well, I accidently ground off too much on my 305 stock head and punctured a hole in the head in the exhaust port. It was my last port too and decided to make them alittle more smoother and all the sudden I notice a strange dark color which is where I went into the water jacket. I didn't think there was a water jacket between the intake and exhaust.

I'm kinda glad I did break through since I was so close anyway it probably would've gave way once it was all together and I would've been out like $70 more for another head gasket set. Also now I can upgrade the heads to a higher performance head with thicker walls, but I still want to get the TPI. Any suggestions on a cheap head that good to port for the 305 or even a 350 seeing how it would be nice to get away from the 305?

 

The fact that you carved right throu the intake bowl adjacent to the exhaust port tells me you didn't under stand or didn't read mine and others info on porting these heads. The flow is highest on the common wall and roof. The common wall refers to the other side of the bowl away from the exhaust side. Consentrate your enlarging there.

Same on the exhaust side don't try to eliminate the port bias by straightening out the port relative to the bowl and guide boss. enlarge it a bit and contour the guide boss but don't get carried away. Concentrate on the roof and around the guide boss on the exhaust side.

Just get another old 305 head the same and start over.

 

thanks, I never even thought to look here for posts about porting the 305 heads. I've got a book on it though, but it talks mainly about aftermarket 350 heads. How thin can the walls be? The autoshop is closed for the next few days so I'm not going to be able to do much of anything right now as far as porting is concerned.

I think next time I will use a smaller bit or at least not shave off as much next time. I've got the swirl heads, that's ok right? I've heard of some junk heads that should just be tossed, but I thought that was an earlier style. It's from a '92 camaro RS 305 TBI.

 

Swirl port heads ARE junk--throw them away.

Try to find a set of 081, 416 or 601 castings (the last three digits in the casting number on top of the head) at a junk yard. Pay no more than $25-30 per pair. Might as well get the valve covers, too, to simplify the whole process.

Then follow the link at the end of my sig.

 

Thanks for the info! I guess losing 10 hrs of work time and finding out they were crap heads is better anyways. Luckily I can't start porting my LT1 9C1 heads for awhile seeing how I don't have them with me. I guess this makes for good practice.

The book I have is called "How to build max performance chevy small blocks on a budget" and porting is just one section of it and part of my problem is I did not read up to the porting section, just skipped to it. I've had it for awhile, just never thought I'd use it. Anyone read this book?

LOL, I took WAY more off than you did sitting bull. I would like to post a pic before I toss the heads, but without a digicamera it's kinda tough... I have a disposable that I am taking pictures of my rescued camaro with and I will add a few shots in there. I am suprized I didn't go through the intake side because I took off almost .125" around the swirl. heh, I tried to stab the other intake and exhaust ports with a screwdriver and could not break through, but it's cast iron and I'm not Mr.Incredible... I think I am going to buy some bits because the ones I was using were a bit too large or dull. I'm using air tools and it does make you hands feel all fuzzy when you are done not to mention you can't hear that well for a few hours (i wear ear plugs now, but it must irritate the hell out of the other people at the autoshop).

 

I found a 601 head or so I think because it was really caked with oil and dust. Is it supposed to be for a 350? It is larger than a 305 as far as the combustion area is concerned. Doesn't this make shrouding worse and lower the compression quite considerably? I imagine they have the pair, but didn't see it. I didn't really look that hard though.

 

601's were used on 267's and 305's, pre-'87 intake bolt pattern. A different shape to the chamber, which is slightly smaller than 416's, 081's, or 191's 58cc (although some have measured them to be in the same ballpark).

You handle shrouding the same as you would on 416's or 081's.

 

five7kid is steering you right.

416s might be a little better for your purposes but 601s are more than adequate, too. Just don't hog out those runners and pockets so much and you'll have a VERY good set of heads for a 350

 

would getting 350 heads be a good idea for a 305? Is there any inpeticular I should look for?

 

No, the 305 heads have ALL the advantages in this respect.

 

in '87 they changed the cam specs to roller hyd. correct? The 601 and 416 are '86 heads. Didn't GM make it where they spaced out where the lifters different that pre87s? It's a '92 engine, but I think that's the only main difference. Well that and the center bolt holes for the valve covers.

The 081's are '87 and up.

 

There were no changes from '86-earlier to '87-later with respect to the block & heads mating/aligning. They swap back and forth with no problems. For 3rd gens, all '87-later got roller lifter cams, but other SBC's didn't get the roller lifters well into the 90's - most TBI trucks, for instance.

You do need to have the proper intake and valve covers for the particular style heads, that's all.

 

Here's a picture of what I did. Quality isn't that great...

 

That's nice....now march them out to the curb and get started on some real 305HO heads.

 

that's what I plan to do. I tossed those heads in the trash and am looking for some more.

 

So besides the fact that a set of '84 heads would need the older valve covers, it will match with a '90-92 TPI intake?