Chevy Nova Forum banner

1 - 17 of 17 Posts

·
Registered
Joined
·
194 Posts
Discussion Starter #1 (Edited)
I would like to split off the engine build of my restoration project from my Oldsmobile Omega 1973 Coupe - maybe this is of any interest for other inliners as well.

After the engine shop confirmed they fixed the motor block a bit more professional than on the picture

I can go ahead with the build project.

The engine shop is a very reputable one in the Austrian vintage car community, but not that experienced with US engines. Therefore I would like to share our build plan to gain some feedback.

Block: GM 250ci inline 6 with 0.060" overbore and 0.015" decked
Crank: the standard 250 crank which will be polished and knife edged
Crank main bearings: any recommendation for a brand?
Rods: standard 250 ones
Rod bolts: ARP performance bolts
Rod bearings: any recommendation for a brand?
Oil pump: sealed power standard
Pistons: Silv-O-Lite Cast Pistons for a GM 307v8
Piston rings: 2x 5/64 + 1x 3/16 Keith Black KB Performance
Cam: COMP Cams high energy with 110 lobe, 212/212 at 050, 260/260 advertised duration, 0.489 lift
Lifter: hydraulic flat tappet
Valve springs, locks,.... everything with the comp cam kit (so should be best aligned)
timing gear: COMP Cams aluminum
Intake valves: 1.94 Summit Racing stainless steel for SmallBlock
Exhaust valves: 1.6 Summit Racing stainless steel for SmallBlock
Rocker arms: COMP Cams Ultra pro magnum roll rockers for standard 3/8 studs with 1.7:1 ratio
Valve, side and timing gear cover: Tom Lowe 12bolt.com
harmonic balancer: ATI super damper
water pump: Adelco standard (short)
pulley kit: MACH performance V-belt
fuel pump: Carter standard
Spark plugs: Pulstar
Spark wires: Davis Unified Ignition LiveWires 10mm/150ohms/ft
Coil: Davis Unified Ignition Inferno
Distributor: standard (maybe HEI if I find one from 1973 to 1983)
Carb: Rochester Q-jet
Intake manifold: Offenhauser 4bbl
Exhaust manifold: GMC Inline 292

with around 75cc chamber we should end up around a 9.3:1 compression and a RPM range from 1000-5500

This is what we think make sense after a lot of reading online and in Leo Santucci's inline 6 bible for a advanced street build.

Any thoughts? every feedback is highly appreciated as I'll spend some money for the build :D
 

·
Registered
Joined
·
2,831 Posts
Karl, I’m by no means an engine builder but it looks like you have a pretty good game plan together for your 250 and I’ll be watching your progress..
 

·
Registered
Joined
·
194 Posts
Discussion Starter #6
Haven't expected lumps would be the main feedback, have I?! :yes::no:

Alex (shop owner) and Robert (machinist) and I have discussed it. They didn't know about that modification, watched some videos about installation. But at bottom line we thought to follow Leo's street build advice and just wing shape the boss.

Should reconsider it :D

Karl I can help you with the lumps .
Larry I recognize you are in the inliner business since the 70ties and your knowledge is highly respected. Found a lot of your shared experience in different forums.
So its a honor that you jump in here! You do your own lumps and how could this work out?

Any thoughts on my selected COMP cam?

for the intake valve job we will use the specs from Leos book:
• 30 ° top cuts .040″ total width
• 45 ° second cut
• 60 ° bottom cuts blended

Working?
 

·
Registered
Joined
·
4,662 Posts
Hi Karl


For a Good 250 engine rebuild go over here . Also, Look at his "Lump Port Install" with Pictures.

His screen name : theycallmelarami ----- Joe from California.

When you get on this Post = his Pictures DO WORK (I just looked) , but
You need too give those pictures some time to-come alive .
Once you get his Pictures - Showing - then, you can even 'click on the top bar' and the pictures will get larger, to view closer detail .

https://www.stevesnovasite.com/forums/showthread.php?t=666207

Karl --- he has even more pictures : just click his 'screen name' ; then, look for his statistic ; click that … it will bring up all post for
theycallmelarami . --- (his last post was back in Aug. 2019) .

good to see you working on your 'Olds Omega'


I'm watching , jim
 

·
Registered
Joined
·
194 Posts
Discussion Starter #8
Thanks Jim, I have read Joes build. I think was one of the first to see 307 pistons used which I run accross.
 

·
Registered
Joined
·
226 Posts
A good friend of mine owned a '73 Omega hatchback back in '84. A straight six, TH350, p/s manual drums it was a tired but nice looker in factory metallic orange with white V top, side stripes & interior. Olds Super Stock wheels in white were a nice upgrade. He gave it up for a low mileage clean '72 Ventura II coupe with a 250 (swapping the Super Stock wheels over).

