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> Engine Rebuild, 2.5L Six
jfort
post Dec 6 2017, 12:44 PM
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update on the build

got the engine tin and the engine shroud done, black and red, respectively and a big improvement.

after the Eric Shea/Jay Leno show, I started giving a twin spark ignition more thought. I was going to have to spend money to refurbish my OEM distributor and I was going to go to an optical trigger. more reliable, I think, but still a pain to get there being so close to the fire wall.

long story short, we are going to do a crank fire and twin spark. Jay has the jig to drill the hole. (Anyone have a suggestion as to who, east of the Mississippi can drill it?) I figure it will be reliable and easier to tune and it's what Jay has on his race car.

as for the cam, apparently there is one a little more aggressive than the Solex, an "S special" or something?, that Jay is going to look into.

can't wait to start the rebuild after the turn of the year
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Mark Henry
post Dec 6 2017, 01:53 PM
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On the twin plug carbs with a trigger ignition here's a couple more options.

Megajolt Jr uses common Ford EDIS components that you have to source from a scrapyard. missing tooth trigger
https://wiki.autosportlabs.com/MegaJolt_Lite_Jr.

SDS has an ignition only system, more money but it's new and more complete, IIRC it uses subaru coils. hall effect trigger
http://www.sdsefi.com/cpiauto.htm


A bit spendy but this company has a missing tooth trigger wheel that come with their pulley
http://www.goingsuperfast.com/FORPORSCHE.html



There's a few more of these type of systems on the market.
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jfort
post Dec 6 2017, 02:51 PM
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thanks, Mark!
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jd74914
post Dec 6 2017, 04:13 PM
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I believe you can also use Microsquirt now for 6 cylinder wasted spark control. It's a bit more expensive than Megajolt, but wouldn't require the super old EDIS components, or the specialized trigger of the SDS system. You'd just be running a few coils and basically whatever crank trigger you wanted.

A number of people on the Bird Board have been using Denso 90080-19016 COPs. They are relatively inexpensive on eBay and I believe have their own internal ignitors so you wouldn't need any coil drivers (**have to check my notes so this might not be 100% and they may need drivers**). Not the same look as the firewall mounted coils with long wires or 12 plug dizzy, but pretty clean/slick setup IMHO.

Just some more things to think about. (IMG:style_emoticons/default/smile.gif)

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Larmo63
post Dec 6 2017, 04:52 PM
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I have a 2.4 7R cased motor with Daugherty cams DC-30, we ported to 36mm and I'm using the Clewett crank-fire ignition.Attached Image
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Justinp71
post Dec 6 2017, 06:29 PM
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(IMG:style_emoticons/default/popcorn[1].gif)

My uncle has a 2.5L in his '70 911, I was lucky enough to drive it a few times as a teenager. Man that is an awesome motor, so much instant power on demand. Got me hooked on flat sixes with webers.
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gereed75
post Dec 6 2017, 06:46 PM
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Assuming mean the hole for twin plugs, I bet Craig can do the twin plug heads. CGAR over on the pelican forums. He does excellent work, easy to work with and very reasonable. He is in Wisconsin or Michigan.

As I am sure you know, these things run fine single plug up to about 9.5 CR. But if you want it you want it.

Probably not your cup of tea, but I saw a novel twin plug set up built by some guys running a 914-6 in vintage events here in Pittsburg. They run one distributor in the normal hole and a second distributor run off the E cam. Kinda cool but you gotta time two dizzy's.

It s really not hard setting the stock timing once you do it a few times.
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914forme
post Dec 6 2017, 07:41 PM
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I have the SDS system here, and the extra coil packs ar pretty easy. Can also do the machining if need be. Just take it into work.

