What would you do?

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John Clarke
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What would you do?

#1 Post by John Clarke »

Hi All
It's engine rebuild time . We have Two engines, One is the Super 75 ( 616/2 ?) that came in the car (61 T5B) not matching Numbers but fairly close.
And the 912 (616/40) engine which we have had installed for many years The Super engine is under the bench in the garage, I do turn this engine over occasionally. We removed this engine cos we had the Oil pressure warning lamp flickering at idle after fast runs, no knocking or smoking, but was swapped out when we had the offer of a very late 912 unit. Not getting any younger and I can 'Only' ! afford one rebuild. Which engine should I choose? It's probably a no brainer but I'm torn between these 2 quite different engines !
Thanks for any input.
Regards Jay
 

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Vic Skirmants
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Re: What would you do?

#2 Post by Vic Skirmants »

912. Just hope it isn't a 1968 with the pre-cracked cylinder heads. :)

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Neil Bardsley
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Re: What would you do?

#3 Post by Neil Bardsley »

Get the 912 rebuild and sell the other to find it. Never is matching numbers so put the best engine in you can

Dick Weiss
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Re: What would you do?

#4 Post by Dick Weiss »

John,

What's the idle RPM during the oil light's flickering? Normally it should go out around 700+
along w/the generator light around 800-900.
Was a wet gage reading taken to verify oil pressure @ idle, and higher RPMs?
Finally, does the B engine have the large oil pump?

Dick

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George Hussey
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Re: What would you do?

#5 Post by George Hussey »

912 definitely, if you had the original numbers matching it would be different
George Hussey

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C J Murray
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Re: What would you do?

#6 Post by C J Murray »

It depends on what result you are shooting for. The 61 should be a large pump engine and that can easily produce 90 hp with Zenith carbs and you end up with a smooth engine that is nice to drive in all conditions up until a little over 5000rpm.

The 912 is better for more hp and higher rpm but late heads do often crack and Solex carbs make for a more fussy engine.

Either engine might be found to need a crank and if so a major advantage of the 912 is mute.

The decision always boils down to how you drive the car and what you like in an engine. If you are aggressive go for the 912 but if you are a "normal" driver that can't stand fussiness then the 912 has little if any advantage.

I would take the 61 apart and see what condition it is in. Then decide.
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John Clarke
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Re: What would you do?

#7 Post by John Clarke »

Hi Dick The Super engine has the Large Oil Pump. Oil warning at 750rpm Idle
Our 912 616/40) was one of the last 4 cylinder engines from 1969. Interesting comment CJ reference the 'Fussy Solex!
I have run both engines using Dellorto 40 DRLA's (with different jetting) so no carburation issues or 'fussiness' ?? I do have the original 40 P11 Solexes but they are the later Split Shaft, I never liked that shaft coupling, I wanted to get them converted to single shaft and try them as they have the extra progression holes for better transition. Some say that these later models are the best carbs ever for the 356! I'm hoping to find a scat crank in the 912 case LOL . Ref driving style , It changes. Sometimes I drive like I stole it , other times I potter to the shops! But I Never Lug It !
Thanks for all advice guys
Regards Jay
 

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Vic Skirmants
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Re: What would you do?

#8 Post by Vic Skirmants »

No question that the split-shaft Solexes are the best in the transition mode. I used to hate them because of the coupling system between the shafts; always loose, sloppy, and partially broken; at least on the ones I came across. Then I ended up with a good set on my race engine. Discovered that I could putter around the paddock in my race car with no difficulty. Hot cam, no low end torque, and did I mention first gear in the race car is actually a second gear ratio. Carburetor Rescue can modify the split-shafts with a solid shaft.

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Re: What would you do?

#9 Post by C J Murray »

Hi John, my friend Jeff Leeds loves Dellortos too. He keeps telling me to see the light and maybe I should seeing as how I am a Ducati Bevel believer and Dellorto is mandatory there.

With Dellortos you can have more than 90hp and the 61 case will handle much more than 90hp. What would I do..... Scat crank, strong aftermarket rods, Shasta 22* p&c, SC cam, mildly ported heads, stock valve springs, 123 distributor, welded fan, stock weight(or close) flywheel, PM oil filter, and 9:1 CR.

That would give you between 100 and 110hp with very good manners. Going for more power will require higher rpm and diminished low rpm power.

If you must have more power then increase the displacement to 1883, 1925, 2002, or 2133cc. That would best be done with the 912 case although the 61 case would work if you don't push the rpm or CR too much.
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Re: What would you do?

#10 Post by Jeffrey Leeds »

I'll add a little background, John. I've had my S90 for 8 years now. I bought it without a PPI or any other personal inspection and my first casual look-over led me to believe it came with Webbers. It had documentation that indicated an engine rebuild was done by Bob Grigsby in Sunnyvale, CA in the early 1990's. When I spoke with him I mentioned that it looked like he had put Webers on and he quickly corrected me that those were Dellortos. When I asked why he did that he said "because they just work". In the time I've been driving the car (about 60,000 miles) I have not made (or had to make) any adjustments (tuning) to the Dellorto's.
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Mike Wilson
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Re: What would you do?

#11 Post by Mike Wilson »

Add me to the Dellorto fan club. Easy to work on and parts readily available.

Mike
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Re: What would you do?

#12 Post by Richard Shilling »

When the Solexes were changed from solid shaft to split shaft we thought it was great. You could then balance all 4 barrels without having to try to bend the solid shaft. Many years later when I helped out at Fred Bush's shop for fun and relaxation, I ran into a couple of split shaft Solexes that showed why some don't like them. First carb had the plastic pad missing, so we made one. Then when I went to adjust the screw in the middle, it broke off. Fred had a couple of other Solexes so we got that one going. Second carb also had the pad missing but the spring was broken. Oh well, they were great in 1969. The 69 carbs were the latest Solex version and worked very well if set up properly: fuel level, accelerator pump discharge and aim (the squirt just clears the butterfly and ventruris), all 4 barrels sucking the same at 2,000 RPM. As pointed out the transition was improved on the latest Solexes. That said it's just a carb and any of the carbs, Solex, Weber or Dellorto will work fine IF set up properly.
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