Rebuild Performance Suggestions Sought

[Bob_Spidell]

Denizens of the Forum,

I need to replace the clutch in my BJ8, and I've decided to pull the engine and gearbox together and do an engine rebuild while I'm at it (the engine has 110K miles +/- on it since last rebuild). Even with low compression, the engine runs like a proverbial 'Swiss Watch'--and just gave another 3,427 miles of flawless performance over 10 days--but it's noticeably lacking in power and runs out of breath pulling up a grade at high altitudes (and will barely rev over 4K RPM at sea level). So, I'm looking for suggestions from the cognoscenti on how to:

- get at east a little more power at the top end (I'm thinking getting compression up around 10:1 would help)
- keep a reasonably smooth idle (I do spend quite a bit of time stuck in traffic)
- still be able to run without detonation on 91-octane (R+M/2) pump gas (or 90-octane when that's available, usually at higher-altitude pumps)
- continue to be bullet-proof (I venture where a lot of people wouldn't even consider taking an old LBC, and almost never see even modern exotics in such places)

The cylinders were bored 0.030" over some time before I bought the car--at 64K miles--and the block was painted black so a PO must have done an overhaul for some reason. I plan to have the cylinders bored--only by the minimum necessary--and to use Denis Welch's Omega brand pistons (3-ring). With nearly 200K miles on the engine I feel it's time to spring for uprated studs and bolts (head, crankshaft, rod). Beyond that, I am considering:

- Cam. The cam was reground at the last rebuild by Crower. My dad specified their mildest grind without asking me--smart man--which, as far as I can tell is very close or identical to stock BJ8. The engine idles nicely around 750 RPM with just a slight lope. I have a Lempert 3.54:1 rear end and do most of my motoring between 2,000 and 3,000 RPM (I usually downshift when I get below 2,000 RPM, which works well in my Mustang as well). I'm leaning towards staying with the stock grind--or a new cam if it can't be ground again--but would consider a hotter cam if I can still get a similar idle but a little more top end.

- Pistons. As mentioned, I'll probably use DW's because I believe only 2 compression rings are necessary and they look to be top quality (BTW, has anyone else ordered DW's new catalog? It is absolutely a work of art, printed in full color on glossy, heavy (photo?) paper and the list of parts now available is incredible. What a resource.)

- Lifters. Leaning towards bucket lifters (just because).

- Rocker shaft. Leaning towards a roller-tip unit from Rocker Arm Specialists (anyone know if they're still in business and still providing quality?). The stock one's ratio is a little under 1.5:1 but the RAS ones claim true 1.5 which I think (hope) may give a small boost in performance (David at DMD--can't remember his last name and I believe he passed away a few years ago--told me this should give a bit more 'grunt').

- Flywheel. I toy with the idea of getting the flywheel lightened--or exchanged--but with the 3.54 getting off the line is a little touchy as it is

- Rear main seal. We put one on our BN2 and it still leaks, but I think that may be due to crankcase pressure (I think the draft tube may be at least partially blocked). I bought a seal years ago and never installed it but am considering DW's Al rear engine plate and seal so I don't have to modify the stock engine plate.

- Head. Would love to have DW's Al head for the weight loss if nothing else, but it's an awful lot of jack and I don't know what I would gain with an otherwise stock setup. Would also consider getting the stock head worked over by someone who knows what he's doing (not me).

- Headers. See 'head.' DW claims "The twin carb manifold will make the single most increase in power and torque possible for the money spent to a standard car." I'm concerned about installation issues and, though I've never run any car with tubular headers I have seen issues with tubular exhaust manifolds cracking (the Jeep I6 engine is notorious for this). I also wonder how an exhaust can be installed without the flex tubing found on stock down pipes--won't vibration wear on the headers or exhaust? If I don't go with headers, I will have the manifolds ceramic coated--would do to headers as well--if for no other reason than to (try to) prevent the stumbling due to vapor lock on hot starts due to ethanol in fuel (had the opportunity to buy ethanol-free premium gas in Oregon this trip, and didn't get the stumbling so I'm convinced ethanol is causing the problem).

