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1725 Engine Rebuild Modifications

JConstable

JConstable

Donation Time
Folks,
Based on what I have read in past and present forum threads about rebuilding a SV 1725 engine most of the basics are clear (e.g., hot tank the block, clear oil and water passages, surface the block, balance all moving parts, rebuild the oil pump, 3 angle valve grind, surface the cylinder head).

The questions arise regarding which modifications generate the greatest bang (in a relative sense) without breaking the bank. The two that rise to the top are re-grinding the camshaft (the KB grind at Delta Camshafts) and the Vizard modification to the head.

Q1. In performing the camshaft grind is it a brand new camshaft that is ground to the new specs or is it the existing cam ground to the new specs?

Q2. If I were to go for a Vizard modification how would I get that done? What are the specs to follow? and who is a reliable shop to perform the work?

I realize that these are questions that have probably been asked before but I'll claim ignorance as my knowledge level is just enough to show how little I actually know. I appreciate you indulgence!:)

John
 
sunalp

sunalp

Diamond Level Sponsor
1725 rebuild

Hi John: I've just about finished doing what you're doing. I spoke to many people about the Vizzard Mods and determined that for my application, which is basically just a nice street car not a race car, that the Vizzard mod wasn't really necessary. I just cleaned up all the ports and the combustion chambers in the head, did a nice three angle valve job and that was about it for the head.

As far as the camshaft goes, I sent my cam to Delta in Washington state and they reground mine. Took about a week and cost somewhere around $75.00 with shipping both ways. I also had them resurface the lifters and they're almost a work of art!

When you have the block tanked make sure that you have the shop check the bores. I thought mine were pretty good and only needed a good honing, but turned out they were ovaled pretty badly and I had to bore the block .030
and get new pistons.

Other than that, it's just been new bearings and gaskets. You may not have to rebuild the oil pump. Just make sure it's tested before you out it in and seal up the sump.
Hope this helps.
Cheers!
Steve
 
B

Bill Blue

Platinum Level Sponsor
JConstable said:
Folks,
Based on what I have read in past and present forum threads about rebuilding a SV 1725 engine most of the basics are clear (e.g., hot tank the block, clear oil and water passages, surface the block, balance all moving parts, rebuild the oil pump, 3 angle valve grind, surface the cylinder head).

The questions arise regarding which modifications generate the greatest bang (in a relative sense) without breaking the bank. The two that rise to the top are re-grinding the camshaft (the KB grind at Delta Camshafts) and the Vizard modification to the head.

Q1. In performing the camshaft grind is it a brand new camshaft that is ground to the new specs or is it the existing cam ground to the new specs?

Q2. If I were to go for a Vizard modification how would I get that done? What are the specs to follow? and who is a reliable shop to perform the work?

I realize that these are questions that have probably been asked before but I'll claim ignorance as my knowledge level is just enough to show how little I actually know. I appreciate you indulgence!:)

John
Click to expand...

Cams are usually reground.

If you are serious about more oomph, the Vizard job is almost mandatory. The Vizard mods can be a DIY project. You will need a Dremel tool (sort of slow, but will do the job) or a die grinder (fast, need lots of compressed air) and some carbide burrs. Do not use a drill motor. Slow and you do not have the proper control for a good job. Printed instructions and templates are available.

If you decide to have it done, Jim Ellis has successively done this on several heads. Only problem for you, he is located on the right hand coast. But Alpine heads are not that heavy, shipping should not be totally prohibitive. There is probably someone on the West Coast that does this. If so, someone will probably come up with a name pretty shortly.

Bill
 
Jim E

Jim E

Donation Time
One thing to make sure you do is have the block crack checked on the intake side down low where the water jacket drain is. This is one of the first things I do before spending any money on the block, cause if it is cracked in the water jacket it is junk.
 
B

Bill Blue

Platinum Level Sponsor
sammaw@bellsout said:
Bill, where does one get the instructions and templates for the vizzard mod?

Thanks
Click to expand...

