C Head Restoration
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From: ON,Canada
C Head Restoration
These heads are going onto a 350 (and I am compensating for the larger chambers and such) I am keeping the stock springs for the near future and going roller rocker with new valves, but aside for the internal and mating surface work, what is the best way to clean the grease and dirty bits to prep, I would usually just use cleaner and rags but the grooves and indents are hard to work with.
Also I know the valve sizes and basics but can anyone put some light on the strength of the dual springs on intake and regular on exhaust, and will these larger heads with bigger flow not change the engine displacement? From 350 to say 355? And if so, if I bore as well would my cubic inch be, with .30 it tells me 355, do the heads change that?
I have also read that it is ok to use carbide bits to remove the rough casting marks on the heads and block is it a good idea?
Also I know the valve sizes and basics but can anyone put some light on the strength of the dual springs on intake and regular on exhaust, and will these larger heads with bigger flow not change the engine displacement? From 350 to say 355? And if so, if I bore as well would my cubic inch be, with .30 it tells me 355, do the heads change that?
I have also read that it is ok to use carbide bits to remove the rough casting marks on the heads and block is it a good idea?
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Posts: 988
These heads are going onto a 350 (and I am compensating for the larger chambers and such)
How are you compensating for the larger chambers, milling, decking, dome pistons or stroked crank?
I am keeping the stock springs for the near future and going roller rocker with new valves, but aside for the internal and mating surface work, what is the best way to clean the grease and dirty bits to prep, I would usually just use cleaner and rags but the grooves and indents are hard to work with.
My best advice for you would be to have them professionally cleaned and checked for cracks before any work is done. Usually this is included with your basic three angle valve job. My machine shop charges $80 for the clean up, check for cracks and resurface.
Also I know the valve sizes and basics but can anyone put some light on the strength of the dual springs on intake and regular on exhaust, and will these larger heads with bigger flow not change the engine displacement?
If you really want I could look up the specs on your valve springs, but it really shouldn't be an issue unless your using a huge cam. The heads will not change the displacement.
From 350 to say 355? And if so, if I bore as well would my cubic inch be, with .30 it tells me 355, do the heads change that?
Yes it will be 355CI, and no the heads will not change that.
I have also read that it is ok to use carbide bits to remove the rough casting marks on the heads and block is it a good idea?
I think you should take some time to read through this thread I started called "Home Porting Techniques". There's a ton of useful technical information in there-
https://classicoldsmobile.com/forums...echniques.html
By the way even if you mill .050" off your "C" casting BB heads, you will still be extremely low on compression. Which intake manifold were you planning on using? There's going to be a huge mismatch going from SB heads to BB heads. If you want to wait one week, I will post up how my 355 race engine will perform at the track on it's shake down run. We're almost ready. Good luck with your project.
How are you compensating for the larger chambers, milling, decking, dome pistons or stroked crank?
I am keeping the stock springs for the near future and going roller rocker with new valves, but aside for the internal and mating surface work, what is the best way to clean the grease and dirty bits to prep, I would usually just use cleaner and rags but the grooves and indents are hard to work with.
My best advice for you would be to have them professionally cleaned and checked for cracks before any work is done. Usually this is included with your basic three angle valve job. My machine shop charges $80 for the clean up, check for cracks and resurface.
Also I know the valve sizes and basics but can anyone put some light on the strength of the dual springs on intake and regular on exhaust, and will these larger heads with bigger flow not change the engine displacement?
If you really want I could look up the specs on your valve springs, but it really shouldn't be an issue unless your using a huge cam. The heads will not change the displacement.
From 350 to say 355? And if so, if I bore as well would my cubic inch be, with .30 it tells me 355, do the heads change that?
Yes it will be 355CI, and no the heads will not change that.
I have also read that it is ok to use carbide bits to remove the rough casting marks on the heads and block is it a good idea?
