Intake manifold question

[rick_rawker]

Hello friends !

I have searched the threads here and on the more appropiate 'ForB-BodiesOnly' site, and cannot find out what intake manifolds might interchange with the 318 poly engine. We have a leaking passage in the exhaust crossover of my son's Belvedere. Any input would be great.

Thanks, Rick

 

[fishy68]

No intake other than a Poly engine intake will interchange. They are their own animal if you will. They made a few different sizes of them. The early Poly 277 and 315 cubic inch engines comes to mind as well as the 318. I think they made a couple more sizes but that's all I the ones I remember. Most likely all you'll be able to find is a 318 intake cause the others are so old and being they were generally only 2 barrel intakes people don't generally keep that stuff laying around for decades. Try posting a want ad in the want ad section. I bet someone has one laying around.

 

[PanGasket]

Edelbrock makes a Performer Street intake for the 318 A. If I remember correctly, its for $209 bucks and the rpm range max on it is 5500. Its a 4-barrel intake.

If you are looking for ones off a different engine, You are gonna have to look for another polysphere 318. or another polysphere with a similar intake pattern. But finding a polysphere engine thats not a 318 is difficult. Poly parts are hard to find. even for the 318, but those engines are absolute torque monsters!

 

[Valvebounce]

There was a dual quad manifold for 318 Poly motor. I saw one on trademe.co.nz a few years back.
The other option would be the weiand WEI-7503 Hi Rise manifold for the 277-303-318 poly motors. Years back my Dad put one on his 318 powered Aussie valiant. the motor had a wee cam in it, but with that manifold and a 4bbl holley it really sang.
I may have read somewhere that they are no longer available. But it is listed in my 2005 PAW catalog.

 

[rick_rawker]

Thanks !
Now for something completly different... we changed-out the timing chain this weekend as the vacuum was reading low, 13-17 lbs. When we took the old chain off, the marks were at the top of both the crank and cam gears. So, we put it back the same way. ( one keyway ) I am being told now that the marks are supposed to be together. Wouldn't it not be running AT ALL if the cam/crank gears were 180 degrees off ? Or, did we do the same stupid mistake as the last one to work on this timing chain, and THAT is why the motor has low vacuum ! ( I just can't get it in my head that it could be 180 off and still start and run )

 

[fishy68]

Thanks !
Now for something completly different... we changed-out the timing chain this weekend as the vacuum was reading low, 13-17 lbs. When we took the old chain off, the marks were at the top of both the crank and cam gears. So, we put it back the same way. ( one keyway ) I am being told now that the marks are supposed to be together. Wouldn't it not be running AT ALL if the cam/crank gears were 180 degrees off ? Or, did we do the same stupid mistake as the last one to work on this timing chain, and THAT is why the motor has low vacuum ! ( I just can't get it in my head that it could be 180 off and still start and run )

Rick did you notice how the cam gear is twice the size of the crank gear? What happens when you have 2 gears and one is twice the size as the other? The big gear turns at half the speed of the little gear, Right? That means if you align them up at 12 O'clock on the crank gear and 6 O'clock on the cam gear and turn the crank exactly one revolution the cam gear (since it turns half the crank speed) is now at 12 O'clock also. When both gears are at 12 O'clock that's when cylinder #1 is on compression stroke. When their at 12 and 6 O'clock #1 is on exhaust stroke.

All this said it doesn't matter if you align them at 12 and 6 or 12 and 12 O'clock cause next revolution their the opposite. One more revolution and their back to what you set them at. Hope I explained that ok.

BTW: low manifold vacuum can be from retarded ignition timing, mis-adjusted carb, intake vacuum leak, etc...

 

[dodgetkboy78]

That stock desoto dual quad manifold was a neat piece, the 58 (i think) 318A made 295HP, LOL, and more torque than the 275HP 340 too.....

Ahh, good ol days, before engines made power......