Opinions on this "recipe" please

[castlesid]

Nick,

Not so much as causing a problem as seem to have the engine running quite nicely.

The main concern is the loss of torque and ultimate BHP caused by the lowish dynamic C/R  

I could swap the composite gaskets for tins and pick up .5/1 to give a theoretical C/R of 9.8/1 which would be about ideal for road use, but erred on the side of caution re valve to piston clearance with the extra 28 thou that the comp gaskets give.

Will be able to check the clearance situation as my mechanic is getting an endoscope that will allow us to see what is actually happening inside the cylinders and if we feel there is enough we can take the heads off and double check with some plasticene and if ok swap to the tins which will also mean i can use the custom fixed length chrome moly pushrods which were made to be used with the tin gaskets.

Just to clarify, the pistons i used are the chevy 305 KB flat tops with cut outs for the chevy valve positions so the Buick 300 heads would require additional relief if the tolerance starts to get a bit too tight.

Question, are the Buick 300 valve centres in the same position as the Rover or Buick 215 heads?

Kevin.

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[NixVegaGT]

That's a good question. I'm pretty sure it's the same but I can't be certain. I used a junk 300 head just to be sure it worked for me. They may have the valves spaced farther from eachother in the 300 head too. Hmmm. Not much help, Sorry man.

[castlesid]

Nick,

Not to worry, that would have been just too convenient. I didnt have any rover heads available as a comparison to the |Buick 300 oneswhen I was assembling the engine. The valve spacing in the 300 heads I believe is wider so that is why you can fit larger valves,

Kevin.

[roverman]

Gentlemen, distance between valves, center/center for All 215's thru 340's should be 1.660" If your going to move valve, usually better to crowd exhaust to cyl. wall than int.  Good Luck, roverman.

[roverman]

How to fill? We've toiled over the issues of DCR vs SCR but isn't the bottom line ECR? Some would contend that from low speed onward, it's a downhill plunge as far as cylinder filling. Point of interest, Edelbrock has made street manifolds that develop around 110% VE. in a very usable part of rpm. range. There are many others who are quiety developing "free supercharging" with ram tuning of the inlet tract. Some highly tuned racing engines are in the 130% V.E. range, normally aspirated! Lets remind ourselves that air and fuel have mass and therefore subject to inertia. When we befriend inertia, good things can happen. I hope some savy airflow types will weigh-in on this. Again my question, whats with the romance of the 4bbl? Better fuel distribution possible and ?, on Rover type heads with min. (2) carbs.  Your thoughts please?  roverman.

[NixVegaGT]

You can get better throttle response across RPM range with a 4-barrel. Not so much with a 2-barrel single plenum setup. Works good at high RPM but that's it. Tunnel ram setups can be made to run at lower RPM but it's not great. From a carburated standpoint, nothing can beat individual runners and webbers IMO. Accurate fuel distribution and optimal throttle response at all RPM.

Obviously there is a trade off for serviceability, cost and simplicity. The 4-barrel is probably the best compromise in that regard. There is no doubt you can get better, more accurate fuel distribution with more expensive and tunable sources. Multiport EFI is probably the best for accurate fuel distribution. Totally tunable but expensive and complicated, not to mention more parts to fail.

[BlownMGB-V8]

True, ECR is the bottom line. Biggest problem with that approach is that most of us aren't instrumented well enough or heeled well enough to really take advantage of that approach, by fully analyzing and then doing enough testing to know exactly what we're building. In short, for most of us it's a crap shoot. We can follow the established pathways to success, or take a chance that might cost us half our engine investment or more. There are just too many variables. But as we establish what works and what doesn't we at least reduce the risks. Fortunately some of us are kind of bold in that respect, trail blazers you might say. What is good for a chebby isn't always good for a BOPR. Plus we still face the traditional obstacles. Lack of space for the induction system, rpm spread, and all the usual compromises. I've gone over almost entirely to MPFI, but when you're talking simplicity, ease, compactness, performance and price it's going to be real tough to beat a good 4bbl system on any V8 engine, if one is available for that engine that is.

Jim