sounds like a fun little ride. Best of luck in your choice.

I’ve had several qualified sources explain to me how superior the afr heads are. Trust in them.

I’ve yet to run my engine yet, but it is getting close and I’m more than ecstatic about it.
 

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Discussion Starter #7
the AFR heads are better than the P51 Kaase? I have seen a lot of people talking good things about the kaase.
Other thing, what do you think about carb spacers? do you recommend them?
thank you
 

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What heads and intake are already on the engine?
What pistons and connecting rods?
What cam?

More details about the 521 will help with more constructive comments.

There is probably alot of room for improvement with what you already have.


Suggesting AFR heads and intake - and pistons (with correct valve reliefs) etc.. will be spendy.
Of course there are a few AFR proponents here wanting to spend others money :)

Cheers
This post needs a "LIKE" button!!!!
 

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the AFR heads are better than the P51 Kaase? I have seen a lot of people talking good things about the kaase.
Other thing, what do you think about carb spacers? do you recommend them?
thank you
Out of the box with no port work P-51's vs AFR 295 or 315's... The AFR's will win.

P-51's with a 2.300" intake valve and port work will run with the AFR 315's.

AFR heads have already made over 1000 hp with out of the box 315 and AFR dommy intake.



S
 

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What's your budget for this freshen up?

What is the car weight?

What size stall converter?

What rear gears?

Cheers, Bob
 

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It is almost comical how a few on here want everyone to buy AFR heads.
I like the new AFR heads, However - the SCJ heads with a little work can make big power too.

You can easily make 100 more HP with what you already have - without the HUGE expense of AFR heads, intake manifold, piston modifications, etc.....

A good valve job with back cut intake valves will yield BIG gains with the SCJ heads.
A custom cam will also add to the power output.
Ported intake will also help. Not sure what carb you are running - 1050 dominator minimum.

Good luck!!

like I said, AFR are decent heads. But SCJ heads are not all that bad either. And with a little work on the SCJ heads and a custom cam you will see a very easy 100 HP increase. And not be spending $2500++ on the shiny new AFR heads.
 

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Nobody said SCJ heads aren't decent heads, or that they can't make good power, but....

Valvejobs aren't free
Replacing worn valve-springs, guides, etc. isn't free
Quality port work certainly isn't free
Transporting parts to and from people isn't free

The hassle of coordinating all those efforts, and the time involved is something to consider. I find it unlikely that there's anything to be saved by jumping through all the hoops to make SCJ heads perform, and no matter how much you rub on them, they're not going to perform as well as the AFR's, at least not without a custom manifold, and spending far in excess of what you would by bolting on a better set of heads.

If the OP prefers to jump through all the hoops to get more performance out of his SCJ's, that's fine. I was just presenting an option that faster/easier/better, and probably cheaper.


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Discussion Starter #15
Ive been looking at the AFR heads and I think its the easiest and faster option and maybe cheapier if I can sell the scj in a short time.
How much do you think it would be for porting heads and manifold in the cnc? around $2000? and how much for a custom cam?
 

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Discussion Starter #16
What's your budget for this freshen up?

What is the car weight?

What size stall converter?

What rear gears?

Cheers, Bob
is a 84 ford thunderbird 2350 lb with driver, a 5500 converter, 4.56 rear, 1050 dominator.
Im trying to decide in this options:
a)bore to 4.5 and new pistons to make it a 547ci, and new cam
b)porting heads and manifold with a new cam
c)new cam with some work on the pistons and changing to alcohol(righ now im running vp c12)
d)new afr heads and intake.

It would be one of these options plus the freshen up, my budget is around $6k.
 

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is a 84 ford thunderbird 2350 lb with driver, a 5500 converter, 4.56 rear, 1050 dominator.
Im trying to decide in this options:
a)bore to 4.5 and new pistons to make it a 547ci, and new cam
b)porting heads and manifold with a new cam
c)new cam with some work on the pistons and changing to alcohol(righ now im running vp c12)
d)new afr heads and intake.

It would be one of these options plus the freshen up, my budget is around $6k.
Is that right 2350 lb?
 

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that is right, all chrome moly and fiberglass, and is a little shorter than the original.
At that weight you should be low 9s. I would sort out this combo out before anything else.

IMO your converter is too loose, needs to be around 4500rpm, your rear gears are too low i would go 3.9........that engine peaks at 5800rpm.

Cheers, Bob
 

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Nobody said SCJ heads aren't decent heads, or that they can't make good power, but....

Valvejobs aren't free
Replacing worn valve-springs, guides, etc. isn't free
Quality port work certainly isn't free
Transporting parts to and from people isn't free

The hassle of coordinating all those efforts, and the time involved is something to consider. I find it unlikely that there's anything to be saved by jumping through all the hoops to make SCJ heads perform, and no matter how much you rub on them, they're not going to perform as well as the AFR's, at least not without a custom manifold, and spending far in excess of what you would by bolting on a better set of heads.

If the OP prefers to jump through all the hoops to get more performance out of his SCJ's, that's fine. I was just presenting an option that faster/easier/better, and probably cheaper.


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Carl makes several good points here.

In addition (for peak numbers) the best pair of Ported SCJ's are going to be no better than an out of the box pair of P-51's, which are based on a pair of Kaase ported SCJ's with some short turn casting revisions. The out of the box AFR castings are going to best P-51's. It is a fact and in no way disrespects Jon K's contributions to the BBF hobby.

I've already done the dyno comparisons between them all. Guess what folks. Unless a client demands it All aluminum headed BBF engines that come out of BOTH of our shops have AFR heads. Nuff said.

I have a pair of SCJ's on the shelf. 2.250" A-429 intake valves, TFS streets proprietary serdi cutter used for the intake side, bowls sized at 91% with a cutter I designed to cut parallel to the intake centerline for 1" and then radius into the longside. 1 chamber hand blended to flow 380+ intake and 250+ exhaust with pipe. They are collecting dust because I do NOT have time to hand port them. Why bother when out of the box AFR's will best them AND are cost effective as he$#... :|

Rant over.



S
 
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