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#41
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"Aluminum heads will reduce low RPM torque"
This post does not represent any endorsement of a KRE product or it's use here. That said, it is my understanding their aluminum d-port head has intake port volume and dimension of a factory size of about 180cc. Or darn close. ANYBODY here change from a factory d-port head to a KRE d-port head on a 400 engine and actually feel the difference on the street with any off idle torque issue, or reduction in low rpm ? With no other changes. This keeping in mind the necessary increase in compression for the aluminum head. .
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'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) 5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE Last edited by Steve C.; 10-18-2021 at 11:00 AM. |
#42
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I made 600tq at 3600rpm with alum heads, not sure id say there is a low rpm tq loss with them.
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#43
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If spark timing and compression are found to be good, your next next option is cam timing. Your camshaft timing may be retarded either through installation error (pretty unlikely) or manufacturing error.
As a kid, I installed a Mellings 300 degrees adv duration .512" lift HFT cam in a Ford FE GT390 "by the book", dot to dot. In those days cam degreeing was a black art left to engine wizards. I wound up with a very disappointing motor that couldn't get out of it's own way under 3,000 rpm. I had the distributor converted to full mechanical advance and changed to a 3.5 power valve in the Holley 3310 to keep it from flooding under low vacuum. Even with those changes, it was a dog on the low end with a huge stumble on clutch engagement under normal driving. Once it hit 3,000 rpm it was like you turned on the "power switch". At the suggestion of the shop who sold me the cam, I advanced it 6 degrees with an offset key and it really woke the car up. The difference was like night and day. You may be in the same boat.
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Triple Black 1971 GTO |
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#44
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A pair of KRE 72cc "D"s certainly cannot hurt, especially if overcammed.
I would order and wait. |
#45
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My mistake regarding the KRE port volume.....
"Port velocity is an important factor in achieving strong low-speed performance for a street engine. KRE chose to limit intake port volume to 185 cc to promote good throttle response and high-torque output. Excellent peak flow allows it to consistently deliver 500 or more hp on moderate builds." https://www.cartechbooks.com/blogs/t...ac-v-8-engines And depending on the combination at that 500 hp with as cast KRE heads you should have at least 540-550 ft. lbs. torque at 3500/3600 rpm ! .
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'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) 5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE Last edited by Steve C.; 10-18-2021 at 12:17 PM. |
#46
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Quote:
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As I said before. He`ll have to sharpen his driving skills, especially if he gets his combo sorted with his new heads. Even with that "small" 400. |
#47
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"I have never regretted spend the $$ for quality converters."
X2 I'm with Jay here. A good custom torque converter is one of the best bangs for your buck.
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'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) 5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE |
#48
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I personally believe you have a tuning issue… has your HEI been worked to adjust the advance curve…
Also what about ignition setting at idle… as far as heads the 5C heads are actually really good so IMO until you can upgrade to Edelbrock |
#49
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Lots of good advice here so I don’t have much to add to the conversation but I agree that first and foremost you need to know what you have in your car to start a baseline and then improve from there. Heads, cam, converter and rear gears are the obvious places to look first.
Regarding the title of your post… I was going to use iron heads (a pair of 62’s) on my 455 build and put a bunch of money into them with porting and what not, plus deep dished pistons. Found out (thanks to some of the good guys on this forum) that the chambers were weirdly machined and less than ideal so I opted for a pair of 87cc Edelbrock 61529’s. Ordered them in mid July and they arrived late September. Some things are worth the money and the wait, they are beautiful and I feel so much more confident about how the car will perform when it’s done. Flat top pistons now with my Butler kit, and low octane pump gas no problem. Meanwhile best of luck with your build. Sent from my iPhone using Tapatalk |
#50
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It was ask for a couple of time but I don't see that a Cranking Compression Test was ever done on this engine.
Stan
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Stan Weiss/World Wide Enterprises Offering Performance Software Since 1987 http://www.magneticlynx.com/carfor/carfor.htm David Vizard & Stan Weiss' IOP / Flow / Induction Optimization - Cam Selection Software http://www.magneticlynx.com/DV Download FREE 14 Trial IOP / Flow Software http://www.magneticlynx.com/DV/Flow_..._Day_Trial.php Pontiac Pump Gas List http://www.magneticlynx.com/carfor/pont_gas.htm Using PMD Block and Heads List http://www.magneticlynx.com/carfor/pont_pmd.htm |
#51
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FWIW a properly ported pair of iron heads will blow the doors off an aluminum head in 90% of the 400ish CID builds.
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#52
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Sent from my SM-G996U using Tapatalk |
#53
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What do you mean ignition settings? I have about 12 hg of vaccum, set at 800rpm, initial timing about 12 degrees Sent from my SM-G996U using Tapatalk |
#54
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#55
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FedEx/USPS , road trip with the family
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#56
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From the research I've done cost wise having my 6x heads properly done wouldn't be too far off in price from new edelbrock or kre heads. I may be wrong though
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#57
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What prices are you getting for ported 6X heads ?
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#58
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Got a chance to look at the heads again they are 5c-8
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#59
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I haven't got any, I just been reading posts about it. I was supposed to have some ported polished etc for my 80 trans am with a 455 but the guy here ran off with my money. All muscle cars in lagrange GA
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#60
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Sorry to hear that. Keep in mind this is the Internet and that's where modern day fairy tales are created.
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