Engine and Transmission Tech

Hi All

I have a TVR M series with a Buick 215 and a LT77 box. Engine has not been run since I bought it; box has been rebuilt & I plan to use it.

I started tearing down the engine this weekend and found a couple of issues.

1-Left side head - apparently shortly after the last engine rebuild, a small screw (looks like 8-32) got sucked into the cylinder and bounced around until it broke into two pieces each about 3/16" long and lodged in the head. Needless to say the head and the top of the piston are showing the effects. I expect the previous owner of the engine had no idea of this. No noticable scarring of the cylinder wall.
2-Right side head. Water in the cylinder. Lots of the fuzzy white corrosion and several deep (1/8" or more) pits in the head. Some staining & possible degradation of the cylinder wall.

I've done some fingetrip inquiries. Ballpark quote is from $50-$350 to weld & machine each head. I've got a couple leads on used heads at fairly reasonable pricing.

Pistons state they are .030. Haven't mic'ed anything or gone deeper. That's for this weekend.
For what it's worth. the engine looks like it had only a few hours running time after the rebuild before it was taken out of service. Oh well.

Questions

1-repair (by welding & remachining) the heads? Or replace?
2-how far does the conventional wisdom say I can go if I need to rebore? 0.40? 0.60?
3-Is replacing the heads with something else more economical? More powerful? (I hope, I hope)
4-Should I just get a 3.5 Rover & rebuild it? Part out the Buick engine? I've got a line on one for a sensible price.

I'd really like to be "all British" but if ithe Buick is an economical fix, I'm not that hung up on it.

Thanks for the advice.
John

John, IMHO your $'s be better spent on 4.0/4.6L rover heads. More air flow/performance and "should" freshen-up for less than trying to save the 215 heads. You might want to cc old vs newer chambers, as later heads could give a compression boost.You should calculate your current compression ratio, as could be as high as 11/1,(63 Buick, 4bbl). The newer heads "may" have the (5 th) head bolt hole, post machined like 215 Buick, but not necessary with standard compression and a good mls gasket. Good Luck, roverman.

(Question 1 and 3)

After running Buick 215 heads for about 17 years, I took them off and replaced them with Rover 4.0 heads as Art suggested. I had bought the Rover heads very cheap from a RangeRover owner who re-powered his SUV. (Rover cylinder heads generally last forever whereas a fair number of later model Rover blocks had cylinder liner problems. I paid $150 for all this guy's spare parts. The heads were basically free after I sold off his old RangeRover headers.)

The advantage of the Rover 4.0/4.6 heads are: smaller combustion chambers (28cc vs 37cc, for a higher compression ratio), larger intake and exhaust valves (1.570" inlet vs. 1.5", 1.350" exhaust vs. 1.312"), and significantly larger exhaust ports. For me, there were disadvantages too. The Rover heads needed to be skimmed 0.010" to flatten them, and they needed a valve job so I had to put some money into them. (By the way, skimming the heads bumped up my compression ratio up a little more - which suited me fine. All assembled, my engine is at ~10.1:1.) The accessory bosses on the Rover heads are completely different than the Buick 215, so I had to fab a new alternator bracket. Also, at the back end I had to cut bosses off the driver's side head for firewall clearance. Probably on account of having to skim the heads, I needed to install shims under the valve-train pedestals.

With the valve job, I got nicely reconditioned valve guides and new stem seals. I hadn't even used valve stem seals when I originally built the Buick heads. The new heads eliminated an annoying little bit of exhaust smoke at engine start-up and a fair bit of oil consumption (which I previously only really noticed on cross-country trips.) On the downside, Rover valve guides are tall, and it proved necessary to have the machine shop shorten them to provide clearance at the rockers (on account of I have a high lift camshaft.)

