More Air Flow for a Model 425 on a 327 SBC

Propane, Butane, LPG, GPL, C3H8, C4H10
storm
Posts: 796
Joined: Wed Jan 10, 2007 10:10 pm
Location: NSW, Australia

Re: More Air Flow for a Model 425 on a 327 SBC

Post by storm »

Marc wrote:
Wed Feb 10, 2021 3:11 pm
I think to add stain steel turnips in the baffle.
If this is steel wool then yes that is a good idea. Something that makes the oil vapour collect and turn back into liquid form is a good thing.
Marc wrote:
Wed Feb 10, 2021 3:11 pm
As said I measured wear on timing chain, and from what I hear it is still some wear... what would you do if you were me? replace it or not replace it? I checked in my old car papers and the mains were line bore (align hone), so I need a 0.005 or 0.010 reduced centerline timing chain but impossible to know exactly with my tools. So I even don't know which timing chain I 'd need?
Realisitcally speaking if the engine was align honed properly there shouldn't be any need for a shorter chain. If the engine is 15 years old the chain "should" be ok but it is cheap insurance to get a brand new good quality double roller chain and fit it with the new cam. I personally would get a rollmaster but I'm not sure if they are available in Europe.
Marc wrote:
Wed Feb 10, 2021 3:11 pm
IWith this question, we can go further and ask about the status of the cylinder bores, main and rod journals...
Yep you could and it could end up being a very expensive exercise if you do. If you are confident in the short block leave it alone if not pull it apart and measure it before you go any further.
Marc wrote:
Wed Feb 10, 2021 3:11 pm
II am questioning myself, also I am thinking my engine is still more than ok for the intended use... but it is good to see what other think/ would do in my position.
I'd fit a new timing chain, new harmonic balancer (the technology in them has gone ahead in leaps and bounds), refit the vortecs, a nice set of headers, and drive it.
Fuel flow requirements calculations
Engine air flow requirement calculation: CFM = Cubic Inches x RPM x Volumetric Efficiency (VE) ÷ 3456

Marc
Posts: 73
Joined: Mon Apr 23, 2012 8:54 am

Re: More Air Flow for a Model 425 on a 327 SBC

Post by Marc »

Good to hear it Storm,
From my papers all the job was made complete on the motor back in the days... but is not 15 years ago.. is it in 1983.
I never really ran this car since I have it (bought end 2000) because I did other things in life and also didn't had experience with rebuilts. It staid for years still in a dry temperate garage.

Anyway I believe yes I should change this timing chain as I am in any way getting it out. Amazon.com is a good place to buy for me, because the worldwide shipping charges are so low, I could also investigeate shops in Europe but they seem to only have standard Melling 'like' parts.

Should I buy a timing chain kit or only the chain? I have a double roller on the motor.
So you confirm I don't even need a 0.005 shorter one?
I will check rollmaster. What are the good brands? Prices vary from 30 to 200 us$

Thanks,

Marc

Marc
Posts: 73
Joined: Mon Apr 23, 2012 8:54 am

Re: More Air Flow for a Model 425 on a 327 SBC

Post by Marc »

On Amazon they don't have rollmaster.
They have
- Competition-Cams-3100-Hi-Tech-Chevrolet
or the same undersized but more than twice the price
- COMP Cams 3100-5 Hi-Tech

Or I can search else where for the rollmaster CS1000 as it sems to be the one for my application.
Thanks

Marc

Marc
Posts: 73
Joined: Mon Apr 23, 2012 8:54 am

Re: More Air Flow for a Model 425 on a 327 SBC

Post by Marc »

Rollmaster : I found this specified for part CS1000 :

" Line Bore Kits available in .002″, .005″, .008″ and .010″. When ordering Line Bore Kits mark order with LB2, LB5, LB8, LB10 after the part number. When installing any new timing componentry we recommend using a degree wheel to set perfect timing. "

Shouldn't it be good to know if I need a undersized version? How could I measure something so small? I have a dial indicateor but I don't know if a measure is possible and if finally this makes any difference.

Regards

Marc

storm
Posts: 796
Joined: Wed Jan 10, 2007 10:10 pm
Location: NSW, Australia

Re: More Air Flow for a Model 425 on a 327 SBC

Post by storm »

Off the top of my head I do not know the relevant oem specifications but you measure the centreline of the cam tunnel to the centreline of the crank tunnel and that will give you the distance. You then compare that distance to the oem specification. It is a fairly precise measurement, which things like deck height and V degree are all linked to, that is why a good quality machine job will not change the block section of the main (crank) tunnel but rather the cap is what receives the vast majority of the machining.

