about the newer engines they can run more LSA because of no carbs, from the factory they do too. its very hard to get the engine to idle on the street with and tighter LSA and longer durations with computers . yes all out race cars will run the tighter LSA.
thumpr cam with a tight lsa and a lot of duration was made for the guys that wants that rough idle. the best way to tell the ramp is at .200 lift.cant find the specs for the thumpr. but the XFI has the most. with a great idle. whats wrong with more under the curve?
help me out then what cam specs should i run in my nailhead. 323 gears 2 speed tranny. the heads are ported.its frame off resto street car not a race car. i like a smooth idle like i have now. it run 12.80 with a bad 1.85 60 ft time. what lift and duration and LSA should i run. what kind of times can you get me down to.
Compression, carb, exhaust system? A wider lobe sep will reduce cylinder pressure, tighter lobe seps typically enhance cylinder pressure. So depending on your compression ratio, that will determine the lobe sep needed as well as intake closing. But in most cases a 116 lobe sep on a small inch motor usually leads to laziness. Something around a 110 in either a single pattern or mild stagger would be good. But again it depends on your intake, heads, compression and exhaust system. Btw- I think Comp is s good cam company, I just think they're a better marketing company.
Did a compression test...all plugs out...not happy with reading for a fresh build. #1 150 #3 100 1st try...came back after all others to do again...went to 90 #5 130 #7 150 #2 150 #4 150 #6 135 #8 145 uzzled:
try a little oil down number 3 cyl and do an other reading. you need to have the carb wide open when doing your testing
Can you define wide open on the carb please...Danks. I assume it is to make sure it can take in enough air???
Yes, you want to perform the test with the engine warmed up, and the carb at full throttle. I disconnect the fuel line, run the car out of fuel then with the coil wire off I do the test. As said above, if you have a low cylinder then try a bit of oil in the spark plug hole to see if that raises the number. It is also a good idea to run a leakdown test if you suspect a bad cylinder since it can help you narrow down a leaking valve etc.
put some fogging spray down that one hole...it went to 100 psi...that's it. made sure the secondaries were open. I know you guys are saying it NEEDS to be all open but...I am getting consistent readings on most other holes.
So then, you likely have either a flat lobe on the cam or a sticking valve in the head. I would make a leakdown test my next move at this point. You can also rotate the engine with the valve cover off on that side to look for a flat lobe on the cam.
doubt a flat cam lobe could cause poor cranking cylinder pressure...most likely either poor sealing valve or poorly seated rings. first the oil in the cylinder .....that will tell you