Art mentioned head bolts. All Buicks 215s and all Rovers up through the 3.9L used five bolts per cylinder. The 4.0/4.6 heads only have four bolt holes per cylinder. The reasoning is that the fifth bolt actually causes LESS even pressure on the head gasket, so with four bolts the probability of head gasket leaks is lower. You could just leave the fifth bolt on Buick 215 heads un-torqued to achieve the same thing. Here's the important thing: don't re-use late model Rover head bolts! They're modern torque-to-yield bolts, so they're only good for one installation. If you like though, you can re-use your old Buick 215 head bolts to hold down your Rover heads. (New studs would be the preferred option.)

Now here's the thing... there was nothing drastically "wrong" with my old Buick 215 heads. I could lap the valves, put them back on my engine, and ignore the oil consumption. If you just want to get your engine running on the cheap, they'd work. (P.M. me an offer if you're interested.) Similarly, I expect half the guys on this message board have spare sets of cylinder heads laying around.

---

(Question 4)

I rather like my old Buick engine. If I were going to bother replacing it with a Rover engine, I'd choose a later, higher displacement version. 3.9/4.0 equates to ~12/13 percent more displacement with no downside... they're usually more readily available than Rover 3.5 engines anyhow. Of course if you can find one that doesn't need rebuilding, that's probably the way to go. They're out there!

Curtis,

I hadn't heard about-

"Here's the important thing: don't re-use late model Rover head bolts! They're modern torque-to-yield bolts, so they're only good for one installation. If you like though, you can re-use your old Buick 215 head bolts to hold down your Rover heads. (New studs would be the preferred option.)"

What head bolts do you recommend? Are there options? What if you're going back and forth with an issue in your engine, do you replace the head bolts every time you retorque?

Tim

The Rover bolts are very good but as Curtis says you can only use them once. When you install them you technically over tighten them and they stretch like a spring. This gives a better clamping range to accommodate the expansion of an aluminum engine. But once they have been stretched they can't be used again. The old 215 bolts can be used as many times as needed, but use the Buick torque values not the Rover ones.
If you are planning to have the heads off and on a few times then ARP sells a stud kit for these engines. It's part # 124-4003

They don't work any better than the Rover bolts and you will have to do a re-torque after the engine is run up. But they won't wear out the threads in the aluminum block and they clamp more evenly than the 215 bolts.
Cheers
Fred




Edited 1 time(s). Last edit at 04/05/2012 12:13PM by DiDueColpi.

Hi all

Thanks for the advice and food for thought. Any opinions on the amount I can "safely" overbore this engine?

Thanks
John

From what I gathered some years ago when I bored an Olds 215 engine +.030, the limitation on overbore was the fact that the early BOP engines had cast in sleeves so the bore centres were not as precise as the pressed in Rover sleeves.
I want to say that +.040 was the limit on BOP and +.060 was the limit on Rover (subject to correction by those who really know -Roverman?)

John, Speaking just for me, If I preferred the Rover engine, and the 215 needed boring,($'s), I would use this as a sound reason to switch. The 215 has rope seals front/back-not good. The 4.0/4.6L short blocks are more plentiful, much stronger, with better value. I suspect "Wing Man" will chime in soon to convert you to an anchor/oops, I mean the finest engine ever designed, of course this would be the 300 Buick. Clan, I would not bore a standard sleeve Rover +.06", simply because of likeliness for sleeve migration, ie. not touching step at bottom and no flange on top. 215 sleeves did not move because they were integral cast,(external ribs on sleeve cast into aluminum). Good Luck, roverman.



Edited 1 time(s). Last edit at 04/05/2012 11:44AM by roverman.

Anybody cut-back on their torque spec's when converting to studs ? I never have. When we do the math, converting from 7/16-14 to 7/16-20,(nut end of stud), this equates to 43% more clamp load with same torque spec. Main studs would equal 54% more. If your aluminum threads are substandard, you might consider less. Given a choice, I prefer the 5th bolt on the exhaust side. Based on my experience, head gasket leakage tends to be more prevalent on exhaust side(weakest area of head at running temperatures). This may also contribute to gasket leaks between cylinders.I also prefer studs with enhanced elasticity, when their shorter. Good Luck, roverman.



