Went to a machine shop today to see if they had Head gaskets....... Told him I was gonna use S/R Torquer 305 heads on my 350 GTA........ He gasped and told me that it would never work! ........
tried it on a lemans blah blah blah ....
Wrong combustion chamber design blah blah blah.......
Compression Ratio too high blah blah blah........
Knock sensor blah blah blah..........

Well, I ended up explaining that I belong to Thirdgen.org and that there have been many members that have done it with no adverse affects. I'm gonna end up running a HSR with LPE 211/219 .530/.560" lift with 1.6RR

I told him that I wasn't about to change my plans because I've been doin alot of research and I bought the Heads at a great price, they have already been machined for dual valve springs which they came with. Pocket porting has been done by previous owner, combustion chamber polished by me (to prevent detonation).

I was wondering if I could/should open up the combustion chamber around the valves? I'm doing the head change on a stock 350 bore. The combustion chamber on the head has a width of 3.88" so I have some room to play with. I'm just thinking that it will improve flow along the wall.....

What would you guys say about tapering the head around the chamber to smooth the transition from cylinder bore to head combustion chamber?

I was also gonna go with fel-pro's 1094 Head Gasket which has .015 compressed thickness for increased compression ratio and decreased quench area. seeing as I have a stock deck height.......

What do you guys think???

 

id say put them on there and hope for the best, i dont see why you would have any problems as long as you run the good gas in her

 

305 heads on a 350 aint going to do you anygood it might even hurt your horse power ..know see if you put 350 heads on a 305 that would work because the ports on the 350 heads are bigger than the ones on a 305 my opinon dont do it

 

That statement is full of false information. The 305 heads have the same size ports as 350 heads of the same vintage and type. IE: Carb/TBI/TPI and Vortec.

 

hmm thats funny then why do people swap the heads then?

 

WHat I would be worried about is the small 305 bore meaning that the 305 heads will leave a large, sharp ridge hanging into your 4" bore combustion chamber. You are setting yourself up to be more detonation-prone than if you had heads designed for a 4" bore, especially at the compression ratio you will be running. Blending this edge (also unshrouding the valves) will probably help flow and reduce detonation tendency, but you will be adding CC's to the head chambers and reducing your CR, which is counterproductive to using the small CC heads in the first place

It will run fine, just pay attention to detonation. I ran ported and polished 305 HO heads on my 327 and the car ran excellent. I did it to be cheap, and it worked well, but I finally ponied up and bought some 64cc 2.05/1.6 World products heads. Nothing wrong with the way you are doing it though.

 

Because they don't know any better.

 

Wouldn't the 350 heads on a 305 make the compression too low? or is it too I know it is one of them but I can't remember....

 

Yes, putting stock 350 heads on a stock 305 usually takes the compression from merely dismal to downright abysmal.

 

I would try and unshroud the valves and blend the head chambers into the cylinder bore to rid it of the sharp edges and overlap. YES that will lower compression "a bit" but realistically it shouldnt lower it much unless you go crazy on the heads blindly grinding away. I would never ask a machine shop person for their opinion, most I've known dont listen to anyone and are the "I'm right, your wrong" kinda people, and will never admit the unkown can work.

I think you will have good luck with this swap if you work the heads right to match em up with the block.
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Unless the heads and deck are milled which creates a host of other problems. But I agree in general.

 

I have 350 heads on my 305... works great! But I need the low compression for the turbo.

 

My 305 heads work great on my 350.
If the engines on a stand, bolt on the heads (with no rotating assy in), and grab a scribe, or sharpie, and reach up the bores and mark where the heads line up with the bores.
Label your heads drivers or passenger then, so you don't mix them up.
Then you can open up the chambers in that area, for a better flow transition, and to get a larger chamber. My 58cc 416 heads ended up at 64cc's when I was done, for a stellar 10:1 CR with flat tops.

 

hey sonix, you ever dyno that engine? i too am one of the guys on these forums that has been running a 355 with 416 305 heads just like sonix, i have flat top pistons with 4 valve reliefs, and i'm making about 10:1 compression.

one important thing about doing this is, you HAVE to lower the timing advance all around the board on the PROM b/c you will get a substantial amount of knocks, i know this because i went through this for about a year until recently when i fixed it, and now instead of getting 100+ knock counts after driving 10 miles, i get about 10..... anyway, good luck! any questions, me and sonix use this setup and it works fine.

 

Not yet WRT dyno results. Probably in august.

 

Thanks Guys for the input!!!!! At least I know that my plan shouldn't backfire.
I was planning on doing exactly what 327 TPI/ Hgffrank was talking about....... opening up the head beside the valves and blending the combustion chamber into the bore of the cylinder........ that's why I was shopping for head gaskets at this point.
The way I see it the 305 S/R torquer heads have 171 cc intake ports ("the largest intake port on a "standard" production Chevy head is 170cc..." Lingenfelter) , great flowing exhaust ports, 1.94/1.50 valves, 3 angle valve job, screw in studs etc..........
I know the best way to go would be running AFR's but I don't have the resources....... besides this way is more fun heheh

By the way, I'll throw some pics up when I can shrink them....

 

Here we go, I hope this works..... The Intake valve may look a little small to the trained eye.... It's a 1.84" I grabbed it from the wreckers so that I don't hit the seat.....

 

Couple more pics

 

Are you planning on porting those? I'd dig into the bowls a bit with at least a sanding drum, and smooth it all out.
Maybe sand the combustion chamber as well. What's the chamber size now, and whats your final CR with the .015" gasket? Might want to open up the chamber a smidge. Near the plug, and intake port sorta area.