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Suggestions: Engine Rebuild/Upgrade  Rating:  Rating
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 Posted: 12-21-2011 07:34 pm
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Bob 13902
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It's been a half-dozen years since a lot of chatter on engine upgrades, so I wanted to "test" what I am concluding for my rebuild - before I purchase the parts - I figure some of those rebuilds got done and I could benefit from any knowledge and if performance expectations were met.
My 1973 Jensen-Healey Rebuild Plan:
Goal:  Street use (ability to autocross once in awhile) with strong power in low/mid-range for acceleration and to stay ahead of most of the Jensen-Healey's out there (especially Brett's).
·         Upper End - upgrades as follows:
o   107 JHPS cams (keep existing springs as long as characteristics still good)
o   EV8 Stainless oversize intake and exhaust valve set
o   HTD Sprockets with half-moons...any suggestions on best place to purchase?
·         Lower End - stay with existing 907 2.0L crank; upgrades as follows:
o   High Compression Forged Pistons (~10.5:1); 0.030" over (retain existing liners which are 0.030" over, provided new piston to cylinder gap is satisfactory after hone) ...any suggestions on best place to purchase?
o   Standard replacement bearings (main and connecting rod) ...any suggestions on best place to purchase?
·         Dell 45's (already purchased)
o   36mm chokes
o   jets: Main (160), A/C (230), Idle (58), 5-hole progression, ...
·         Electronic Ignition (existing), with distributor conversion for mechanical advance (due to change from Stromberg to Dells)
·         Jet coat headers (Delta high performance header) ...any suggestions on someone to perform?

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 Posted: 12-22-2011 01:57 am
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Jensen Healey
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Hi Bob,

My setup is similar to what you propose:
Stock crank balanced with the stock flywheel, pressure plate, pistons and rods.
107 cams with 104 sprockets.
JAE .030 over flat top pistons from Delta.
Stock Dellorto 40's with 35mm chokes 140 mains and custom air correctors.
Pertronix and MSD 6A.
Stock headers with single tube exhaust. Koni shocks, Hawk brake pads, sway bars, poly bushings, and summer only 205/60-13's round out the package.

I haven't dyno'd it but the seat of the pants meter says it was a huge improvement over the stock.

If I were doing it again I would get a 2.2 crank, 11:1 pistons, a lightweight flywheel.

I'm also getting 17 MPG on the highway after installing the cams. There's your tradeoff!

Kurt

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 Posted: 12-22-2011 10:32 am
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Dan (Florida)
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Joined: 03-16-2005
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I've never had a chance to compare performance with another JH but in my experience, getting rid of the Strombergs for Webers / Dells , lightening the flywheel 3 pounds , and putting in a Jegs super coil (65000 volts) covers most of it.  Of course careful attention to valve shimming and valve spring pressures have been preached to me for years.   If you have the rope seal engine I suggest shimming the base of the seal groove as much as you can without  binding the crankshaft.  The seal you buy is just a tad bit undersized and may leak if not shimmed . Going back in after a leaking rear main seal is not a fun job.    32 chokes work fine, the biggest air cleaners you can fit, ( I use 6 / 6 shop vac filters)  and  lighter 175 width tires.              hth Dan

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