TR6 engine.

[pennydog]

Hi All,

After fitting serviced injection system to the TR6 the car runs like a bag of bolts the engine pops & bangs and does not idle very well the revs die off and then they pick up again(the engine

number stamped on the block is CR1879HE the metering unit was set up for a 125bhp engine).

The car has been to a tuning centre but they were unable to get the car to run any better they

recon the car has the wrong camshaft is fitted.I have another engine in the garage the number

stamped on the block is CP 7691 HE is this a 150bhp engine?,but the cylinder head needs to be serviced or could i fit a 150bhp camshaft to engine CR1879HE would this make it a 150bhp engine or

would other work be required to be done to the engine.I know the metering unit will have to be recalibrated to 150bhp.Would it be better to get the CP engine overhauled & fitted into the car.

I await your your opions fellow TR6 drivers what is the best way forward for me now.

Best regards Pennydog

[robgeev]

Did it run ok before fitting the Pi system?

If it did, it's unlikely to be the camshaft.

Sounds to me like an air leak, also, go back to the basics-firing order, points gap, timing, leads, plugs-my red 6 was running rough on start up, ten minutes of plug change and it is like a new car.

 

Many modern day tuners only really have electronic diagnostic experience, so maybe they would overlook "old fashioned" problems like you're experiencing.

Perhaps if you post your area, then someone local could have a look at it, or recommend a proven repairer.

 

Rob.

[Richard Crawley]

Welcome to the forum Pennydog; There is a whole load of information in the archive posts on how to check the system methodically to trace what’s wrong, the other alternative is to go to some one like Malcolm of Prestige Developments who is very highly regarded in TR circles. More info needed to help really, as Rob says, pops/bangs are indicative of weak mixture or wrong timing; could be simply an air leak, could be the cam or could be a whole load of other things!

 

Was the car running PI successfully before or was it on carbs? Who serviced the PI system & what bits? Has the new M/U been correctly timed? What fuel pump are you running & what pressure are you getting? Have the injector lines been bled properly? Have they been correctly set up? Are you getting a good spray pattern on the injectors? Do you have any air leaks on the induct system or M/U vacuum hose?

 

Re upgrading the CR series engine to 150 BHP; this has also been covered before but from memory the differences are cam, head & dizzy (I think).

[pennydog]

Hi All,

In reply

to the two previous posts.The injection system was serviced by Prestige Developments

and a new boosch fuel pump was fitted,.The tuning garage was in contact with Malcolm of Prestige Developments by phone he advised the garage try out different things but to no avail the car still ran ****,The conclusion both parties can to the engine had some odd ball camshaft fitted and without knowing the profile of the camshaft the metering unit could not be set up to suit the engine.When the car was bought the engine was running twin SU carbs the engine had no real go about it but the sound from the exhaust system was fantastic.After phone calls to 2 previous owners they also said they could never get the engine to run with the injection system fitted. One owner had fitted twin strombergs and the other fitted the twin SU carbs they described the same problems as i have had with the injection system.

The parts serviced or replaced are as follows,

PRV- serviced. new boosch fuel pump ,injectors seviced,new injector pipes,M/unit seviced and new fuel pipes fitted.

One of the previous owners stated that the CR engine may have been fitted in a triumph which was competing in the London to Sydney in 1976.He thought road/race camshaft may have been fitted and maybe some work carried out on the head.

Regards Pennydog.

[Richard Crawley]

Pennydog;

Considering the ‘guru’ class advice you’ve already had, I would get myself busy checking out/refurbishing that spare CP engine as it sounds like the best option you’ve currently got!

[Tom Fremont]

The cam lift and duration can be determined, I believe, without going further than the rocker box. Since changing out a cam is ~ 20 hour proposition it may behoove you to find out what you can this way 1st. Seems to me the P.I. system ( though I've never had one ) is adaptable to quite a range of cams. I would have thought pros like those mentioned above could get it to run OK by trial and error with the help of CO and fuel/air ratio meters

[JohnC]

Tom's quite right (and so is everyone else...) - you can check the cam profile with pretty much everything in place except the rocker cover. You need a dial gauge, and you need to remove the tappet adjuster in one rocker. Position the dial gauge so that the probe sits in the cup of the pushrod, running through the rocker arm. You can then rotate the engine a bit at a time, noting the cam lift every few degrees. A tedious process, but you'll have an accurate picture of what cam you have.

 

FWIW, I have a high-overlap cam, and the PI is quite capable of handling it. Assuming everyting else is working as it should, a few steps will get you a dramatic improvement in how the car runs - and you can do some of it yourself. You will need to set up everything bar the PI, and then note the manifold vacuum at idle. It would also help if you had an idea of the exhaust gas oxygen (i.e. mixture) at full chat. I use an EGO sensor in the tailpipe for this purpose, but a rolling road is even better (just more expensive). With these two pieces of data, Prestige should be able to get very close to the correct PI setup for your car. The idle vacuum is by far the most important of the two, and at a pinch you can tweak the full throttle mixture yourself by adjusting the max fuel setting (little screw under the MU).

 

I still get some spitting & farting on overrun, but the car performs well. In spite of the cam (which was a mistake caused by miscommunication between me & cam grinder), the car is no more powerful than a well set up 150bhp car, but that is probably because the head is bog standard.

 

Hope this helps. Let us know how you get on.

 

Cheers,

John

[JohnC]

<snip> Duplicate post - oops!

Edited December 29, 2006 by JohnC