I think you should take some time to read through this thread I started called "Home Porting Techniques". There's a ton of useful technical information in there-
https://classicoldsmobile.com/forums...echniques.html
By the way even if you mill .050" off your "C" casting BB heads, you will still be extremely low on compression. Which intake manifold were you planning on using? There's going to be a huge mismatch going from SB heads to BB heads. If you want to wait one week, I will post up how my 355 race engine will perform at the track on it's shake down run. We're almost ready. Good luck with your project.
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Joined: Feb 2014
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From: ON,Canada
I honestly haven't chosen anything for the motor yet, I just know I will need to compensate. Where can I find domed pistons?
and if I do flat top pistons what do I do to the heads.and for intake I will either be opening up one like the performer rpm that says it has enough metal to be shaved off for larger ports, or go with the victor which apparently has the larger ports.
and if I do flat top pistons what do I do to the heads.and for intake I will either be opening up one like the performer rpm that says it has enough metal to be shaved off for larger ports, or go with the victor which apparently has the larger ports.
Out of Line, Everytime😉
Joined: Dec 2006
Posts: 10,083
From: Melville, Saskatchewan
Get Speedpro flat top pistons or pistons like the 3cc Probe or 1.5cc CP, 0 deck the block, the higher quality pistons will need the block milled less due to a taller compression height and mill your C heads to whatever chamber size you need for 9.5 to 1. Use the RPM intake and port matching can be done but isn't totally necessary. You will need to mill the intake side of the heads or the intake itself after milling the C heads. Even small valve C's with minor work should be an improvement. Get an estimate, Procomp heads might not be much more if totally rebuilding the C heads.
Thread Starter
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Joined: Feb 2014
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From: ON,Canada
Get Speedpro flat top pistons or pistons like the 3cc Probe or 1.5cc CP, 0 deck the block, the higher quality pistons will need the block milled less due to a taller compression height and mill your C heads to whatever chamber size you need for 9.5 to 1. Use the RPM intake and port matching can be done but isn't totally necessary. You will need to mill the intake side of the heads or the intake itself after milling the C heads. Even small valve C's with minor work should be an improvement. Get an estimate, Procomp heads might not be much more if totally rebuilding the C heads.
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Joined: Jul 2012
Posts: 2,990
From: Vancouver BC
Why
The stock small block head works fine,don`t waste your time and money running big block heads on a small block.
The small block Olds is a great engine that responds well to intelligent builds.
What are your goals
The stock small block head works fine,don`t waste your time and money running big block heads on a small block.
The small block Olds is a great engine that responds well to intelligent builds.
What are your goals
Last edited by Bernhard; Jul 16, 2014 at 11:56 PM.
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I'm not looking for something that works fine, I won't have many costs other than milling the heads, once I am able to compensate for having the Big Block heads I can take advantage of the bigger valves and flow, the motor is going to be bored, flat tops, roller rockers, hydraulic roller cam and lifters possibly chevy 6 inch rods, edelbrock OL4B intake, headers, Edelbrock 750 carb.
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From: Vancouver BC
Any of the early heads 5 or 6 castings work very well. They respond well to the larger intake valve and other performance modifications.
To make use of the larger ports you will have to rev the engine and the OL4B intake is great for producing TQ at lower RPM.
Carefully match all you components look what others have done on ROP or here before using a big block head on your small block.
The small block olds can be a very stout engine if well built and planed.
To make use of the larger ports you will have to rev the engine and the OL4B intake is great for producing TQ at lower RPM.
Carefully match all you components look what others have done on ROP or here before using a big block head on your small block.
The small block olds can be a very stout engine if well built and planed.
Engine Builder
Joined: Jan 2010
Posts: 552
From: Louisville, ohio
Speaking from experience I can tell you I've seen a few 350 Olds that were absolute screamers with a pair of BBO heads, cam, and intake. I wouldn't hesitate to use them. Especially since you already have them. Only concern you really need to pay attention to is how well the intake covers up the larger intake port. Some standard intakes will, some won't.
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Joined: Feb 2014
Posts: 157
From: ON,Canada
Any of the early heads 5 or 6 castings work very well. They respond well to the larger intake valve and other performance modifications.
