Moparts

Holley carb question with 440 .509 Cam.

Posted By: Chargerfan68

Holley carb question with 440 .509 Cam. - 11/19/09 04:54 AM

Is it your experiences that you have to lower the stock power valves to lower than 6.5's with the .509 cam. I know, I know..."take a vacuum reading and see what it wants". But just looking for your experiences. Have you guys had more than 7-8" vacuum with this cam on a 440. pretty stock motor with maybe 9.0 compression.

Thanks for any input.
Greg/
Posted By: 383man

Re: Holley carb question with 440 .509 Cam. - 11/19/09 05:01 AM

My son and I both use the MP .557 cam in our street/strip cars. I have 3.5 P/V's in his 750 and my 850. Both work very good. I dont remember the idle vacum but I believe mine was about 11-12 in nuetral and about 6-7 in gear. Ron
Posted By: Joshs68

Re: Holley carb question with 440 .509 Cam. - 11/19/09 06:46 AM

I have a 4.5" pv . I have the .590 cam. I have 9" of vacuum at idle. I also run 20* of initial timing.
Posted By: MrFoFody

Re: Holley carb question with 440 .509 Cam. - 11/19/09 07:53 AM

I have a 3.5 power valve in my 383 which has the "509". It idles at 7" vacuum
Posted By: an8sec70cuda

Re: Holley carb question with 440 .509 Cam. - 11/19/09 12:32 PM

My old 440 pulled 8" of vacuum w/ the 509 cam. I ran 3.5 PVs front and back in the Holley 830 DP I had on it. CHIP
Posted By: Dodgem

Re: Holley carb question with 440 .509 Cam. - 11/19/09 02:13 PM

I used to run a 5.5 on my 509 advance the cam a bit and the bottom end and idle improve a hole lot so a 6.5 would be fine!
Posted By: Chris2581

Re: Holley carb question with 440 .509 Cam. - 11/19/09 03:24 PM

I use a 6.5 PV in my 750 Holley.383 with the 509 cam.
Posted By: maximum entropy

Re: Holley carb question with 440 .509 Cam. - 11/19/09 04:41 PM

6.5 here with a 496 and a 509. runs killer. gramma could drive it.
Posted By: tex013

Re: Holley carb question with 440 .509 Cam. - 11/19/09 08:58 PM

3.5 in mine.auto with M1 single plane 825 M Demon
idles@725/750 in drive
Tex

Attached picture 5614730-tex013.jpg
Posted By: Chargerfan68

Re: Holley carb question with 440 .509 Cam. - 11/20/09 07:33 AM

Thanks for the responses, guys. It is a friend;s engine and I think I need to look for a vacuum leak. The 6.5 valve should work. When I covered the choke horn, the rpm picked up and the idle mix screws did not choke the engine down when screwed all the way in. I think we uncovered the idle transfer slot by idling up the rpm to get it to idle.

I'll try spraying some carb cleaner around the carb and manifold to find it. Im pretty sure we have one.

Thanks,
Greg.
Posted By: RobX4406

Re: Holley carb question with 440 .509 Cam. - 11/20/09 11:03 PM

Make sure the initial timing is sufficient before bothering with anything else. If it's got less than about 18 initial, it doesn't have enough.
Posted By: blownzoom440

Re: Holley carb question with 440 .509 Cam. - 11/21/09 12:20 AM

wouldn't a vacuum gauge help to determine the best idle advance and vacuum?
Posted By: Cranky

Re: Holley carb question with 440 .509 Cam. - 11/21/09 01:46 AM

Where is the cam degreed in at?
Posted By: Chargerfan68

Re: Holley carb question with 440 .509 Cam. - 11/22/09 04:47 AM

Quote:

Where is the cam degreed in at?



This is one of those "I have no idea. The guy I bought it from said it's a worked to the balls 440...." I have a feeling this is a stock low compression 440 with way too big of a cam bleeding off too much cyl pressure.
I am just trying to help him out as much as I can, but he doesn't know too much about the motor. Just know he installed the 509 cam and put back the performer 440 manifold. I just put on a fresh 750 holley and needed to use a 1" spacer with the fuel line he wanted to use. The vacuum leak was detected between the spacer and manifold. I think the transition slot is uncovered and the power valve will be fine once I can turn out the idle speed screw to cover up the transition slots.

Thanks.
Posted By: Chargerfan68

Re: Holley carb question with 440 .509 Cam. - 11/22/09 04:51 AM

Quote:

Make sure the initial timing is sufficient before bothering with anything else. If it's got less than about 18 initial, it doesn't have enough.



Thanks. When I took a look at the engine, the vacuum advance canister was planted up against the heater hoses. Someone installed the dist way out of phase. I have to pull it out and move the oil pump driveshaft around to rephase the distrib. so that I can correctly dial in more advance.

I hate messing with things I haven't built
Posted By: blownzoom440

Re: Holley carb question with 440 .509 Cam. - 11/22/09 04:59 AM

as long as you have the dist out put a lock coller on the dist shaft to keep the timing steady holding down the intermediat shaft from floating.Granger sells the coller for about 3$ 1/2"
Posted By: Kudakidd

Re: Holley carb question with 440 .509 Cam. - 11/22/09 03:58 PM

I use a 6.5 PV in my 750 Demon. 440 with the .509" cam.If you have an older Holley. you may need do drill 1/8" holes in the primary throttle blades to get it to work off the idle system.
Posted By: Mr.Yuck

Re: Holley carb question with 440 .509 Cam. - 11/23/09 01:26 PM

Quote:

Thanks for the responses, guys. It is a friend;s engine and I think I need to look for a vacuum leak. The 6.5 valve should work. When I covered the choke horn, the rpm picked up and the idle mix screws did not choke the engine down when screwed all the way in. I think we uncovered the idle transfer slot by idling up the rpm to get it to idle.

I'll try spraying some carb cleaner around the carb and manifold to find it. Im pretty sure we have one.

Thanks,
Greg.



the 509 will not pull Donk for vacuum in a low compression engine. 9:1 is too ow for a 509 cam. If it's a vacuum carb it will be even worse. What stall is he running? what gear? it's all part of the problem. the 509 cam needs 3 things to work. Compression, gear and stall. especially the last two.
© 2024 Moparts Forums