73' Chevy Nova (porting the head)

#1

I have a 73 Chevy Nova with a 205 L6. I have been pursuing ways to make more horsepower with the engine for as little money as possible, and I’ve heard that I can’t get much until I start thinking about porting the head. So I saw there is a porting kit with instructions on Eastwood Co.'s website, and my question is, first, can this kit have any sucess, second, is there serious possibility of destroying my engine if I mess up, and last, would this make my fuel economy go down drastically(I plan on driving relatively short distances e.g. 10 miles a day)



P.S. Could I get porting done at a machine shop and if so how much would it cost?

#2

Save your money for a turbocharger. That will give you the most bang for the buck. Porting is best left to the experts, is very expensive, and the power increase is often not worth the money spent.

If you are really obsessed with power, bite the bullet and drop a 350 V8 in. Just buy a 350 cu in 350 hp crate motor from Mr. Goodwrench and away you go.

#3

do they make a turbocharger for a 73’ Nova? because most replies dealing with a turbo or a supercharger have said I would probably need to make it the attachment for it or something like that.

#4

Porting requires a lot of knowledge and experience - you could easily do more harm than good. If you have long-term plans to go to a cam, headers, etc, it might be worth it, but right now it’ll yield very little. And it’s not that hard to pull the head down the road, I’d have somebody do it in phase 2, with cam and valves. Phase 1 being a header, intake manifold, and carb.

#5

The 250 C.I. L6 in the Nova came with the smaller T-250 tranny. If you were to go to a high 300hp+ V-8 you are going to have to upgrade the tranny or you’ll tear it apart.

How do I know ? I have a mint Nova of that era with 40k ( my dads ) with the 250.

You can get rid of the points and go with an electronic ignition, very easy to install and then you can run a wider plug gap.

This way you won’t have to be bothered with re-setting or changing points every 5 or 6k. When the point gap changes due to wear it also effects the ignition timing.

You can also bump up the base ignition timing by a few degrees but will require higher octane fuel for a little more pep. ( really not worth it )

That engine is almost bullet proof, no timing chain or belts. It uses cam to crank gears. You can still get any engine part for your car as they are still available.

One downside was the stock alternator which was only rated at 37 amps as
it was marginal with the headlights/wipers and the heater/air conditioner blower going full blast.

I did an upgrade on mine to a 65 amp and was a direct bolt up.

As far as HP goes that 100hp you mentioned in previous posts is rear wheel HP.
That engine had a rating of 155 gross HP measured out of the vehicle.

In 1972 they rated vehicle HP at the rear wheels, and that was with the engine installed in the car and everything operating so thats why the big HP drop as auto makers were overstating actual engine HP.

Now the only optional engine for a 73 or 74 was the 350 2BBL V-8 and only had a rear wheel hp of 145 which replaced the optional 307 V8 in earlier models which was rated at 130 hp.

I know 100hp sounds anemic but I left my engine alone and if properly tuned that car should have good pep for a daily driver and get around 20-22 mpg on the highway.

If the cars body / interior needs some work, I would spend the money on that…get a nice paint job and have a great looking 35 year old ride.

Another thing to consider is the age of the vehicle concerning safety even with low miles. When my dad gave me his car due to his age I replaced all the brake lines/hoses, master cylinder, drive belts and all coolant hoses, all fluids changed and front suspension checked which needed upper & lower ball joints.

Car still had the old “hard” bias ply tires on it which I changed over to radials and what an improvement in handling and ride.

Another nice thing with the L6 is, so easy to work on. I don’t think there isn’t anything you can’t get to without scraping your knuckles or having to take half the engine apart to get at something.

My cars I own

1959 T-Bird
1974 Nova
1989 Mustang GT

#6

It’s a common procedure easily done at most performance auto machine shops. You could figure on several hundred dollars to do this.

I’ve ported a number of heads with a die grinder and assortment of bits with success but it is a bit tedious and time consuming. No idea about the Eastwood kit but when DIY care must be used.

It won’t hurt your fuel economy but you need to keep in mind that simply porting a head won’t gain you much. Head porting is part of a bigger plan that includes intake/exhaust upgrades, camshaft change, etc.

#7

sorry I forgot to include that my Nova is a three speed with the stick on the steering column, but that’s beside the point. one question I do have is should I look into replacing the master cylinder or could I just stick with the one i have which only has some surface rust(I have drums with out the brake booster). And recently, I read on the inside of the passenger side drawer and it had a sticker instructing me to use 91 octane gas, do I really need to use such a high octane of gas or can I just use regular 87 octane gas?

P.S. would the following be a good conversion HEI distributor?

http://www.eastwoodco.com/shopping/product/detailmain.jsp?itemID=3296&itemType=PRODUCT&iMainCat=574&iSubCat=575&iProductID=3296

#8

nikolahrgic,

Most master cylinders of that age will show some surface rust on the outside of the casing. If you have good brakes I would still check all the brake lines for rust and the hoses. I would advise to have the brake fluid flushed.

I had to replace the MC on my Nova because, if I would only apply very light pressure on the pedal it would slowly sink to the floor but be fine for normal driving.

This was due to worn seals in the MC where the brake fluid would bypass under very light pressure but expand enough for normal braking.

As far as 91 octane, they are referring to “Research Octane” of that era which was a about 4 or 5 points points higher than the method they use today. ( R/M ) where they average out the two.

It should run fine on 87 as mine does. I just verified this info with my owners manual as it states you can use either low-lead or unleaded with a “R” octane of 91 or R/M of 87. This was during the era when they started rating octane under the new method, when leaded gas was starting to be phased out, due to catalytic converters being installed on most 1975 models.

That engine does have the hardened valve seats so no problem with unleaded.

Make sure the EGR valve is operating properly as that vehicle does have one
and if it gets stuck closed it “could” cause the engine to knock on regular fuel.

I am using the Pertronix ignition, very easy to install.

#9

does the link in my previous comment go to a new distributor or is it just a kit to make my points distributor into and electric one?, and if so how much does and HEI distributor cost?

#10

Here’s the HEI dist: http://store.summitracing.com/partdetail.asp?part=PRO-67081&view=32&N=700+4294925074+4294908216+4294907681+4294881256+4294908399
About $190

#11

if i do upgrade to the HEI distributor, what will I need to do with my coil(should i get a flamethrower one or is the stock one good) because I noticed there is no terminal to which I would attach the coil to via a wire.

#12

With HEI, the coil is part of the distributor cap. They came stock 1975-1982. A simple drop in swap. You should be able to find a complete unit, plug wires and all.

Yes, a turbo WILL require some custom fitting but there are shops that do that kind of work… Two things you should research. The 1954 Corvette which used your basic engine but was equipped with some trick carburetion and the Pontiac “Sprint Six” , the so-called Baby Goat, again your basic engine equipped with a OHC head and decent breathing. That engine would drop right in your Nova and provide a big performance boost… If you want one bad enough, you can find one. Poke around the Pontiac Tempest boards, talk the talk until you can do the walk…Somebody might give you one that needs rebuilding…