Home 
Home Search search Menu menu Not logged in - Login | Register
> Jensen Healey & Jensen GT Tech > Engine & Transmission > How much of a rebuild would you do?

 Moderated by: Greg Fletcher
New Topic Reply Printer Friendly
How much of a rebuild would you do?  Rate Topic 
AuthorPost
 Posted: 09-24-2015 05:00 am
  PM Quote Reply
1st Post
answerman
Member
 

Joined: 09-10-2012
Location: Little Chute, Wisconsin USA
Posts: 381
Status: 
Offline
With the momentous occasion of Ms. Jenavieve's odometer rolling over to all zeros, I'm thinking that this winter will be a good time to really do what I can to ensure that I'll have her in good running order for the foreseeable future. I subscribe to the "I'd rather do it right once than do a half a**ed job and have to redo it later" principle. The questions are how much do I need to do, and how much should I do.

The two issues she currently has: (1) I think there are some valve issues, possibly a broken spring among other things, and (2) she leaks a LOT from the rear main seal. She may be burning oil too for all I can tell, but it's hard to be sure with the amount of leakage. The indication of the valve issue is that I can't get a vacuum reading at all, the gauge just swings around wildly. Otherwise, as far as I can tell she is running fine... no complaints, compression seems ok, plugs look good, etc.

So, I am preparing to just go ahead and do something approaching a total engine rebuild, since I have to pull her engine anyway to replace the rear main seal (it's a later lip seal engine, not a rope seal). I'm curious to see what everyone else here thinks I should do, what I don't need to do, etc.

Keep in mind that the goal is to return her to as close a condition to factory original as I can, not to try to squeeze extra horsepower out of her. I don't need to turn her into a powerhouse... not considering a stroker or anything like that. I'm overall happy with the way she runs and drives now... I just want to keep her that way as long as I can. So, I'd rather be proactive and do it now than wait for a problem to develop down the road and then be forced to deal with it.

The "for sure" items:

Pull the engine, for a bunch of reasons. One will be to clean up the engine compartment and give it a proper paint job, which didn't happen when her body got its new paint.

Remove her head and have it reconditioned. I figure that it's worth it to have the head redone with new valves, guides, seats, etc. by a pro shop (considering West Coast for the job). It seems like the kind of thing that will be worth the money.

Replace the rear main seal. Self-explanatory.

The "I should probably do them" items:

Hone the cylinders and install new rings. I can't say that there are problems now, but since I'm in there now seems to be the time to do it.

The "might as go all the way" items:

Replace the pistons with new, and also have the crank and/or cam reconditioned. New bearings, etc.

So: if you were me, how much of this would you do? Is it overkill? Not enough? What I'd like to have accomplished when I'm finished is to have an engine that I can expect to get another 40,000 to 50,000 miles out of, which at the rate I drive her will probably be 15 to 20 years.

Last edited on 09-24-2015 05:03 am by answerman

Back To Top PM Quote Reply  

 Posted: 09-25-2015 07:15 pm
  PM Quote Reply
2nd Post
Jensen Healey
Super Moderator


Joined: 03-11-2005
Location: San Anselmo, California USA
Posts: 976
Status: 
Offline
During a normal rebuild, you will be reluctant to stop halfway through. If you're replacing the lip seal, the crank will need to be polished at the very least. Since the crank will be removed, you might as well have it balanced.
The pistons will be scuffed and the ring grooves worn so a set of 9.5:1 pistons will be needed. You'll be surprised at the increased drivability.

Any engine shop can rebuild the head since most engines have 4 valves per cylinder these days. You will have to source parts for them. Shimming the cams is the most difficult job since not many shops have a good selection of shims.

Remember, the Dellorto 40's were the stock carb. The Strombergs reduced HP by about 20 and were a pollution control compromise for the US. It's amazing how much more responsive the engine becomes.

Have fun! Kurt

Back To Top PM Quote Reply

 Posted: 09-28-2015 06:31 am
  PM Quote Reply
3rd Post
subwoofer
Member
 

Joined: 04-01-2008
Location: Sandefjord, Norway
Posts: 583
Status: 
Offline
Agreed! A new set of pistons and liners are in order, at 55£ each you might as well get new ones instead of honing and going for oversize pistons and rings. Pistons are available for compressions up to 11:1 for the 2.0 907, with the stock or 104 cams you would like to go as high as possible, with E cams or 107s you can have less compression.

But as Kurt just said, 9.5:1 and Dellortos is a completely different beast compared to 8.4:1 and Strombergs. You don't want to go back...

--
Joachim

Back To Top PM Quote Reply  

 Posted: 09-29-2015 08:44 pm
  PM Quote Reply
4th Post
answerman
Member
 

Joined: 09-10-2012
Location: Little Chute, Wisconsin USA
Posts: 381
Status: 
Offline
Well, I did some asking around at the local British car club, and they all recommended a local machine shop which I hadn't heard of. Talked with them yesterday, and now that I know I have someone local who actually has some experience with this "exotic" engine. He doesn't seem too concerned about getting necessary parts, and I always have Delta a phone call away.

I did a good compression check on Sunday morning just for fun (warmed to operating temperature, throttle wide open) and front to back I got readings of 130, 125, 130, 135. So the rings seem to be in good repair, anyway.

So, I think what I am going to do is pull the engine, pull the peripherals, and then bring the whole thing over to them to have them (a) take a look at the head and do whatever valve work and reconditioning they recommend, and (b) have them do the job of replacing the rear main seal, along with doing whatever crank work ends up being associated with that. The nice thing about having them local is that they will call me at any stage where a decision needs to be made (new rings? etc) and I can just drive over and see what they are finding instead of having to do it all over the phone or email. Only concern is that they are REALLY booked up (figuring an April completion at this point) so I need to "get in line" if I'm going to go this route.

Here's a question: I have absolutely NO plans to replace the Strombergs to Dellortos (it's just not worth it for how I drive the car). Considering that, is it worth going to the higher compression pistons if I do decide to replace them?

Last edited on 09-29-2015 08:51 pm by answerman

Back To Top PM Quote Reply

 Posted: 09-30-2015 07:38 pm
  PM Quote Reply
5th Post
Jensen Healey
Super Moderator


Joined: 03-11-2005
Location: San Anselmo, California USA
Posts: 976
Status: 
Offline
Yes. This engine has an appetite for compression and won't require premium fuel. I ran mine with stock cams for several years before switching to the 107 cams. Now it has enough torque to push a 5 speed axle with a 4 speed transmission.

I was trying to build a solid driver that would keep up with modern traffic.

Kurt

Back To Top PM Quote Reply  

 Posted: 10-02-2015 05:13 pm
  PM Quote Reply
6th Post
answerman
Member
 

Joined: 09-10-2012
Location: Little Chute, Wisconsin USA
Posts: 381
Status: 
Offline
Thanks for the info, Kurt. At this point what I'm going to do is bring the head and block over to the machine shop at the end of the month and wait for his opinion on the condition of the lower end. If I do end up replacing the pistons, then it sounds like the HC pistons may be the way to go.

Back To Top PM Quote Reply

Current time is 09:18 am  
> Jensen Healey & Jensen GT Tech > Engine & Transmission > How much of a rebuild would you do? Top




UltraBB 1.172 Copyright © 2007-2011 Data 1 Systems