Well I have these nice heads that I got for a real good deal. They were only used one time on a chevy love that broke his 4 speed muncie pulling a wheelie down the drag strip. I know they are not right for my stock engine Right now and my intake manifold won't even fit on them. Well what technically happens if you put those kind of heads on a car like mine?

 

ummm if they flow too much you can lose power if the cam is not match to them...as well as the intake, exhaust.

 

If I build this engine in stages where do the heads come in?
I know I'll have to match the cam to the heads because I already have the heads. So far I know I need a cam, possibly different lifters seeing that mine are roller lifters, intake manifold, and as for the TBI I really dont want it and would like to get a TPI but that will run up a bill. I need more power in this bird thought this stock 305 is not cutting it for me. What else do you think I might need?

 

First of all, you need to find more information on those heads. You need to determine the combustion chamber volume, the intake runner volume, the valvespring installed height, valvespring coil bind height, and valve stem seal to retainer clearance. After that, there is the issue of flow: What will these killer heads really flow in terms of cfm @ 28 inches of water at .050, .100, .200. .300. .400. .500. and .600 inches of lift.

With all that stuff known, you can now determine their suitability for your engine. If you know that information, you can calculate the compression ratio, and determine the optimum cam profile to take advantage of the head characteristics.

Once you have the head information, compression ratio, and have chosen a cam profile, you'll know what size header primary tube to pick out, what torque converter you'll need, and whether or not you need a single plane / dual plane intake.

Now, you dont need to get all of these parts at once, but I highly suggest you investigate the heads FIRST before installing them. That way you can buy the appropriate parts when the time comes. The only thing that will happen with the installation of those heads on an otherwise stock engine is that the compression ratio will most likely change, and the off-idle characteristics might suffer. You might find that your engine is a dog at sub-2500 RPM operation due to poor intake airflow velocity, if the heads have too much intake runner volume. BTW, anything greater than 200 to 220cc of volume is probably too big for an otherwise stock and streetbound 350.

 

Ummm..... it goes faster?
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Did I pass?

 

yeah i was gonna say it gains power. im sure anything is a slight improvement over stock.

 

If its not matched right?!

 

Well I might just save these and just build a engine from scratch. It doesn't seem that they are going to work right on my car with out basicly rebuilding the whole engine.




<----39mm---->

 

<----34mm--->

 

VALVE SPRINGS

 

...

 

thought you might want to see them

 

Looks like 2.02 1.60 valves. Probably at least 64cc chambers. I wouldn't put them on my 305.

 

Those are 400 heads too. See the steam holes ?...

 

Yeah, they're 76cc smog heads, the steam holes look like the way the factory does them for a 400, probably 882 castings. Somebody probably had them on a blower or nitrous motor.

 

From his metric measurements they would be 1.6 and 2.02 (2.047 by exact conversion - I'll take that as 2.02 not 2.055)

Look like angled plugs to me and I suspect less than 70 cc, with all those pictures the casting numbers would have been nice :-).

Springs look like double with damper in between not triple.

Agree not a good head for a 305, large valves and low compression.

 

I'll agree with the "400" fit, but the chambers don't really look like 76cc. And they might be 2.05/1.60 valves - those are pretty common too. (Look at the way the intake overlaps the quench area.) They may have been designed as 76cc chambers, but they don't look that large now.

You could always ship them to me for "evaluation" - those are some big exhaust ports, and lightweight retainers on the springs.

 

"Ummm..... it goes faster?"

If u just go and take some heads that are too much for an engine, can't it make it slower or will it just not be as fast as it would if it was matched right??

 

With valves like that, if you install them on a 305 you wont go very fast at all. In fact, you wont go anywhere. The valves will crash into the cylinder wall and bend as soon as you turn it over. Your compression will be nada and your valves will be ruined.

Those heads are for cylinder bores of 4.0 and greater, for sure!

You have to stick to 1.94 intake valves in a 305, unless you cant the valves in the head, such as the early model Trick Flows.

 

Ws6 beat me to it. Shoving big intake valves down a small-bore 305 can often cause catastrophic valve-to-bore interference at lifts as low as .400" Even if they don't hit, they'll be shrouded by the bore very badly and may not flow anywhere near their potential. 1.94" max, usually, on a 305.

They are NOT 400 heads. No 400 head ever came with angle plugs. All straght-plug 76cc chamber heads on 400s. Somebody drilled 'em out for 400 steam holes, but those are definitely not stock 400 heads.

I think you should cc the chambers. I think you'll find they are somewhere between 64 and 67cc, using my calibrated eye.

Looks like somebody also spent some time porting out the heads to some extent. Those are some pretty big intake ports and they look like they might have been gasket matched at least. Who knows what's behind the valves, though.

Those aren't triple springs. Doubles with a dampener ring inside. Still, probably pretty stout springs for a mild hydraulic cam. Probably too stout. You really don't want more than 120 lbs of seat pressure and those monsters could probably easily exceed that spec.

They might be good heads, but not for a mild 305. For a hot-rodded 350, probably they'd work very well.

 

Without seeing the ends of the heads, my guess is they are the 'Turbo' #292 heads (not 291s which were regular double-hump heads) from the early to mid '70s.

Notice there is no heat cross-over passage.

Over the counter only. Angle-plug and small chambers.

Just a guess.

jms

 

Do these casting #s tell ya anything?



840282 21 GM
g35 49


BTW if you want another pic somewhere on them just tell me. That wont be a problem with this digital camera, just for those with dial up modems.