compression question

[skynyrdcat]

1988 V-4 110 hp

Newly rebuilt, only 90psi per cylinder. I know it's rebuilt because I did the work, new pistons, new rings, bored all cylinders.

Where am I loosing compression?

I should have at least 120.

Also runs terrible WOT (wont even plain out) new fuel pump was needed but it didn't correct this.

Any thoughts?

 

[tashasdaddy]

Re: compression question

did you check flatness of heads. and exhaust covers. your right, thats very frustrating.

 

[kenmyfam]

Re: compression question

What was it before rebuild ?? Have you verified the compression tester ?? Do you have the correct rings for the rebore size ?? What else was done to the motor ?? Is the fuel system clean and flowing as it should ?? mentioning the fuel pump replacement has me thinking.

 

[skynyrdcat]

Re: compression question

What was it before rebuild ?? Have you verified the compression tester ?? Do you have the correct rings for the rebore size ?? What else was done to the motor ?? Is the fuel system clean and flowing as it should ?? mentioning the fuel pump replacement has me thinking.

Compression was 90, 90, 90, 60 before rebuild.

Now 90 on all.

New rings bearings and cyl bore. I checked the ring gaps, they were good according to manual.

Took carbs apart, they were very clean, checked all reeds during rebuild, all were good.

Could I get low compression because of exhaust cover gasket?

I didn't get one with my kit and used the old one.
Could this cause the very sluggish performance?

 

[skynyrdcat]

Re: compression question

also, where can I get the gasket (exhaust cover to block)??

Marine store only shows part number (replaces xxxxxxx) so I'm not sure which one to get.

 

[tashasdaddy]

Re: compression question

try ishopmarine.com enter original part # at the center top of the page, will give you proper replacement.