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post #1 of 256 (permalink) Old 10-17-2010, 06:31 PM Thread Starter
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Building a 200HP Twin Spark

Building a 200hp Twin Spark

A quick history first . I put my Twin Spark into my spider with a Jim Steck distributor and Weber 45's . Over the last two winter I have gone to aftermarket fuel injection /ignition using motorcycle throttle bodies and GM coil packs all run by a DTA Fast computer. This and an Alfaholics stainless exhaust system. You can find more on that here. Twinspark running on Motorcycle Throttle Bodies


Now that the control side of things is all sorted I have been looking at getting a Twin Spark head from Alfaholics . They can supply a 198 hp or a 215 hp. Both of these heads come at what I think is good value for money but I think I can do a lot of the work myself. I am under no illusion that I can do as good a job as Max and the boys but I think I will end up with a great motor .

I am hoping to make 200 hp and to be able to spin up to 7000 rpm . I am going to follow the plan set out in Jim Kartalamakis book The Alfa Romeo DOCH Engine High-Performance Manual .

From what I have read the biggest problem with the TS heads are the Inlet Valve seats. They are recessed into the head.
To fix this problem I will replace the seats and the valves with ones 2mm larger than stock.

The next step to make more power is a camshaft change . I have yet to decide on the "right " cam for the job.

With the change to bigger intake valves and a higher lift cam comes the need for bigger cutouts in the pistons.
There are a few different sets available Alfaholics, AH Motorstorts ect . The ones I like like the best right now are from JE Pistons . This is because of cost and that there are no problem to have them modified. For a few hundred bucks I am going to upgrade to lighter wrist pins and Total seal rings.

The final compression is still to be decided on . I am thinking 11:1 or a bit higher . I want to run on pump gas. We can get 94 around here. But if I have problems I can use the 2nd map function of the DTA to retard the timing .

Since I will have to open up the bottom end I am going to get a set of Carrillo I beam rods. They are 56g lighter and good up to 200 hp and 7500 rpm. I have to find out if will be using standard bearing set.

Then there are the other items like reshaped valve guides , performance valve springs, valve shims and a gasket set.

So all that and the machining / porting should keep me out of trouble over the winter.

Also when the motor is out I am going to replace the four gear box studs on the back of the block with bolts.
I know a lot of people say it is easier to take the motor and gear box out together but this is not true with a Twin Spark in a spider. This kit should make the job even smoother.



Here is the parts so far from Paul Spruell and Alfaholics

1 - Set of Pistons 11:1 Alfaholics (EDIT)
4 - 47mm Intake Valves Alfaholics (EDIT)
4 - Reshaped bronze Intake Guides
4 - Reshaped bronze Exhaust Guides
1 - Set performance Valve Springs
1 - Set Carrillo Rods I beam type
8 - Valve Shims / Lash Pads
1 - Main Bearing set
1 - Block rear Stud Kit


1- 13mm Intake Cam 1-12.9 Exhaust Cam Alfaholics (EDIT)

To do

Head
Remove head and strip
Replace Intake Valve Seats
Remove Valve Guides
Port intake and exhaust ports
CC of Combustion Chambers
Surface head if required
Install new Valve Guides
Valve Job
Install new Valves, Cams , Springs , shims


Block
Pull crank
Remove rods Pistons Liners
Fit rods to Crank
Install new pistons
Find and fix oil leek (rear main seal?)
Change Gear Box studs to bolts


Well that is the plan for now . Did I miss anything ? Input on Cams and Compression welcomed .

Is it worth having the pistons coated? I am wondering about Crown and skirt coatings how much
difference do they make ?


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[SIZE="2"]David Munro[/SIZE]
Toronto ON Canada
1969 Spider JR Twin Spark

Last edited by 69alfa; 11-27-2010 at 12:12 PM. Reason: Update Parts List / spelling
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post #2 of 256 (permalink) Old 10-18-2010, 12:49 PM
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David,

My winter plans are very similar so I will be following your progress closely. I am a bit ahead of you though with the engine already stripped down. But all the parts have been in boxes for a year or more going through a couple of house moves. So maybe I am not ahead of you after all.

Jason
Bloomington, MN
74 Spider (maybe Twin Spark in 2011)
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post #3 of 256 (permalink) Old 10-18-2010, 02:50 PM
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Hi Dave,
I'm sure it would be worth while to drop RJ (Alfar7) a note on the cams.

[FONT="Comic Sans MS"]Ken Lee
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Oakville, ON[/FONT]
73 GTV
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post #4 of 256 (permalink) Old 10-18-2010, 02:59 PM
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Ditto---the cams.

With the right cam RJ says that for most purposes there is little need to go to bigger valves.


Bob,
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post #5 of 256 (permalink) Old 10-18-2010, 06:03 PM Thread Starter
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Jason where did you get your parts ?

Ken I have not forgot the tape .

Yes you guys are right about the cams.

From what I have read the bigger valves will make a huge difference .
It' no just the extra 2mm but also moving the valve into the proper position in the chamber.


