Engine and Transmission Tech

300 HP would be nice! I’m assuming the oil mods aren’t needed on the 300?

Thanks Jim! So, if I find the 300 i would still need the bell and a T5 tranny right? And would probably have to shorten the drive shaft or lengthen. It’s seems that finding a 215 short block would be easier. What has to be done on a 215 block to make my 300 crank work? I’m thinking of all the changes needed to get the 300 (if I found one) to work VS finding a 215 short block and making it work with my crank, not to mention I have the Olds heads which have the extra bolt holes.
I’m in a holding pattern until the cam and crank are done. But all the info is helpful!

I believe oiling mods are recommended for all of the old school Buick V8 engines.

You would need your rear seal adapter and if a Buick 215 you would need to tap the 6th bolt holes (rocker mounting) and the four small steam holes on each side using your head gasket as a template. On the 300 you are right. The best bell is the GM V6 H body that was originally a cable clutch. Pop up on Ebay now and then.



Edited 2 time(s). Last edit at 05/28/2025 06:59PM by mgb260.

I don't know of anybody who has drilled and tapped the Buick deck for the extra Olds head bolts. Might be a bit thin there, good idea to drill a small pilot hole first to see if there is enough metal. At least that wouldn't ruin the block. You'd be a Pioneer and that carries a risk. An Olds block avoids this risk, or Buick heads. Either one is going to need the oiling mods, and again, please use a piloted bit to avoid this problem. It's easy enough to make one from a standard bit so there really is no excuse not to. It takes all the risk out of the operation.

The desired cable operated bell (which allows use of an external slave) usually costs about $125 off ebay. Make sure you get the clutch fork. (Possible to use an S10 fork but requires mods) If your present setup uses the HTOB (likely) you can use any BOP bell, even the one with dual starter humps, just have to slice off the one not needed. Usually about $75-100, occasionally less. You can sell your existing 5 speed and bell for enough to cover the cost of the T-5 and the replacement BOP bell. Likely more. The T-5 is not necessarily any better but also no worse. Might not shift as smoothly, could be a little stronger, has no internal oil pump to fail, fits the tunnel easier. Not sure what has to be done with the driveshaft, possibly just change the yoke.

If your existing crank is from a 300 it will fit another 215 block as is. That also means your flywheel will work with any 300 you use. If you have a mini starter and it's in good shape you can sell it for what a new SBC (SAE) mini starter will cost, possibly more.

I don't know what sort of seal adapter you have on the 215. Drop-in Viton 2 piece seals are available for the 300, they require the hash marks to be removed from the seal journal on the crank.

I have heard of replacing only the lower rope seal half and getting good results. Makes sense to me. If the engine is otherwise sound the oil suction galley can be drilled while on the engine stand, the cam swapped out, new timing gears, replace the lower rope seal, install a viton or neoprene front seal, grind or redi-sleeve the damper, set minimal oil pump end gap, fit a V6 (5/8" tube) pickup and you are good to go. HF sells a cheap leak down tester that is worth getting to check out the donor engine with.

The Olds heads came in 3 flavors depending on compression ratio. You can cc the chambers to see which ones you have or someone here may know the casting numbers. Only the 10.25 and 11:1 heads are desirable really but the 8:1 ones are by far the most common. You need to know which ones yours are. Sometimes engines got built with the LC Olds heads and the LC Buick pistons due to availability, the result was about a 6.5:1 CR. A usable engine but not a good one.

Again it depends on what you find as a donor engine. The right engine can greatly simplify your job. BUT if you have a 300 crank now, that flywheel is not going to fit a Late Rover or BOPR no matter how fine it is otherwise and a new one will cost around $500 and maybe more.

A complete engine with a good leak-down and decent oil pressure (can be run on the engine stand long enough to check it.) is a much better starting point than a bare block.

Jim

Jim B, The flywheel is custom and only works with the 300 crank in the 215 block. The rear seal adapter uses the 300 rubber seal in a spot where there are no hashmarks. Both Jon's and Scott's are Buick blocks drilled and tapped for the extra bolts. Probably done at the Olds factory. He has the 2 barrel heads and the same GM V6 pistons that Jon had. One thing I noticed is those pistons give about 10.3 compression with the composite gasket and it looks like Scott had the steel shim which would bump the compression even higher, close to 11 to 1. Buick block is identical except lack of the threaded holes and 4 small steam holes on upper block deck





Edited 3 time(s). Last edit at 05/29/2025 02:29PM by mgb260.