Here's a picture of my low-deck six on the stand.

Good 250 with a worked-on early 292 crank (clearance notches on the bottoms of the bores, custom Eagle rods & Diamond high-pin pistons), plus lump ports, Harland Sharp roller rockers, ARP studs.


Hey exotec, do tell about your ATI damper. :) Pulley grooves are on the factory damper. Are you going to run a small-block damper & electric fans?
I need a proper damper but want to run a conventional fan... A rebuilt 292 damper as a minimum, but my early 292 crank is only 6-counterweights rather than the later 12.
 

·
Registered
Joined
·
194 Posts
Discussion Starter #10
re ATI Super damper: yes, I'll go for a SB one
ATI does offer pulleys to be mounted on them, but just serpentine belt versions and than i for sure run into issues with the space between engine and radiator.

Therefore we choose the MACH performance V-belt SB kit for short water pump. The ATI dumper will move the crank pulley 1.5" forward so we will have to fabricate some spacers and modify the brackets for generator and A/C compressor.

the 1.5" move should be no issue with the fan fitting infront of the radiator
 

·
Registered
Joined
·
4,662 Posts
Hey exotec, do tell about your ATI damper. :) Pulley grooves are on the factory damper. Are you going to run a small-block damper & electric fans?
I need a proper damper but want to run a conventional fan... A rebuilt 292 damper as a minimum, but my early 292 crank is only 6-counterweights rather than the later 12.
Cam …

On my 292 ; my front 'crank damper' IS huge ---- (3 v-belt grooves).

So, I thought about getting that (292 damper) from 'Tom Lowe'. It shows that his 292 damper is shorter , more like on my 250 engine.
I'm not sure about --- 6 counterweights or 12 cw's ------ like if it will interchange & still work.

I CAN - NOT move my 'radiator forward any' , because of my A/C
(which I would like too keep "intact" ) . So, if I do use my 292
(truck motor -- Mexico - block, complete engine) …. I also need a 'shorter crank damper' to fit in my engine bay.
Keep us posted ….. thanks


Karl ---- I'm NOT trying too 'hi-jack' u'r build thread , just asking a question about our 6 motors ,,,,, (keeping any questions in one post, makes "searching for info easier" .

Thanks, guys …. jim
 

·
Premium Member
Joined
·
2,102 Posts
Third lump-port recommendation. I would suggest Forged 307 pistons, just for peace of mind.
I dont know of anybody who makes off the shelf forged 307 pistons. These would have to be custom made which means more expensive.
 

·
Registered
Joined
·
194 Posts
Discussion Starter #14
I would like to split off the engine build of my restoration project from my Oldsmobile Omega 1973 Coupe - maybe this is of any interest for other inliners as well.

After the engine shop confirmed they fixed the motor block a bit more professional than on the picture

I can go ahead with the build project.
unfortunately the fix wasn't that good - so the shop itself isn't happy about it and will not guarantee on the repair.

So I'm searching for a new motor block
 

·
Registered
Joined
·
194 Posts
Discussion Starter #15
even there are plenty of Chevy 250 and 292 blocks around in US, having them shipped to my shop in Austria will become crazy expansive and wasted money.

So I was looking at all places in Austria for US engines for alternatives and found something similar! I located a 1967 Pontiac 230 ohc 6 sprint version - complete engine with intake and split exhaust manifold as well Rochester Q-jet.

After some research about parts availability and such swap projects, I think I will go for it!!

so more to follow in my build project than :)
 

·
Registered
Joined
·
4,662 Posts
So I was looking at all places in Austria for US engines for alternatives and found something similar! I located a 1967 Pontiac 230 ohc 6 sprint version - complete engine with intake and split exhaust manifold as well Rochester Q-jet.

more to follow in my build project than :)

check this post out ---- then, haven't heard anything about this, lately

https://www.stevesnovasite.com/forums/showthread.php?t=657319


Then, back along time ago --- I bought a '67 Firebird with the OHC-6, with the factory 4bbl carb, 4 speed, split-exhaust.
That car did-not run well ---- could have been that "Flat - Cam" ----- so, I bought a new cam and 'cam follower' , and then, on my 1st drive from the house , got pulled over by a Garland Cop.
Speeding & running through the Gears ------------ turned - out, that he was an old High-School buddy ….. :rolleyes:

But, that OHC motor ran very well, for the short time I had that
'Bird . Plus, that motor is in your area.

Keep us up-to-date about your build …………….. :cool: … jim
 
1 - 17 of 17 Posts
Top