Why do my intake ports look like this?

[340_833 dart]

I just pulled the intake manifold off my 340 in preparation for pulling the engine and transmission.
The bottom of the intake plenum is bone dry and clean.
But, look at the intake ports on the heads. I haven't run the engine for two weeks. Yet, they are wet. Is it because of the PCV system?
The manifold looks the same way at the ports.

 

[MopaR&D]

Are you running pump gas? That stuff leaves behind a lot of junk when it burns/evaporates, and the gas that collects on the walls of the intake ports evaporates when the engine is hot. The inside of my intake manifold started out looking like clean aluminum but now has a significant brownish tinge to it in the plenum and I'm sure the ports are wet like yours.

 

[Guitar Jones]

PCV could contribute to it as will pump gas. Reversion is another cause with large overlap cams.

 

[Cudafever]

PCV could contribute to it as will pump gas. Reversion is another cause with large overlap cams.

My 360 head's on my 340 looked just like that, when i pulled then off.

(bad porting by...a ...me, that cause lots of reversion with the same cam)

My stock X head worked much better in the low rpm range(2-3000 rpm range )

Been on my 340 for too many years now, hope to have then off this winter to see what they look like.

340_833 dart, what duration cam(Mechanical? )are you running and what compression?

 

[340_833 dart]

340_833 dart, what duration cam(Mechanical? )are you running and what compression?

I'm running the Lunati Voodoo 60403 cam.

• Duration @ .050 (Int/Exh): 226/234
• Gross Valve Lift (Int/Exh): .494/.513
• LSA/ICL: 110/106

Plus, I burn a 50/50 mix of Sunoco 104 and 93 octane premium.
My C.R. is around 9.8:1.

 

[Cudafever]

I'm running the Lunati Voodoo 60403 cam.

• Duration @ .050 (Int/Exh): 226/234
• Gross Valve Lift (Int/Exh): .494/.513
• LSA/ICL: 110/106

Plus, I burn a 50/50 mix of Sunoco 104 and 93 octane premium.
My C.R. is around 9.8:1.

I have that cam still in its box, sitting in it original box. was planning on using it with the next build...........but think i will be going Roller now...........


Not a lot of duration. I'm running the MPP cam .474/280(238@.50) cam advanced 4*

Is there any porting done on the heads? What rpm done the cam start to work or come a live....................

 

[MopaR&D]

I'm running the Lunati Voodoo 60403 cam.

• Duration @ .050 (Int/Exh): 226/234
• Gross Valve Lift (Int/Exh): .494/.513
• LSA/ICL: 110/106

Plus, I burn a 50/50 mix of Sunoco 104 and 93 octane premium.
My C.R. is around 9.8:1.

You could probably run 89 octane gas with no problems. Heck, dgc333 runs 89 octane pump mid-grade in his 10.6:1 iron-headed street-going 360 Magnum. Any higher is pretty much a waste of money and BTUs.

 

[340_833 dart]

I have that cam still in its box, sitting in it original box. was planning on using it with the next build...........but think i will be going Roller now...........


Not a lot of duration. I'm running the MPP cam .474/280(238@.50) cam advanced 4*

Is there any porting done on the heads? What rpm done the cam start to work or come a live....................

No port work other than some very minor bowl blending when the heads were built. But, while the engine is out, I plan on gasket matching the intake and exhaust ports.
I really like the cam. It's got a nice idle around 750 rpm with 11" of vacuum.
The power really starts coming on around 2000 and pulls well up to 6250, which is where I have my rev limiter set. But, I normally shift at 5800 to 6000.

 

[340_833 dart]

You could probably run 89 octane gas with no problems. Heck, dgc333 runs 89 octane pump mid-grade in his 10.6:1 iron-headed street-going 360 Magnum. Any higher is pretty much a waste of money and BTUs.

The engine just does not run well with less octane than what I currently use. I'm running 16* initial advance with a total of 34*, all in by 2500 rpm, and no vacuum advance.
I may have more compression than I think.
I just know the mix I use makes the engine run cooler, smoother and better. It used to ping like crazy on 91 pump premium. Making no changes except for the gas made all the difference.