Are there any markings on the current chain and gears? If yes you may be able to cross reference them to new part numbers but even then you are relying on the previous owner and machine shop doing the right thing back in the 1980s (I was still at school in the early 80s :shock: ).

You are not going to like this but realistically an engine that old that has such little usage as you described would be well served with a full refresh. Others will probably disagree with me but now I know how old it is that is my gut feeling. Because the 327 is not the original engine, you mentioned the car was originally a 6 cylinder, I'd be seriously considering a 350 or 400 small block, or a 454 big block. I'd probably lean towards a 400 small block with roller cam to take advantage of the technological advances of the vortec heads.
Fuel flow requirements calculations
Engine air flow requirement calculation: CFM = Cubic Inches x RPM x Volumetric Efficiency (VE) ÷ 3456

Marc
Posts: 73
Joined: Mon Apr 23, 2012 8:54 am

Re: More Air Flow for a Model 425 on a 327 SBC

Post by Marc »

Hey Storm,
Just spent some time this late afternoon calling an engine machine shop nearby and reading things making my mind on the possible shorter center to center dimension of cranck to cam...
And considered what I understand I trust your word. The machine shop should have removed so little material that basically the new center position is short of 0.0001" or maybe 0.0005" because of the imprecision of the dial gauge. So indeed there should be no need for a timing chain short of 0.005. And 0.001 will be unnoticed. From this consideration I don't even understand why line bore + hone would generate center to center shorter of 0.01? - they sell kits for it.

So... I quickly found on ebay, a good offer for a harmonic balancer #206 red serie and a timing chain #CS1050 gold serie. It is some money but I purchased it.

My camaro will get Australian parts ! :-)

Marc
Posts: 73
Joined: Mon Apr 23, 2012 8:54 am

Re: More Air Flow for a Model 425 on a 327 SBC

Post by Marc »

I didn't read your msg before wirtting... Though you wouldn't be there...

Yes sure it should be great to have a fresh 400 ci sbc... I also need to have a plan to drive this camaro somehow to justify this money spent. So far it is all ok as I have the heads (I bought them in 2005 fitted for LPG/propane and more power). the cam swap and small other stuffs is cosmetic.
Changing the block... well I would need to look for it in Europe, make it rebuilt, this takes time and is a different project.
Finally I could come up with that solution in the future when
- I have a problem with my 327
- I found another fresh block and am ready to invest the money in it

Maybe another option is also to look for complete builts in US for sale used and get it shipped.

Or a imminent choice is to get this 327 out of the car and get it checked by the machine shop and I don't like it ...


Regards,

Marc

Marc
Posts: 73
Joined: Mon Apr 23, 2012 8:54 am

Re: More Air Flow for a Model 425 on a 327 SBC

Post by Marc »

Dears,

I think Tom68 may be right, compression is pushing this oil everywhere...
and I am made my mind I 'd better get this engine out on a stand, removing a piston and see the actual status of the piston segments.
Not planned initially, but as I understand I could do this....

I could replace segments, main journal bearings and rod bearings.
No need for a machine shop.

I'll keep you updated.

Mac

storm
Posts: 796
Joined: Wed Jan 10, 2007 10:10 pm
Location: NSW, Australia

Re: More Air Flow for a Model 425 on a 327 SBC

Post by storm »

Good to see you are moving along. Take plenty of photos and share your findings.
Fuel flow requirements calculations
Engine air flow requirement calculation: CFM = Cubic Inches x RPM x Volumetric Efficiency (VE) ÷ 3456

Marc
Posts: 73
Joined: Mon Apr 23, 2012 8:54 am

Re: More Air Flow for a Model 425 on a 327 SBC

Post by Marc »

Hi guys,

We hoist the old motor with trans last Wednesday with my friend. He is a mechanic, he looked more closely, the cylinders are glazed. We didn't take measurement, I have no tools. I considered cost of rebuilt with boring and honing versus buy a short block. Then I considered for the money a roller long block is more interesting with a roller cam already on it. I considered the place to purchase and I have a forwarding company ready to ship goods for me.

So the initial project is by far changed by now!!

I am considering a Blue Print engine.
There is either a 383 stroker aluminum heads 450 lbft torque 430 HP or the more reasonable 350 vortec heads 400 lbft torque 375 HP, thee heads are unported.
Going the 430 HP route will also need a larger propane mixer specially fabricated (impco 600), a better matching intake, a second vaporizer, new propane valves, ... this adds up! Or forget about propane and go back to gasoline.
This engine also cost a lot more.

