1987 V6 4.3L OMC Cobra-Same Engine for Both Carbs?

[frank1492]

I recently had the original block replaced with a Mercruiser long block- supposedly the identical block to the OMC. It was a fairly easy conversion- a simple "drop in." We used the original carb which was a 4bbl. The original engine was rated at 205 hp.
I am puzzled because the remanufactured Mercruiser block seems to indicate a hp of 190.
My question is this. Is the Merc block internally identical to the OMC I had or not? The OMC Cobra had two package variations at the time, one with a 2bbl and one with a 4bbl, and I wondered if the 4.3L engines were in any way different internally, in which case the Merc block may not be quite right. I can't find any data that says the original 2bbl was 190 and the 4bbl was 205, or any suggesting subtle engine differences between the two.
Thanks for your help. The bottom line is that I hope my new package is giving me 205 hp not 190.
Frank

 

[180shabah]

Re: 1987 V6 4.3L OMC Cobra-Same Engine for Both Carbs?

Dont panic there was a change in the way HP is rated. It used to be rated at the crank, it is now rated at the prop, i difference of about 30hp on a sterndrive.

I assume that the new 190hp engine has vortec heads? If so, you will be pleasantly suprised the first time you open the throttle.

 

[180shabah]

Re: 1987 V6 4.3L OMC Cobra-Same Engine for Both Carbs?

Forgot - the only difference between the 2 and 4 bbl versions was the intake manifold and the carb. All internals are identicle.

 

[frank1492]

Re: 1987 V6 4.3L OMC Cobra-Same Engine for Both Carbs?

Thanks. I was told by the guy that installed it that it was not a Vortec- although the valve covers do say Vortec on them. I think that is strange. This engine is the one with the mechanical (not electric) fuel pump. We wanted an engine that would drop right in and bolt on to the 1988 Cobra stern drive housing without any modifications.
Your follow-up email does put my mind at ease. If you are sure the only difference between the 4bbl and 2bbl 4.3L 1988 OMC's was the intake manifold and the carb, I feel much better, since the OMC manifold was moved over along with the carb. If that's the case, I should still have 205hp.
Thanks again, Cap!
Frank

 

[180shabah]

Re: 1987 V6 4.3L OMC Cobra-Same Engine for Both Carbs?

HP numbers were all over the place from the mid80's to mid90's, even though the power changed very little.

As for vortec valve covers on an engine withou vortec heads - also normal. My '96 came that way from the factory. GM started using the vortec name in '87 on the TBI engines. When people say "vortec" they are talking about the LT1 style heads that came out in '96 and were phased into the marine world between '96 and '98. These heads can be easily identified by the bolt holes for the intake manifold. 4 vertical for the vortecs and 6 angled for the standard heads.