L98 engine questions - The 1947 - Present Chevrolet & GMC Truck Message Board Network

toolboxchev · 04-25-2018, 03:12 PM

So picked up a core for rebuild and looking to install it into my truck. Yea I know so far the heads date to an 87 083 casting number.

What type and or mods need to be done to get this thing going?

I am looking to keep it carburetored, mechanical fuel pump boss is there. I do not know if those heads have the 72 degree intake bolts.

Can I also keep my stock power steering? Any help is appreciated.

GASoline71 · 04-25-2018, 03:22 PM

If it's a true L98 it had a TPI bolted on top. The center intake bolts were probably straignt up and down.

No idea what mods you "need" as you haven't specified what you want from this build. Stock? No mods... just a stock rebuild.

Gary

toolboxchev · 04-25-2018, 03:54 PM

Just doing a build that will yeild 300-375 ponies with lots of low to mid range torque.

May or may not keep the serp belt system.

Trying to keep costs down and build something that is durable and will last. My aspirations have gone to the sky!

toolboxchev · 04-30-2018, 08:38 AM

So after searching over the site, and other info I have decided to weigh in on the L31 Jegs or Summit GM crate motors.

I am surprised that this motor is so forgotten, most articles out there deal with the injection system. I found one new modification on this block, it came from the factory with an oil cooling system. I have been also clued in on oiling problems that GM was working on to bring about higher efficiencies with tight bearing tolerances using a 5-10 weight oil.

With the cost of an L31 with warranty being so low, I am on a holding pattern until I tear this L98 down to figure where to start on it.

**dennislbrooks** · 04-30-2018, 09:14 AM

I have an 85 vette - nearly bone stock --- with the original L98 engine, all 230 hp with 350 ft lbs of torque. Your 87 would have had I believe 235 hp with aluminum heads. It has low end grunt and with the 4+3 trans gets about 22 mpg highway. I agree with you on the crate as the L98 core is probably worth more to a vette owner.

**Captainfab** · 04-30-2018, 11:02 PM

With a simply cam upgrade to the L31, you will be able to easily meet your 300-375hp goal.

toolboxchev · 05-01-2018, 01:50 PM

Thanks Capt! I knew this motor was worth picking up for a reason. I have to go through it and spec it out for the correct upgrades I will be needing.

04-25-2018, 03:12 PM	#1
toolboxchev Registered User Join Date: Jul 2015 Location: 2nd left past the stump on a dirt road. Posts: 2,629	L98 engine questions So picked up a core for rebuild and looking to install it into my truck. Yea I know so far the heads date to an 87 083 casting number. What type and or mods need to be done to get this thing going? I am looking to keep it carburetored, mechanical fuel pump boss is there. I do not know if those heads have the 72 degree intake bolts. Can I also keep my stock power steering? Any help is appreciated.

04-25-2018, 03:54 PM	#3
toolboxchev Registered User Join Date: Jul 2015 Location: 2nd left past the stump on a dirt road. Posts: 2,629	Re: L98 engine questions Just doing a build that will yeild 300-375 ponies with lots of low to mid range torque. May or may not keep the serp belt system. Trying to keep costs down and build something that is durable and will last. My aspirations have gone to the sky! Last edited by toolboxchev; 04-25-2018 at 04:16 PM.

04-30-2018, 08:38 AM	#4
toolboxchev Registered User Join Date: Jul 2015 Location: 2nd left past the stump on a dirt road. Posts: 2,629	Re: L98 engine questions So after searching over the site, and other info I have decided to weigh in on the L31 Jegs or Summit GM crate motors. I am surprised that this motor is so forgotten, most articles out there deal with the injection system. I found one new modification on this block, it came from the factory with an oil cooling system. I have been also clued in on oiling problems that GM was working on to bring about higher efficiencies with tight bearing tolerances using a 5-10 weight oil. With the cost of an L31 with warranty being so low, I am on a holding pattern until I tear this L98 down to figure where to start on it.

04-30-2018, 09:14 AM	#5
dennislbrooks Senior Member Join Date: Feb 2004 Location: Williamsburg, Ohio Posts: 1,760	Re: L98 engine questions I have an 85 vette - nearly bone stock --- with the original L98 engine, all 230 hp with 350 ft lbs of torque. Your 87 would have had I believe 235 hp with aluminum heads. It has low end grunt and with the 4+3 trans gets about 22 mpg highway. I agree with you on the crate as the L98 core is probably worth more to a vette owner. __________________ 1942 Chevy 1/2 ton Rod, 1959 GMC 1/2 ton Fleet Stepside, 1967 Chevy SWB K10, 1985 Corvette Coupe 4+3, 2015 Chevy Duramax reg cab 4WD W/T

04-30-2018, 11:02 PM	#6
Captainfab 60-66 Nut Join Date: Mar 2007 Location: Coeur d'Alene, Idaho Posts: 23,246	Re: L98 engine questions With a simply cam upgrade to the L31, you will be able to easily meet your 300-375hp goal. __________________ Power Steering Box Adapter Plates For Sale HERE Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE Hydroboost Mounting Plates HERE

05-01-2018, 01:50 PM	#7
toolboxchev Registered User Join Date: Jul 2015 Location: 2nd left past the stump on a dirt road. Posts: 2,629	Re: L98 engine questions Thanks Capt! I knew this motor was worth picking up for a reason. I have to go through it and spec it out for the correct upgrades I will be needing.

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