Just to be clear--that .pdf is WONDERFUL since Buicks use the same starter as Chevys that have the smaller, 153-tooth flywheel/flexplate. So converting your Buick to a Genuine GM (or at least, GM-style) Permanent Magnet, Gear Reduction (PMGR) starter motor is REALLY easy, you just buy a PMGR starter for a small-flywheel Chevy...but the PMGR starter does require special starter bolts. The suggested starter motor family in that .pdf is the PG260. The PG260 bolt holes are metric, while the threads in your block are SAE 3/8-16. Therefore the required knurl has to be stepped--bigger where it fits in the 10mm starter nose, smaller where it goes in the 3/8-16 engine block. Guys try to bolt on these starters with normal SAE hardware and end up with problems. Step-knurl/step-shank bolt photos: Genuine GM, and ARP. Truth is, in this application I like the GM bolts more. Buicks may need different part numbers, but the step-knurl or step-shank is similar.
Does anyone know the ARP number for standard Buick 455 starter bolts? The ARP website does not list them.
Wow. Some of you guys are really into metallurgy. My post was to help those having starter/flexplate clearance issues. And as I stated. It was pretty difficult to figure out on my back. But I made it work at that time by fabricating a spacer plate. To move the bendix back. And it barely cleared. So. Now with the engine out I took a chance for a few $$ bought a Hays flexplate. I'm trying to relate. It WORKS. I appreciate the science behind the starter bolt shear rate. And am schooled. I will absolutely use GM starter bolts.
These following 4 pictures were from my previous flexplate. JW? (not to be confused with Jim Weise) I personally don't know. No markings. But as anyone can see. The clearance between the bendix gear and the flexplate ring was obviously minimal. Again. I reached out at that time about a year ago. Larry (Wizard) and others had a whole lot of fixes. I'm here to tell you. This is what is working for me. Before and after pictures.
ARP 430- 3516 Summit says: Chev Beginning Year: 1970 Ending Year:1990 Engine Type: V8 Engine Size: 7.4L/454 These do not work. The knurl does not extend past the block: I'll try the 430-3508 next. Anyone know if they work? Anyone know the right ARP part number? update - these are for the after market mini-starters.
The Robb Mc starter uses the stock starter bolts. They tell you that in the instructions. The knurl locates the bolt inside the mounting block, not the engine block.
Agree - so does ARP make a kit to replace "stock starter bolts"? I dug deeper into the ARP catalog and finally found the starter bolt kit listings. The 3508 looks closest. The one above is for the "mini starter" like a Hitachi-Style I guess. I'll report back when I get the 3508 kit.
IDEALLY, the knurl is acting as a dowel-pin, half in the starter housing, half in the block. This is why I like the Genuine GM PMGR "step-knurl" bolts vs. the large-shank (starter motor), smaller-knurl (engine block) ARP mini-starter bolts. (Photos posted previously.)
Not an option with the Robb Mc and starters like it with a mounting block. I used the stock Buick bolts. I never really paid attention to the stock knurling. Not sure where they end up in that mounting block.
Winner winner chicken dinner - the ARP 430-3508 matches the stock OEM starter bolts. The knurl is more generous at .390 vs .381 used stock bolts. They are nice pieces made from stainless. Knurls stick out like they should: RobbMc shown - which is the same mounting as a stock starter.
This is what I got from the old starter bolts. Not exactly a German caliper but nonetheless. I will definitely go with the ARP bolts
