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my69dz
Sitting Bull

USA
120 Posts

Posted - 02 Nov 2017 :  11:35:03 AM  Show Profile  Reply with Quote
I had a 65 389 built a few years back .40 over10/1 positions. Ram air 4 cam 72cc edlebrock aluminum heads,and Doug's headers.it has a edlebrock p65 intake with 2 500 cfm edlebrock carbs.msd 6la box.m21 trans and 390 gears..the car runs great runs at 180 no matter how hot it is out.but I would like to get a little more out of the motor?I have a rpm intake and was thinking maybe a different cam but don.t know the best for the set up I already have?

Phil
The Great White Buffalo

USA
7218 Posts

Posted - 03 Nov 2017 :  11:30:13 AM  Show Profile  Reply with Quote
More as in bottom end? That's a bit more cam than I'd use in a 389/400. Those E-carbs are practically useless in a performance application due to the non-tunable/ bad design of the secondaries. The Thunder series is better but still not a home run, more like a base hit.

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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tjs44
Cochise

USA
412 Posts

Posted - 03 Nov 2017 :  4:51:25 PM  Show Profile  Reply with Quote
Put a offy 2-4 intake on it and put a pair of 625 early AFBs like buicks.The best would be pontiac SD carbs but are stupid expensive.Car will run way better as I described.I you want to woose out and go single,a RPM with a well preped pontiac QJ would be my choice.Tom
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Blued and Painted
Chief PONTIAC

USA
3406 Posts

Posted - 04 Nov 2017 :  12:06:37 PM  Show Profile  Reply with Quote
Change to a 3.73 gear to have more time in the power range.
Double check the AFR through out the full pull.
Don't stay in first gear to long.


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.

Edited by - Blued and Painted on 04 Nov 2017 12:10:24 PM
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Phil
The Great White Buffalo

USA
7218 Posts

Posted - 05 Nov 2017 :  07:27:16 AM  Show Profile  Reply with Quote
69dz, would be able to elaborate a bit on what your looking for regarding more power? Where is it most lacking?

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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my69dz
Sitting Bull

USA
120 Posts

Posted - 05 Nov 2017 :  12:22:00 PM  Show Profile  Reply with Quote
I guess low end.the carbs were jetted and tuned on a dyno.so I guess that's the best I.'ll get out of them.the motor runs really good.maybe I.'ll try the rpm intake and a good carb before I open the motor up for a cam change.
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tjs44
Cochise

USA
412 Posts

Posted - 05 Nov 2017 :  5:20:55 PM  Show Profile  Reply with Quote
The E carbs are famous for not great street diving!Also the position of the E 2-4 intake is not great for our pontiacs.Tom
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my69dz
Sitting Bull

USA
120 Posts

Posted - 05 Nov 2017 :  9:25:18 PM  Show Profile  Reply with Quote
When they dyno.d the motor they said the duel carbs hurt the profomace some.and I would get more power from a single 4bbl.but I had the intake already and just bought two new carbs.so I thought I would try it.
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tjs44
Cochise

USA
412 Posts

Posted - 06 Nov 2017 :  10:10:57 AM  Show Profile  Reply with Quote
2-4s will make more power than a single 4 but the proper intake and carbs are needed to do it.The Edelbrock 2-4 intake is not a good intake and the carbs are too small.IF you dont want to stick with a 2-4 setup then a RPM and a properly setup QJ IMO would be your best choice.Tom
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my69dz
Sitting Bull

USA
120 Posts

Posted - 06 Nov 2017 :  11:07:53 AM  Show Profile  Reply with Quote
You think a offy intake and two afb 625.s would make more low end power than what I have now?I see the offy intakes for sale once in a while.the carbs might be a bit harder to come by.
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Phil
The Great White Buffalo

USA
7218 Posts

Posted - 06 Nov 2017 :  4:06:38 PM  Show Profile  Reply with Quote
I'd back off the cam a little for much better low end and street performance.

In the meantime, if you want to try something cheap (as in FREE), remove the secondary linkage rod on both carbs and Drive it. Report back. I'm not kidding!

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.

Edited by - Phil on 06 Nov 2017 4:07:30 PM
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tjs44
Cochise

USA
412 Posts

Posted - 06 Nov 2017 :  6:02:05 PM  Show Profile  Reply with Quote
I dont think more low end power,your RA IV cam is killing your lowend.I would try a lifter change before you do anything.You need to figure what you really want,more HP or more low RPM drive-ability.You put on heads with bigger ports(lower velocity)and a cam made for higher RPM HP.As I said,try the lifter change first.They will make noise kind of like a solid lifter but will give you better lowend.Tom
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tjs44
Cochise

USA
412 Posts

Posted - 06 Nov 2017 :  6:04:56 PM  Show Profile  Reply with Quote
Rhoads are what you want to try first before making a cam or intake change.I do hope you have you carbs setup progressive.2-4s setup solid IMO are not street friendly.Tom
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tjs44
Cochise

USA
412 Posts

Posted - 06 Nov 2017 :  6:12:55 PM  Show Profile  Reply with Quote
Phil,AFB type carbs are VERY tuneable,you just need to start with the right ones and the E type are not them.They can be done but WAY harder then the true pontiac or buick early 60s AFBs.Tom
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Phil
The Great White Buffalo

USA
7218 Posts

Posted - 07 Nov 2017 :  10:42:09 AM  Show Profile  Reply with Quote
Tom, yes I am aware of that. However, the OP stated he was running (2) 500 cfm Edelbrock carbs which are basically useless regarding tuning of the secondaries. I have found a significant improvement just by removing the linkage rod to the secondaries on E carbs which is only done to demonstrate the problem is in the secondaries.

Love the AFB on my vintage Chris Craft and its dialed in perfectly for my Q engine. (Thanks to Jon Hargrove for having a correct NOS Carter AFB in original box!)

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.

Edited by - Phil on 07 Nov 2017 11:00:16 AM
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my69dz
Sitting Bull

USA
120 Posts

Posted - 12 Nov 2017 :  1:35:35 PM  Show Profile  Reply with Quote
I think I.'ll try the Rhoads lifters before I change to much on the motorI am not to sure how to set the rockers? I have Harland Sharp 1.5 on it.somebody told me to torque them to 20 foot pounds and that's it??sound right?
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tjs44
Cochise

USA
412 Posts

Posted - 12 Nov 2017 :  6:39:33 PM  Show Profile  Reply with Quote
You cant TQ them to any number.Once you have a adjustable valve train you need to set them properly.Tom
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