Archive for the ‘Starter’ Category

IMI Hi-Torque Starter Setup Part III

Saturday, December 26th, 2009

The modified starter finally arrived from IMI.  IMI machined about 0.020″ from the top of the aluminum block to correct backlash and around 0.125″ from the starter housing to correct engagement.   When checking the distance between the starter pinion and flywheel teeth (IMI recommends between 0.040 to 0.100″) the feeler gauge measured 0.036″ but was slightly loose.  A 0.044″ stack wouldn’t fit so I estimate that the distance is probably right at 0.040″.  This time I used an acetylene tip cleaner to fit between the teeth to measure backlash.  One of the cleaners meaured in at 0.027″ and fit snug.  The next size up 0.033″ wire would not fit.  After the modifications I was very pleased with the fitment.  I was however concerned as to why they chose not to machine the starter that I sent back.  IMI elected to send a different starter.  I found this out only after I took it out of the box.  I could tell the starter was different a few ways.  The ring on the end of the pinion is black instead of gray.  I’m curious if they have had problems with the gray rings and opted to change material.  The same style starter was installed on the GTO and the ring broke in two after about a month.  When the starter was returned there was a black ring also.  The logo stickers are in slightly different locations.  The grain pattern on the aluminum mounting block was vertical on my original and horizontal on the replacement block.  Parting lines in the casting varied slightly.  Lastly, the starter housing and rubber boot is slightly greasy where the original was new and clean.  I don’t expect to have any problems with the replacement but I would have liked to be informed about the replacement.

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IMI Hi-Torque Starter Setup Part II

Saturday, December 5th, 2009

I checked the actual engagement of the pinion in the flywheel per IMI’s request.   After taking a few measurements I was able to determine that I had roughly 60% engagement at best.  [(Flywheel teeth width 0.444″) – (Distance of engaged pinion and edge of flywheel teeth 0.084″) – (Pinion tooth taper 0.078″)] = 0.282″ Engagement.  Or [(0.444″ / 0.282″)x100] = 63.5% engagement.  Matt at IMI and I agreed that this was not enough engagement.  Matt told me that they have a Pontiac test block where they check every 25th unit as a quality measure.  The test block utilizes an automatic flex plate instead of a flywheel.  Matt also said that there is a local Pontiac club where a fair number of members have installed the IMI starter without issue.  We then discussed backlash.  When the starter was bolted to the block without any shims, backlash measured in at 0.044″.  This was verified by sticking a piece of welding wire between the teeth.  I started with the smallest diameter.  The idea is to keep stepping up to a larger diameter until ideally one no longer fits.  In my case .044″ was the largest  available at the time.    The fit of the 0.044″ welding wire was slightly snug so actual backlash is not far from that value.  IMI specs appropriate backlash between .020″ and .030″.  The starter was shipped back to IMI in Whittier CA on Tuesday December 8th to be machined to fit my application.

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IMI Hi-Torque Starter Setup Part I

Saturday, November 28th, 2009

I decided to go with a high torque mini starter primarily due to it’s compact size.  Since I’m not running high compression (about 9.5:1) starting even with a factory starter wouldn’t really be a problem.  The difference in size between the mini and stock starters is simply amazing.  Since I’m running headers, I figured I’d need as much clearance as I could get.  The aluminum body aides in heat dissipation better than the stock.

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