PDA

View Full Version : Spitfire So THATS why my Spit didn't seem peppy!



Basil
09-12-2001, 10:11 PM
A couple of years ago, I had rebuilt the engine in my 78 Spitfire. I wanted to "pep it up" a bit, so I replaced the stock pistons with .030" over flat-top (euro spec) pistons, installed a hotter cam, dual webber DCOE carbs, headers and an Ansa exhaust. I also removed all the smog equipment. After getting it all back together, it seemed to run ok, but I was disappointed that it didn't have as much "zip" as I thought it would have with all the mods I did. Anyway, I drove it like that for a couple of years until by son took it out once night and two of the push rods popped off the rocker arms and got bent. That gave me an excuse to pull the engine and tear it apart (I had been wanting to replace the rear seal anyway). What I discovered was that the cam timing was off one tooth and probably had been since I first rebuilt the engine. My expectation now is that my little Spit will run like a Banshie now that I have the cam timing right! (I hope so anyway). I will keep you all posted on the outcome.

Basil

JBsC5
09-22-2001, 09:38 PM
Cy..your sons a lucky man..to have a dad as cool as you..

Let us know how it comes out...

I bet your right!

Basil
09-22-2001, 11:06 PM
Originally posted by JBsC5:
Cy..your sons a lucky man..to have a dad as cool as you..

Let us know how it comes out...

I bet your right!



Ain't it the truth https://www.britishcarforum.com/ubb/images/icons/grin.gif I will be getting the head back from the machine shop this week and should have it all back together by next weekend. I am putting all new seals in and a new clutch (all three pieces). Also putting in a new (even hotter) cam and heavy-duty valve springs. Can't wait to get it back together.

Basil

Z28Quetzal
09-25-2001, 09:34 AM
Basil,

Great forum! I just joined up, and I already have a question!!

I too own a Spitfire. Mine is a '78 with the 4 speed non-overdrive. I currently have the Zenith carb on the engine, however, I am in the process of rebuilding a pair of SU HS2's.

I read your post about your Spitfire, and am curious about the mods you made.

- Are the original pistons flat tops or are they dished?

- I have access to a machine shop, and this winter I plan to remove the head and do some work to it. Clean it up and then take it to have it milled down just a tad. How much did you have yours milled down?

- You mentioned you were going to put a new cam on your engine. Have you decided what you are going to do with the hot cam you already have? I'd be interested if you tell me more about it...

Just some questions, hope you don't mind me asking...

Regards,
joe

Basil
09-25-2001, 12:04 PM
Originally posted by Z28Quetzal:
Basil,

Great forum! I just joined up, and I already have a question!!

I too own a Spitfire. Mine is a '78 with the 4 speed non-overdrive. I currently have the Zenith carb on the engine, however, I am in the process of rebuilding a pair of SU HS2's.

I read your post about your Spitfire, and am curious about the mods you made.

- Are the original pistons flat tops or are they dished?

- I have access to a machine shop, and this winter I plan to remove the head and do some work to it. Clean it up and then take it to have it milled down just a tad. How much did you have yours milled down?

- You mentioned you were going to put a new cam on your engine. Have you decided what you are going to do with the hot cam you already have? I'd be interested if you tell me more about it...

Just some questions, hope you don't mind me asking...

Regards,
joe




Hi Joe, and welcome to the forum.

Activity here is still a bit slow but has been steadily improving the last month or so. As we get more members the activity level will pick up - so hang in there and above all - POST!

Now, as to your questions. The original pistons on my car were dished. This, I presume, was to lower compression for emissions reasons. I put 30 thousandths over-sized flat-top pistons in (Euro spec).

As for the head, I just had it milled enough to make it even – wasn’t trying for anything more than just ensuring the head was flat. I was afraid that if I went too much, in combination with the flat top pistons and the hotter cam (which increases valve lift) I was afraid that I might be in danger of fouling the valves onto the piston tops. I don’t know how much clearance there was to play with, so I decided not to take any undue chances.

My old cam is bad. Two of the lobs are flattened off on the tips. I suspect the problem is that when the machine shop that did the work to put it all back, they used the original springs and those springs did not compress enough to accommodate the increased lift of the new hotter cam. This time, I am buying a set of springs made specifically for the cam I am buying - a Kent cam from British Parts North West in Oregon. $166 if you don’t have a core – less if you do (only a stock cam will work as a core – they will not accept a hotter cam as a core). I would not recommend buying a used cam.