 

[Cudafever]

No port work other than some very minor bowl blending when the heads were built. But, while the engine is out, I plan on gasket matching the intake and exhaust ports.
I really like the cam. It's got a nice idle around 750 rpm with 11" of vacuum.
The power really starts coming on around 2000 and pulls well up to 6250, which is where I have my rev limiter set. But, I normally shift at 5800 to 6000.

Gasket matching the exh my not be a good idea!.........

If the air is hitting the header on is way out, then yes port the header to the port, but if you want to keep reversion in check, don't port match the exhaust.

when doing the bowl area, don't enlarge the bowl at the bottom of the 75* cut, under the seat, just smooth round it. If you enlarge this area you will kill bottom end.......ask me how i know:angry7:

gasket match intake, look closely before you do it to the exh...........wish i had know about this before i gasket match my header perfectly:angry7:.......Just a little FYI

 

[340_833 dart]

Gasket matching the exh my not be a good idea!.........

If the air is hitting the header on is way out, then yes port the header to the port, but if you want to keep reversion in check, don't port match the exhaust.

when doing the bowl area, don't enlarge the bowl at the bottom of the 75* cut, under the seat, just smooth round it. If you enlarge this area you will kill bottom end.......ask me how i know:angry7:

gasket match intake, look closely before you do it to the exh...........wish i had know about this before i gasket match my header perfectly:angry7:.......Just a little FYI

Thank you for the tips. :thumblef:

 

[Cudafever]

If the air is hitting the header on is way out, then yes port the header to the port, but if you want to keep reversion in check, don't port match the exhaust.

EDIT! that should read: don't port mach the exhaust port!

 

[stroked 340]

Thats a very nice cam i ran that in my 416 when i first built it with excellent results..why are you using a 50/50 mix with only 9.8 to 1 compression??..i ran my 416 with 11.9 to 1 comp. on 93 octane and my 360 with 10.7 to 1 on the same gas..but did mix in some 110 at the track but it made no difference in my timeslips..it just smells great..lol...

 

[Guitar Jones]

I love the smell of race gas in the morning, it smells like victory.

 

[rumblefish360]

I love the smell of race gas in the morning, it smells like victory.

:cheers: Ditto!

 

[340_833 dart]

Thats a very nice cam i ran that in my 416 when i first built it with excellent results..why are you using a 50/50 mix with only 9.8 to 1 compression??..i ran my 416 with 11.9 to 1 comp. on 93 octane and my 360 with 10.7 to 1 on the same gas..but did mix in some 110 at the track but it made no difference in my timeslips..it just smells great..lol...

The 9.8:1 CR is only a guesstimate.
As I said earlier, the car ran like crap on pump 91. It pinged, it ran bad, and I couldn't keep it under 200* around town.
With absolutely no other changes, except for the gas mix, all those problems were eliminated.
The engine no longer pings, it runs smoother, and even on the hottest days, it stays at 195* in town.
Besides, I don't drive the car that much so I don't mind spending the money for the 104/93 mix.
And, yes, I do love the smell of 104 in the morning.

 

[Cudafever]

The 9.8:1 CR is only a guesstimate.
As I said earlier, the car ran like crap on pump 91. It pinged, it ran bad, and I couldn't keep it under 200* around town.
With absolutely no other changes, except for the gas mix, all those problems were eliminated.
The engine no longer pings, it runs smoother, and even on the hottest days, it stays at 195* in town.
Besides, I don't drive the car that much so I don't mind spending the money for the 104/93 mix.
And, yes, I do love the smell of 104 in the morning.

Sounds like the compression my be higher then that. How high above see level do you live???

 

[340_833 dart]

Sounds like the compression my be higher then that. How high above see level do you live???

It's about 1300 feet here.

 

[Cudafever]

It's about 1300 feet here.

That's part of the requirement for higher octane.

my compression is 9.4 and i can't get it to ping on the 89........here at almost 7,000 feet


Mother Nature push a little more air in, down there.:-D