should i polish my heads

[olds48]

I have a 496 BBC with a set of Canfields.I port matched them to a Felpro 1275 intake gasket,plus the standard bowl blending blahblahblah.....Thing is I only slightly smoothed them out,since I was running the car on the street mostly.Now it spends 80% of its time at the track.Is it worth the troble to go back and put a real smooth polish in the heads?I'm running brackets,so I don't need every ounce of power available,plus I only rev the motor to 7000 MAX.No need to ring out a bracket motor.Would it help consistency any?

[altune]

Polish the exhaust only
intake should be slightly rough
polished combustion area is ok.

[olds48]

Really?Whats the reason for that?

[cepx111]

Anything you can smooth out in the heads and intake will help flow and will build upper rpm HP which I'm not sure is something you'd tap into that much if your only reving to 7 grand, also I agree with what the other reply stated you dont want a super smooth intake port, you want it some what rough to help keep the air / fuel mixture atomized before going into the clyinder rather than having it bead up in the port.
Now, as far as making the car any more consistent?
I don't think you will notice any change there.
The biggest thing I've found that makes a car consistent in bracket racing is by doing the SAMETHING EVERYTIME!
I.E. Same burnout, staging in "EXACTLY" the same spot everytime ( very important ), stalling up the motor exactly the same rpm each time,having the engine at exactly the same tempature each round( harder to do late in the rounds ) keeping up with the air pressure on the rear slicks and not changing it in eliminations much if any from what you dialed your car in time trials, a properly tuned engine and properly jetted carb are also important factors.
( CARB TUNING NOTE )
I like to go on the lean side a bit on my carb (we race nights) so the car doest pick up much when it cools down at night. A rich mixture will drive you crazy trying to dial in right cause the car keeps picking up numbers every round as the cooler more dense air makes more power.
Sorry for the book just trying to help.


Goodluck,
><Charles

[olds48]

The more "books" the better.I've been to the track alot,but never actually raced yet.Any info at all is a great help to me

[olds48]

Is there any advantage to port matching my exhaust ports?I built a set of fenderwell headers for my car,and am sure they will be on there for years to come.

[us7race]

Everything like that helps power when done properly..
I have heard people say your crazy not too..basically free HP..

[curtisreed]

Hey Olds48,

Go over here and do some searching for your questions. You would be amazed at some of the knowledge that is on this forum.

http://speedtalk.com/forum/index.php

Curtis

[olds48]

Thanks doorracer,I'll check it out.BTW my names Eric.Easier than stretching up for those number keys

[poncholvr]

Really?Whats the reason for that?

i 2nd this question
the faster in- the faster out--- it needs to flow-
try a set of screen style gaskets (reed style)
they will help separate the fuel into air better- instead of using the rough intake,
if fuel doesn't atomize you might as well just (dump) gas in it
thus - fuel injection was born

[Tod74]

Really?Whats the reason for that?

i 2nd this question
the faster in- the faster out--- it needs to flow-
try a set of screen style gaskets (reed style)
they will help separate the fuel into air better- instead of using the rough intake,
if fuel doesn't atomize you might as well just (dump) gas in it
thus - fuel injection was born

I thought they had to be a little rough to keep the fuel from seperating from the air. :?

[poncholvr]

Really?Whats the reason for that?

i 2nd this question
the faster in- the faster out--- it needs to flow-
try a set of screen style gaskets (reed style)
they will help separate the fuel into air better- instead of using the rough intake,
if fuel doesn't atomize you might as well just (dump) gas in it
thus - fuel injection was born

I thought they had to be a little rough to keep the fuel from seperating from the air. :?

still wantin my head polished-- any women around--lol

[olds48]

Looks like the screen-style gaskets would kill flow?

[poncholvr]

Looks like the screen-style gaskets would kill flow?

might slow it a lil- depends on the size of the screen- they had to run some kind of tests on them- :shock:

but you could change those - the heads need to be smooth to flow

[dcarr511]

I looked into the screened intake gaskets back in the 80's when they came out and was told by Co. Reps. that they were only good up to 400 HP Max. Mainly used for low end torque.

I have also always heard that you want the exhaust flange approx. 1/8" larger diameter than the port, you dont want the same smooth transition that the intake likes.

[poncholvr]

exhaust size doesn't make sense -they need to flow-
if you restrict it it will be restricted through all of the rpm range- with no potential to change on top end, i would rather use the exhaust for the back pressure -- for a tuned exhaust- with head flow tuned for the complete power range

[edvancedengines]

I like the Canfields for their purpose and price.

I am gong to suggest to not home brew them anymore than you have unless you fully understand what is needed. Bowl work and the relation of valve seat angles and throat shaping can be critical at making the head work to make power. Doing mods to either slow or to speed airflow in each section of the port can be very critical to make the port work. Most heads have port runner areas where they are too turbulent and other areas where air speed is too slow. The key with a cylinder head person whom is experienced and has learned the art or skill is where the runner needs to be faster and where it needs to be slower.

I know of two guys that are very experienced and will do you good work for an affordable fee of helping to make the heads be more compatable with your engine and what you use it for. PM me. You will have to phone or email or both to them. I have some understanding of what some engines need as far as porting so I do some porting in lower horse engines. When doing higher horse engines the heads go to professionals and depending on the budget also depened on where they go. The best or better cylinder head guys are not cheap. They are really good and have the latest equipment. The two I am speaking of do not have the latest in equipment but have tons of experience so I put those in my opinions as below for exampe RfD Curtis Bogggs. Now days he is one of the best

The intake port surface benefits none from a polishing and it could at times make it worse and not better.Usually a lightly sanded finish works pretty good. Even the CNC finish works pretty good if port has correct shape.

Never port match exhaust port to a header unless the port is needing to be made larger and you can use an exhaust gasket for an idea of not opening too much. Port matching exhaust to header is just another magazine myth. If you have a small headeder it may help but if you have a big header primary you can ruin a head by opening it too much. The exhuast needs to be opened and ported for what works, not for what your header is.


Ed