Inliners International Forums General Discussion Engines Building a street 250

I've got a 73 Nova, 250/powerglide, and I'm leaning more towards building up the six instead of doing the usual and dropping in a 350. I'm looking for a decent compromise between gas mileage and power. I've alread got a clifford header coming in, but I need some help with intakes, carbs, heads, and cams. I'm looking to keep the budget around $500-$700 dollars. I'm not looking for a street machine, just something that won't I won't dread to take on the interstate. What should I be looking at for the best power/economy gain? Offenhauser, Clifford, etc.

Any help would be greatly appreciated. Thanks.

well the headers are a good start. Keeping under the 700 bucks? maybe close if not maybe a little more.If you not going to do anything to the block itself. So Ok lets see here You already have headers on the way. and you have 500-700 bucks your willing to spend Yet??

Ok fist off Look for a used intake clifford Or a offey a Good used carb either already Rebuilt Or a VERY GOOD rebuild able one. The head can EAT UP ALL that 500-700. So I'd say go with a rv type cam or a little more. Get the head cleaned up Get New springs( i'm saying New because I don't know how many miles You have on this motor and The old ones may not be up to PAR) And also a New set Of Timming Gears. and NOT THE FIBER Gear.

The new CAM will need to be HEATED BEFORE INSTALLING ( THIS IS A MUST DO OR IT WILL AND CAN COME OFF THE CAM )( been there done this Because a machine shop didn't listen to what i had ask them to do and it came OFF/walked off the end of the cam) Because the Gear is ALUM and if pressed on cold It will shave the Inside of teh gear and IT WILL HAVE a lose fit to the cam. It is also GOOD if you can COOL/Cold/frez the cam
BUT HEATING THE GEAR IS A MUST like i said before not just the center of the gear the whole thing set it in oil or hot water and heatup
Hope this helps.}[oooooo]
Ps any other question Just ask us.

The 250 has about 70,000 on it. It sat for a year before I bought it, and with new plugs and an oil change it ran the first day. As for the intake, should I look at Clifford or Offenhauser, or is there little difference? The Offenhausers seems to be much cheaper than the Clifford intakes. On the head topic, I recall someone on another nova forum I visit mention something about replacing the stock 250 head with a 194 head, because of the smaller combustion chambers. Is this a good idea?

Thanks.

I have a 62 Nova with about the same setup you have. Go get this book and read it twice. I am almost done the the 1st round... it good stuff!

http://www.motorcyclebooks.com/chevy6cyl.html

Clyde

From what I have learned over the last year (and anyone that knows better feel free to jump in)

The offy intake will give you higher velocity flow in the runners for a given CFM. At the high end of performance with the larger 292, the Clifford makes sense - but with a 250 and a mild build, you will be happier with an Offy. I have seen them go for under $100 on ebay.

Head work is expensive - I am in mine over a grand :rolleyes: I am beginning to think that $/hp for a 6 is about 4x as expensive as a V8

you can port the head yourself wich should save 400-600 bucks. on my webpage i have a good doityourself porting guide. Porting is a good HP helper.

Twisted, don't you mean cam GEAR? Joe

Never mind , I went back and reread the whole post. Joe

I'm reconsidering my choice in headers...I was going to get a Clifford header, but the cast iron headers on Stovebolt look a little more interesting - anyone run these?

Also, does anyone know if the Offy intakes - at least the ones they have on Stovebolt (http://www.stoveboltengineco.com/acartpro/category.asp?catcode=21) are heated?

Thanks

Well, I do know the Offy 3 pot manifold for the late Chevy 6 is a heated manifold. It has a water jacket cast into the floor of the log. The water connections are in a plate that bolts to bottom of the manifold. The water connection plate did not come with my manifold. I had to buy it seperately.

Yes, the Offy manifold sold by Stovebolt is set up for manifold heat. Just bought one. But if you are running headers, you will have to fabricate a way to get water to the manifold to provide that heat. The other option is a split stock manifold, which will provide the heat from the exhaust.

does anyone have the number to Offenhauser?! I tried calling with an old number but its disconnected.