Has anybody modified an intake manifold for 305 to 350 swap ?

sarantis

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You can't imagine my disappointment when i find out that it wasn't the bolt's size but the different angle that the central bolts didn't fit.
Do you think if i fill in (welding) the 4 central holes and i open new ones at the right angle that will work?
#the 305 is 1979 the 350 is brand new old style one piece rear seal#
 

WizeOne

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Re: Has anybody modified an intake manifold for 305 to 350 swap ?

Why bother, I'm sure that 350 intakes are cheap enough.
 

Bondo

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Re: Has anybody modified an intake manifold for 305 to 350 swap ?

Do you think if i fill in (welding) the 4 central holes and i open new ones at the right angle that will work?

Nope,... Don't Weld it,....
Just use a drill or die-grinder to realign the holes......;)

That's just 1 of the Gothas when swapping Vintages.....
 

Gazza1

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Re: Has anybody modified an intake manifold for 305 to 350 swap ?

I asume that the new motor is a vortec.
Another way is to screw a bolt into the head, cut it off, loctite it and place your manifold in position, center punch through the manifold bolt holes and drill new holes at an angle to suit the manifold , tap them and your done. You wont have to wear a striped apron (butchers wear them) either. This way is a whole lot neater.
But as someone said, buy the right manifold if you don't want to stuff around.

By the way Don, if you are reading this post, a vortec intake will fit an older style if you modify the holes as above because the heads are the same height.
The only difference is the size of the ports, the heads are smaller and the intake are bigger.
 

Bondo

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Re: Has anybody modified an intake manifold for 305 to 350 swap ?

I asume that the new motor is a vortec.
By the way Don, if you are reading this post, a vortec intake will fit an older style if you modify the holes as above because the heads are the same height.

Ayuh,... Unfortunately,... You're Wrong....

Sarantis has what are known as Fuelie Heads,... Produced from 87 to 95....
They have the 4 center holes Straight up,+ down...
Vortec heads have No center holes, At All...

Vortec heads, Introduced in 96 have No center bolt holes,+ the ports are .250" Higher....
An older manifold won't even cover the ports on the heads,... It'll be a 1/4" Short.....

As for fitting a Vortec Intake onto a pre-Vortec headed motor,....
Why would you Want to,..??..??
Pre-Vortec manifolds are a dime a dozen....
 

TilliamWe

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Re: Has anybody modified an intake manifold for 305 to 350 swap ?

Ayuh,... Unfortunately,... You're Wrong....

Sarantis has what are known as Fuelie Heads,... Produced from 87 to 95....
They have the 4 center holes Straight up,+ down...
Vortec heads have No center holes, At All...

Pre-Vortec manifolds are a dime a dozen....


I agree with all that, except that the center two bolts on each side are not "straight up and down" they are at a 72 degree angle... and that makes them very hard to match up the intake, if you grind out the holes. We did just that on a 1987 5.7 in a boat, and the intake leaked air from the get go. Go out and buy an intake manifold for the 1987-1995 engine, you'll be better off.

Also, get a starter while you are at it, your start from the 1979 won't work with the new flywheel.
 

dan t.

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Re: Has anybody modified an intake manifold for 305 to 350 swap ?

easy to do,grind out the holes, make up 1/2 in long sleaves to go between the bolt head and the manifold, grind the bottom end to match the angle of the manifold and put a flat washer between the sleave and the manifold.I have a intake from a 1966 chevelle 327 that used a carter afb on a 1992 305 6 years no trouble
 

dan t.

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Re: Has anybody modified an intake manifold for 305 to 350 swap ?

and where do you find a used manifold? this style of head was used with TBI exept for marine, I wouldnt trust anything that was run with raw water cooling,so, this leaves used FWC manifolds, pretty slim pickings
 

Howard Sterndrive

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Re: Has anybody modified an intake manifold for 305 to 350 swap ?

Aluminum - so not for RWC in anything but fresh water
Weiand 8170 "Stealth" intake manifold
Fits 1987-1995, 305-350 cu.in. small block Chevrolet V8s with cast iron heads.
$139 @ Jegs

not sure if that's for a spread bore carb tho ' -call them
 

sarantis

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Re: Has anybody modified an intake manifold for 305 to 350 swap ?

Thanks for your replies,they helped me a lot.
Here in Greece it's not easy at all to find a used manifold.For new one it would cost me about 400-500 Euros since the basic monthly wages is 700E.And since my manifold is at a very good condition i decided to fix it.
So i drilled the 4 holes at the right angle (pix1) and i bought a piece of brass shaft at a bigger diameter of the new hole and with drill and grinder i shaped the spacers at pictures 2 and 3.
I tried them on the manifold and they match fine.I can't see the reason to leak.Hoping it'll work.I'll report the results.
 

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sarantis

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Re: Has anybody modified an intake manifold for 305 to 350 swap ?

As about the starter a friend gave me a bad 350's starter, i kept the front part of it and the rest is exactly the same as my 305's which was in perfect condition
 

dan t.

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Re: Has anybody modified an intake manifold for 305 to 350 swap ?

you will run into some issues with the flywheel , the 2 piece rear main used a 0 ballance flywheel, the 1 piece uses a counterweighted flywheel to compensate for the counterweight that was deleted to allow for the 1 piece rear main seal,the bolt pattern is different so your coupler wont fit either.nice job on the bolt sleeves for the intake:)

good luck on your motor swap
 

sarantis

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Re: Has anybody modified an intake manifold for 305 to 350 swap ?

Thank you for encouraging about the intake, as about the flywheel i've aready paid the cost of a used flywheel 150euros + a new triangle coupler200euros and i modified the flywheel cover to match the triangle coupler,a lot of work...
 
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