![]() ![]() Vwlover77 wrote:So, what values do I want to plug into a CR calculator?ĭeck Height = Measured value +. Look at your old intake/exhaust gaskets too, see if there is any mismatching between ports and manifolds/runners. As you work with your engine, make all cylinders configured identically so they will behave similarly. At idle, any discrepancy in the engine's air pumping flow characteristics will show up soonest. Idle quality is most affected by camshaft lobe identical lift/lack o' overlap/identical lifters, calibrated clean injectors with good seals, clean tight manifold gaskets on clean straight phenolic spacers mated to a clean straight manifold flanges, tight exhaust components, identical combustion chamber cc's/deck heights/valve seating depth, clean ignition performance, etc. I think you might have a stack-up of variables all conspiring to wreck your idle. I was pausing here because Jim from Air-Cooled Ranch had mentioned that he did not think the "Torque Special" was actually a very radical cam.īut, I do NOT want to put everything back together and wish I hadn't! 050 between piston and cylinder edge, cylinders torqued down to about 20 ft/lbs with nuts and washers on each head stud corner. It is nice, of course, to get the piston further out towards the edge of the cylinder. But, I do not acutally know your combustion chamber volumes. 028 sealing rings (if your flycut will allow you to) will give you a 7.5:1 compression ratio, which is perfectly acceptable. If you have the deep 15cc dished pistons, then deleting the. The need for a cylinder head sealing ring may have been caused by the usual bugaboo, too deep of a flycut. you are spot-on with a 7.3:1 compression ratio. Would these deck heights, with the additional clearance of the shim, result in too much deck height?Īssumption I : you have 7mm shallow dish pistonsĪssumption II : you have 52cc combustion chambersĪssumption III: you have that. I don't know if that would indicate that these heads have ever been flycut or not. I have not cc'd the heads yet, but on both heads, the cylinder mating surface is approx. ![]() I bolted the cylinders down and took measurements between the top of the cylinder and the top of the piston right at the outer edge of the piston, at 12, 3, 6, and 9 o'clock positions. I pulled the heads tonight, and measured the deck height of each piston as best I could with my digital caliper. the AFR is around 11.0 and it stutters.Vwlover77 wrote:Jim at the Air-Cooled Ranch suggested that too much deck height might be the reason why the CB Performance Torque Special camshaft in my engine idles so poorly. Maybe i should just stick to VE tuning and save a file with an extra degree of timing to see if it picks up power on the dyno.Īnother question I have is on Closed loop. that was used with a very similar cam and the same intake duration. im using a timing table from a VERY reputable tuner in my area.no names. Yes i have bolt ons including Ls6 intake. I don't have any rules of thumb but I've seen more than a time or two where that intake needs a little less timing than it's counterpart. I don't tune anything in accordance with what anyone says, I just work with the cars. It actually picked up 16rwhp (more than I would have guessed) and the biggest difference that was noticeable was WOT timing going from 27.5 deg up top to about 25.5. ![]() I just touched up a car on the dyno last week that was left here to have an LS6 put on in place of his LS1 intake. I don't know what you mean exactly Glenn, ![]()
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