BTW, If I was building a 2.7L std / std, I would go with a set of Nickies if money no object. And that would get you to the 2.9L mark with better cooling and higher compression. For the cam, I have no idea as I am still debating that one, myself. (IMG:style_emoticons/default/shades.gif)
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Mark Henry
post Dec 6 2017, 08:43 PM
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QUOTE(jd74914 @ Dec 6 2017, 05:13 PM) *

I believe you can also use Microsquirt now for 6 cylinder wasted spark control. It's a bit more expensive than Megajolt, but wouldn't require the super old EDIS components, or the specialized trigger of the SDS system. You'd just be running a few coils and basically whatever crank trigger you wanted.


Yeh who wants to put that super old 90's EDIS tech on a car designed in the 60's.
SDS comes with the trigger sensor and on a six it's fairly easy to do.

And the Toyota COP's don't ignite by magic, guys that use them are often using MS and a missing tooth trigger setup. Or hall effect... or optical....
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jd74914
post Dec 7 2017, 03:40 AM
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QUOTE(Mark Henry @ Dec 6 2017, 09:43 PM) *

Yeh who wants to put that super old 90's EDIS tech on a car designed in the 60's.
SDS comes with the trigger sensor and on a six it's fairly easy to do.

And the Toyota COP's don't ignite by magic, guys that use them are often using MS and a missing tooth trigger setup. Or hall effect... or optical....

I get using EDIS 10-15 years ago, but now it seems like there are better options with more trigger flexibility since you need another controller anyways; getting rid of the EDIS module just removes part of the system if you use coils with built in ignitors.

Like I said, just trying to give some more options. Obviously you need a trigger for any non-distributor system. It's pretty economical to run COP with an MS-based system and doesn't require a specific type of trigger like SDS. You could even likely use the SDS CDI you like with a COP setup. It doesn't have internal drivers to direct fire coils (as seen by the presence of the Hurco/Bosch ignitor modules on their website), so provided SDS allows you to tune dwell, you could wire any coils you wanted to the output of the ignitor module.
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Mark Henry
post Dec 7 2017, 06:09 AM
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Since the OP is running carbs the MS box is another controller, just like in any other ignition only system.
But a debate on this is getting into hijack territory, if you want to argue this please start a new thread.

QUOTE(jfort @ Dec 6 2017, 01:44 PM) *


after the Eric Shea/Jay Leno show, I started giving a twin spark ignition more thought. I was going to have to spend money to refurbish my OEM distributor and I was going to go to an optical trigger. more reliable, I think, but still a pain to get there being so close to the fire wall.

long story short, we are going to do a crank fire and twin spark. Jay has the jig to drill the hole. (Anyone have a suggestion as to who, east of the Mississippi can drill it?) I figure it will be reliable and easier to tune and it's what Jay has on his race car.

as for the cam, apparently there is one a little more aggressive than the Solex, an "S special" or something?, that Jay is going to look into.

can't wait to start the rebuild after the turn of the year


So now you're getting into the good ol' Slippery Slope (IMG:style_emoticons/default/biggrin.gif)

There's absolutly no advantage in running twinplug ignition unless you are running high CR pistons. So you basically need a 10:1 to 11:1 CR

So Mahle's are likely off the table mostly due to availability, If you do find a set it will be around the same price as nickies if new.
The two other choices are JE pistons with replated stock cylinders, ballpark around $2400 or a set of nickies at $5500.

And that's not the end of it, with Nickies (IMO replated stock/JE's as well) you also need $6-700. worth of head studs, the twinplug labour to the heads and lower covers, add the cams, ignition, etc.
So you have now more than doubled (or tripled) your parts only bill.
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mepstein
post Dec 7 2017, 06:25 AM
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QUOTE(Mark Henry @ Dec 7 2017, 07:09 AM) *

Since the OP is running carbs the MS box is another controller, just like in any other ignition only system.
But a debate on this is getting into hijack territory, if you want to argue this please start a new thread.