Sam, the best thing would be to make a general call for help on this board. I'm sure someone will help you. I used to have the info, but after I decided to go with the Ford engine, I got rid of all that stuff. Vizard has a book (now out of print, I believe) that goes through the process, step by step. But of course I don't even remember the name of it. Something like "The Theory and Process of Head Modification"

Bill

edit: Theory and Practice of Cylinder Head Modification Can be bought here;
http://www.amazon.com/Theory-Practi...r_1_11?ie=UTF8&s=books&qid=1205945677&sr=1-11

Starting at a piddly $141 for used copies! And I sold mine for about 15 bucks a couple of years ago. You might be able to do an internet search and find them a lot cheaper.
 
JConstable

JConstable

Donation Time
Folks,
Thanks for all the good info, the main thread has centered on the Vizard modification and exactly what to do and how to do it. As for the book, a very quick on-line search suggests that the $141 at Amazon is cheap and that at other sellers prices only go up:(.

As my Alpine budget is relatively tight, my cash is likely better spent lining someone else's pocket where the job will be performed correctly. As I am reluctant to grind into my cylinder head given my level of experience, is there any one on the west coast who has familiary with this process to whom I can farm out the task? Also in performing the Vizard, are there other linked changes that need to go on in the engine to realize the gain? I have heard it is required to have piston modifications as well.

Thanks

John
 
B

Bill Blue

Platinum Level Sponsor
As I remember the mod, no other modifications are required. The modification reshapes the combustion chamber which lowers the compression ratio, so most guys mill the head to try to regain some of the lost compression. But even if you don't, you will see a HP gain. Shucks, might even allow you to save $.10 a gallon.

Bill
 
Wombat

Wombat

Donation Time
Here is the page from the Vizard Book that shows the mod to the Rootes head. It is low res to fit within the size of files allowed on this forum. PM me with an email address and I will send a PDF of the relevant pages of he book.
 

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Armand4

Donation Time
It seems to be generally accepted that the Vizard mod is the way to go if you're looking for extra power in the Alpine motor. But has anyone tried the basic porting outlined in the factory's Special Tuning manual? The combustion chamber isn't reshaped, so flow isn't improved by unshrouding the valves, but on the other hand it won't lower the compression ratio. The Special Tuning manual promises 94.1 horses at 6000 RPM with the ported head and hot cam--nothing spectacular, but I think it might be worth exploring.
Speaking of compression ratios, what's the difference in CR between flat-top (1592) pistons and dished (1725) pistons? It seems that one could compensate for the added volume in the combustion chamber of a modified head by using the flat-top pistons.
And finally, is there a way to get upgraded bolts or studs for the Alpine motor? I've been told that ARP or other high-end fasteners are a good investment when building any kind of engine for serious performance. Since Rootes used standardized threadings, can one just order stock studs, bolts and nuts, or is it more complicated than that?
 
B

Bill Blue

Platinum Level Sponsor
Why would anyone want to go the factory route? If I remember correctly, the Vizard mod makes more hp with the lower CR than the factory modifcation setup. Vizard contends the goal is to make hp, not run a high CR. Funny guy. Although the factory mod would probably give a little better fuel economy.

Something I think should be kept in mind. The CR is a static, mathematical number. What is the effective (running) CR of an engine with say, 10% lower CR, but breathing 15% better?

Bill
 
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Armand4

Donation Time
Didn't someone on the forum compile all the information one would need to build a high-performance Alpine motor? Where can I get that?
 
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Armand4

Donation Time
So how does one get one's grubby little hands on these articles about engine modification and performance? Can we order back issues of the newsletters through the club?
 
Series3Scott

Series3Scott

Co-Founder/Past President
Platinum Level Sponsor
Armand4 said:
So how does one get one's grubby little hands on these articles about engine modification and performance? Can we order back issues of the newsletters through the club?
Click to expand...


I think sometimes we all forget there's far more to this website than just the forum. Go to the home page, click on "SAOCA Info", then click on "Alpine Marque". You'll find all the issues in pdf format.
 
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Armand4

Donation Time
Thanks, Scott. There's a Mercedes 190SL that's been driving around town like it owns the road, and it needs to be taught a lesson.
 
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