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BJ7 Engine Rebuild

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Ray Smith

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I need some advise from Healey owners who have had experience with the following alterations during a rebuild:

1. Cam regrind. Is it best to go for a stock "grind", or go for the BJ8 "grind"?

2. Is it advisable to mill the head, or leave stock?

3. Should the flywheel be "lightened" or just skimmed?

4. Would you advise balancing the internal moving parts of the engine?

5. Any other mods that can be done during the rebuild that will make the big beast a little more "spirited"?

I am not a boy racer, but would like to get a little more performance out of the engine if I am going to spend the money to rebuild.

Any advise, suggestions, or no-no's would be greatly appreciated.

Ray
 
Ray,

I'm going through this right now. The following is what I have decided to do but since it's not finished, I can't give you report on the results.

1. Cam regrind. BJ8 grind. Generally accepted as the way to go for a street car.

2. Is it advisable to mill the head, or leave stock? Leave it stock.

3. Should the flywheel be "lightened" or just skimmed? I'm having mine lightened. Other BJ7 owners I talked to say it is a great mod.

4. Would you advise balancing the internal moving parts of the engine? Yes.

5. Any other mods that can be done during the rebuild that will make the big beast a little more "spirited"? I have roller rockers with 1.5" ratio. I also had the intake and exhaust ports matched to the manifolds (they were way off). You could also look at tubular exhaust headers, 2" carbs/manifolds (BJ8 spec).

Cheers,
John
 
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by Ray Smith:

1. Cam regrind. Is it best to go for a stock "grind", or go for the BJ8 "grind"?

2. Is it advisable to mill the head, or leave stock?

3. Should the flywheel be "lightened" or just skimmed?

4. Would you advise balancing the internal moving parts of the engine?

5. Any other mods that can be done during the rebuild that will make the big beast a little more "spirited"?
Ray<hr></blockquote>

Some of the answers will be subject to many different opinions. What you modify will depend on how you like the car to work & how much you can spend. With some modifications driveability or reliability will be sacrificed.

1. The late BJ8 cam grind is pretty good. Be sure to use new lifters (cam followers) that have ALL been hardness tested to RC50 or higher.

2. Mill the head only enough to make sure that it is flat. The CR is already fairly high.

3. In any case the flywheel should be skimmed. Lightening it is one of those drivability factors. I'll let others comment on this. I would personally remove a little weight, like 10 lbs, but only in the correct places as known by an experienced flywheel machinist. An incorrectly lightened flywheel is worse than a hand gernade beside your feet.

4. By all means, all of the rotating & reciprocating parts should be balanced.

5. You could switch to the larger type HD8 carbs of the BJ8. I don't know if you would need to change manifolds or could modify yours for this. If there is any doubt at all about the harmonic balancer condition, replace it NOW. There are several options for the damper/pulley, from original to BJ8 type to aftermarket. I'll leave this to someone else.

I would personally switch to a Pertronix ignition but again, many different opinions.
D

[ 03-01-2004: Message edited by: Dave Russell ]</p>
 
John makes some pretty good suggestions. In fact, with the exception of the roller rockers and carb choice, it follws precisely what I've done.

I haven't looked into these yet, but I understand that there are now composite lifters/pushrods on the market. These would reduce valve-train mass and the lifters are supposed to be very "camshaft friendly". I'm seeing that as a major benefit to users of reground cams.

Paying close attention to details will get the most out of your rebuild, whether it's stock or uprated.
 
If you want, I believe you can add the 2" carbs and have your BJ7 manifold bored to 2" plus a little clearance. Saves on buying a manifold. Anyone else have a thought on that? Then you could also have the crankshaft lightened.

SB
 
I am rebuilding an engine now also. I agree with the advice above and will add the following:
1. Don't skim the head any more than necessary to be flat. I have an extra head that will add a lot of extra horsepower to a healey but the higher compression ratio (245lbs) requires racing fuel. Very expensive for a street driver.

Headers? Kirk racing is reviewing the manufacturer of headers at this time. Are there any other choices in the US for these things?

Anyone looked at different type of rings? There are many different types and since there are limited manufacturers for our old cars, most use DEVES steel rings.

Oh, and add a rear main seal!
 
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by Jerry:

Anyone looked at different type of rings?
<hr></blockquote>

I have been very satisfied with Total Seal Gapless Rings (gapless is only used on the second ring).

I have them in my Healey and have put them in numerous MGBs, TR-6s and Buick 231" V6s.

Leakdown numbers of less than 2% are very common.
 
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by Ray Smith:
How many pounds can safely be milled from the flywheel without having a negative effect on drivability?

Ray<hr></blockquote>

Ray, You should contact Bill Bolton at tricarb@aol.com about the flywheel lightening. He is highly recommended to do the work and should be able to answer your question (let us know what he says). Also check out the following link for performance mod's.

https://www.ntahc.org/techtips/CompEngine1.html

Cheers,
John
 
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