Jump to content

New sport exhaust + k&n = new niddles ??


SeanG
 Share

Recommended Posts

Hi everyone, tomorrow if the compression test i m doing is fine, i will install my new 6-3-1 manifold. I will then put a new phoenix twin sport SS exhaust and k&n filters. I know it sounds like chirstmas !

I was wondering do you reckon i will have to change the needles of my stromberg cd150, currently i use B5DG.

Any thoughts ? Thx

Link to comment
Share on other sites

I believe the range of available needles is small. So in all honesty I would get a session booked on a rolling road. Probably worth checking the dizzy carefully too. The RR should be able to reprofile the existing needles.

Are you arranging a cold air feed for the air filters and short rampipes? They will both make the most of your other changes and are usually overlooked.

Link to comment
Share on other sites

CD150 on a 2.5. Stop now. Carbs are just too small for what you are doing. 

You need to fit some dolomite sprint HS6 carbs.

 

As to dizzy, if that is worn/not giving the correct advance it will drastically affect the performance.

 

Cold air is much denser than hot air from the engine bay. So you need to get cold air ducted in. Yes, K+N's flow more but they will need to just to match the old paper filters and airbox. Likewise rampipes can make a 5% difference to airflow into the carbs. That is more than the manifold and exhaust can do!

Link to comment
Share on other sites

It s been converted to 2.5 during a rebuilt, don t have much info from previous owner. But yeah, you could tell there was a lack of power, compare to my 1976 mgb the triumph was much slower, very low torque. Btw i m gonna post the results of my compression test on the engine section. If you guys got a sec and let me know what yoh think it ll be amazing

Link to comment
Share on other sites

Right. ALL 2.5 engines have flat top pistons. 

most 2 litre cars are flat top, but approx 1972 (and of course many have been changed between cars) Triumph  used the same block and head for both 2litre and 2.5. The 2.5 just had a longer throw crank. However, as the 2.5 head had a larger combustion chamber, they added dome top pistons to correct the compression.

 

If your car has dome top pistons, it is a 2 litre (or a 2.5 with massive compression, about 12:1, it would have serious running issues!)

 

Now, some people have taken a late GT6 engine (or equivelent saloon engine) stripped it and reused the head but fitted a 2.5 crank and 2.5 flat top pistons.

 

Please let us know what you have, important to be able to help.

Link to comment
Share on other sites

I have dome piston 100% as i have changed head gasket.

The car is registred as a 2.5 on the number plate, the previous owner (young mechanic student) told me it is a 2.5 conversion while engine rebuilt. So it s bit confusing. Is there any easyway to check ? Thx

Link to comment
Share on other sites

You need to measure the throw of the crank. ie front bottom of stroke to the top, can be measured easily with the head off!

Another check that may say if it is deffo a 2 litre.....have a look at the sump. It should be the same height both sides and have a factory round bit pressed to clear the steering rack. If it does, check to see if 2 dents down have been added in the front part of the sump inline. These are needed to fit a 2.5 crank using a gt6/vitesse sump.

 

If they are NOT present, it is a 2 litre crank.

 

If they are, it could be a 2 or 2.5 as somebody may have swapped the crank/sump or whatever. 

Link to comment
Share on other sites

Had another thought linked to your compressions. They are too uneven and probably low. 

when you replaced the head gasket did you check if the block was a recessed one (small ring machined around the edge of the top of the bores, head gasket should have a tab sticking out at the back) The engine number should also tell (though again, somebody MAY have had the block skimmed (decked) to remove them, and that would also remove the engine number. Which may have then been restamped. Good game this. Guess what somebody did to the car sometime ago! 

Link to comment
Share on other sites

Here is a picture of the oil pan, looks like a 2L one right ? Yeah head was recessed and my head gasket has a bit that is sticking out at the back. It s a 1973 very late model. Who knows what the previous owner did... So you guys guess it s a 2L right ?

post-1175-0-74845200-1445793776_thumb.jpeg

Link to comment
Share on other sites

Cant quite tell from that pic. The "recess" for the rack does not look even across the sump. And it gives the impression that the sump is angled, ie the bottom (or in that pic the highest flat section) is not level. Makes me think it is from a saloon. maybe, t an end on pic is needed.

The engine number will help too. But with the above caveats. 

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...