levisnteeshirt wrote:a vacume gauge
if you checked the manifold vacume at lets say 3 different RPM levels , with odd timing settings ,, like only 5 degrees ahead, then 2 ,, record what a stocker does ,
then check the winner against those readings ,,,
i don't see how anybody could hide a cam with different specs against a test like that
alot of circle tracks around here ,, and crate racing is getting big ,,, but so are the cheaters ,,
i gotta believe there is no way to hide a cheater cam against a test like that
someone could argue low vacume readings is because of a worn engine or streched timing chain ,,, but a worn engine shouldn't be winning IMO
i had one friend mess with a 604's cam , it picked up by putting it on a 110 ,, then they went back to a stocker ,, didn't want to chance it
Keith Morganstein wrote:Ignition timing alone will change vacuum readings.
levisnteeshirt wrote:hmm ,, idle one at 750 rpm with 10 degrees ahead , , 12 degrees 6 degrees
check it at 800 , same deal ,
then lets say 900 ,,
record the vacume readings at each timing setting for each rpm
if they're stock ,, they should be very close
yes i know timing changes vacume , so , you need to map out what a stock , " legal " one does
i go to alot of dirt tracks ,, crate late models are very popular here on dirt ,, i gotta laugh everytime one comes out to hot lap ,, and it sounds like its cammed to death going slow ,,, a game of cheaters ,, enough of that already in circle track IMO
i think thats worth a try anyway ,, you might have to check his TDC on the timing mark to see if he changed it to pass the test , but thats no biggie , then use a timing tape for that balancer to check the timing marks ,
this test might validate if there is a need to dig deeper in the engine IMO
Headcase wrote:you could use a compression test.....A given engine w/xx to 1 static compression and an intake closing event of xx degrees abdc can only generate xxx pressure....(there are calculators on line specifically for this you would have to plug in your advertised max static compression limit and factor in +4 or -4 on the "intake closes at event" if they are allowed to advance or retard the cam)....anything over that then break out the degree wheel and check the actual timing events and obviously valve lift...you have to get up pretty early to catch those circle track guys....Headcase
JDR Performance wrote:They're sealed motors and approved rebuilders are the only ones supposed to have replacement bolts. When they're rebuilt they're blueprinted to optimum legal tolerances. Like anything else there's some extra stuff that's going to be done here and there but the majority of them are found legal when torn down and inspected. Some of the head castings are better than others so they're sought out and used, etc. etc. The bolt on stuff picks up a lot of power on those. Using a good carburetor set up for the crate stuff makes a difference and so does the fuel being used. E-85 and the VP CHP work great. If the stock 4777 made the best power on the 604 dyno test you did you didn't have the right carb there. That alone was losing hp for you. All in all, the crate stuff is very competitive and keeps the car count up. No car count, no track. No track, everybody loses.
levisnteeshirt wrote:, if GM were to attempt to prosecute someone for copyright enfringement ,,, who would they go after ??
levisnteeshirt wrote:vacume at 1000 rpm , that isn't going to show you much IMO
idle it down to 650 rpm ,, see what it does ,, move the timing so timing won't compensate for overlap ,, set it not where the engine runs smooth , then check its vacume there compared to a stocker ,, thats where you'll see a difference
they let them be rebuilt by approved locations now ,, soo ,, i think the cat is out of the bag really ,, if GM were to attempt to prosecute someone for copyright enfringement ,,, who would they go after ??
Fastrak puts a seal on them now i think themselves ,, once they inspect it
but its so obvious when you hear them run , that something has been done to 'em ,, or they're putting nitro or something in the fuel , because they just run beter ,, they might think they're fooling some people ,,, not people that have listened to engines most of their adult life and know what to listen for
i played with a 604 on my buddies dyno ,,, it made 415 hp ,,, not a very strong engine ,,, it idled smooth , like a pass car ,,, did not want anything other than a 4777 regular 650 dp ,, you name it , they had it there to try it as far as carburators go ,,, 650 hp , 750 dp , etc etc etc , some i hear at the track sound way better than that one did ,,, like its got a way more radical cam in it ,,, more like a solid roller with about 250 @.050 ,, just a whole lot stronger
i think the crate thing sux because its forcing out other classes that did have built engines ,, its why i don't like nothing about them ,,, my .02
i think a gear rule , tire diameter rule and carb rule ,, would be more effective
i wonder if a " stock appearing 604 " class would be more of attractive class to put the engines once they need rebuilt instead of letting them be rebuilt back to so called GM specs and be allowed to go back to crate racing ,, 604 heads block, valve spring diameter, and intake , the rest is up to you