All other wear items--bearings, etc.--will be replaced. The crankshaft is still stock, but will do a regrind if necessary. My dad has a friend/former student who owns a racing engine shop and Dad says he has a New Zealander machinist working for him who is an absolute perfectionist, so they will do the work (I'll do final assembly).

Your thoughts and suggestions are appreciated (probably by others as well). I've floated these ideas here and on the (now defunct?) mailing list before, but this time I'm serious

- Bob

 

[DerekJ]

Bob,

If you are building a slightly zippier, but still very much road use car I recommend the DWR fast road cam. DWR8 I think it is. You will need to pocket the block but this cam runs really well with twin 2 inch SUs and gives flexible performance. I had this on my car before fitting Webers and a 3000 degree cam for sprints and hill climbs. Lightening the flywheel is well worth it. They are too heavy at about 28 lbs although that does contribute to the standard Healeys motor boat style tick over. Mine was lightened to 20lbs but I now have a DWR all steel on which weighs in around 13 lbs which may be too light. The alloy head is a real nice to have but I can't justify the big bucks. The weight saving is great but you can improve the iron head quite significantly and its much cheaper.

 

[EV2239]

FWIW I don't share Derek's opinion because you're using the low end of the Rev range and a higher axle ration. I had a TR3A with a TR6 axle ration and a hotter cam and all it meant was I had to rev a very noisy engine harder because I'd lost some torque. The standard cam in the TR is exactly right for the road and so is the BJ8 one.

As standard a BJ8 is 1.8 seconds to 60 slower than a 2L MX5 Miata and about 2 secs slower to 100, so very fast for a 1952 chassis.

Therefore I'd build a very very good, balanced standard engine as I just have. Mine's smooth and more than fast enough for what it is. They're a very good and durable engine.

What must be correct is the head. Most of the power the engine has lost, if the Tappets are silent, will be pocketed valves. The lift of a BJ8 cam is 0.368 and if the inlet has sunk, it will have to be fully open before it clears the surface of the combustion chamber. Therefore the chamber shape needs deepening to bring the valve clear of the surface when it's closed and the face of the head needs skimming to bring the compression ratio up to around 10 to 1, which works well.

This is a lot of work, I had mine done by a BMC engine expert and overseen by someone from the Abingdon shop in the sixties and I and Dan Howell were amazed at how well the old girl goes.

Sports/racing Camshafts cannot add power without increasing revs and what you gain at the top is lost at the bottom, so for losing acceleration at normal road speeds you improves things above seventy or eighty. Or if you're winning vintage races with your Healey like Mark Campfield, your engine will barely run below 4000 but whips round to 7000 once it is in the power band.

i hope this helps.

 

[John Turney]

Bob,

My setup is much as recommended by Derek, with the DW8 cam, pockets in the block, BJ8 manifold and HD8s, and lightened flywheel. I don't find the lightened flywheel a detriment. I bought my DW Al head back when they weren't so dear, and they sized the combustion chambers for our 92 octane. The engine is pretty flexible - I certainly don't need to rev over 4,000 RPM to get going. I can feel it really make a jump in power above 3,000 RPM, but I still start off in 2nd unless it's a steep uphill or I have to go slow into the garage.

I also have Kirk Headers. I fabricated a flex section to fit between the header flanges and stock muffler with side exhaust. The downside is that we have to wear headsets to talk to each other.

We just finished up the Yosemite Healey Week at altitudes up to almost 10,000 feet (Tioga Pass). Mine didn't like the high altitude, and I had to keep the revs up to at least 2,300 above 6,000 feet to keep running smoothly.

We also had a presentation from Lake Speed, Jr. of Gibbs Racing where he touched on ethanol in fuel. Ethanol raises the octane by about 4 points at 10%, so the underlying gasoline doesn't have to be as good to give the same octane. That may be the real issue.

 

[DerekJ]

EVV, The DWR8 is nothing like the DWR race cam that is used by most Healeysport racers, or even the DWR rally cam. It works really well with the twin 2 inches and gives you extra punch. After all, these are supposed to be sports cars! :smile-new:

 

[Randy Forbes]

Bob, there's some things I'd be doing for the next engine I build for myself; a bit more labor mostly, so the added expense will depend on how much you're willing to do yourself (it's all still quite doable in the average home garage, but you have to want to do it).