The desirable Monza Skyhawk V6 bellhousing. Note the pivot on the other side like Ford and downward angle where the other bells go straight out into the tunnel. I would cut off the driver side starter hump.




Edited 1 time(s). Last edit at 05/29/2025 11:40AM by mgb260.

Mike Moor's setup with that bellhousing, S10 clutch fork, throwout bearing and Nissan slave. We are using a slightly larger Toyota slave on Jon's setup.

[forum.britishv8.org]




Edited 1 time(s). Last edit at 05/29/2025 11:48AM by mgb260.

Scott, since you have a 3.0 rear gear a 93-2000 Camaro V6 T5 with the 3.75 first would work fine.96-2000 has ITOB. It has the Ford pattern though instead of GM. The Chevy V8 T5's are getting scarce. This old thread of mine shows an easy way to fit the Ford pattern T5:

[www.mgexp.com]



Edited 2 time(s). Last edit at 05/29/2025 03:25PM by mgb260.

It seems that just getting another olds 215 short block and moving on is going to be the easiest and least expensive option. If i found that nice 300 engine I fear that the cost of everything involved will be far greater than picking up a good 215 short block. I have all the parts sitting here except the crank and cam which are being sorted at 2 shops. It doesn’t help that I’m learning on the fly here and putting this thing back together will be far easier that starting over with a different engine.

I Emailed Brian Macmillan in Seattle. He used to have a large assortment of 215 and 300 stuff. Maybe he'll get on this thread?



Edited 1 time(s). Last edit at 05/29/2025 08:56PM by mgb260.

Thanks guys!, I think I saw Brians stuff in the classifieds and PM’d him. If he has any of those engines or blocks, that would be sweet. I changed the rear ring and pinion to 343 gear ratio. I still have the 300 set up. I was thinking the 300 was why it wasn’t barking the tires on spirited starts. I was wrong. The gear ratios in the LT77 aren’t great I’ve heard and going with a different tranny has been mulled over. But, this tranny works fine and to save costs I would delay that change if possible. What are the chances there’s an Olds 215 block or a Buick with the 6th head bolt sitting around? Fingers crossed Mr. McMillan has something I can use.

Scott, Actually the machine shop can drill and tap and helicoil the 6th bolt hole. Maybe you should Email Johnson Machine with the picture of the breakout and ask them what they think. The more I think about it, may be easier to Tig a piece of aluminum tubing to patch and just make a straight 1/2" hole. You know the later Rover and the Buick 300 only use 4 bolts per cylinder. The 6 that Olds uses is great but was meant for Turbocharging, A lot of guys just leave the bottom bolts on the Buick just snug or leave them out completely. Another alternative block is the 3.5 Rover, pretty much the same as the 215 Buick .If you use the Olds heads you still need the steam holes. You could even put threaded inserts in the Olds rocker stands and bolt your heads right on the Buick block.That is pretty much the Buick setup.



Edited 1 time(s). Last edit at 05/29/2025 10:14PM by mgb260.

OK, thanks Jim. I’ll reach out to the machine shop. It’s good there are some options. If my block can be fixed, that would simplify everything.

Probably so. I didn't realize you had the custom flywheel. The shop should be able to do a repair on the breakout. Might even be able to straighten out the hole. Worth asking about.

Jim

I sent a picture to Johnson Machine and got word back that they don't do any welding and they wouldn’t be able to fix the break out. At least I didn't drive down there for nothing. They also said they are backed up and have a waiting list. They aren’t doing any assembly work due to the backlog. So, on to plan B.

Scott, There has to be a good welding shop in your area. You could call these guys:

[www.kitsapmuffler.com]

I have heard good things about this machine shop:

[www.yelp.com]

Seattle Autosport does a lot of work on Rover's.

Kitsap muffler referred me to DJs Welding in Gorst. Talked to him and he’s willing to give it a shot. No guarantee , but he seemed to believe it was worth a shot. I’m cleaning the area with acetone before I take it over to him in the next couple of days. Action Machine were helpful but I dont think were interested in drilling it back out. They can bore it for me I’m sure but he was quick to state they were not 215 experts.

Scott, For a Machine shop try Pacific Engine and Machine in Tacoma. Here is a video of their shop work:

[www.youtube.com]

Thanks Jim, I’m calling them tomorrow or Monday if their closed.