Still stuck on my 4 cylinder

Started by Beck, September 03, 2021, 02:25:21 PM

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Beck

Sometimes I wonder why I keep trying.

I am still fighting with the 4 cylinder that has haunted me for the last several years. I thought I had it ready to go. Initially I thought battery/cable/starter issues. It is making so much cylinder pressure during cranking that the starter just cannot do the job. When the pressure was checked it was 280-285 psi while cranking. From what stupid me is told, that just won't work.

There are a couple of options. 1) Cut the tops off the pistons. They are currently 13.6 compression for E85.  2) Install a thicker head gasket. 3) Install a bigger cam.

With this odd-ball motor there are issues with most of the options.

Cutting the tops off of pistons would be a challenge for any engine. The 13.6 compression is right where it needs to be for E85.
Head gaskets are a bit weird on this motor and not all work as claimed. Cometic says they do have them available. Again lowering compression lowers the power output.
You just don't buy a cam for this engine. You buy a used cam, then have it reground. My current cam is a wimp. It needs a bigger one, so this is the route I have chosen.

enjenjo

Do you have specs for what you want the cam to be? I have used Delta Cams for regrinds for the last several years and the did a good job for me.
Welcome to hell. Here's your accordion.

chimp koose

retarding the cam might help to lower cranking compression . I had a 13.7:1 400sbc that used to break off the starter nose until i used a gear reduction starter 275lbs cranking compression

Beck

Bullet Racing Cams did my 1st one. I believe they did a good job given the information I had given them. They are easy to talk to and work with. I have again sent the "new" used cam to them for regrind.

I considered the cam retard option. I really need the bottom end which goes away a bit with retarding the cam. Once I am deep enough to retard the cam it doesn't take much to just put a different one in. It's just $ signs floating by, and I have seen a lot of those with this build.

Charlie Chops 1940

Can you make use of 4 compression release valves? I admit that I'm not getting light bulb turning on moment and I haven't a clue how it might be done. Could you use an external starter like top fuel cars? Sound like yo need a starter with more horsepower than your 4 banger.
A good friend will come and bail you out of jail...but, a true friend will be sitting next to you saying. "Wow...that was fun!"

Poster geezer for retirement....

A Hooligan!

kb426

Is a 24 volt starter an option? As much work as it takes to build compression, I would try everything else before lowering it. That's a bunch of injected alky engines with 15 to 1 comp running around. I don't know what their cranking comp is. When I was running my dragster, we needed 200 lbs at sea level to be good. As I remember you lose about 5 lbs. per thousand feet of elevation. Is there a chance you can get it to start cranking and then turn on the ignition?
TEAM SMART

Beck

I got it to fire once putting 24V to the 12V starter. I think that is a breakage problem waiting to happen.
Using the Holley Dominator the ignition doesn't turn on until the engine is cranking at 200 rpm.
At that low rpm when the motor fired once with my initial advance it slowed the engine, so the next plug never lit.

I'm like you Charlie, I wouldn't know how to make that compression release.