To make use of the larger ports you will have to rev the engine and the OL4B intake is great for producing TQ at lower RPM.
Carefully match all you components look what others have done on ROP or here before using a big block head on your small block.
The small block olds can be a very stout engine if well built and planed.
To make use of the larger ports you will have to rev the engine and the OL4B intake is great for producing TQ at lower RPM.
Carefully match all you components look what others have done on ROP or here before using a big block head on your small block.
The small block olds can be a very stout engine if well built and planed.
Thread Starter
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Joined: Feb 2014
Posts: 157
From: ON,Canada
Speaking from experience I can tell you I've seen a few 350 Olds that were absolute screamers with a pair of BBO heads, cam, and intake. I wouldn't hesitate to use them. Especially since you already have them. Only concern you really need to pay attention to is how well the intake covers up the larger intake port. Some standard intakes will, some won't.
I really do want to have the BB heads on it, but I feel like those screamers decked the crap out of the heads, or did they??
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Joined: Jul 2012
Posts: 2,990
From: Vancouver BC
Before you go any farther
What are your goals?
Street strip car?
street car?
Budget?
ET MPH goals?
With big block heads you will need a big gears and a loose converter the engine will have to rpm to make any use of the big block head.
Its not peak hp that makes a car quick or fun to drive its usable hp/tq throughout the rpm range.
What are your goals?
Street strip car?
street car?
Budget?
ET MPH goals?
With big block heads you will need a big gears and a loose converter the engine will have to rpm to make any use of the big block head.
Its not peak hp that makes a car quick or fun to drive its usable hp/tq throughout the rpm range.
Last edited by Bernhard; Jul 17, 2014 at 10:10 AM.
Registered User
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Posts: 2,990
From: Vancouver BC
Speaking from experience I can tell you I've seen a few 350 Olds that were absolute screamers with a pair of BBO heads, cam, and intake. I wouldn't hesitate to use them. Especially since you already have them. Only concern you really need to pay attention to is how well the intake covers up the larger intake port. Some standard intakes will, some won't.
Do you know his budget?
Goals for the car?
Street strip car?
Street car?
Skill set?
There are lots of very fast 5, 6, 7 small block headed cars.
To make a 350 run hard is as easy as it gets as it is a very good engine!
Engine Builder
Joined: Jan 2010
Posts: 552
From: Louisville, ohio
Engine Builder
Joined: Jan 2010
Posts: 552
From: Louisville, ohio
Do you know how much head work has been done to all these hard running 350s you speak of? Any possibility a large majority of them have had port work done that brings them up to the port volume and flow range of a stock BBO head?
Once again, what is your personal experience with this swap?
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Posts: 2,990
From: Vancouver BC
My experience with the small block 350 Olds.
1975 350 wrecker engine low km
Bolt on number 5 heads with 2'' intake valves, stock ports,cross over not filled.
headers hooker
intake holly street dom out of the box
69 q jet carb tuned for the engine
factory points distributor blue streak points and lighter springs.
Mild hyd cam from Dave Smith
4:11 gears
3000 stall conv
13.04 et
3500 lb car with out driver pulled the front wheel.
Min 150 passes at the track
shifted at 5500 rpm
stock suspension and shocks
no hop bars and slicks only traction add on
There was 12's in the car just never had the time to tune our way there.
1975 350 wrecker engine low km
Bolt on number 5 heads with 2'' intake valves, stock ports,cross over not filled.
headers hooker
intake holly street dom out of the box
69 q jet carb tuned for the engine
factory points distributor blue streak points and lighter springs.
Mild hyd cam from Dave Smith
4:11 gears
3000 stall conv
13.04 et
3500 lb car with out driver pulled the front wheel.
Min 150 passes at the track
shifted at 5500 rpm
stock suspension and shocks
no hop bars and slicks only traction add on
There was 12's in the car just never had the time to tune our way there.
Last edited by Bernhard; Jul 18, 2014 at 01:00 AM.
