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Old 12-30-2004, 08:33 PM
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give me an estimate of HP on a 302

i am in the process of building a 302 and was just curious about what you all would estimate its Hp at. bored 30 over, speed pro forged flat top pistons, compression is supposed to be 9.13, weiand stealth intake, holley 600 double pumper, crower cam 577 lift not sure about duration, headers, stock heads, the heads have had some work but not ported or anything just roller rockers, valve springs. the guy building my motor said about 350-375. what do you think?

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Old 12-30-2004, 08:58 PM
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estimated hp

From what I see, everything is fine except your cam. Its way too big for the rest of the components, judging by the lift. If you are going to run unported heads, then going over a .540" lift on intake is a waste of time.
Is this a roller or flat tappet cam? Either way, I wouldnt go much over 220 degrees at .050" lift for duration, on intake and 230 degrees on exhaust.
With the right cam, you would be in the neighborhood of 325- 345 hp.
As I said, I think with what you gave for lift on that cam, knowing some cam specs, I think you have too much cam for your engine.

Your carburetion, intake manifold, headers and compression will make for a good stout street engine.

with a cam in the perameters I recommend, this would be a good engine with either a stick or automatic trans, and you wouldnt need to go with a high stall converter on an automatic.
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Old 12-30-2004, 09:05 PM
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well i already have the cam from another motor i had, it ran strong in it but who knows it probably could have been stronger with a different cam, i also have a c-4 auto with a shift kit and a 3500 stall. i am planning on making this a street/ strip car and would love to be able to take my brothers 2000 trans am ws6, you think i could? oh yeah its a 66 mustang.
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Old 12-30-2004, 09:13 PM
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estimated hp

I would recommend getting a good performance distributor as well. Since you are running a 3500 stall, you could go as high as a 235-240 degree duration on intake side, then you might be up in the 350 + hp range, and yes the 600 CFM carb will handle all that rpm.
What gear in the rear?
I still suspect you have way too much camshaft for your engine.
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Old 12-30-2004, 09:31 PM
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right now the gear is 4.56, we did just drag race it, i want some top end but want to be able to get out of the hole too. what would a good gear be that would still let me hit 100 and get out of the hole in a hurry, i was thinking maybe 4.11 or 3.73

i also have a crane cams xr-i electric ignition converter, crane cams ps-60 coil and moroso blue max wires if that would up your estaimate any

and the cam is flat tappet

and the cam is flat tappet

Last edited by f8lpony; 12-30-2004 at 09:31 PM.
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Old 12-30-2004, 09:42 PM
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estimated hp

As for gears, I would say with that stall, that a 3.73 or there abouts would be sufficient.

In the early 70's I ran a 69 Mustang with a 302, ,with stock 9.5:1 compression, stock heads, a Sig Erson 226 degree/.475 lift hydraulic cam, 500 cfm carb, 1 5/8ths headers, Weiand hi rise intake, and Accel distributor. I had origionally put a 650 DP on it but actually ran half a second faster with the 500 vacuum job, and the 500 was a stock Holley off of a Ford pickup truck.
Running stock torque converter with a 3.88 gear. I launched with 2000 RPM stall and shifted at 6000 RPM, running G-60-15 tires.
It ran in the low 14's and average speed of 95-98 MPH, if thats any guide for gearing. Your engine, is a little warmer than mine, other than on compression.

