odqlesz

If i were to convert my 67 300hp to a 350 hp what would i need to change?

I know i have to change the intake and valve covers.
Not sure about the dist. It shows a different casting number but
am not sure what the difference would be.

Everything else seems to be the same.
Carb, alt., oil pan.

What about the internals? cam?

STING67RAY

all depends on how far you want to go.
just for looks or identical in every way ?
cam is diff. crane sells a blueprint 350hp cam. identical lift , duration, etc.
your heads are the same but i think 300hp had smaller valves.
1.94 as opposed to 2.02.
intake yes. a winters # 3890490. you also need a different breather tube from the back of block that feeds into carb. it is just a little bit longer and angled more. the balancer and timing cover .
tab for timing is diff.
and don't forget what makes it really fast, the sticker on the air cleaner that states 350 hp.

just my .02

STING67RAY

almost forgot. yes the dist. is diff.
the advance curve and the vacum advance has a diff. part number. the tag around dist. is a diff. number

hope some of this helps and not confuse you.

odqlesz

Initially, i'm just going for looks, if possible.
I figure no one will know what cam it really has in it.

My question now is, if i replace just the intake and valve covers and nothing else, will it run ok.
Or do i have to do the whole thing. 202 valves, dist, cam.

Side note, does the winters # 3890490 have a date code on it.
I know it's the same for 66/67 casting.

Sting67ray - have you done anything like this before. Do you have any extra parts your willing to sell.

STING67RAY

date code i think may be on underside of man. ( who cares ! )
as long as it has correct snowflake and casting # 3890490 that should be enough.
some say that a z-28 or LT1 manifold will gain a little more horse.
but it is a diff casting.
no i'm sorry i do not have any 350hp parts.
but if you just do int. v/covers and sticker. that should be enough for most everyone except people who really know the diff.
car will run well w/o 350hp cam.
but like most say. don't try to pass off as a real 350hp when selling. not right.
it's yours , do what makes you happy.

68shark

Paul67 did exactly what you are looking to do, basically to dress up a 300hp engine to look like the 350hp engine. He had a number of posts on this, so suggest you search for them. He's very thorough and took many pic's which would help you with your project.

JohnZ

Pistons are different too - 11:1 forged vs. 10.25:1 cast, and you'll need the water pump with the bypass fitting to match up with the intake.

Jeff Garner

I did the same upgrade to my 66 300 HP. Get ready to spend some cash, even if it's just the cosmetics. The intake has a date code, but you would never see it unless you removed the baffle shield?? on the underside of the intake. A couple other pieces not mentioned are the cast iron thermostat housing and upper radiator hose. Actually the 66 didn't originally have the air cleaner decal, but I added anyway. I kept all the original 300 HP components boxed up should the next owner want to put back original.

Paul L

I received your IM and replied but will repeat the message here for general information.

It's not cheap. Here are a few parts that come to mind:
-a 1966-67 #3890490 aluminum intake manifold. Used on Novas as well and show up regularly on EBay.
-waterpump bypass snouts, hose and clamps
-finned valve covers
-chrome oil fill tube
-chrome oil fill cap

Because that intake sits higher than the cast iron:
-longer gas line
-longer crankcase vent steel tube
-longer choke rod
-upper rad hose

Aside from the intake, all those parts are available from Paragon and other suppliers. The intake varies in cost according to condition. They are subject to cracking from improper torquing and water/t-stat housing corrosion so you have to be careful.

Unfortunately I do not have duplicate parts but I wish you well with the project. It really does make the engine look much better.

This is where I started.



I chose not to install the waterpump bypass. This is a pic from a year ago. My Holley went bad in June and I am now using an Edelbrock. I will probably have the Holley rebuilt during the winter.



As matters now stand.