1986 GP V8 305 _help with making this engine faster!

[elcolombiano]

Hi,

I have a 1986 GP, 5.0L 305 engine with the 165 HP. I verified this through the vin. I would like to make the engine a bit faster and after reading a little it seems like the easiest way is to allow the car to breath better. meaning doing headers, plus cat back system and possibly carburetor.

Here is my challenge, I would like to increase HP but maintain a stock look. for example I noted that Eldelbrock sells tubular headers with the emissions that bolt right on. I would also like to have a dual pipes coming out from the sides but without too much noise. Kind of like a sleeper.

I would like to know what you guys have installed 0n this type of engine and what was the outcome. It's helpful if guys could give me the pros and cons on the upgrade performed. In addition, it would be great if you could provide pictures, and source for the parts.

Thank you in advance for you help!

 

[Brick442]

What rear gears do you have? 3.73 or something alike can wake that 305 up a bit and make it a lot snappier off the line.

What transmission?

I wouldn't go too crazy spending money on parts for the 305. See if you could get some inexpensive headers and just make sure its running right in general (tune-up). You can use the headers again if you ever decide to upgrade to a 350.

If you want a stock appearance, drop in a 350 and you can keep all the other stuff. In the long-run, it may be more cost effective to find a mild 350, even a crate engine. All your accessories will bolt right up.

Basically, you are not going to get too much more out of the engine unless you open it up (cam, etc.) and that's were it gets expensive.

 

[85GPLef41]

i just swapped my 305 to a 350 and just revving it up at idle moves the whole car....WAY more than the old engine. Its just a regular old 350 crate with stock everything. When i took it for the test drive it actually squealed the tires without trying. :lol: I just have to figure out my trans bracket issue so i can take it out on the highway. But it was definitively worth it. Hopefully next year i will do a head and cam swap. But as far as bolt-ons i would do the ones you could transfer to another engine if possible.The headers and dual exhaust is usually the best upgrade without digging into the engine. Just make sure its in top tune.

 

[elcolombiano]

Regarding the transmission, I have the overdrive version. I'm not sure if this helps.

I hear you guys about going with a 350, but that is what I'm trying to avoid. Overall, I will be happy if I can increase the horse power by 40 -50. I believe this is reachable by doing headers, and catback and possibly manifold and carburetor.

The car I have is in really good condition, and my intentions are to maintain it's classiness and therefore when I take it to shows i want people to admire it for it's natural beauty. I just feel like is slow for a V8... I had a Regal T-Type before, this is my first GP.

Thanks for the help.

 

[Munkey B]

i've actually thought about the same thing. i eventually will do a LS swap. but that's a few yrs down the road.

cam, headers, intake, carb, maybe some increased compression (does anyone make 9:1 or 9.5:1 pistons?) maybe pocket port or gasket port heads/intake?.
nothing outrageous, just a little cleanup.

all this w/a fresh rebuild would do wonders.

 

[JESSE]

305

the 305 sbc is a dog don't do anything to the motor.... save your money....jesse :wink:

 

[85GPLef41]

Headers and some duals should probably net you at least 20-40 hp and some good torque..IMO

 

[Kiko]

I have an 83 GP that I factory ordered in August 82 with the 305. It was OK on the highway, i.e., 150-160 km/h felt nice, but getting there took some time.

One of the first things I did was to take out all the emission control stuff and put in a true dual exhaust. A really good Quadrajet tune up with a re-curved distributor helped quite a bit. If you want to save money, that's what I would do first.

What I did next, was put a 350 with a nice cam, then later I changed the transmission to an overdrive (700R4). I also put in a shift kit with posi. I could spin tires in second gear.

If you plan to keep your car for a while, then doing it this way saves money. You also drive it for a while a get a good feel for the weak link, then address it with an upgrade. One step at a time.

 

[el_sonoma]

I had a 305 with Edelbrock Performer, headers, and a CompCam XE262H in an old pickup, nobody believed it wasn't a 350. :shock:

 

[axisg]

Headers and Dual exhaust will help; then figure out which ratio rear you have and try to get some 3.42's or 3.73's in there and a Posi unit as well.

Both of these will wake up your 305 and are good with a 350 as well.

If you swap out the carb then the distributor has to go as well. If you do that then you lose your overdrive. There is not much gain to be had with those mods on on a 305 so I would suggest leaving it alone until you want a 350 under the hood ( which is the best bang for the buck ).

If you really want to keep the 305 you are due for a camshaft swap but you need to be sure the bottom end on your 20+ year old car can handle it.

It really is just easier to find a used 4 bolt roller motor out of a mid 90's truck and drop it in then go