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1679 SP build advice / or easy way to 75hp single port
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bcrazy
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PostPosted: Sat Jul 12, 2025 9:46 am    Post subject: 1679 SP build advice / or easy way to 75hp single port Reply with quote

In my 63 beetle i have this SP engine:

1584 (1500 heads with very light porting work, 3 angle valve job)
Scat C25 (1.1 intake rockers, exhaust 1:1)
7.9:1
1 3/8 4-1 header with "quiet pack" exhaust
2xSolex 35PDSIT

This engine runs ok, but compression should have been a bit higher, and especially the deck height ~0.060, should be closer

Got myself a small mill, and now plan to build the engine again.
My aim is 75 Hp and good low end torque

Got a good set of 88mm P&C, but can bore the case for for 90.5 if needed. (put i prefer to no split the case)

So my plan it is to cut the heads for more compression (8.5-9.0?), or if necessary also deck the case.


Is this a good recipe for ca 75 HP, and 130-135 nm?
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67rustavenger
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PostPosted: Sat Jul 12, 2025 10:26 am    Post subject: Re: 1679 SP build advice / or easy way to 75hp single port Reply with quote

Machining on a short block is not a good idea. How would you keep machining chips out of the block?

Also, how would you go about securing the block to the table (<wrong term but, this is the best I can describe it) with the rods sticking out of the case?
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bcrazy
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PostPosted: Sat Jul 12, 2025 11:13 am    Post subject: Re: 1679 SP build advice / or easy way to 75hp single port Reply with quote

If i need to correct deck height i will take the block apart.
If deck height measures to less than 1.5mm, i will just adjust the compression by machining the heads.
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RWK
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PostPosted: Sat Jul 12, 2025 12:04 pm    Post subject: Re: 1679 SP build advice / or easy way to 75hp single port Reply with quote

Decking the case is always a good idea, a used case is usually sagged between the cylinders.
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Teeroy Premium Member
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PostPosted: Sat Jul 12, 2025 5:24 pm    Post subject: Re: 1679 SP build advice / or easy way to 75hp single port Reply with quote

If you dont want to split case to correct deck , take it off the bottom of the cylinders
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Alstrup
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PostPosted: Sun Jul 13, 2025 2:45 am    Post subject: Re: 1679 SP build advice / or easy way to 75hp single port Reply with quote

bcrazy wrote:
In my 63 beetle i have this SP engine:

1584 (1500 heads with very light porting work, 3 angle valve job)
Scat C25 (1.1 intake rockers, exhaust 1:1)
7.9:1
1 3/8 4-1 header with "quiet pack" exhaust
2xSolex 35PDSIT

This engine runs ok, but compression should have been a bit higher, and especially the deck height ~0.060, should be closer

Got myself a small mill, and now plan to build the engine again.
My aim is 75 Hp and good low end torque

Got a good set of 88mm P&C, but can bore the case for for 90.5 if needed. (put i prefer to no split the case)

So my plan it is to cut the heads for more compression (8.5-9.0?), or if necessary also deck the case.


Is this a good recipe for ca 75 HP, and 130-135 nm?

Easy.
Replace the cam to something proper. CB2280 w. 1,25´s for good overall power. CB 2232 for very good mid rpm grunt. W100 for more rpm power.
Reduce deck to 0,040-0,045"
Set CR to 9-1 (8,8 with the 2232)
Figure out what intake length the engine wants. - Most likely about 20 mm more than what it is.
There is the potential for a true 75 hp sgl port.
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Dusty1
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PostPosted: Sun Jul 13, 2025 2:33 pm    Post subject: Re: 1679 SP build advice / or easy way to 75hp single port Reply with quote

Alstrup wrote:

Easy.
Replace the cam to something proper. CB2280 w. 1,25´s for good overall power. CB 2232 for very good mid rpm grunt. W100 for more rpm power.
Reduce deck to 0,040-0,045"
Set CR to 9-1 (8,8 with the 2232)
Figure out what intake length the engine wants. - Most likely about 20 mm more than what it is.
There is the potential for a true 75 hp sgl port.


There is just about everything I need for my so- called "Formula Street" motor.

I'm going to cheat and use dual port heads. Twisted Evil

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