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Posts: 2,990
From: Vancouver BC
So you are going to have to mill the heads to get the comp up and you have head to intake seal and fitment issues. Skill required to get it right and you still have the potential for fluid leaks. Time and money well spent I think not. What about push rod length and rocker geometry with excessive head shaving what about header fitment?
All the points I listed are valid you design and build based on your skill set, goals,and budget.
All the points I listed are valid you design and build based on your skill set, goals,and budget.
Last edited by Bernhard; Jul 17, 2014 at 04:16 PM.
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Posts: 2,990
From: Vancouver BC
One last thought there have been many hard running 350 engines with stock or mild port work on ROP and a few here. If you are taking all out race 350 bolt a set of big block heads on but for 90% of all builds the cast iron small block heads work good. If you want a little cheep HP/TQ follow the head porting thread and do a mild clean up of the bowl and block the heat riser. We have a local racer knocking on the tens with cast iron 5 heads and stock rods. Yes the heads are ported but not by some big name porter he did them himself.
The key to any build is have your build well laid out and don't shoot yourself in the foot.
The engineers did a great job designing the 350 Olds engine its just a mater of adding the right parts.
Spend your money on a good set of full length headers hookers are cheep and good
a good intake used or new holly street dom or Ebrock RPM.
good hyd cam from BTR or Dave Smith not to big but one matched to your build and gas that you are going to run.
Heads start with a good 5 or 6 head cores and have them rebuilt by BTR or Dave Smith
2" intake . Cheep hp use a quality ss valve that has necked down steam and good flowing back face to the valve.
The stock heads that we used to run 13.04 used stock 2'' steel valves no back cut.
If you are going to rebuild the engine buy a quality set of pistons and use a good machine shop that has a TQ plate for the Olds engine.
Buy Bill T/ BTR book on how to build a Max High performance Oldsmobile engine.
Don't rush your build make informed decisions.
The key to any build is have your build well laid out and don't shoot yourself in the foot.
The engineers did a great job designing the 350 Olds engine its just a mater of adding the right parts.
Spend your money on a good set of full length headers hookers are cheep and good
a good intake used or new holly street dom or Ebrock RPM.
good hyd cam from BTR or Dave Smith not to big but one matched to your build and gas that you are going to run.
Heads start with a good 5 or 6 head cores and have them rebuilt by BTR or Dave Smith
2" intake . Cheep hp use a quality ss valve that has necked down steam and good flowing back face to the valve.
The stock heads that we used to run 13.04 used stock 2'' steel valves no back cut.
If you are going to rebuild the engine buy a quality set of pistons and use a good machine shop that has a TQ plate for the Olds engine.
Buy Bill T/ BTR book on how to build a Max High performance Oldsmobile engine.
Don't rush your build make informed decisions.
Last edited by Bernhard; Jul 17, 2014 at 04:05 PM.
Engine Builder
Joined: Jan 2010
Posts: 552
From: Louisville, ohio
Well, I'll succom to the internet born wisdom of Bernhard. Not worth arguing about it. Basically no experience but the internet and books one has never followed a recipe from definitely trumps 30yrs of experience.
If the op wishes to contact me via PM I'll gladly help him out.
If the op wishes to contact me via PM I'll gladly help him out.
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Joined: Jul 2012
Posts: 2,990
From: Vancouver BC
No I have never put big block heads on a small block true, I have never built a small block that could make use of them.
I did not tell him to follow my build but to educate himself with wisdom and knowledge from master engine builders.
Dave Smith Pro Stock engine builder.
BTR Bill T Top shelf Oldsmobile engine builder.
The 350 Olds engine has set many stock records using factory cast iron heads and intake.
I posted my first experience with a Small block Olds build when I was 19 years old.
These engines respond well to basic modification.
There is a parts pusher in California with a Big name that starts with a M and has lots of experience with unhappy under performing engines.
Experience is not enough the above is case and point. Look at the track record of Dave and Bill and you will see why I posted there names as top shelf engine builders and a great sources of information.
Do your home work
Post a question like this on ROP
At what power level should I bolt a set of big block heads on a small block?
How much work is it to bolt a set of big block heads on a sbo
1. Whats involved?
2.Costs?
