I think that checking spring pressure was simply seen as the only practical way of enforcing the cam rules as written. It's not practical to somehow measure the lobe profile for 360 degrees of rotation; even if it was, where's the manufacturer or AMA or NHRA spec to compare it to? I like the spring pressure check, but maybe a 10 - 20% allowance should be added to cover component tolerance, obsolescence and availability of equivalent replacements, and situations such as Brian's.
Trans ratios have been changed on autos for years. AMC manual trans's have several different ratios, and Knowing that several have been swapped for more preferable ratios are you sure you want to go there. Muncie rebuild kits now offer different ratios. I just did one for a guy ,changed over from a M21 to a M22 with lower first gear. Parts are now becoming available. (CHINA) Richmonds I don't see as an advantage other than a cheaper direct bolt in. And built in USA . Call Summit racing and it'd be delivered the next day AND IT's got a Warranty.:3gears: No trickery here, When the gentlemen running the race tell you just to order a Richmond after you scatter a trans ,you do it. Bringing up one thing to throw off another I don't think will work in this case. The spring pressure thing is just to limit bogus cams that should Never be allowed anyway. Once again I think Pete was just trying to pick a number everyone could live with.o No: o No:
I agree, the ranges stated earlier seemed reasonable. Just disagreeing with using AMA as it would effect lots of people and is over a decade too late. Looking through some old manuals for fun, a '61 solid lifter tripower 348 had max 105lbs, a '57 through '61 dual quad or fuelie vette had max 79lbs and 1969 Olds 350 through 455 lists 84lbs max.
Sooo.... When they were under warranty they didn't have enough pressure to control the valvetrain? Now 40 years later we need to add more pressure to control the valve on a 40 year old camshaft lobe ? Those silly engineers never know what the hell is going on ou:
this is froQuote: Originally Posted by Jeff Morgan (31791) What is the closed valve spring pressure on the L88, ZL1, L72 and LS6 motors? We are having a pure stock race next week and they are talking about checking valve spring seat pressures and are talking about allowing up to 180lbs on the seat. My understanding was that they were around 125-130? Did the l88 and ZL's use more than the 435hp and LS6 motors? Jeff----- Valve seat pressure at installed height for the L-88/ZL-1 valve spring, GM #3916164, is reported, variously, at 116 pounds or 125 pounds. Valve seat pressure for the 1969 L-71 and 1971 LS-6 using spring assembly GM #3970627 is 105 pounds. This comes from the corvette guru JOE LUCIA from the NCRS board
well, Tommy, if these cars are build to legal NHRA specs, then the piston to valve distance is less than it was 40 years ago........ the specs mentioned are a great starting point, maybe not the ideal point for the event, then again maybe they are, but they are low enough to sniff out rectangular cam lobes.....
Hmmmmmmm.... are those 350 and 455 Olds spring pressure specs for all of them or different for the W cars? (Hint: I think they were ....:bglasses
But Donny, I just checked NHRA blueprint specs and my 09 NHRA rule book and would you believe that they don't have a spec for valve spring pressure.
Suppose I put a set of 180 pound (on the seat) valve springs in my car today. How many pounds pressure (on the seat) will I have next week, next month, or next year, if I race the car a couple of times a month? o No:
I'll see if I can find the W31 spring specs. They were special....at least in 1968, not sure about 1969-1970. Due to the much higher RPM's of the W31 over the W30, they used a special Swedish steel in them. We checked the original springs in my Ramrod when it came apart in 1999 for the first time. Seems to me they were still pretty high after all that time. 68 and 69's had shallow valve seats in the heads. Think that contributed to the higher seat pressure.....especially if an aftermarket spring was used.
Omg Cant We All Get Along? Lets Just Have Our Usual Fun And Keep It Going. Who Cares About Brands Or Advantages? We Are Really All There For The Same Reason. Hanging Out Meeting Friends, Cookouts, And The Thrill We All Get For 2 Days Away From Work Whippin Our Cars. Just My Opinion. I Love Martin, Chris Robertson
Tim I had no intentions of changing the subject and the first sentence of my first post said I agreed with the idea on spring checks, I appologize if it appeared so. Instead I was hoping for some clairity on the specs allowable. I was thinking that a rule without any specs for the racers to follow made it difficult to implement. Pete called last week and explained the reasoning behind the rule and the reasoning for why he intentionally left the specs out. I am on board with what he is trying to do. My only hope is at some point the specs will be printed in the following seasons as they get a handle on how this is going to work and what is the best resolution. For now and this season I understand what they were trying to accomplish. A subject change I was not looking for when asking about manual trans', suspension and blocks. I believed they should be added to the list of items that need to return to a more pure state along with the items to be teched more closely that Pete had listed. My point was made when people started talking about auto and manaul trans' that have altered gearing. Isn't that the point? If you can not change lobe profiles, piston shapes, then why trans gear ratio's? We can not exhange a Q-Jet for a Holley...I am just appling the same logic trail. Plus I can not see how changing gear ratio's is not an advantage and why are people doing it if it has no effect? If you change from an M21/22 first of 2.20 to a Richmond with a 2.43, 2.64 or a 2.88 it surely will get a car moving quicker. My Judge with 4.33 gear, 6000 rpm shift point and G70 tires would have these specs with stock and changed gears: M21 2.20 x 4.33=9.56 gear amplification in first gear with a max speed of 50.0 mph @ 6000 T10 2.43 x 4.33=10.52 gear amplification in first gear with a max speed of 45.4 mph @ 6000 T10 2.64 x 4.33=11.43 gear....max speed of 41.8 mph @ 6000 The gear rpm drops between shifts are excellent on the 2.43 trans just like an M21/22. It becomes obvious that the shorter gearing would certianly help a 3864 lb. car get moving much quicker. That is why I argue against trans gear changes. It is just my opinion and it appears I may be the only one who cares. I just thought when we were in a time of requesting a more pure build for the cars this is another item to possibly include in the future. Of course I understand that the difficulty in checking gear ratio's may kill the idea alone. If they choose not to include those three items I requested I will accept the ruling (I would actually like to see a ruling either way) but I just might run out and buy a Richmond to join the gang that has already made the change and call JEG's to find the best suspension components. That way I can join the "everything does nothing" crowd. Or better yet I will save the money and just go and enjoy the racing and people as Chris Robertson suggested. Mark
