427 hp estimate
Thread Starter
Racer
Joined: Jul 2008
Posts: 323
Likes: 18
427 hp estimate
Hello
What do you think about this engine?
427 cui #942 casting
12.5 Compression
fully ported #291 rec port heads.
comp cams mec Roller 0.680/0.680 - 306/319 dur.
https://www.summitracing.com/parts/cca-11-702-9
Single plane intake.
Roller rockers.
Thank you
What do you think about this engine?
427 cui #942 casting
12.5 Compression
fully ported #291 rec port heads.
comp cams mec Roller 0.680/0.680 - 306/319 dur.
https://www.summitracing.com/parts/cca-11-702-9
Single plane intake.
Roller rockers.
Thank you
Last edited by 70rs/ss396; Aug 21, 2021 at 02:34 AM.
Race Director
Joined: Jul 2015
Posts: 13,082
Likes: 3,399
From: SW Florida.
really nice engine for the drag strip. nothing else. and detuning and lowering compression on an engine somebody wants premium money for cuz they built very high compression long duration cam is a non-starter. a 454 truck engine from an 81 silverado would be a better starting point...
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
To actually answer this question you would also have to give the heads CFM flow rates at all the .100 lift increments, type of single plane, carb type and CFM, and header type and size. Then you plug it all in to an engine dyno sim and it would come out with very real to life graphs.
But in my opinion it's not a very well thought out engine combo. 50+ year old heads are not a good chamber and port design. I was watching a long You Tube video comparing two equal CC heads. The AFR and a Profiler head. They just didn't measure total CFM at all lift points, but also port velocity and different points within the intake track. Very informative and clear out to 1.00 inch lifts at .100 increments.
So 291 ported head with maybe 2.25/1.88 valves would rate very poor in todays standards.
12.5 C/R is on the fence for pump gas and race gas because a cam can make it require high or lower octane fuel. So it's not a ***** out race engine and it's crappy for a street car. Dynamic compression Ratio calculators are a good tool. Race engine should be 13.8 - 14.3 for race gas with modern aluminum heads, Street machines like my 427 run very well with 11.7 c/r on pump gas with a little thought.
they make lower rpm single planes and all out single planes.
But in my opinion it's not a very well thought out engine combo. 50+ year old heads are not a good chamber and port design. I was watching a long You Tube video comparing two equal CC heads. The AFR and a Profiler head. They just didn't measure total CFM at all lift points, but also port velocity and different points within the intake track. Very informative and clear out to 1.00 inch lifts at .100 increments.
So 291 ported head with maybe 2.25/1.88 valves would rate very poor in todays standards.
12.5 C/R is on the fence for pump gas and race gas because a cam can make it require high or lower octane fuel. So it's not a ***** out race engine and it's crappy for a street car. Dynamic compression Ratio calculators are a good tool. Race engine should be 13.8 - 14.3 for race gas with modern aluminum heads, Street machines like my 427 run very well with 11.7 c/r on pump gas with a little thought.
they make lower rpm single planes and all out single planes.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Is it missing some parts in the cam valley? Those springs look like a rev kit, but it should have a cross bar on each side?
It's very feasable that motor is over 600 hp especially if you set something like 7500 into the rev limiter which I highly recommend.
It's very feasable that motor is over 600 hp especially if you set something like 7500 into the rev limiter which I highly recommend.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Racer
Joined: Jul 2008
Posts: 323
Likes: 18
I think it is lunati lifters, they have a vertical bar towards the block.
Melting Slicks
Joined: Jul 2006
Posts: 3,103
Likes: 802
From: Massapequa Park NY
The 942 is a 2 bolt main motor correct?
Last edited by ed427vette; Aug 21, 2021 at 06:06 PM.
Thread Starter
Racer
Joined: Jul 2008
Posts: 323
Likes: 18
$2500 for a mostly complete 427 is a very good price. It’s in fact very cheap. But what do you know about the block/heads? Any repairs? Is it punched out to where if it needs a rebuild it will need sleeves? I think at worst you would still do ok with that price unless the block is cracked in half and you can’t see it. Sounds like a great deal.
The 942 is a 2 bolt main motor correct?
The 942 is a 2 bolt main motor correct?
Its a 66 Corvette block If I remember correct.
Burning Brakes
Joined: Sep 2018
Posts: 1,002
Likes: 410
The big block heads are much more exhaust port dependent, -- re: Flow - the short turn radius is the big impediment.
Additionally without a proper set of headers or manifolds which are extrude honed you will negate any of your gains on the intake side.
But that engine looks to have been done well, how nice is the crank and rod prep? polished beams and arp fasteners? full floating wrist pins I imagine. Pull a rod and main cap and look at them.
Additionally without a proper set of headers or manifolds which are extrude honed you will negate any of your gains on the intake side.
But that engine looks to have been done well, how nice is the crank and rod prep? polished beams and arp fasteners? full floating wrist pins I imagine. Pull a rod and main cap and look at them.
Last edited by firstgenaddict; Aug 22, 2021 at 03:48 PM.
