Thread: 400 Chevrolet with 305 Heads

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Hi

I am a Wild West German so Sorry about my English.

No here is my Question. I have a 84 G20 Van with a 305 Engine for daily driving. The Engine is in bad Condition and now I rebuild a 400 Small Block from a 69 El Camino. The Engine is ready now with new bearings, Piston Rings, High Volume Oil pump and Edelbrock Performer Cam.
I would like to use the 305 Heads on the 400 Engine. Is that possible or is it to much pleasure?

I will use a 600 Ede Carburettor , Performer Manifold, and Headers with a dual Exhaust .

THX

its not worth it you wouldnt be able to use pump gas with that much compression and it would be alot of work.....im not familar with big blocks but i know you cant match a cylinder head with that small of valves and small combustion chambers dont do it just get some different heads

you as autocityman4 has said, the compression would probably be 11- 12/ 1 compression and the rule of thumb max for running pump gas is about 10/1 compression, therefor, you would ither need to use just a little laquer thinner in the gas ( toulene and xylene, main ingrediants, big octane booster, ingrediants used in most off the shelf octane boosters ) but I wouldn't recomend that, think of it this way, the 305 heads you have, will raise the compression and lower the performance because of the port size diffrences, you could buy a new set of Vortech heads from any GM dealership, for around 600 a set, or if performance isn't a problem, any 350 head would work fine, some might limit performance like a stock 80's caprice or somthing set of heads but, a set of 461 heads would be nice.

305 heads on a 400, way too much static compression ratio for pump gas. Plus, you'd have to drill the 305 heads for steam holes. Do you have the 400 heads?

but tech, whats wrong with 12:5-1 ......................

At first thx at all

It is a 400 er Small Block no Big Block.
Yes I have the Original Heads .But I read that Chevy Heads before 1974 are not so good.
I can get some used old Heads from a 350 for a low Price.
Some Power in my Engine will be fine but the important thing is to drive it every Day without Problems. Gas is very Expansive (like everything in Germany) and it will be fine to ride with low Octane

Originally posted by gassersrule_196
but tech, whats wrong with 12:5-1 ......................

12.5 is fine on a 283, Scooter

Originally posted by outlawz
At first thx at all

It is a 400 er Small Block no Big Block.
Yes I have the Original Heads .But I read that Chevy Heads before 1974 are not so good.
I can get some used old Heads from a 350 for a low Price.
Some Power in my Engine will be fine but the important thing is to drive it every Day without Problems. Gas is very Expansive (like everything in Germany) and it will be fine to ride with low Octane

Unless someone has added them since the 1969 400 heads were produced at the factory, they will not have hard valve seats to contend with the unleaded fuels which are available today at the gas pumps in America. I don't know if you can get leaded fuel where you are.

1973 and later heads will have induction hardened seats and will be compatible with unleaded fuels unless multiple valve jobs have been performed on the heads, thus cutting through the hard material.

The 400 heads which you have can be upgraded by having them machined and hard seats installed, or you can use 1973-up 350 heads with 76 cc combustion chambers and have the same thing, except that the 350 heads must have steam holes drilled in them in order to be compatible with the 400 block. (use a 400 head gasket as a pattern).

the 305 heads will give added compresiion yes, so much so, that to be able to use them, youll have to use dished pistons to run pump gas, + the 305 heads dont flow ...although on a van Im gonna assume thats not a big issue.
I think I use World Products s/r heads for that application...whatever heads you choose...make sure to add steam holes to the heads for compadibility with the 400.

We don’t have leaded Gas anymore. So what I hear is that I better take a look for the 350 Heads with the right Holes inside. That will doing a good Job and I probably can run with low Octane. The Power from this little Engine will be enough for a daily driver.
We have only a normal timing point lamp. In my books I can find many different settings fore this Engine. Is it ok to set it on 8 degree?

Regards

Andy

un-leaded fuel can you say parts washing material

HEHE you are soo right.
Be Happy that you live on the other Side of the Orange
Over here its real hard if you like old Cars with real Engines

"Is it ok to set it on 8 degree?"

Yes. Once you have the motor running, it will tell you where it wants the timing to be. It's called "timing by ear". Keep turning the distributor a little at a time in the advance position (counter-clockwise) and lugging the motor down by going uphill or stalling it against the foot brake until the motor spark knocks, then retard the distributor position a little (clockwise) until you have no knock. Lock the distributor down there and enjoy.

Techinspector I think you play a long time with Chevy V8s and know a lot about those Engines. Thank you and all the others. It was very helpful for me.
Maybe I will found the time to complete the Engine this Week . Than I let you know how it works.
I have found a great and interesting website.

Best regards to all and bye for now

Andy

You're welcome Andy, now be sure and pay attention to the steam holes you must drill in the heads if using heads other than the 400 units. The 400 block is siamezed (water does not flow between the center cylinders), so steam pockets develop that must be relieved through these steam holes into the heads.