swap 1995 5.7 for 1998 5.7

[1979 Quartermasters]

I have acquired a 98 5.7, from a 98 GMC Sierra Z71, with a blown head gasket and an antifreeze milkshake currently in it. I am considering changing head gasket, all electricals, intake, core plugs,etc for my 95 5.7 currently in my 95 Sea Ray. There is nothing wrong with current engine and it is punched out .60 over. Would this exchange be worth the effort in terms of performance.

Thanks for all input......

Ken

 

[Bondo]

Ayuh,.... All you'd gain is Vortec heads, over the '95 in there now,...

Performance gain will be minimal,.... maybe 20hp, at tops,...

 

[alldodge]

I have acquired a 98 5.7, from a 98 GMC Sierra Z71, with a blown head gasket and an antifreeze milkshake currently in it. I am considering changing head gasket, all electricals, intake, core plugs,etc for my 95 5.7 currently in my 95 Sea Ray. There is nothing wrong with current engine and it is punched out .60 over. Would this exchange be worth the effort in terms of performance.

Thanks for all input......

Ken

If its already bored .060 over I wouldn't touch it, cylinder walls way to thin

 

[1979 Quartermasters]

Thanks for the response. So maybe keep, stroke it and save it for a replacement?

 

[1979 Quartermasters]

I may have miss spoke. I believe the engine currently in the boat is 0.030 over and the Vortec is stock.

 

[Bondo]

I may have miss spoke. I believe the engine currently in the boat is 0.030 over and the Vortec is stock.

Ayuh,.... Vortec heads, aka; Fast Burn combustion chambered heads, weren't introduced til '96, so yer '95 motor is Vortec in Name Only,....

Countin' the intake bolts will verify what ya got, pre-Vortec has 12 bolts, 'n Vortec heads use 8 intake bolts,....

 

[flipbro]

Be very carfull with the vortecs head wise they come out in 1997 up and are very prone to cracking. So what you think is head gasket could be bad head.. look for 906 head they had hardned exh valve seats and didnt crack as easly from an over heat.try to avoid the 062 casting.

 

[1979 Quartermasters]

Thanks for that tip, flipbro. Bondo; I must not be communicating clearly. My apologies. The engine currently in the Sea Ray is 95, roller cam, replacement reman motor bored 0.030 over the previous own put in 2008 due to a cracked block. It is not a Vortec. The engine I have acquired is from a 1998 GMC Silverado, Z71. It is a Vortec. So far, it would seem, from the responses, that it's not worth it to swap out the engine purely for performance improvements. Would it be worth it to use the Vortec heads on my block?

 

[Bondo]

Thanks for that tip, flipbro. Bondo; I must not be communicating clearly. My apologies. The engine currently in the Sea Ray is 95, roller cam, replacement reman motor bored 0.030 over the previous own put in 2008 due to a cracked block. It is not a Vortec. The engine I have acquired is from a 1998 GMC Silverado, Z71. It is a Vortec. So far, it would seem, from the responses, that it's not worth it to swap out the engine purely for performance improvements. Would it be worth it to use the Vortec heads on my block?

Ayuh,...... What's on the motor in there now,..?? 2bbl. Carb,..?? 4bbl. Carb,..?? Efi,..??

If, it's a 4bbl. carbed motor, swappin' the heads, 'n matchin' intake, oughta net ya 'bout 20hp, maybe 30hp difference,....
Noticeable,.... might need a new prop, dependin' again on where yer startin',....

A compression test oughta come 1st, to access the condition of the motor to start with,...

 

[1979 Quartermasters]

Thanks for the response. It's the stock four barrel (Carter 600cfm). Did a compression test last summer and it was 175 across the board. I believe the motor, in the Sea Ray has about 300 hours on it. It also has a a 17p five blade stainless prop and hits wot 4800rpm (boat tach) at 49mph (GPS).

 

[Bondo]

Thanks for the response. It's the stock four barrel (Carter 600cfm). Did a compression test last summer and it was 175 across the board. I believe the motor, in the Sea Ray has about 300 hours on it. It also has a a 17p five blade stainless prop and hits wot 4800rpm (boat tach) at 49mph (GPS).

Ayuh,.... Then I'd guesstimate the 20 hp,.... ya really need the proper pistons to make the heads shine, but anyways,....

I'd think, with the swap, you'll be runnin' 5,000 rpms, at Wot on the ragged edge,.....
It may, or may not pull a 19" prop,....

Outa the hole, the change will be minimal, mid-range, it'll really Wake Up,....

Personally, I'd build the motor, stand alone, as a stroker, for a later time,....
At 300 hours, yer motor is barely broken in,....

My 4.3l is clickin' 2,000 hours, without skippin' a beat, 'n no sign of slowin' down,....

 

[1979 Quartermasters]

Thanks Bondo, that's what I wanted to know. Maybe I'll let it sit for now and build a stroker for later.

 

[Scott Danforth]

I recommend the stroker as well

 

[1979 Quartermasters]

Some of my friends are saying the engine is garbage cause there is coolant in the oil. Does that trash the bearings?

 

[flipbro]

Its not good and I would bet the heads are cracked. But the block is what you want for a stroker. So the crank and bearings will be replaced so no worries. The heads you have a 30% chance maybe less that they survived

 

[Scott Danforth]

Its not good and I would bet the heads are cracked. But the block is what you want for a stroker. So the crank and bearings will be replaced so no worries. The heads you have a 30% chance maybe less that they survived

the 98 block is exactly the same as hit 95 block. the difference between the two is the heads. what makes a good high torque, low $ stroker motor is the vortec heads, KB kidney bean shapped dish to match the vortec heads, zero decking, and the 0.041" thick quench zone in addition to the extra 1/4 or 3/8" stroke.

 

[1979 Quartermasters]

The new engine is diferent than the old one. Can someone identify this number from the the water pump. K0319PAC. Also the new engine has a distrutor and the old one doesn't. Thanks guys!!

 

[Scott Danforth]

Post a pic of your new engine, specifically the heads. 1998/1999 was a transition year to the LS motor in trucks. your statement on the blocks being different is a red flag. if you have a gen I SBC, then the blocks should be identical. if you have a Gen III motor (LS), that is an entirely different animal.

 

[Bondo]

Post a pic of your new engine, specifically the heads. 1998/1999 was a transition year to the LS motor in trucks. your statement on the blocks being different is a red flag. if you have a gen I SBC, then the blocks should be identical. if you have a Gen III motor (LS), that is an entirely different animal.

Ayuh,.... Agreed,..... random numbers off a water pump means nothin' to me,...

 

[1979 Quartermasters]

That number is stamped into the block on the passenger side at the water pump.