FAD2BLK93

Ok so i got the 1406 exhaust gaskets and put them on my heads that are on the workbench, because i have put a ton of time into them with my dremel. So i put put a bolt on eith end and dropped the gasket on, just as i would on the car. This gasket has about 1/8 clearence on sides and a 1/4 on the bottom surface. Holly **** thats alot of meterial to blend and enlarge to get a true gasket match!! I saw in a few posts that this is the gasket people are using. What have u guys done? If i elarge this i dont want to break into a water jacket! Any help would be grat thanks !!

Puck

iTrader: (17)

Do not gasket match your heads to your exhaust gasket, you will ruin them.

guppymech

iTrader: (7)

I don't think it's necessary to gasket match the exhaust. You're not trying to eke out every tenth like a super stock racer and I doubt you would see much HP difference back to back if you did. The exhaust has much greater dynamic flow than the intake side. I used the LT1 1470 felpros and they fit the stock ports good.

FAD2BLK93

I didn't think the gaskets would be an interferance since they are bigger than the port, thanks i wont touch them.

FAD2BLK93

On another note, i have ported the heads nothing to big just smoothed them out and blended. But when it comes to polishing how much is enough? I mean i could get a mirror finish out of the sides and ceiling the leave the floor with some tooth to it correct? But how far do i polish the bowls ect with the dremel? Thanks

quik95lt1

iTrader: (7)

what he said ^

96capricemgr

iTrader: (1)

Don't bother polishing them.

RamAir95TA

iTrader: (2)

Put down the Dremel. Hopefully you haven't ruined the heads. Polishing is BAD.

FAD2BLK93

If they are ruined i have many more to play with, till i get to my 643's to have cnc'd. It is called a port and polish isn't it, we will see when i have them flowd this week. Thanks

BIGCAT7274

as long as the gasket and header opening is larger than the head your fine.

96capricemgr

iTrader: (1)

That is 70s terminology that goes wonderfully with 3/4 race cam.

Flow numbers are NOT the measure of a head, they are more for marketing than to indicate true function. A steady state flow test does not measure how the port works in a running engine. Ever stop and think about how many times per second the valves are opening and closing at 6000rpm?

WS Sick

Whats funny is even in the 70s the real "pros" knew that polishing the intake runner was bad, but the saying still caught on.

quik95lt1

iTrader: (7)

keep in mind the rough finishes are more carb car oriented to keep the fuel suspended in the air charge...........past the point of the injector this still kinda is in play but not as much as a carb'd car seeing the fuel is being sprayed directly at the back of the intake valve.......sections prior to the injector being smooth arent an issue.....look inside a fast intake or a plastic ls intake the runners are very very smooth......gm also built a "fuel puddle" feature into their newer ECM's to try and control the fuel puddle that can form on the walls........wonder why? as for exhaust ports i finish the ones i do very fine just like the combustion chambers......helps cut down on carbon sticking to the walls and efi intakes i finish finely the same (220 grit plus some other tweaking).......and ive had all great resutls on the ones ive done....keep in mind its not a generalized statement what i said above......different ports are designed with different characteristics in mind and the finish plays a role on how they can act.....

96capricemgr

iTrader: (1)

I was not saying polishing was bad per say, I was saying don't waste the time. On something like a combustion chamber, a good smooth surface can reduce carbon and I suppose if we are going to benchrace it the smooth surface has less surface area which should absorb less heat.

I wouldn't really call 220 polished though either.

I remember a few years back someone nearly mirror polished a whole lifter valley to improve oil return, so defining "polish" like you did saying you use 220 was a good point to make, one guy will use 220 the next will aim for mirror finish.

quik95lt1

iTrader: (7)

very true......i said i start with 220.....and finish it with some "other stuff" lol......ill snap a pic of my intake later when i get home......i did some cleaning, chamfering and polishing in my lifter valley also for drain back.......then finished it with gyptal paint......