Hope this helps. Let me know if you have any other questions,

Basil

Z28Quetzal
09-25-2001, 12:13 PM
Thank you Basil.

I found your ad in British Car Magazine. I pick that magazine from time to time, its OK. I have found the articles to be so-so sometimes - that is why I don't subscribe or buy it on a regular schedule.

I certainly will pass along your forum name to others. This site is particularly interesting, because I have this 'thing' for British Cars - I guess is the part of me that likes to suffer. https://www.britishcarforum.com/ubb/images/icons/smile.gif

Thanks for the advice on the cam. I will stay away from used ones and I did not realize they were 'affordable'. Heck for $160 bucks, that is not too terribly bad. I will take your advice and use new springs when installing one. I'll also keep in mind the name of the place you bought your cam from.

The mods you made seem to be along with what I want to do with my Spitfire's engine. I am planning to do the head work first, then if money is looking good, I might go with the pistons also. While I'm in there, the thrust washers will be replaced too.

Say, did the machine work on the head cost much? Also, have you given any thought at using roller rockers? I have seen several places that carry roller rockers, don't know if the benefit is worth the price they charge for the rr's though...

Well, let me know.

joe

Basil
10-01-2001, 10:01 PM
Originally posted by Z28Quetzal:
<snip>
Thanks for the advice on the cam. I will stay away from used ones and I did not realize they were 'affordable'. Heck for $160 bucks, that is not too terribly bad. I will take your advice and use new springs when installing one. I'll also keep in mind the name of the place you bought your cam from.

<Snip>

Say, did the machine work on the head cost much? Also, have you given any thought at using roller rockers? I have seen several places that carry roller rockers, don't know if the benefit is worth the price they charge for the rr's though...

Well, let me know.

joe



Joe, keep in mind also, that if you have your original Cam (not an after market hot cam, but must be the original), then you can turn it in and get a core charge of about $75 back on the new Kent Cam. It's only $160 if you don't have a core (mine was a former hot cam and not a stock original and they won't take those as core).

The head work on mine was $122. That included one new valve, a complete valve job. Milling the head (just to make it even) and knurling the guides. They also installed my new springs, which I supplied. (About $40-50 at British Parts NW ).

As for the roller rockers - a LOT of money and not sure I'd do that unless I was seriously into racing, in which case I'd also have the head and intake polished and ported and probably add a lightweight flywheel, heavy duty clutch, and beef up the suspension. As it is though, I think what I've done will make it a nice snappy little road car.

Let us know how it goes with yours,
Basil

Caretaker
10-03-2001, 07:41 PM
[QUOTE]Originally posted by Z28Quetzal:
[B]Basil,


I too own a Spitfire. Mine is a '78 with the 4 speed non-overdrive. I currently have the Zenith carb on the engine, however, I am in the process of rebuilding a pair of SU HS2's.

Just a minor note, I assume from th '78 reg, that it's a 1500, if so HS2's will choke it, HS4's (1˝") were the standard fitting.

Dave

Z28Quetzal
10-04-2001, 10:48 AM
Dave,

My '78 is a 1500 indeed. And, you are correct about the carbs being smaller. However, I have done a ton of reaserch on this, and I have found that there were some 1500's that were fitted with HS2's.

Also, in the process of all my reaserch I have found a way to improve the 'breathing' qualities of these carbs. I have done some of this work, however the carb project is on temporary hold.

I am rebuilding the entire suspention at the moment. The PO did not properly rebuild the wheel bearings and they need replacing. As soon as that is all back together, the carbs will follow.

I will post here my findings...

joe

Ron
10-04-2001, 10:51 AM
Before the current Spit 1500 that I have now, my previous 1500 had a set of HS2's on it that I had picked up used of off an earlier Spit. The car ran great and was a huge improvement over the single Strom. The SU's had the original size needles in them. They could have used slightly richer needles to get rid of a flat spot around 2500 rpm, but they certainly did not choke the car.
the HS4's that are on my current Spit do give a little more top end breathing, but HS2's will certainly fit the bill to any somewahat stock 1500 engine.

Ron
vancouver, BC

Basil
10-04-2001, 11:10 PM
Ron, have you any pictures of your Triumph? I have a members picture gallery where I post pictures of people's cars.

Basil