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907 engine in a fit car?  Rating:  Rating
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 Posted: 10-12-2005 05:47 pm
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thurman
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Hi,

I am building a kit car (not a fit car, sorry) that normally would use an MGB engine and trans.  I have a line on a 907 and 4 speed from a JH that I would like to use instead.  I found a website from a guy that put a 907 in an MGB, and he wrote that the 907/4 speed requires that the driveshaft be offset to one side.  Is this correct?  Is the differential in a Jensen Healy not in the center of the rear axle?  If so, can anyone tell me how much it is offset?

Thanks,

 

Thurman

Last edited on 10-12-2005 05:58 pm by thurman

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 Posted: 10-12-2005 08:07 pm
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Jensen Healey
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2 inches off center towards the passenger side.

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 Posted: 10-12-2005 08:11 pm
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thurman
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Thanks!

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 Posted: 10-13-2005 11:23 pm
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Esprit2
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That's a space constraint. There is nothing inherent about the 907 that requires an offset. If the car you are building has room for the slant four on center, and if the asymmetric Center of Gravity of the slant four isn't an issue to you, then there's no reason to re-engineer the chassis to offset the engine. Lotus didn't offset the engine it it's own cars.

Regards,

Tim Engel

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 Posted: 10-14-2005 12:41 pm
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thurman
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Thanks, Tim.  I don't know if there will be a space contraint until I attempt to put the engine in.  The fact that the builder of the 907 powered MG had to use the healey solution tells me that I may need to think about the same problems in my car, as it is designed around an MGB donor.  Did Jensen use an asymmetrical axle set on the Healey, or did they use an offset differential to create the 2 inch offset?

On a topic more germane to the creators of this list, how hard/expensive is it to obtain parts for a Jensen Healey?  My interest in the car has increased a good bit since I rediscovered it a couple of years ago.   I noted that the one that I am getting my engine from did not get any bids on that unmentionable auction site, even with a $600 no reserve start.  Pretty cheap for a complete car!  Do the 907 engines continue to deserve their reputation for fragility, or are newer components available to make them more reliable?

Regards,

thurman

Last edited on 10-14-2005 12:43 pm by thurman

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 Posted: 10-14-2005 01:44 pm
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Judson Manning
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Thurman,

To know the 907 is to love it...most don't understand what it is, its potential or its quirks.  The MkI version of the 907 found in the earliest JHs was barely out of prototype testing and was sold to Jensen w/o warranty by Lotus.  For all intents and purposes, Jensen did Lotus' real-world development work. 

Few know the story of how Lotus debuted the engine in full Formula trim, pumping out 230 some odd horsepower.  Most only know about the chronic (fixable) problem of oil dripping on the headers.

Fragile?  The 907 rods, pistons, and crank are the same size as a Chevy 305/327/350 series V8.  When compared to most 2.0 engines, the 907 is huge.  If you adopt some of the later 910/912/920 features, it's basically bullet-proof.

907s 'die' only for a couple of reasons:

1.  When the timing belt isn't properly adjusted (bent valves).

2.  When the oil, carbs, and/or ignition aren't properly maintained (won't run).

3.  When the valves aren't properly adjusted (dropped valve).

The only 'weak' part of a 907 is the engine builder and his machinist.  The 907 is an exotic engine, and just like Porsche or Ferrari, it's not for the timid.  So ask yourself:  "Do you want an engine originally designed for a truck or do you want an engine designed for a Formula Car."

Keep me in mind if you want me to build you one...

Judson Manning

DLC Motorsports Div

Atlanta, GA

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 Posted: 10-28-2005 02:37 am
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Esprit2
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thurman wrote: On a topic more germane to the creators of this list, how hard/expensive is it to obtain parts for a Jensen Healey?  (Snip)...  Do the 907 engines continue to deserve their reputation for fragility, or are newer components available to make them more reliable?

Thurman,

All parts are readily available.   In some cases,  OEM parts are becoming difficult to obtain.   However,  some independent parts houses like JAE are stepping up to provide excellent alternatives.   Don't avoid the 9XX engines because of parts concerns.

Reliability is in the eye of the beholder.   No low production,  high performance specialty engine gives the ignore it and turn the key reliability of a modern, mass produced engine.   The 9XX demands a certain amount of attention,  and it demands it regularly.   Keep up with the demand and the engine is reliable.   Ignore it and it becomes expensive in a hurry.

The maintenance isn't hi-tech or expensive if you do it yourself.   Just change the oil and filter often,  use premium quality oil,  check the valve clearances frequently/ adjust as required,  and check the timing belt tension on a paranoid schedule.   If you are running the original style trapezoidal timing belt and tend to drive the car hard,  then cut the recommended replacement interval in half...  down to 12,000 miles or 2 years,  which ever comes first.   Replace the ignition points with an electronic system.   Keep the carbs balanced (Dellortos require less fiddling than Strombergs).   Non-engine,  but flush and bleed the brakes annually with Castrol GT LMA for street use.

Then drive the car !!   Nothing kills 'em like sitting idle for long periods.   The "Garage Queens" generate a disproportionate number of the horror stories.   Exercise it regularly (at least weakly, daily is better) and give it a good work-out.

I'd take off cross-country with one of my 907's at the drop of a hat...  no worries.   My two longest 907 trips were sudden with no prep.   Asheville, NC to Minneapolis non-stop (23 hours) and round-trip Minneapolis-Columbus OH-Minneapolis in a weekend.   Never missed a beat,  including 2 hours of inching along in a Chicago rush hour.

Treat the 907 right and it's a good engine.   Your reward for a little extra effort is the pleasure of driving a really fun engine.

Regards,

Tim Engel

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 Posted: 10-31-2005 02:46 pm
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thurman
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Thanks for the input all. I am now the proud owner of a 907 and 4 speed trans. I was totally amazed when I picked up the trans/bellhousing/shifter assembly. It is so light! This should be a great combo for my car. My engine appears to have been recently rebuilt. The PO said it was done by the PO before him. I pulled the intake assembly, alternator, and starter while it was still in the pickup bed to reduce the weight, then the two of us lifted it off the truck and placed it in the house. When I pulled the intake, I found the center water passage 50 percent clogged with blue silicon. A little sloppy on the assembly! I think I will strip it down to a short block and reassemble it for piece of mind. I love this engine!

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