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#21
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Bruce this is a true testament to your ability to piece together a good combination of parts and more importantly showcases your expert tuning skills. Wow, I'm impressed to say the least. Sometimes less is more when choosing cams, converters and rear end gears for a street Pontiac.
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1964 Tempest Coupe LS3/4L70E/3.42 1964 Le Mans Convertible 421 HO/TH350/2.56 2002 WS6 Convertible LS1/4L60E/3.23 |
#22
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60916 with 1.65 rockers would be a great improvement. Your headers are fine on a 400.
3.23 gears are really a good compromise between performance and freeway driving. Tire diameter will also play a role in how well they work on the freeway. My Formula with 3.23s and 27" tires cruises along just fine at 70 MPH at 3000 RPM and pulls like crazy at those speeds. Don't be afraid of a good converter with as much as 3000 stall. The key is to spend the money to get one that is very well coupled below its stall speed. I have a Coan "Pro Street" 3000 stall and it drives like stock in normal driving. I never had any problems hooking on street tires.
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---------------------------- '72 Formula 400 Lucerne Blue, Blue Deluxe interior - My first car! '73 Firebird 350/4-speed Black on Black, mix & match. |
#23
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Some very helpful information in this thread! I will run 295/50/15" tires, which will be about 26.6" in diameter. Will check some more options about the converter.
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1960 Bonneville 2dr HT 389/400ci 363hp 1965 Bonneville 2dr HT 455/501ci stroker 600hp+ |
#24
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I'll play devils advocate here....after swapping 3 cams on the same 400, I found that the cam alone did not turn my engine from a zero to a hero (meaning after cam change I thought, "wow").....nothing wrong with the crower or the 068, I just wouldn't expect miracles by just swapping cams
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71 GTO, 463, KRE 295 cfm heads ported by SD Performance, RPM intake, Qjet, Dougs Headers, Comp cams HR 246/252 ...11 to 1 , 3.55 cogs, 3985lbs.....day three- 11.04 at 120mph ....1.53 60', 6.98 1/8 mile |
#25
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B-man my build is nearly identical specs as the 420 hp 406 pump gas combo KRE offered in their 2002 catalog. Jeff said this was the cam and to degree it at 108 which is what was on timing card. My MPH indicates I'm not making anywhere near 420 hp. (Even if race weight was significantly higher.)
Others at similar weight with similar motor, same cam, have gone 12.60's with traction, better gearing and convertor. I doubt there is 50 hp difference between us though. And fwiw my 3310-1 has been with me since the 70's and has done well even on others vehicles. |
#26
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did you ever change to the 60916 was thinking to do that my self?
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#27
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I helped a local customer here a few years ago with a near identical combo put his Firebird into the 11's.
His 400 also uses ported iron heads, #62's and just over 10 to 1 compression, 406CID. I rebuilt his TH350 and supplied a custom torque converter for it. We moved up the larger Crower 60243 cam, HS high ratio rockers and Rhoads lifters. The car runs over 114mph in the 1/4 mile and solidly into the 11's in full street trim on DOT's. The engine is topped with a 1968 cast iron intake and factory Q-jet we prepared here . He uses 3.73 gears out back. Nothing really fancy with the set-up, no aluminum heads, stroker crank, or roller cam set-up. Just a nice solid 400 build with better rods, pistons, cam upgrade and professionally ported factory iron heads. For what you are doing the converter will be the single best upgrade to vehicle performance especially with the cam upgrade. I've tested and replaced the GM 20 Hughs stall converter on several occasions here. Behind a 400 build, those converters are not overly impressive anyplace. Replacing them with a custom converter was a HUGE improvement in overall vehicle performance with no loss anyplace in drivability.........Cliff
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
#28
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I would absolutely go with the Crower 916 over the 068.
My opinion trying to wring all I can out of an 068 is that it's just a small cam and has it's limitations. Here's my 400 RAIII. All stock, RA manifolds, no porting anyplace, 10.13:1 compression. 068 with stock converter and running 3.31 gears out back. I've pretty much hit a wall no matter what I tweak or tune or change with this thing. 13.10 is the best ET and 104 is it's best mph at a 3890 race weight in the Arizona heat. This particular pass corrects to a 12.76 at over 106 mph. https://youtu.be/er1z7PpqsnY Makes decent grunt for a little engine but it's all done at 5,000. It shifts at 52-5300 on it's own. I've tried as much as 5700 and while it doesn't lay over or have a big feeling of power loss, it does nothing for ET or MPH and runs exactly the same. I've squeaked about all it has to offer, I feel it's cam limited and the Crower 916 is certainly a camshaft I would look at for this combo. Last track outing I even installed an L88 converter that flashes around 2600 rpm. I was expecting improvement but the car again, ran exactly the same. 60 foot hardly changed. Best 60 with stock rubber and original converter is 1.89. With the L88 converter it went 1.91 Just shows this engine being as stock as it is, doesn't seem to care. It needs a cam change! |
#29
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Did you ever try the 90916 in your car? |
#30
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I haven't. I still use the car as a daily and have enjoyed racing it in its PS form but honestly I lean more towards building a bigger sleeper engine for it rather than tearing into this engine.
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#31
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I'm faced with the same thing. My LeMans is very similar setup to your car. Changing to RA manifolds and pypes system at the moment to improve it. |
#32
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GT |
#33
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Somewhat related. Old discussion involving the Crower 60243....
http://forums.maxperformanceinc.com/...d.php?t=741658 60243 284/290 228/235 . .479/.494 112 .
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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 |
#34
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I ran the 916 in both a 400 and 455 a few years back. Just about right for a mild street car in the 400. A little too small, in my opinion, for a 455.
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My money talks to me-it usually says goodbye! |
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