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post #6 of 256 (permalink) Old 10-18-2010, 07:03 PM
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David,

The parts I have so far are general rebuild parts mostly from Centerline. I have been on the fence regarding pistons, cams, valves, etc. One upgrade leads to a slippery slope of additional costs. The real hang up for me has been the decision on whether to go to an aftermarket EFI set up. I have read the write up you did on your car closely and almost pulled the trigger on the DTAfast when the dollar was strong earlier in the year. But I still go back and forth. Some days all stock. Others Autronic, DTAfast or Emerald. I should resign myself to the fact that I will go toward the dark side sooner or later. And then I wouldn't have to worry about fitting that big plenum and MAF under the Spider hood.

Jason
Bloomington, MN
74 Spider
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post #7 of 256 (permalink) Old 10-18-2010, 08:26 PM
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I wouldn't go over 10.4 CR if you want to burn pump gas (93). I maybe all wrong though and 11.1 may be just fine if you can get 94 gas where you live.

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post #8 of 256 (permalink) Old 10-19-2010, 03:10 PM Thread Starter
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Thanks Murry I was asleep at the keyboard when I typed 11:1 to 11.5:1
I changed it .

I should stay to the safe side with the compression as it would be a pain to have to add octain bust all the time.


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[SIZE="2"]David Munro[/SIZE]
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post #9 of 256 (permalink) Old 10-19-2010, 04:47 PM
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Quote:
Originally Posted by 69alfa View Post
Thanks Murry I was asleep at the keyboard when I typed 11:1 to 11.5:1
I changed it .

I should stay to the safe side with the compression as it would be a pain to have to add octain bust all the time.
Anymore with the EPA I'm afraid that premium someday might be a thing of the past. My engine was tuned on 93 gas which was not sold in Nebraska but was sold everwhere across the river in Iowa

At the time in Nebraska the highest octain I could get was 92 which was close enough but then that disappear and 91 was the only thing I could find for 3 years..........that's when I started to blend octain boost. I did this for one season and what a pain that was.

Then I found a dirty little gas station just across the river that had 93 which was a real pain too but just this summer a brand new gas station a mile down the road starting carring 93.......Boy how nice it is to just drive down the street and fill up now.

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post #10 of 256 (permalink) Old 10-25-2010, 03:45 PM Thread Starter
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It looks like I am going to go with the Cams that Max At Alfaholics Sells.
The price is not too bad and they are hollow. That will make my car sooo much lighter.

He has also got 47mm intake valves I think I will go for them also.

Anyone know of any downsides of 47mm over 46mm ?

And the pistons that Wes Ingram is selling 10.8 : 1 and very light.


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post #11 of 256 (permalink) Old 10-26-2010, 12:33 PM
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Be sure your TS crank has the drilled end and add the bronze bushing for the transmission input shaft.

11:1 is pretty high CR even for 94 rated gas. I had 11.2 CR in a 2L race motor that ran gangbusters on 112 octane, but cr*p on any pump gas, even with those unreliable octane boosters. In the early 70's SUNOCO had pump gas as high as 108 (SUNOCO 260 brand), which worked well. That was RO rating, not the generally lower MON or the current 'blended' rating of modern gas.

Ultimately I put a race-class solid copper 2.0 mm (0.80 in) thick head gasket that dropped the CR to about 10.7. Still have knock problems on summer blends.

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post #12 of 256 (permalink) Old 10-26-2010, 04:20 PM Thread Starter
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Robert, the motor has been working in the car for years now so yes I have the pilot hole and bushing .

The 10.8 :1 pistons I am going with are from Wes Ingram and he told me they are good for 92 octane. So I hope he is right.

The Twin Spark should take more compression because it does not need as much spark advance ?

Also with the cams being of long duration the motor should stand more compression.

The other thing is my computer setup has a second fuel / ignition map so if I need to I can have a good gas and bad gas map.


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post #13 of 256 (permalink) Old 10-26-2010, 07:56 PM
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Some of the newer small engines have knock sensors. Essentially a specialized microphone, their EFI /computer set-up uses them to retard ignition as needed.

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post #14 of 256 (permalink) Old 10-27-2010, 05:06 AM Thread Starter
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Would be nice if we could use them but I have heard that the Alfa motors make too much noise for the knock sensor. I would think it would be the cam chains ? Not sure where I read that I will have to look it up.


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post #15 of 256 (permalink) Old 10-29-2010, 08:38 PM Thread Starter
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First order placed

The ball is rolling. I placed the first order this morning with Max at Alfaholics.

I ordered the Cams , 47mm Intake Valves, Valve Springs and 11:1 Pistons that Alfaholics use to make 215 HP.

Max told me that he has sent two motors over here with the 11:1 pistons and the customers have reported no problems with pinging .
He runs his car on 98 over there but mapped it on 95 .

I read about Octane ratings before I placed the order and it seems that on this side of the pond we take the RON + MON /2 to get the number on the pump.

In the UK they have the RON on the pump .

So ... I think it will all work out.


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1969 Spider JR Twin Spark
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