I'm a big fan of polymer coatings; you may only see minimal gains in quantifiable horsepower, but real gains in efficiency and longevity are a proven advantage. Any part that is exposed to heat, oil, combustion gasses, or sliding/rotating friction are candidates.

-Heat shielding the piston tops (keeps the heat INSIDE the combustion chamber, and less heat radiated through the crown to the oil on the underside.

-Heat shielding the valve faces and combustion chamber, reducing heat transferred into the water jacket. Keeping the combustion gasses from cooling maintains a higher velocity, improving scavenging and assisting drawing in each next fresh fuel/air charge.

-Thermal barrier coating the insides of the exhaust ports (and likewise, inside/outside of headers); same benefits as above.

-Thermal dispersant oil-shedding coating for the undersides of the pistons, connecting rods and oil pan, side-covers, etc.

-Dry-film lubricant coatings for piston skirts, main, rod & cam bearings, timing sprockets, lifters (yes, I like the bucket type, as used in all later MGB engines) pushrod ends, rocker arms/screws/shaft, retainers/springs, etc., etc.

I've been using Tech Line products for the past two and a half decades (>24 years) but there may be other suppliers newer to the market. https://www.techlinecoatings.com/hi-performance/index.html Their website is not the easiest to navigate, but with some patience, you can find a ton of information there. Leonard has been working with and developing these products since Regan initiated the transfer of (NASA's space shuttle) technology to the private sector. Truly, rocket science for a sixty year old car!

My engine is fitted with an Isky T3 cam (since 1986) initially with a trio of 1-1/2" SUs, but mostly with 3 x 45 DCOEs. I do not know how that compares, lift/duration-wise with the DW cams, but certainly A LOT more local to you. This is not an aggressive cam either, retaining plenty of low end grunt, and still pulling strong over 6000 RPM (it's been running with a rev limiter for so long, I don't remember the highest it's been revved, but scary high.

The flywheel has been cut to 20.2 pounds, from approximately 26.8 Lbs. This is NOT too light, but better attention should be paid to radiusing the cuts more generously that the guy that did mine.

-Inline 6-cylinder engine have inherent good balance, but it is well worth having all rotating/reciprocating components balanced.

-The topic of crankshaft dampers has been well covered recently, and at an absolute minimum, have your existing unit rebuilt, or go with one of the brand new units on the market (benefits include accurate degree markings).

The following are just some random shots of either polymer coatings, or the Longbridge engine I built a while back.

Verifying clearances on crankpin with dry-film lubricant coated bearings.

Curing several sets of bearings after applying DFL coating.

If you have any specific questions, or clarification, let me know. Again, these are just some things that I do/would do, and it's hardly the last word on buildng an engine, for performance, economy and/or longevity.

 

[GregW]

I have the Isky T-3-6 profile as well. Don't recall the lift ATM but the duration (total) is 268 degrees vs. 252 for the stock BJ-8 grind. With a Rocker Arm Specialists 1.55 rocker, lift is .455" if I recall correctly. Isky also does a 286 degree for the wilder at heart. Note: when I had my original cam done, Isky only re-profiled. You couldn't buy a new one from them. That may have changed, but I doubt.

 

[EV2239]

It's great fun tuning a engines and I've been doing it since the seventies, but horses for courses. The manufacturers usually got the best power they could from their engines without sacrificing slow driving and traffic manners, so don't forget that. In the intervening fifty years no one has discovered a faster cam grand that doesn't sacrifice torque.

However VSR or valve seat recession, as happens with high mileage engines, is the primary cause of lost power and I maintain that with the head sorted and a BJ8 spec engine, there's more than enough power to overtake dawdlers and make good process. As I said, there isn't much difference between a 2 litre MX5 and a BJ8's 0-100 time.

Have a look at this picture of where inlet valves should be.

 

[Bob_Spidell]

Thanks, Randy. The coatings look terrific, and I bet they work a treat, but I have no idea how I'd do that and don't know anyone in this area who does. Do you do it for customers?

And, where did you got those nifty pistons?