QUOTE(jfort @ Dec 6 2017, 01:44 PM) *


after the Eric Shea/Jay Leno show, I started giving a twin spark ignition more thought. I was going to have to spend money to refurbish my OEM distributor and I was going to go to an optical trigger. more reliable, I think, but still a pain to get there being so close to the fire wall.

long story short, we are going to do a crank fire and twin spark. Jay has the jig to drill the hole. (Anyone have a suggestion as to who, east of the Mississippi can drill it?) I figure it will be reliable and easier to tune and it's what Jay has on his race car.

as for the cam, apparently there is one a little more aggressive than the Solex, an "S special" or something?, that Jay is going to look into.

can't wait to start the rebuild after the turn of the year


So now you're getting into the good ol' Slippery Slope (IMG:style_emoticons/default/biggrin.gif)

There's absolutly no advantage in running twinplug ignition unless you are running high CR pistons. So you basically need a 10:1 to 11:1 CR

So Mahle's are likely off the table mostly due to availability, If you do find a set it will be around the same price as nickies if new.
The two other choices are JE pistons with replated stock cylinders, ballpark around $2400 or a set of nickies at $5500.

And that's not the end of it, with Nickies (IMO replated stock/JE's as well) you also need $6-700. worth of head studs, the twinplug labour to the heads and lower covers, add the cams, ignition, etc.
So you have now more than doubled (or tripled) your parts only bill.

(IMG:style_emoticons/default/agree.gif) Twin plug doesn't make more power in its self. Just lets you use more CR and not have to use race gas.
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JmuRiz
post Dec 7 2017, 09:27 AM
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Another in agreement with the two above....I'm going the replated cyls with new higher CR pistons running single plug on pump gas.

Twin plug is cool looking for you'd nee more than 9.5:1 CR to make it worthwhile.

BUT those coil-on-plugs shown above are very interesting.
For now, I'm just going with my good carbs and dizzy (will check the curve to see if it's close enough to 2.7RS spec or send out for recurving) and running like that for a while. If I get flush with $ (haha) I'll do EFI and crank-fire ignition. But I figure doing changes in stages works well to not change too much at a time and feel if an upgrade is worth the $$.
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brant
post Dec 7 2017, 09:38 AM
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I agree with the above.
no need to go to twin plug (and spend anywhere from 1k - 5k on ignition) without changing to a high compression piston.



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914Toy
post Dec 7 2017, 09:53 AM
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Like Larmo, I have just installed single plug Clewett ignition on my 2.7 911 engine with Weber carbs and street cams, along with stock pistons and crank. Excellent outcome (IMG:style_emoticons/default/piratenanner.gif)
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Mark Henry
post Dec 7 2017, 10:01 AM
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Nice (IMG:style_emoticons/default/wub.gif)

But I'll raise you by 3.0 (IMG:style_emoticons/default/happy11.gif)

(IMG:http://www.914world.com/bbs2/uploads/post-26-1497554034_thumb.jpg)
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jfort
post Dec 7 2017, 11:01 AM
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beautiful! now we're talking. almost too beautiful to put back in a car. mine should look about like that.
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Mark Henry
post Dec 7 2017, 11:35 AM
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Brant and I are running TP dizzy's, Brant (like most) is doing it because certain race classes demand that you use a dizzy, I'm running it because a customer gave me a deal I couldn't refuse.

Don't get hung up on how beautiful the TP dizzy looks, because in a 914 you can't even see it, just a mess of snakes peeking out the top.
Like I said with TP you are going down the expensive slippery slope, you can make a very potent /6 with a single plug system at between 9 and 9.5CR. TP on it's own doesn't make a speck of HP, but it allows you up CR by at least a whole CR point, thus the HP gain of doing that.

A /6 engine is like a good recipe, there's a hundred different ingredients, but it only takes one bad ingredient to spoil the sauce.
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mepstein
post Dec 7 2017, 02:34 PM
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Unlike a 911, you see mostly see the back of the engine in a 914.
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pete-stevers
post Dec 7 2017, 09:55 PM
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I won't be running twin plugs in any engine builds...but I will definately will be watching this thread! (IMG:style_emoticons/default/happy11.gif)
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