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Author
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Topic: another 400hp 302 question
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FloJoe
Gearhead Posts: 577
From: Port Orange, FL, USA
Registered: Dec 2000
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posted 06-17-2003 10:34 PM
   
In the article they used 60cc chamber heads. I was told by indyphil that the 58cc chamber heads were the way to go. What would be the difference between the two? ------------------
Joe Fields
68 Fastback 289ci bored .030 over
C-4
"Never fry bacon in the nude.
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steve'66
Gearhead Posts: 8826
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 06-17-2003 11:10 PM
Flo,2 cc's and that's not much. 
60cc heads with a thin head gasket would net the same compression ratio. SteveW
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indyphil
Gearhead Posts: 2398
From: Senoia, G.A. USA
Registered: Jul 2002
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posted 06-18-2003 12:49 PM
I only suggested it since you have a 289. I thought the article was 64cc on a 302? Anyway If you have the choice why force yourself to use thin gaskets. Not to mention everyone always says that to MAINTAIN compression with Aluminum heads you need to go higher because of the thermal losses. If it were me I would go with the 58cc, but it depends on your future plans for the engine. A stroker might prefer the larger chambers. ------------------
'68 coupe 289 C code
66 heads, edel 600cfm carb, performer intake, dual exhaust
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indyphil
Gearhead Posts: 2398
From: Senoia, G.A. USA
Registered: Jul 2002
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posted 06-18-2003 01:03 PM
In short though the answer lies in choosing your compression ratio. In general aluminum heads prefer higher ratio than cast iron to make the same power output. Higher ratios are more prone to detonation (pinging) so as you go higher in ratio you need to run more expensive gasoline. Thats the advantage to aluminum heads though, because of the aformentioned heat transfer they dont detonate as easily so you get away with higher ratios, and cheaper gas.A 68 289 (with original heads - unlike mine) has low compression. I thought this was due to larger chamber heads, but could have had different pistons? anyway if yours is original itll have about 8.5:1 compression. One of the reasons the 68 was down on power (195hp compared to eariler engines over 200hp). Probably had something to do with emissions too. If you get 58cc in theory you will have a 9.5:1 compression ratio (assuming 68 pistons are the same as all the others) That will be very pump gas friendly with aluminum heads, allowing 87 octane gas with initial timing set to 10 degrees. You might want to use thin gaskets WITH the 58cc heads and get a little MORE compression and use 91 octane gas. Its all up to you. As far as I could tell the chamber size does not affect price, am I right?
So its up to you what kind of gas you want to run, and if a few horsepower makes a difference. I think someone on here has a rule of thumb for what compression ratio is worth in terms of horsepower. Its not much, maybe 10hp per ratio? Someone put me straight. ------------------
'68 coupe 289 C code
66 heads, edel 600cfm carb, performer intake, dual exhaust
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FloJoe
Gearhead Posts: 577
From: Port Orange, FL, USA
Registered: Dec 2000
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posted 06-18-2003 06:17 PM
Welp, I am using a 1990 5.0 HO block for the job, like they did in the article. The stock compression is 9.0:1 They used the 61cc (sorry it was 61cc and not 60cc) heads and fel-pro head gaskets with a 0.041-inch thickness to keep the compression close to stock.I would like to keep running pump gas, 93 octane. (not sure what compression ratios they are, then again I'm still learning  ) Any suggestions??? (btw, thanks for all the effort indyphil ) ------------------
Joe Fields
68 Fastback 289ci bored .030 over
C-4
"Never fry bacon in the nude. [This message has been edited by FloJoe (edited 06-18-2003).]
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69maverick
Moderator Posts: 1455
From: Thomaston,CT.
Registered: Jan 2001
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posted 06-18-2003 06:22 PM
I'm running 50cc 69 heads on a 302 with 93o.
10.4:1 C.R. with no ping! Angle them and cut!!!
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SundanceKid
Gearhead Posts: 1260
From: UT
Registered: Feb 2001
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posted 06-19-2003 05:08 AM
About that engine, not that I hold much stock in a magazine tech article, but it does show my personal theory on a good street engine in action.
I've received alot of flak about my opinions on how to build good street engines in the past both here and in life. I have changed alot of peoples views once they see how streetable and fast my engines run.I'd just like to say that article mirrors my ideas very closely. I have had great success building several engines with the same priciples as the engine featured in CarCraft.
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indyphil
Gearhead Posts: 2398
From: Senoia, G.A. USA
Registered: Jul 2002
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posted 06-19-2003 09:38 AM
Sundance,
I have been thinking the same thing too for a while. FloJoe
I re-read the article last night I saw 60cc mentioned. Anyway since you are building it on a 302, if you follow the article you cant go far wrong. I dont think the 2cc makes a big difference in compression ratio. I thought from your sig you were putting them on a 68 289. (which is what i want to do) If you plan on using 93 octane I would get the 58cc heads and for now avoid cutting them, at least at first. Where did you get your stock 302 HO motor? ------------------
'68 coupe 289 C code
66 heads, edel 600cfm carb, performer intake, dual exhaust
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'69Stang
Gearhead Posts: 205
From: Detroit, MI USA
Registered: Jan 2002
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posted 06-19-2003 09:45 AM
You should be able to run 10:1 compression with no problem. I did. 54cc's, go for it.
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FloJoe
Gearhead Posts: 577
From: Port Orange, FL, USA
Registered: Dec 2000
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posted 06-19-2003 04:49 PM
I got it from a 1990 Lincoln Mark VII at the junk yard for $170. 87-92 Mustangs and I think its 89-92 Lincoln Mark VII have it as well.------------------
Joe Fields
68 Fastback 289ci bored .030 over
C-4
"Never fry bacon in the nude.
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