i have a stock 75 with a minor smoking problem at idle i would like to fix that problem as well as the performance. i found heads on ebay with small combustion chambers that sound great. any recommendations on cc size? ill stick with stock manifold and carb till wife recovers.

 

If its smoking sitting idle then its rings, if you start it and it smokes then stops its valve seals or guides.
For your setup, don't pay extra for 202/160 valves and all the add on stuff, just get a good set of 76 cc heads and some .029 heads gaskets.
194/150 valves.
Forget the the vortec heads unless you want to buy a different intake to up the price. So much hype over these heads I wouldn't run them if someone gave me a set!
Don't spend over $400 for everything ,heads, gaskets ETC or your wasting your money.

 

Interesting...
Are you talking about a set of used heads? Any ideas on casting numbers or where to get these? I would like to do a budget head swap as well. What about cam? I'd like to know more.

BTW, got the intake, thanks.

 

The valve guides are probably worn and the seals are probably long gone. You could stop the smoke from the guides with a cheap set of umbrella valve stem seals. A valve job would be a better fix. A head swap is a good way to solve the problem if it is guide related and up the performance at the same time.

A lot depends on what heads we are talking about. We can help but we need to know what heads you are considering buying.

-Mark.

 

Here's a set of Aluminum Edelbrock heads and Q-Jet manifold that you could use and still be emissions friendly. Just a thought.

http://forums.corvetteforum.com/show....php?t=1797801

 

http://cgi.ebay.com/ebaymotors/HIGH-...QQcmdZViewItem

 

Yep, looks like 305 heads on a google search.

 

Big valve size is not that important unless you want higher rpm
power, but do yourself a real favor and get rid of the 76cc
heads as fast as you can slam them off the garage wall.

 

Any recommendations for a budget head?

 

Could be carb making it smoke.....just a thought. There are no cheap good heads !

 

I guess cheap is different than budget, and it is all relative. I was kind of curious what Tim H had in mind when he stated $400.00. He recommended 76cc, but Little Mouse said to slam them against the garage wall. As always, lots of talk, but no solid evidence to back up dogmatic statements.

Again...

 

Gave a link for some heads/intake that would be a major improvement over the stock 76cc heads your have. Already have all the upgrades that could possibly be done to your heads, just time and money. The Vortecs or these type Edelbrocks with a small cc intake ports (165/170cc) are gonna be an improvement.

Throwing on a set up heads without doing other improments "while your in there" is just a waste of time. Buy or borrow a leakdown tester, this will help evaluate if it's rings or valves. If your rings have low blow-by values I'd throw in a different cam with the heads and intake, maybe some headers for your total hp upgrade. Obvisously this is over simplified but basically don't think "to big" and you'll be happy. You'll be going from less than 180hp to over 300 hp with ease.

If the rings are worn, high milage engine, then maybe you should lean towards completed engine and drop it in. Or find another and build that and continue driving yours till ready.

This coming from someone who's built a few and currently cannot drive his own because of the ever changing project plan.

Later.

 

To give an example, someone I know with 68cc heads, dished pistons
had a 9.2cc .041 gasket. 145 cranking comp. only changed the gasket
to a 3.2 cc voluum ( pulled 6cc out of the cylinder ) he did pull a small
amount of duration out 9 degrees that helps, cranking comp went up
to 175, most people put a 64cc head on a 350 not 68cc.
Theres 12cc of extra voluum in the cylinder with a 76cc over the 64cc head, is the picture getting brighter as to why I said slam the 76cc heads off your garage wall as fast as you can. The vortech heads
have modern shaped smaller combustion chambers flow air a little
better then what came off the assembly line, but they are really a pickup head they are a long way from the best airflow, and you do
have to buy a new intake to run them, I'm thinking for new vortechs
there closer to $550.00 then theres the cost of the manifold,
a 180 runner dart complete is around $875.00 would flow air better
has 202/160 screw in studs. the vortech has smaller valves
pressed in studs. A really nice airflow head for the money if
you can afford them would be the brodix 180IK aluminum, the one with 64cc. $1050.00 theres a 58cc ( works if you have dished pistons L/48)
aluminum head that had small runners to work with the low rpm
airflow of the fuel injection that was on C4 vettes. it won't flow
a lot of air but would give good compression. Bottom line just my
02 if I were you and can afford them go brodix 180IK, if you
cant do that go 180 dart iron head. But whatever you do get rid
of the 76cc heads combined with dished pistons you are in a world of hurt
for comp.

 

Thanks for the explanation, Little Mouse. I would have replied sooner but I was out of town for a few days.