Compression and Vaccuum loopholes
 

Alright, i am hoping there are some loopholes to passing a compression and vaccum test. This is for the 2.3 carb engine. The head is done and bigger valves. Someone give me some help for more performance so i can pass these test with stock reads... thanks :tongue:

whats the problem? too high compression and too low vacuum?

my compression and vaccuum has to be normal... it is nor to high or low right now... i am wanting more power from my motor but i have to show stock compression and vaccuum...

well, the only way to show different compression is to have a differnet compression, i dont believe there are any tricks to get it to show differently... vacuum you can possibly get away with an adjustable cam gear, you may be able to get it dialed to where it reads normal vacuum then dial it back to where it performs best... but what are you planning to do to change things anyway? it may still read perfectly fine even after doing things.

thats what i am asking... i am wanting to do some mods but my compression can not be over 175 i think and a vacuum of 16 or so... i just didnt know what would effect my comp. and vac.

well, the only thing that will change the compression is different pistons or milling the head or block some to increase it. the vacuum can be changed by a higher lift and duration cam, however a lot cams are still designed to pull a decent amount of vacuum. normally a good running engine at idle should pull 20-22 inchs of vacuum, so keeping it about 16 shouldnt be too difficult. for came you can look into esslinger or racer-walsh, they both specialise in lima performance stuff. i would think even with a really aggressive cam you wouldnt go much below 16 inchs vacuum at idle on the 2.3, the only thing that would give you much of an issue is having a vacuum leak somewhere.

• Engine cylinder compression must not exceed 175 pounds.
• Engine vacuum must exceed 16 pounds

That is what i got to have... now go from there....

ok, well for performance stuff you should check out racer-walsh and esslinger. they can be pricy, but you can use them for information. as for cams (the thing that will affect vacuum) I'd send them an email describing which engine you are useing, what you plan to be doing (circle track, dirt racing, whatever it is that is limiting you with these rules because different types take different cam grinds), and tell them that you must stay over 16 of vacuum. they can recommend different grinds and differnet cams that will work for you and keep you over 16 of vacuum. then some good head work (porting and port matching and some basic things) and some good valves with a good grind and the rest of the valve train components, you cant go too large on the valves though, it will hurt performance and you cant fit much larger valves into these heads.

depending on what you are doing with the engine an adjustable cam gear can help to move the power to where you are going to use it. whether you need it higher up in the rpms or lower. it all depends on what you are planning to do with it.

for the comrpession, i wouldnt worry too much about it, i wouldnt really try to raise the compression ratio much over what it has from the factory, you will start to get into detonation and other un-fun things. you could probly get it up to about 10:1 by milling down the head and the block a little, and still be in the compression ranger you need to be into, but again that is something else that you could send an e-mail to R-W or esslinger or both about. these two companies specialize in lima performance and race applications, so even if you dont buy anythign from them (you dont have to let them know you're not going to) they would be a very good place to get information from and their products are amazing and worth the price... which is unfortunately a lot on some things. but id start by asking them some basic questions explaining what you plan to do with the engine and where you want the power to be in the rpm band and the limits you have on it and see what they say.

Maybe your vacuum problems can be solved by variable duration lifters. They increase vacuum at idle, which is where it is usually measured because it can fluctuate so greatly at any degree of open throttle.

hey, thanks alot guys... you have really helped me out alot...