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fl59bug Samba Member
Joined: November 23, 2005 Posts: 1976 Location: North Carolina
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Posted: Fri Oct 09, 2020 6:55 am Post subject: 1300 heads with 83mm big bore kit |
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Can 1300 heads be opened up to accept an 83mm big bore 40hp piston and cylinder? I'm thinking "Why couldn't they?" but wanted to take the lazy man's way out and ask others who have already tried
Just asking because I believe switching my big bore 40hp to later heads with their angled intakes would open up a lot more possibilities.
Not looking to mess with the stock 64mm stroke of my engine and I'd like to keep my stock 40hp rods with their stock 20mm wrist pins. That said I'm only open to the idea of swapping the top end ie heads and intake manifold.
If I do go this route I'm also aware of potential issues with compression ratio and pinging (thats what flycutting and shims are for!) and the need to manipulate the 1300 intake manifold to fit the narrower engine with its 5mm less stroke. I thought about just cutting the ends off the manifold and using rubber boots and clamps, similar to the boots on a dual port setup. Not sure if that would work though.
Thanks for any feedback - Ted |
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gears Samba Member
Joined: October 28, 2002 Posts: 4391 Location: Tamarack, Bend, Kailua
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Posted: Fri Oct 09, 2020 4:16 pm Post subject: Re: 1300 heads with 83mm big bore kit |
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To really open up possibilities, try to source a set of Euro 1300 dp heads/manifolds.
If I recall correctly, 1300 heads may very well have the same cylinder spigot dimension as 40hp. _________________ aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com |
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fl59bug Samba Member
Joined: November 23, 2005 Posts: 1976 Location: North Carolina
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Posted: Fri Oct 09, 2020 4:26 pm Post subject: Re: 1300 heads with 83mm big bore kit |
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Thanks. I'd certainly be open to using Euro 1300 DP heads, but I'm not sure where/how to find them. I searched on "Euro 1300", "1300 Dual Port" and "Euro Dual Port" but found nothing.
I believe you're correct that the SP 1300 heads match the stock 77mm P&Cs that come on '61 - '66 engines. That said, although I'm running 83mm P&Cs, they have thinner walls to allow for the larger piston, and I believe they have the same O/D as the 77s, so I'm not sure why I was thinking the head spigots would need to be opened up. Oh well, I believe that question is answered
Now the search is on for a good used or NOS set of 1300 S/P (or D/P if I can find them!) heads. I found several good S/P ones in the samba classfieds. |
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[email protected] Samba Member
Joined: June 24, 2015 Posts: 715 Location: Rialto. CA
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Posted: Fri Oct 09, 2020 5:19 pm Post subject: Re: 1300 heads with 83mm big bore kit |
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Why not just just open the head for the later 1500cc /1600cc use the 1500cc barrels "83mm cylinders" and trim them down for your correct compression instead of using shims as is the 1500cc cylinders are longer and can be trimmed down instead of playing around with shims ... |
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RWK Samba Member
Joined: June 24, 2009 Posts: 1337 Location: S.W. MI
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Posted: Sat Oct 10, 2020 5:46 am Post subject: Re: 1300 heads with 83mm big bore kit |
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The 1300 heads would be an improvement, they should accept the 83's those along with 82s which I had on a 40hp are all slip in. You cannot cut the manifold and use boots, the head is what it is bolted to to hold it, DP mani has a case mounting boss to hold it. you would have to cut, shorten and re weld it, or add a bracket so it mounts to case if you go the boot route. _________________ 73 Type 181
63 Type 113
63 Type 261- 428 071
62 Type 241-378 025 178 530 |
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fl59bug Samba Member
Joined: November 23, 2005 Posts: 1976 Location: North Carolina
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Posted: Sat Oct 10, 2020 10:00 am Post subject: Re: 1300 heads with 83mm big bore kit |
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Thanks guys. The 1500cc heads/barrels are an option but I already have the 83mm big bore kit which I'm happy with, so I'd like to keep that and just swap heads. That stokes my interest in the 1300 heads.
RWK, I forgot completely about how on the dual port setups the center section has the boss that bolts to the case. I'm wondering if I could use something like what CB sells to get around that:
https://www.cbperformance.com/product-p/3151.htm
They are out of stock right now, but this manifold reportedly works with 28-34 carbs and at least from the pictures it appears to have a bracket welded on that is long enough to bolt to one of the center engine case bolts. |
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fl59bug Samba Member
Joined: November 23, 2005 Posts: 1976 Location: North Carolina
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Lingwendil Samba Member
Joined: February 25, 2009 Posts: 3987 Location: Antioch, California, a block from the hood
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fl59bug Samba Member
Joined: November 23, 2005 Posts: 1976 Location: North Carolina
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Posted: Mon Oct 12, 2020 10:17 am Post subject: Re: 1300 heads with 83mm big bore kit |
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thank you Lingwendil, I didn't know CB sold these. |
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Lingwendil Samba Member
Joined: February 25, 2009 Posts: 3987 Location: Antioch, California, a block from the hood
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fl59bug Samba Member
Joined: November 23, 2005 Posts: 1976 Location: North Carolina
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Posted: Mon Oct 12, 2020 1:30 pm Post subject: Re: 1300 heads with 83mm big bore kit |
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Nice! I can't wait to do this mod. |
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Lingwendil Samba Member
Joined: February 25, 2009 Posts: 3987 Location: Antioch, California, a block from the hood
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fl59bug Samba Member
Joined: November 23, 2005 Posts: 1976 Location: North Carolina
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Posted: Mon Oct 12, 2020 4:04 pm Post subject: Re: 1300 heads with 83mm big bore kit |
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Lingwendil wrote: |
I think with maybe a little jetting you should get a nice, strong, economical little engine out of it |
That's what I'm thinking - My little 40hp will be stronger than a "built" Okrasa 36hp, and should approach the output of a a stock-ish single carb'ed dual port 1600! |
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Protodog Samba Member
Joined: August 02, 2006 Posts: 160 Location: DEARBORN, MICHIGAN
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Posted: Sun Feb 13, 2022 10:39 pm Post subject: Re: 1300 heads with 83mm big bore kit |
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fl59bug wrote: |
Thanks. I'd certainly be open to using Euro 1300 DP heads, but I'm not sure where/how to find them. I searched on "Euro 1300", "1300 Dual Port" and "Euro Dual Port" but found nothing.
Now the search is on for a good used or NOS set of 1300 S/P (or D/P if I can find them!) heads. I found several good S/P ones in the samba classfieds. |
Part Number: 113101355EX
Opening in the head for the cylinder is 90mm
Scored a set from England. Got on their waiting list. A few years later the sent me an e-mail asking me if I still was interested.
Most often the twin port 1300 heads were bored for larger cylinders and will no longer fit the 77mm cylinder.
https://www.coolairvw.co.uk/product/113101355ex/ |
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Slow 1200 Samba Member
Joined: July 02, 2004 Posts: 2103
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Posted: Mon Feb 14, 2022 5:02 am Post subject: Re: 1300 heads with 83mm big bore kit |
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besides the heads not being available as a spare, more often than not the 1300 DP heads are cracked beyond repair, so they seldom get reused, most people just rebuild the engines as 1600s and don't look back |
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