New to the 240sx community and need help

[irregular.s13]

Hey guys I'm new to the 240 community. I have a 89 240sx coupe with jdm front. Currently doing a different and unique build. I am building the ka24e with weber carbs and r4 cam. I need some help here, I replaced the timing chain, guides, and tensioner and now im having very low compression. I did match up the timing mark on the chain and the gears (cam/crank), but for some reason cylinder 3 & 4 have very low compression. Did I miss something? thoughts or suggestions? thanks

[the converted]

How low is low? Did you rebuild the engine or just did the timing components and cam? Sounds like an interesting build, I love dcoe's!

[irregular.s13]

low compression on all but the lowest is 3 & 4. #1 120, #2 115, #3 65, #4 65.

[irregular.s13]

well I have 2 motors. One I rebuilt completely, only original part was the bottom block and crank. I had the same result, low compression in all. cyl 1 & 2 had the highest compression at about 115 and 120, but still lower than the recommended, cyl 3 & 4 was the lowest at 65 and 65. I started with the re-built motor, and i thought maybe the valves need to be reseated, so I took that motor out and used the original motor that came with the car (which ran perfectly). All i did with that motor was replaced the timing components (chain, guides and tensioner) and took switched the cam to the r4 cam. And still, I'm getting around the same figures.

[the converted]

That's really strange. I'm assuming you are doing the compression check with the throttle wide open?

[irregular.s13]

Well, no, should I? I read that somewhere but was not sure that it was the correct way to do it. Wouldn't it be less compression since the butterfly is open and the intake valve is open to atmosphere?

[the converted]

Definitely should be. With the throttles closed you're limiting the amount of air that can get into the chamber, and you want no flow restrictions. I'd be willing to bet that if you look at the throttle on your carbs that the ones on the rear two cylinders are just a little bit more closed than the ones on the front one. If that's the only problem that you're having right now, I'd say you're good to go. I might tweak the throttle stop on the rear one just a little bit more to even it out with the front one until you get it started up and get them balanced out.

[irregular.s13]

Ok I'll try that tomorrow and hopefully this will solve the problem. Thanks for the suggestion.

[5280VertDET]

I wish you luck, but I would like to see this and in much more detail. You plan on, or already have, doing a build thread? I'd want to see the numbers too!