Late Model Chevy Truck Heads (1998) on a 1981 305 block?

J

Jeff

Not-quite-so-new-guy
Apr 29, 2017
5
3
I saw a recent Car Fix Episode where they put heads off a 1998 Chevy truck on one of our 305 motors mine is in an 81 Monte. They put a cam in a performer intake manifold on and topped it with a Holley 600 CFM Carb and claim 300 Horse Power. Anyone have experience and success with such a modification? I am looking for more details. Thank you for your time. Jeff
 
1320John$$$

1320John$$$

Master Mechanic
Sep 18, 2019
428
93
Pennsylvania
I did a similar swap on a 8.6 compression 305 ported 416 castings with 1.94 intake valve edelbrock performer intake small crane camshaft 216 @.050 600 Holley vac carb comp 1.52 magnum rockers 1 5/8 headers I did chassis dyno this car it made 229hp and 243tq ran very high 13s before the Auburn diff in the 7.5 rear broke
I think your vortec headed 305 would be closer to 300hp at the crankshaft
38A54417-325C-45E2-8BFB-A28EA2CE36FA.jpeg
 
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Streetbu

Streetbu

Royal Smart Person
Supporting Member
May 22, 2011
1,585
113
Central NY
Make sure they are Vortec heads off a 350 and not off a Vortec 305. Completely different heads. The 305 heads don't give nearly the performance gain.
 
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olds307 and 403

olds307 and 403

Geezer
Oct 14, 2008
5,596
113
Melville,Saskatchewan
Make sure they are Vortec heads off a 350 and not off a Vortec 305. Completely different heads. The 305 heads don't give nearly the performance gain.
I am surprised they even bothered with different heads. I assume smaller valves and ports? I know the 5L Vortec were rated at 230 HP, got mid to high 20's mpg Imperial and only made a couple of years.
 
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TURNA

TURNA

Rocket Powered Basset Hound
Jul 24, 2009
10,441
113
Socialist NY
Streetbu

Streetbu

Royal Smart Person
Supporting Member
May 22, 2011
1,585
113
Central NY
I am surprised they even bothered with different heads. I assume smaller valves and ports? I know the 5L Vortec were rated at 230 HP, got mid to high 20's mpg Imperial and only made a couple of years.
Honestly not sure about port sizes, the valves are the same, but the chamber is like an older 882 head, bathtub design. Not like the actual good Vortec head that flows so well.
 
J

Jeff

Not-quite-so-new-guy
Apr 29, 2017
5
3
Thanks everyone. New here and started two threads without realizing sorry. All good information and lots to consider. I am leaning to not doing an engine swap even though I know a 350 would be a better option. The 305 in the car is fresh well about 25K on a rebuild (verified) the person I bought if from had done at a reputable machine shop. I called that shop and they will hook me up with the right 350 Vortec Heads in good shape for $300. I figure a cam $125 and the shop will sell me a performer intake they have for $75. My sons friends Dad is giving me a 615 CFM Predator he does not use. Headers $150 or so. My kid who is getting this car for his 16th birthday will definitely be surprised. He and I have spent allot of time getting the brakes, steering components all bushings etc. shocks up to par. He thinks its my car. I got until September to finish the engine mods. I think this will be enough power for a young-in anyway.
 
R

RabbitHoleSS

Greasemonkey
Dec 8, 2019
190
63
Indianapolis
Thanks everyone. New here and started two threads without realizing sorry. All good information and lots to consider. I am leaning to not doing an engine swap even though I know a 350 would be a better option. The 305 in the car is fresh well about 25K on a rebuild (verified) the person I bought if from had done at a reputable machine shop. I called that shop and they will hook me up with the right 350 Vortec Heads in good shape for $300. I figure a cam $125 and the shop will sell me a performer intake they have for $75. My sons friends Dad is giving me a 615 CFM Predator he does not use. Headers $150 or so. My kid who is getting this car for his 16th birthday will definitely be surprised. He and I have spent allot of time getting the brakes, steering components all bushings etc. shocks up to par. He thinks its my car. I got until September to finish the engine mods. I think this will be enough power for a young-in anyway.
He hasn't asked if its gonna be his? My boys only 7 and is staking claim to my monte lol. That's an awesome 16th bday present. To get the car you and your old man fixed up. I wish my dad woulda done stuff like this with me. Nothing better then bringing joy to your kids imo. Mine isn't a teenager yet so well see how I feel in another 7 yrs.
 

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