351e intake on 305?

[wc63]

hey folks,
im new to the site, though its helped alot with ideas on my truck. im thinking of changing my carb to the holley 500 and cant help but think that i have read somewhere that you can swap the stock 305 intake with a 351 on the gmc as a performance upgrade. i tried to find out where i read this but couldnt find the site. i also tried looking for the intake manifold gaskets to see if they have the same part # but couldnt find either one. does anyone know if there is any truth to this or should i just get the holley with the 305 adapter?
thanks in advance
adrian

[Corts60]

Welcome to the site Adrian! Glad to see you are keeping your V-6!

As far as bolting the 351 intake to the 305, it will bolt up as long the 351 was not a magnum engine, which had larger ports. If it's a two barrel intake your after, later 305's had the square rochester bolt pattern also.

You'll know the difference between a magnum and non-magnum intake because the magnum had a trapezoidal bolt pattern.

Also, The site you were probably thinking of is www.6066gmcguy.org

I am currently setting my 305 for two Strombergs. You can do a search on here for 305 with dual strombergs and my thread should come up....

Oh yeah, PICS!

[wc63]

thanks cort for the quick response. yeah i read your thread. i really like what your doing with your truck. thats kind of what got me in gear to give my truck a little umph. it seems like you had a bit of an issue with your first supplier but it looks like its coming along nicely. ill try to get those picks up asap.
thanks again

[wc63]

im looking for the 351 intake to bolt on to the 305 and im a little confused. if i understand correctly, the 351E and 351M are both magnum engines and the 351 and/or 351C are ligth duty, meaning the intake bottenecks to the smaller port heads of the 305. anybody willing to confidently confirm?

[retodd7711]

If I read right you have a 305. Correct?
There's really no need to swtch intake manifolds as the adapter works fine.
Check out my resto thread. The holley made a HUGE! difference and the adapter was all of $20
http://www.6066gmcguy.org/holley.htm
Here's the link for the swap including part numbers!

[wc63]

thanks retodd7711,
i have visited that site before and know of the carb swap. my intentions were to add an intake with greater air flow as there are very limited upgrades available for these engines. i want to keep the engine, but also want it to run as smooth as possible.

[Corts60]

Originally Posted by wc63

thanks retodd7711,
i have visited that site before and know of the carb swap. my intentions were to add an intake with greater air flow as there are very limited upgrades available for these engines. i want to keep the engine, but also want it to run as smooth as possible.

The beautiful thing about these engines is that they were designed very well from the factory. Those intakes and exhaust manifolds perform very well. Even the set-up I am doing on my rig isn't guaranteeing any better flow or performance, I am mostly just doing it because nobody has yet (that I can find). I did buy some header flanges to make custom headers for it, but after researching online, it turns out the scavenge ability of the factory exhaust manifolds are pretty much spot on so, again, the headers would only be for looks......

[Chuck78]

the 351E was not called a Magnum engine, but it essentially is a magnum. Not sure if those were special heads or not, but I think one version of the Magnum parts was slightly different from the rest. You need magnum heads to go with a magnum intake, and I believe all but the special ones you would need magnum exhaust manifolds as well.

Just do the Holley swap with the mr gasket adapter, and add the custom modified Buick 3.8L V6 HEI distributor (or PerTronix HEI conversion to the GMC distributor), add a clutching fan (or Ford Taurus V6 electric fan, DCC fan controller, and upgrade to a 10SI 62amp alternator or 12SI 70-100 amp) to free up a little more power. The first two will definitely make the truck respond a lot better. Oh yeah, and some good mufflers , dual exhaust with an X-pipe.
Then if you really want to do more, swap in a V8 Camaro T-5 transmission with the S10 truck tailshaft/shifter section, and it'll be about as sporty and peppy as you can easily get it. Adding front discs, front Suburban sway bar and poly mounts, 80's Camaro rear sway bar and some frame spacer blocks, and power steering, and you'll have a really fun driving truck. No real speed machine, but it'll be sporty and will have tons of torque from the big V6. I highly recommend Firestone Firehawk Indy 500 tires also if you want a good affordable tire that handles like something twice the cost.