Race Director
Joined: Jan 2000
Posts: 13,018
Likes: 2,262
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
I see good and questionable. The worst thing is it looks like a cast crank? Tried to zoom in on it but the parting like appears cast? It does show to be balanced and aftermarket rod bolts in stock rods (3/8" ?) and 4 bolt main studs, welded pickup...so that all points top someone trying to do things right. I'm assuming it's got forged pistons? They used to make cast 12.5 ones too...LOL I ran a set once!
Those look like the spring loaded Lunati lifters that allow you to change a cam without pulling intake. Need to find out how many miles/runs on them. And check them closely anyway for roughness.
It can easily be a near 575-600 HP engine if you spin it up a little...which 427's like. Need to get an idea of how old valve springs are and if those retainers are titanium or aluminum? Be nice to see a bearing or two at least to make sure all is healthy.
It's a lot of cam and will be rowdy...but a lot of fun once you get to 5000 RPM at WOT!
JIM
Those look like the spring loaded Lunati lifters that allow you to change a cam without pulling intake. Need to find out how many miles/runs on them. And check them closely anyway for roughness.
It can easily be a near 575-600 HP engine if you spin it up a little...which 427's like. Need to get an idea of how old valve springs are and if those retainers are titanium or aluminum? Be nice to see a bearing or two at least to make sure all is healthy.
It's a lot of cam and will be rowdy...but a lot of fun once you get to 5000 RPM at WOT!
JIM
Last edited by 427Hotrod; Aug 22, 2021 at 11:40 PM.
Thread Starter
Racer
Joined: Jul 2008
Posts: 323
Likes: 18
I see good and questionable. The worst thing is it looks like a cast crank? Tried to zoom in on it but the parting like appears cast? It does show to be balanced and aftermarket rod bolts in stock rods (3/8" ?) and 4 bolt main studs, welded pickup...so that all points top someone trying to do things right. I'm assuming it's got forged pistons? They used to make cast 12.5 ones too...LOL I ran a set once!
Those look like the spring loaded Lunati lifters that allow you to change a cam without pulling intake. Need to find out how many miles/runs on them. And check them closely anyway for roughness.
It can easily be a near 575-600 HP engine if you spin it up a little...which 427's like. Need to get an idea of how old valve springs are and if those retainers are titanium or aluminum? Be nice to see a bearing or two at least to make sure all is healthy.
It's a lot of cam and will be rowdy...but a lot of fun once you get to 5000 RPM at WOT!
JIM
Those look like the spring loaded Lunati lifters that allow you to change a cam without pulling intake. Need to find out how many miles/runs on them. And check them closely anyway for roughness.
It can easily be a near 575-600 HP engine if you spin it up a little...which 427's like. Need to get an idea of how old valve springs are and if those retainers are titanium or aluminum? Be nice to see a bearing or two at least to make sure all is healthy.
It's a lot of cam and will be rowdy...but a lot of fun once you get to 5000 RPM at WOT!
JIM
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
It is an old school drag engine as Vortec states......but no good for anything but drag racing for three reasons.
1) Bottom of the page camshaft
2) Too much compression if you did change the cam
3) Rec port heads are not the hot tip......they create little velocity and the engine has to be spun to the moon to make them work.......especially on a 427.......large oval port is much better. Head port tech had a ways to go back then and GM didn't even realize the heads that they had was a world beater......a ported large oval port will run circles around any rec port and all rec ports are good for these days are for restoration......
But.....if you had a nice drag car.....this could be fun as a sum of its parts......but it would require to many changes to make it cost effective to run on the street.
Anyway....575 + horsepower and nothing down low.....it would have to rev beyond 7000 to accelerate on the track.....zero low end torque.
Jebby
1) Bottom of the page camshaft
2) Too much compression if you did change the cam
3) Rec port heads are not the hot tip......they create little velocity and the engine has to be spun to the moon to make them work.......especially on a 427.......large oval port is much better. Head port tech had a ways to go back then and GM didn't even realize the heads that they had was a world beater......a ported large oval port will run circles around any rec port and all rec ports are good for these days are for restoration......
But.....if you had a nice drag car.....this could be fun as a sum of its parts......but it would require to many changes to make it cost effective to run on the street.
Anyway....575 + horsepower and nothing down low.....it would have to rev beyond 7000 to accelerate on the track.....zero low end torque.
Jebby
Last edited by Jebbysan; Aug 23, 2021 at 08:15 AM.
Race Director
Joined: Jul 2015
Posts: 13,082
Likes: 3,399
From: SW Florida.
that 680 lift MARINE cam scares me. it is worse than drag strip. on a drag strip you shut down after 8 to 15 seconds. in a boat, 15 seconds at full throttle and you haven't even got up on plane and above 40 mph yet. then it is held on the firewall for 2 to 20 minutes. that valvetrain will be completely worn out. right down to the seats with 500 lbs over the nose and 150 seat spring pressures. i repeat. start with a 500 buck 454 out of a pick up!
Last edited by derekderek; Aug 23, 2021 at 10:35 AM.