Does quench affect power?

[juuhanaa]

Soo what makes the 882 different to require same timing vs smaller vortec chamber with more centered spark plug?

[skinny z]

Yes very tight effective quench on this one too.. .033".

.033"? Isn't that pretty fine margin?
And are you saying that quench is effective or makes no difference? Or a little from column A and a little from column B?

[F-BIRD'88]

I am saying it is not the holy grail it is promoted as....
I am saying. "your mileage may vary".

[F-BIRD'88]

Soo what makes the 882 different to require same timing vs smaller vortec chamber with more centered spark plug?

You tell me.... (disclaimer: the vortec heads are much better in every way that matters)

But the other open chamber old sbc heads .336(x) 920, 487 441 heads I have used over the years. Same timing as the vortecs.. Same as the 492 and 186 and 040 heads and the various 305 heads (in various forms) I have used..The best WOT power timing has been the same.

(The 882 and similar 462624 heads seem to be "the worst of the worst" power) in stock form.

Various different quen ch clearances did not effect best power timing. Ones with much bigger measured quench than .040". were not knock prone. Or knock limited.
Tight quench did not allow running more compression ratio.. An engine can have just a bit too high a cr and be very sensitive.. But then lowering the cr just enough (even if that means bigger quench clearance is the result, is very effective to brining that engine into a happy no knock sensitive zone. A little bit too much compression ratio can be a WHOLE LOT too much compression ratio.

[juuhanaa]

Soo what makes the 882 different to require same timing vs smaller vortec chamber with more centered spark plug?

You tell me.... (disclaimer: the vortec heads are much better in every way that matters)

Me? Maan i have never even changed a spark plug to a V8! But strange, because at the moment i like picking some stuff to grind and thats why i asked.. i have no idea, maybe 882 swirl more?

[F-BIRD'88]

Soo what makes the 882 different to require same timing vs smaller vortec chamber with more centered spark plug?

You tell me.... (disclaimer: the vortec heads are much better in every way that matters)

Me? Maan i have never even changed a spark plug to a V8! But strange, because at the moment i like picking some stuff to grind and thats why i asked.. i have no idea, maybe 882 swirl more?

If you are looking for a sbc head to try porting and learning on avoid the 882 heads and avoid the 462624 heads..

Pretty much any all of the many other choices are BETTER.
The end result and satisfaction of your efforts will be much BETTER...

[F-BIRD'88]

If I was going to hunt for a cheap "good deal" sbc cylinder head that is good and will get a Whole LOT GOODER with home hand porting I'd find a set of the 305 Vortec heads 059 casting..
You can port the hell out of them , you can go to bigger performance valves too. You can modify that combustion chamber with that to good effect too.
Lots of room to play.. Use a Vortec style intake manifold. Low cost Tons of power porting and mods high performance potential.

[juuhanaa]

I was with a friend to get him a gasoline sbc engine (some cid stroker i believe it was) i didnt like it had aftermarket aluminium heads on it. Its a small pick up chevy, i think he would like to move some bricks fast.. not a ton of rpm. Just curious what could be done if the timing is "set". I think you are right, i should consider what makes the other castings better to start with. Thanks,



-juhana

[rebelrouser]

Where is this bulk of evidence of testing?

Do not confuse bulk of repeating stuff on the internetas being evidence . with bulk of real testing. evidence.



You have the ability to juggle the quench clearance on yiur upcomming build. Test and post your results.
What I am saying is don't believe everything you read as gospel.

Yes I have other examples.

I have never found a difference in best power WOT spark timing on any of my different engines over the years ..
Reguardless of different net measured quench clearance. No effect on timing or combustion efficientcy
All the sbc's wanted the same WOT timing.. All the BBC's wanted the same WOT timing for best perf...

On this 350. one other difference was intake manifold
Eddy performer VS Eddy Performer RPM (vortec).

This is also the same short block I did most all of my ported 305 head testing on.
(everybody kept buying those off me. ha ha)
Used to tell people any any dissatisfaction at all with these heads. just bring them back. I will buy them back.
Not one return... I would have liked to get one of those sets back after someon elses testing them out.
Proof is in the pudding. (Other people getting good results with them vS just me.)

I use performance trends to generate a timing curve if the engine has a distributor, especially if it is to be a pump gas engine. But I will agree the vast majority of engines I have done on a dyno are 34 to 36 degrees timing at WOT My race car likes a little more timing at launch and a little less at WOT. I have the distributor locked out and it leaves best at 38 degrees and I pull out 2 degrees after 5,000 rpm.

[F-BIRD'88]

Yup.. When the diz is locked out the timing tends to self retard a bit with high rpm. You can tweek the timing setting and at what rpm you set the timing at, accordingly fir effect +/-.. Especially the HEI module and locked diz.

[rgalajda]

All this reminds me of when Cliff Ruggles said, he has tested a truck load of intake manifolds. I stop listening

[Bigchief632]

Food for thought, many high level na engines are using "softned" chambers and make more power and are less sensitive to timing.

[hoffman900]

Food for thought, many high level na engines are using "softned" chambers and make more power and are less sensitive to timing.

Source / examples?

[ClassAct]

Food for thought, many high level na engines are using "softned" chambers and make more power and are less sensitive to timing.

Source / examples?

MBE and others hav been doing it for quite a while. I’ve said for a looooooooooooooooong time that a soft(er) chamber is better NA in most cases.

[juuhanaa]

Food for thought, many high level na engines are using "softned" chambers and make more power and are less sensitive to timing.

Source / examples?

MBE and others hav been doing it for quite a while. I’ve said for a looooooooooooooooong time that a soft(er) chamber is better NA in most cases.

In case of soft(er) chamber, is the valve sizes still same compared to non soft(er) chamber?