Edited 1 time(s). Last edit at 04/10/2012 04:03PM by roverman.

Interesting thought, Art. I actually stripped the threads out of a 3.9 block using ARP studs. I was right at 55 ft/lbs when it happened.

So an update and solicitation for additional advice.

Heads went off to the machine shop for an estimate. They quoted me $200 for the pair to grind out/weld up/restore to rebuildable the combustion areas of the heads. That and a valve job, I'm thinking not too bad. Then they pointed out some additional areas of pitting I hadn't noticed during the teardown around the intake ports and quoted an additional $150 to sort that out. So $350 plus a couple of valve jobs. I haven't seen the "new to me" damage to the heads so I can't yet comment on whether they're overselling their services or not. I suspect not.

The water staining of the cylinder wall honed out pretty well so I'm inclined to use the block anyway without a rebore.

Everything mic'd out at what would be predicted by the marks on the piston and bearings - 0.030 over for the bore, 0.10 under for the mains, and 0.020 for the rods.

Pretty surprising amount of scoring on the crank journals and associated bearings - apparently the previous builder wasn't very meticulous about cleanliness.

Questions
1-So I have a line on a couple of heads - real cheap (like maybe free?). I don't know what they're from - how do I identify them? At first blush they look pretty much like what's on the engine now but I haven't laid them out side by side to compare.
2-There's a crank in with those heads - and at the same price - if it has better journal starting point how do I identify the donor - and can I use a Rover crank? I can certainly measure things up. I expect the crank will interchange but would like the assurance of the collective wisdom of the forum.
3- To Art's comment about the rope seals on the Buick -are there ways to upgrade this block to have a modern rear & front seals? Or don't bother? Coincidentally there are two timing covers with the batch of parts. Maybe from a Rover.

Thanks for the feedback
John

I don't know why you'd pay $350 to repair these heads if you can get undamaged heads for quite a bit less. If in doubt about identification, post photos or casting numbers.

The front crankshaft seal is mounted in the timing cover, not the engine block. Buick V6 timing covers bolt right onto the 215. You can buy them new, and that's usually the easiest way to upgrade to a neoprene front seal. More info: [forum.britishv8.org]

D&D Fabrications offers a kit to upgrade your engine to a neoprene rear seal. It's basically a matter of trimming a Ford service part and installing it on a Buick. (Two 180 degree sections.)

Hi Curtis-

Thanks for the info re: the seals. Exactly the info I was looking for.

John

Hi All

The machine shop and I have arrived at the conclusion that these heads cannot be repaired economically. We'd have reached this conclusion weeks ago if I weren't out of the country so much.

The cheap heads I had available will not suit. I'm sorely tempted to go as Art & Curtis have suggested - the Rover 4.0 heads. I have a couple of questions:

1-Curtis - you have a high lift cam - how high is high? At what point do the Rover 4.0 valve guides need to be docked to fit?
2-Can I re-use the rocker gear from the Buick or is that not a good idea?

Thanks
John

Well, I've looked it up and my cam has a lift of 0.462", and I used the same old Buick rocker arm assemblies after I installed the 4.0 heads. I'm not sure if I ever knew just how much the 4.0 valve guides were shortened, or how bad the interference issue was. I had mailed my Rover heads to Abacus Racing in Virginia, and my discussion (with Chuck Botwright at Abacus) about exactly what they needed was handled by phone.

Clan, Yes you can, easy! Isky, Jeg's/ etc. sell guide cutting tools. Drill motor and "reasonable" skill will do the job. It's best to to use an optimum cam and cut the guides. Welding aluminum heads is a last resort because the welded area will remain "dead soft" ! Stock heads don't posses too much hardness and need all they can get. Cheers, roverman.