One thing to consider is that its who gets to the other end the quickest rather than the fastest. I ran a lot of cars that turned slower ET's but higher MPH, and its the ET that wins.
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Old 12-30-2004, 10:45 PM
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how much will porting the stock heads actually help, i have had people to tell me that its not worth the money to have it done, that you should just go ahead and put the money toward a set of after market heads.
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Old 12-31-2004, 12:37 AM
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heads

Edelbrock aluminum performer rpm heads are designed for a maximum of .575 lift. They are a whole lot more head than you have. This should give you an idea of how much too big your cam is.
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Old 12-31-2004, 06:04 AM
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becareful...

with flat top pistons, more than .5000 cam lift you can be getting the valves very close to the pistons, depends on the gaskets and decking done to the block and heads during the re-build

buy or borrow a compression tester, 9.5/1 = 150psi, 9.13/1 = ? 145psi ?,
when you bored it .30, you increased the tdc chamber volume so with bigger diameter stock head gaskets you lost some compression.

with the gorilla your building, aluminum after-market heads are the way to go for better exhaust flow and you lose 40+ lbs off the engine

tight budget, the $500 "Windsor" 302 cast iron after market heads help and you can do more to make them even better

Last edited by red65mustang; 12-31-2004 at 06:10 AM.
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Old 12-31-2004, 10:58 AM
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estimated HP

With a professional porting job on your stock heads you will be getting about 145 CFM flow on the intake side, and you really can never get enough flow out of the stock exhaust ports, no matter what. By the time you port out a set of stock heads, put in larger valves, you will have close to the price of a good set of aftermarket heads invested.

I have a set of Twisted Wedge heads that flow 191 CFM at .500" lift out of the box.

It all depends on whether you want to run steel heads or aluminum. The Roush heads by World products are about the best you can do in a steel head and they are some $3-400 less in price than aluminums.

I would recommend if you are going to go with aluminum, to go with a set of Trick Flow Specialties heads, and I would consult them on which version to use.

The reason I recommend Trick Flow is that from what I have seen, they have probably done more R&D on SBF heads than all the other head makers.
The alternate choise would be to go with AFR.
If you look at thier heads, the prices, CFM capabilities, I think you will find that Trick Flow and AFR offer the better heads, and they are competitive in price with Edelbrock and the rest.
I dont recommend using the Brodix heads for the SBF. My son has a set on a 347, fully worked over, and for what he payed for them and what he got for his money, just doesnt line up in my opinion.
One thing to consider, if you go with a head that has larger than 1.94 intake/ 1.60 exhaust valves, other than with the Twisted Wedge head, you will have to have your pistons flycut to clear the larger intakes.

The Twisted Wedge has 2.02 intake/ 1.60 exhaust valves, but due to the combustion chamber and valve arrangement, unless you are running a cam with more than .540" lift and 230 degrees duration @.050", and flattop pistons, you dont have to use special pistons.

Trick Flow makes pistons for higher compression, with the valve flycuts to be used with these heads.
Valve piston clearance will be critical with your cam as it is.
As a rule of thumb, anytime you start getting over .550" lift with a stock flattop piston with any head on your SBF, you are generally getting close to metal to metal contact.
What ever you decide to do, I would highly recommend doing a clay test on your pistons and valves, or else go ahead and have deeper flycuts made in the pistons.

As red65 stated, even getting over .500" lift will get you in the realm of contact between pistons and valves. I have run cams with as high as .544" lift with factory heads and never had any problems of that type. But as he also said, head gasket thickness, compression height of the piston, whether the head has been milled down or not all play into the equation.
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Old 12-31-2004, 11:29 AM
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i thought the cam was probably to big but the guy building my motor has built 302's all his life and drag races them now, see, i did have another 302 that i blew up about 3 months ago, i talked to him and he said just to use everything i had that was still ok, the only difference between it and the one i am building was it had dome tops. i figured it would be ok, the other motor ran 8.17 @ 84 in the 1/8th ,but if i can get more power out of a smaller cam i would spend the extra money no problem. he also recommended the windsor jr heads, but it will be awhile before that is even possible........ im a college student so im poor.
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Old 12-31-2004, 11:40 AM
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Heads and bumpsticks

The Winsor Jr is a Jack Roush design head, and that would be a very good choice for your 302. They flow quite well. The Jrs have a smaller combustion chamber than the other Roush head, and with the 1.94 intake/ 1.60 exhaust valve, you wont have to worry about having larger valve reliefs cut in your pistons. Of the two heads, if I were going to use them, even on a 351W, I think I would opt for the Jr., Unless I was going all out for high rpm.