3. Problems that I will encounter?
4.Would I be better off using a small block head for what I'm trying to accomplish?
I did not tell him to follow my build but to educate himself with wisdom and knowledge from master engine builders.
Dave Smith Pro Stock engine builder.
BTR Bill T Top shelf Oldsmobile engine builder.
The 350 Olds engine has set many stock records using factory cast iron heads and intake.
I posted my first experience with a Small block Olds build when I was 19 years old.
These engines respond well to basic modification.
There is a parts pusher in California with a Big name that starts with a M and has lots of experience with unhappy under performing engines.
Experience is not enough the above is case and point. Look at the track record of Dave and Bill and you will see why I posted there names as top shelf engine builders and a great sources of information.
Do your home work
Post a question like this on ROP
At what power level should I bolt a set of big block heads on a small block?
How much work is it to bolt a set of big block heads on a sbo
1. Whats involved?
2.Costs?
3. Problems that I will encounter?
4.Would I be better off using a small block head for what I'm trying to accomplish?
Last edited by Bernhard; Jul 18, 2014 at 09:21 AM.
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Joined: Jul 2012
Posts: 2,990
From: Vancouver BC
Registered User
Joined: Jul 2012
Posts: 2,990
From: Vancouver BC
I posted the question on ROP to get more feed back from the Olds community.
Smitty you are a professional engine builder and have built more Olds engines than I ever will.
I just question if it is a good idea for his build.
I'm sorry if I offended anyone as that was not my intent, except for the parrot. I wish the original poster good luck in what ever he uses for cylinder heads.
Smitty you are a professional engine builder and have built more Olds engines than I ever will.
I just question if it is a good idea for his build.
I'm sorry if I offended anyone as that was not my intent, except for the parrot. I wish the original poster good luck in what ever he uses for cylinder heads.
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Posts: 988
Well I don't have anywhere near the experience that Smitty has when it comes to BB heads on a SB, but we did just finish putting one together. I have close to $6000 into it which really isn't that much. 80Rocket (Don) took it to the track today. He called me after his first pass. The car went 12.18 with a crappy 60 foot and he lifted a couple hundred feet before the finish line. He crossed the beams going only 97 MPH. I will post a full report on the porting thread after we do some more testing on Sunday. He's going to switch over to the MSD grid system. IMHO the BB heads on a SB do require a lot of planning to get compression back up, but I really don't think the larger ports, or valves hinders the lower RPM torque responsiveness. It's all about putting together the right combination of components. If a person was considering bolting the ProComps, or Edelbrocks onto a SB, but they did not have the money, I think the BB cast iron heads are a great alternative. They flow very close, the combustion chambers are close, and you can't beat the price as long as the guides and seats are in good shape. If you guys were following along with the porting thread then you witnessed my SB heads flowing better than the ProComps out of the box, and just behind the Edelbrocks. The cast iron heads have their place. I don't think I will be porting any more SB heads. Jeremy pointed out to me that you could bolt a set of junk "J" heads on a SB and it's like getting a free port job. I don't think the Speed Pros are the best choice for pistons either. If I was to turn the clock back on my SB build, I would have done a stroker to get the compression ratio back up there. Omega man when you're ready to get serious, shoot Smitty a PM or give him a call. You won't be sorry. Bernard I think you mean well with your advise, but without ever actually bolting BB heads on a SB I believe your comments were based on others failure to get the combination of parts right. I agree you can not simply bolt on BB heads and expect them to perform well without having all your ducks in a row.
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Posts: 988
If you want to see track proven results of SB heads on a BB, go to page 19 post #737 here-
https://classicoldsmobile.com/forums...echniques.html
https://classicoldsmobile.com/forums...echniques.html
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Joined: Feb 2014
Posts: 157
From: ON,Canada
Hadn't got any reminders from this thread, indeed the ol4b has enough material, I would actually have to open the heads up because the intake has bigger ports, I measured them. AND YES HEI will work as long as it is a space saver like many Mallory ones. About a 4.5 diameter is max
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