ChevyRacer

i've searched and search to find different answers. Mortec says 53cc and other sites say 52cc chambers. If i use such a small chamber on my 350 wont my compression be through the roof? My pistons only have a totall of -8cc, and thats from the 4 valve reliefs.

I dont have the money for a super thick gasket that will lower it to a suitable ratio. If i had the $100 for those gaskets i migth as well get these heads ported and the sort. But the heads were bought with brand new valve guides and new valve job. they kept stock size valves but there was no porting done.

I dont have the money to port as once you port i hear you have to get the guides and seats done. I dont have that money. I need to have a controllable compression ratio. I can easikly get 93 octane gasoline. Available almost everywhere.

Whats the max compression i can run suitably? I was hoping for a 9.7CR but seems 10.7 is the best i can get with stock style .031 thick gasket.


anyone have any idea?

I have a set of brand new 083 heads, they sat for 3 years under a tarp and have slight surface rust on the block mating surface. that means i will have to mill them. No money for that. Plus they'll need centerbolt valve covers but i have an ewxtra set of them.

I bought the engine with 882 casting heads. But they have huge 76cc cahmbers, but big valves, 2.05/1.6, they were modified on that perspecive. I could of used them but they are just so big. Yet they flow so much more air. Decisions decisions.... gosh...

Coda79

I can only half-way help you with this one. Not sure of the compression ratio but search google for compression ratio calculator, should get you close.
As far as porting goes, there's no need for a valve job and guides to be done after the port work, the machinist just has to re-assemble the heads and if he's smart he'll demand new valve seals, but that's it (providing the heads are in good shape to start with)

good luck

chad

blue85305

305 heads on a 350 doesnt that kind of defy the point of even having a 350 i mean the ports arent really that good are they? and all the cost considered why not go with a set of vortecs? itll be a little more expensive but they flow better and they have a 64 cc combustion chamber so the compression will be a little lower than 10.7. just my 2sense

SSC

It's a quite debated subject as far as actual compression ratio since every part of the equation needs to be added up. Mortec had a conservitave cc on the 601's last time I checked 58cc. I had the machine shop check a set of stock ones 56cc. I also found book at another machine shop that listed them 56cc and 416's @ 56cc.

F-BIRD'88

You have to cc the 601's to see what the chamber size is.
The book is a nominal spec. Most head gaskets cost about the same. you need to port the 601's and install new larger 350sized valves to get the effect you're looking for. Once you unshrould the chambers, they will be larger anyways.
Do not pay someone else to port your heads. Do it yourself.

The 083's look like your best bet right now. They do not need to be resurfaced. You can clean of the decks yourself with a bodymans bodyfiller file board and a long strip or two of 80 grit sand paper. ( its used to sand body filler to shape) Look in the autobody supply section of your favourate auto parts store. You could clean up the 083's ports with some porting etc and throw them one. they will work well. Don;t bother with the 882's. Sell them to some one that doesn;t want to go fast, to fund your head hopup.

You cannot determine your actual compressionratio by asking someone else. they cannot see inside your motor for you.
You need to know the cc of the heads, the piston deck height clearance, the bore size, the stroke, the piston valve relief volume and the gasket volume. Most replacements are .039-.041" or 8.9-9.1cc
ususall once you accuratly measure these factors and calculate the actual cr its not as high as you think.

ChevyRacer

Well the 601's are most likely going out of the picture.

The 083's I can use however I almost refuse to, I don’t want to use center bolt valve covers. Although I have a couple set's I inherited, I don’t want them. Have the 882's, and inherited another set of 993's.

I hear the 993's actually are a very nice heavy casting great for porting work. With valve sized already 2.02/1.6, I can work with them little. They still have 76cc chambers however.

I ordered a set of camel hump heads for $300. I get an email today and the guy said he can’t sell them now. So I lost my hopes there.

If I were to use the 083's, which I am now thinking about. I have a few questions about your method.

I can sand the deck down with 80 grit? Isn't that a bit rough for metal? Should I gradually increase or will that hurt sealing abilities?

If I can fix the deck then I almost say to myself what am I waiting for. But if I wanted to increase air flow. What steps could I do to get the most out of my time and effort? I will try to smooth the wall, that’s for sure. But what areas should I remove? What parts should I stay away from so I don’t have to get machine work done to them?

Gladstoneiroc

iTrader: (1)

Why don't you like centerbolt covers?

ChevyRacer

Becuase the only two sest i have are Modified stock Lt1's for larger aluminum rocker arms, and another crappy vortec head set. They are ok quality. but i want shiny, something way better then stock.

Gladstoneiroc

iTrader: (1)

Shiny never added power In your case I'd really go with those dull 083 they are the best you have considering your selection. And xmas is always coming up, (to treat yourself to a nice set of valvecovers).

Actually I remember a kit that converts perimeter covers to centerbolts. That's what you need.

Fast355

iTrader: (2)

The 601s are the best. Mildly worked over they will flow better than the 083s can. They also have the 52 cc chambers. The 601s are real detonation resistant. I only had detonation problems on a 10.7:1 355 in very hot weather pulling 6,000 lbs in a 5,000 lbs van with 3.08 gears. That engine was working hard. I also had very mild cam timing which further boosted DCR. My DCR was over 9:1 (try 215 psi cranking compression) and I was still runing 93 octane with full timing (no audible ping or knock retard). In a car as light as a F-body with a larger cam it wouldn't be a problem.

blue85305

summit has a kit out to convert centerbolt to perimeter bolt , just thought id share the info.

ChevyRacer

I'm going to go ahead and just use the 083's. I can alwasy bet the adapter plate later.

I'll start porting them tomorow. i guess i'll show pics but i doubt my camera batteries are up for the job. Cant seem to find those expensive suckers.

Project Peachy 350 is underway.

Randy82WS7

i have a set of 487X heads i need to unload, are 71 dated good runners, someone put them on this 82 caprice 305 out here i dunno why, it ran good, but its too much for it,. so i removed them



i need a set of 305 heads any year 80-up centerbolt or not..
i dont want the 487X

does anyone know what i can do ?

good luck with yours

ChevyRacer

487x? whats that mean? can you list the complete casting number or the last 3 numbers please. I may be interested.

F-BIRD'88

If the 80 grit finish on the decks looks too course to ya step up to 120 after. Thats all you need. Too fine a snading paper won't get the rust off. You do not want a perfectly smooth polished surface on the decks of the heads. A little texture is best. There are lots of theads with pic on porting factory heads here.


Specific threads for 083 heads

https://www.thirdgen.org/techbb2/sho...&threadid=96065
part 2 https://www.thirdgen.org/techbb2/sho...&threadid=97882
part 3 https://www.thirdgen.org/techbb2/sho...threadid=101489

Gladstoneiroc

iTrader: (1)

Links aren't working.

ChevyRacer

i'll fix em,

https://www.thirdgen.org/techbb2/new...threadid=96065

https://www.thirdgen.org/techbb2/new...threadid=97882

https://www.thirdgen.org/techbb2/new...hreadid=101489


lol easy to fix, they work now.

but i've started cleaning up the 083's. I started to ease the short side radius. its weird i can feel the difference been an unfished set and a finished set.