So I have my vortec heads and I call this cylinder head shop. Says he can mill them down for me from 64cc to 58. So i head on over and he takes a look at them. Hes like so what do you want done. I called about getting the cumbustion chamber milled down to 58cc from 64. Hes like ok and how much do you want off. Im like huh. Hes like, I donno if I should take 10 or 20 or 30 off. And im hella confused at this point. And I tell him ill find out and go back. So could somebody please tell me what to tell this guy. Thanks a ton.

 

Some of that will depend on your finished bore size. Are you going oversize? How much?

With a standard setup (3.736" bore, 3.48" stroke, .015" deck height, 3.8" head gasket, flat-top pistons with 6cc worth of valve relief, and .039" gasket, the 64cc chambers should net 8.76:1 static compression. Milling off 0.030" will raise that to 9.32:1. You can install a thinner gasket (down to 0.021" compressed) to raise that to 9.57:1.

Rather than guessing, ask the supplier for the pin position/deck height of the pistons, dome volume, and relief volume, so you can make a more accurate determination. Pistons are typically listed for compression ratio with 64cc heads, but that isn't a universal constant, and you have no idea about the other variable they've used, like gasket thickness, deck height, gasket bore, etc.

 

Ok well yes the bottom end is a completely stock 89 305 TBI, only thing I can tell you about the heads is that I got it from SDPC2000 and they really didnt give 2 many specs its just a stock vortec head with upgraded springs heres the link if it helps.

http://www.sdpc2000.com/cart.asp?act...2175&pid=89540


Gasket is .028" thick thats all I can really give you sorry.

 

Anbody know if the general rule of thumb for a sbc's is .0055" for every cc in a 64cc head also applys to vortec heads? I can lose a lil compression so im going to go with 60ccs which would then be a .020 mil. Anybody know if this is correct and the compression I can expect with a .028" head gasket. As long as it runs on 91 octane thats good enough 4 me.

 

Do a search in the TBI board for the name "Chuck!"

He had his milled. PM him and he should be able to tell you.

 

I took mine down .020 and run the fpp-2094 or something like that gasket shim. Its .017" compressed so that took the cc down even more. Runs like a champ.

 

I'd like to get my 062 vortecs milled down to 58 from stock 64, doesn't the intake height/angle change as well as pushrod length or is it really that insignificant of a change?

 

How did this thread get so far along without me seeing it? I machine SBCs for a living. Have him take 0.030" off your vortec heads. Install them with a pair of Fel-Pro part number 1094 steel shim head gaskets. Put everything else back together.

 

Atilla, .030" is going to yield a 9.5:1?? I am doing the same dmn thing.

 

Why is everyone so hung up on 9.50:1? What's wrong with 9.66:1, or 9.42:1?
I remember back when the magazines used to push 9.5:1 as a guideline, but that's dumb.
9.5:1 is a good upper range for most older iron heads, with streetable cams, at sea level. And by streetable, I mean an intake closing at 50 of around 35 degrees.
But with Vortecs, which are more efficient and like less spark advance, the same combo can go 10:1 or so, safely. And by safely I mean pump premium without knock sensors.
Vortecs are NOT 64cc. Most check in at 62cc, but many check in at 61cc.
And if you flat-mill Vortecs, you can get as small as 53cc from some 906s and some 062s.
And the (0.006" per cc) rule is close enough.

 

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I'm not here to do your homework for you. I present technical facts that will help the vast majority of enthusiasts. If you don't find them helpful, don't blame me. Or complain to me.

 

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see, there ya go complaining to me. I'm not being a dik, you are. I'm being so good as to set the facts straight, despite not getting paid for it.

 

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I don't know how to send messages except this way, sorry. Can't help you with your problem but saw you were on line and maybe you could help me with mine. Light covers won't lift on 1986 transam and I checked fuses they seemed fine, turned ***** inside motor. Still would not lift. Can you suggest anything

 

Im going to PM you my phone number...

 

It's okay to dislike me, it's true that I'm blunt, and I sometimes point out errors in a negative way, and it's true that sometimes I type like I know best. But I give away info that the other famous guys won't sell you. You don't know my real name, but you would recognize it.
The info I give away is useful to most enthusiasts, because they take time to think about how to apply the info I give to their own projects. I get lots of thanks from lots of different usernames. You're only the third person to dislike me in the 3 years I've been on here. And notice how many guys say it turned out just as I'd typed, and so far not one has ever claimed that I'd mislead them. When guys do as I suggest, I get thanked in their threads.
I'm here to help, and that's 99% of what I do. Your hostility must mean that you somehow feel threatened. Why?
Your nasty PM was heavily laced with references to the Texas drag-racing scene. It's your whole world, obviously, but that doesn't make it a valid basis against which to judge me. And who do you think you are, anyway? You're the one who contributes nothing to TGO. Just angry smack talk.
You want a moderator to publicly declare me wrong and you right? Well, I did the PM thing, and I'm big enough to accept the verdict, calmly. Are you?

 

This resurrected-from-the-dead thread needs some clean-up of the recent off-topic and non-tech posts.

I'll give those involved the chance to do it themselves first.

 

hi , new to the forum wanted to ask you a question. I have a set of 1966 3809642 64cc cast iron dubble hump heads is it possible or worth it to mill them down to a 58cc for a 85 305 or should I save them for a 350? Respond at your leisure and thank you for your input.

 

Any 1966 heads lack the bolt holes for the accessories on the front of the motor starting in about 1969.

Sell them to someone with a 60s car and buy something else that fits yours.

 

Why not Cometics gaskets?