I see a lot of ads for heads that tout the CC of the runners, but that doesnt indicate CFM flow, which is what I look at.

The problem with a head with large CC capabilities, is that they could be actually too large of runners for the application, that being the reason that usually more than one version can be found on some head designs.

Your .577" cam would probably work well with the Jr heads. The only problems being with valve piston clearance. But thats already been covered.

Personally I have never been a big fan of domed pistons. I have seen test done that showed that while they did indeed increase compression, there was power loss due to the domes disrupting the fuel air mixture flow into the cylinder. This isnt the case with all of them, obviously, but Ive had oldtimers tell me that the best setup is with flattops, and if you want higher compression, cut the head down, or use heads with a smaller combustion chamber. I know thats old school but its worked for 100 years.
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Old 12-31-2004, 12:08 PM
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For home porting stock cast iron heads it doesn't get much better than the following website:

http://www.diyporting.com/



ONe thing that caught my attention, max keith mentioned a heavily ported stock head would only flow 145 on the int at .5 and his twist wedge 191 at the same lift. I am assuming he flowed both on the same bench which demonstrates a difference of 46 cfm. What might confuse you, you will see mention of ported stock heads that flow 210-220 cfm on the intake, either by advertisers or various forums. They may very well flow this on another flow bench, if they stuck the twist wedge on the same bench the numbers would (should) be much higher. All flow benches differ, however I didn't think that much...I will let max keith clarify on that one.

Check this link out for some stock headed inspiraton, just remember, those running crazy times with stock heads have put a lot of time into cutting the heads apart, trying different approaches to get them to flow, etc. but it makes for interesting reading.

--->http://bbs.hardcore50.com/vbulletin/...ad.php?t=21955


Sent you a PM


good luck

Last edited by 357f-150; 12-31-2004 at 12:22 PM.
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Old 12-31-2004, 01:56 PM
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Ported Heads

OK. First off I got some numbers backward here. Sorry about that. The numbers I published earlier, the 145 CFM and 191 CFM are exhaust numbers rather than intake, and I apologize for the mix up.

However, exhaust numbers, particularly on an SBF are very critical, as you all well know due to the stock soda straw ports.

Thanks to 357F-150 for challanging me. Far be it from me to intentionally give out bad info. Gives me a chance to correct this error.

Standards:
The industry standard for flow bench ratings of CFM for cylinder heads is 28" of water, and most all the major head builders and producers use that standard.

I was just looking at a test done, on a set of stock heads that were worked out and did indeed flow 209 CFM on the intake side, and 143 CFM on the exhaust side, with 1.94 intake/ 1.60 exhaust valves, with necked down stems, at 28" of water. This was with .550" lift on both valves. (Note that this was a test run back in the early 80's).
These are a set of professionally worked out heads.

To compare, my Twisted Wedges flow 251 CFM on intake and 191 CFM on exhaust side, with .500" lift, both sides, out of the box. Were I to spend the money to have my heads worked over that it will cost to have your stock heads optimized, my heads would be capable of flowing over 305 CFM on intake, not sure what the exhaust would flow, but know its well over 200CFM. I base that on what the company claims for the head. And no, I wouldnt do those heads myself. I would send them back to the Trick Flow to do them. I have experience with head porting but Im NOT THAT GOOD at it.

I hope this clears up any misconception I may have given out.
Think Im going to spend more time proofreading my epistles, from now on. This is my third major goof up.
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Old 12-31-2004, 02:57 PM
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ok just got back from the guys house who is building my engine, he said that he had the cam special ground from crower and that he wouldnt get a smaller cam because it doesnt have much duration, i think he said .25X, we were also thinking about have the block 0 decked but then we might have an issue with the valve tagging, we will just have to see, he also said the same thing about the dome tops but that was a racing motor, i am going to run this one mostly on the street.
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