So I am making my mind to go for the cheaper 350, which is a 355ci.
https://blueprintengines.com/products/3 ... -bp3503ct1
I have an option on their last available engine.
Then I would port these heads (I cannot use mine as they don't accept the lift), keep my single Impco 425, reuse my intake, and go and correctly tune this engine on propane with IWEMA in Netherland, I am in contact with them and we are organizing for the job.

Of course, on these new vortec heads now I don't have anymore the special material propane valve inserts... But they do come with SS valves on it. Are you familiar with the flash lube systems? I had one on my mercedes years ago, this intended to save valves and inserts... don't know people running these on V8 though.. I guess some do.

Meanwhile, I stopped working on my worn out engine and will try to sell all parts.

I have another projet waiting for the new engine and accessories: install a new electrical harness making by the same time a clean freshly painted engine bay.

Regards,


Marc

Marc
Posts: 73
Joined: Mon Apr 23, 2012 8:54 am

Re: More Air Flow for a Model 425 on a 327 SBC

Post by Marc »

or
"383 stroker aluminum heads 450 lbft torque 430 HP "
fitted with a dual carb intake manifold and twin impco 425 ?

I have to check my bank account :-)

storm
Posts: 796
Joined: Wed Jan 10, 2007 10:10 pm
Location: NSW, Australia

Re: More Air Flow for a Model 425 on a 327 SBC

Post by storm »

Blueprint have a pretty good reputation as far as I am aware.
Fuel flow requirements calculations
Engine air flow requirement calculation: CFM = Cubic Inches x RPM x Volumetric Efficiency (VE) ÷ 3456

Marc
Posts: 73
Joined: Mon Apr 23, 2012 8:54 am

Re: More Air Flow for a Model 425 on a 327 SBC

Post by Marc »

If I go for the 430 HP motor, I would go dual impcos 425, and I will need an low rise dual carb intake, and I think one with a 90° flange connection for the mixers...
I looked 5 minutes on the web and found this
https://theamcforum.com/forum/custom-in ... 22222.html

I also think that, with the 90 ° angle both carbs shall be on the same side , passager side.
The problem unclear is the linkage, because on my car the linkage is on the driver side, connected to the pedal in a straight line. I didn't look into that.

What do you think?

From what I understand I would need to custom build such an intake, and I cannot weld. However I can make drawings and I know workshops.
But do you think I need a dual carb intake to start with? Which type?

I seriously think to go this way, with both Model E evaportaors on the passeger side as well close to the mixers, so the hoses are short.

I need to make a choice for the engine soon because I have an option for the low cost 350 for the moment. Money will flow again later :)

Before making a choice on the engine, I want to know if I can have a solution at least for the built.

Another option is listen to go to IWEMA in the netherlands, they said they can custom built a impco 600 for such high power application. I think their cost will be more than if I modify an intake and install 2 impcos. but maybe I am wrong...

Of course, the 375 HP 355 ci is more easy and less costly to built, staying single mixer (maybe not the impco there are other types at IWEMA), and I am not yet decided, because maybe I would still be very happy with that smaller engine.
It is just that, I am 40, I think it is once in a life time that I would built an engine...

THanks,

Marc

Marc
Posts: 73
Joined: Mon Apr 23, 2012 8:54 am

Re: More Air Flow for a Model 425 on a 327 SBC

Post by Marc »

This is certainly e optimum fuel air mixture distribution to the engine, and this is my idea to install laterally 2 impcos , but only on 1 side...
http://1u4we0207ruc34o1s412c2ca.wpengin ... 2.JPG.jpeg

This is a lot more easy and maybe it works also fine? Just a Y on a normal intake for 1 single 4 barrel carb :
https://cache.gmh-torana.com.au/img.pho ... 0748-1.jpg

My feeling is that the fuel distribution is better when intake has a large plenum with 2 base plate.


Your comments are appreciated.

Thanks

Marc

Marc
Posts: 73
Joined: Mon Apr 23, 2012 8:54 am

Re: More Air Flow for a Model 425 on a 327 SBC

Post by Marc »

This one would fit under my hood just fine with straight impcos.... it is very low rise.
it comes with a carb linkage option.

but advertised for power 1500 to 5000. and no plenum. So?

I think a german guy, Al , use it on its big block car?

Or go with the air gap version 7520 and install elbows + impcos vertically? linkage?

When considering 2 model E vaporizer, is it ok to have 1 liquid fuel line 8 mm OD?

I don't need to decide anything in a hurry, just interested by what you think would work best with this engine to have good performance, so I can consider my budget approximatly.

Marc

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