A Question of HorsePower

[MarkVeryard]

HI,<br>
<br>
Am new to this forum, so I appologise if this is a frequently asked question...<br>
<br>
I took my Sprint to a rolling road recently - the guy reckoned that I should get around 100hp at the wheels - we only found 47!!<br>
<br>
Ok, have you stopped laughing yet? He thought that the jets were worn - he didn't have any new jets, so put in some richer needles to compensate in the short term - we then found 60hp.<br>
<br>
Since then, I have bought and fitted some non-waxstat jets from Malcolm at the TDC - I tuned then using a colortune plug and a carb balancer and have tried the original and the richer needles, but unfortunatley haven't noticed any difference. I should say that I have also cleaned and rebuilt the carbs using new needle valves and throttle spindles - but I am still being outrun by grannies in Ford KAs!!<br>
<br>
I haven't been back to the rolling road yet because I know that he is still going to say that I have around 60hp - any thought as to what my problem could be?<br>
<br>
Thanks<br>
Mark.<br>
<br>
P.S. Engine in a reconditiobned Rimmers unleaded engine which has done about 30k (my third recon Rimmers engine as the first two lunched themselves after 1k !)

<p></p><i></i>

[2F45T4U]

Check your igition... My points gap was non existant and I had such a slow 1850. Now its much better

<p></p><i></i>

[MarkVeryard]

Thanks for that, but I have recently replaced the points and plugs and have a low mileage recon distributer. The guy at the rolling road thought that the ignition was fine once he had retarded it a bit to get rid of the 'pinking'.<br>
<br>
I've also tried a full tank of 'super unleaded' - made no difference as far as I could tell.

<p></p><i></i>

[Jon Tilson]

First off you need to do a compression test. You want to see numbers around 160 psi on all cylinders. Next check your ignition timing....both static and advance. You want to see the advance curve working with the strobe light. The guy on the rolling road should have checked this for you. If he didnt do so and explain it he wasn't doing the job properly.<br>
<br>
Worn jets will lead to rich mixture usually so the fact that he used richer needles to get an extra 20 bhp is surprising.<br>
<br>
Your cam timing could be slightly out. If you have the std cam the marks should all line up. I forget the figures but there should be one for peak inlet opening...something like 106 ATDC.<br>
<br>
Jon

<p></p><i></i>

[MarkVeryard]

Thanks Jon,<br>
<br>
I think i'll buy a compression gauge and have a look (I love any excuse to buy more tools!).<br>
<br>
I know the richer needle thing sounds a big backwards, but the guy explained it based on some problems I was having while tuning the mixture (seemed sensible to me, but I have only just started learning about carbs):<br>
<br>
Symptom: I had found that if I tuned the mixture to be correct at tickover, then the car would have no acceleration whatsoever and would missfire if I tried to accelerate. To get round this I had to make the mixture very rich at tickover, this then gave me some acceleration.<br>
<br>
The guy said that the fact that the jets were worn meant that, when the mixture was correct at tickover, the jets would be too high up and the needles wouldn't be able to rise far enough when I tried to accelerate. The richer needles were fitted to compensate for the high jets. Replacing worn jets would mean that they would be lower down and hence the needles could then rise enough to give the acceleration.<br>
<br>
There must be some truth in his theory, because when I changes the jets and reverted back to the original needles, the original problem with accleration vs tickover mixture went away (though I still havn't got enough of it!)<br>
<br>
Cheers,<br>
Mark.

<p></p><i></i>

[MalcGE]

Some potential contributing factotrs, over and above, fuel, ignition that you have checked and adice Jonners has given you<br>
<br>
Cam Timing, is this correct, do the cam marks line up when engine is a Top Dead Centre.<br>
<br>
Blocked Exhaust - What sort of system r u running, sports or std, how old is it and are there any 'rattles in the baffles', is it allowing all of the spent combustion gas out easily<br>
<br>
Dist Cap, R'arm and leads. how old are the leads, just put a new set on Alan Clarke's Sprint, had to back the idle off about 250 RPM!!!!!

<p></p><i></i>

[MarkVeryard]

Thanks Malcolm,<br>
<br>
It seems I have a few things to checkout when it stops raining. A few people have mentioned the cam timing to me - if it's wrong it means that it was wrong when it left Rimmers as they fitted the engine - i'll check it out.<br>
<br>
The exhaust is a stainless sports system - no idea how old it is as a I bought it second hand, though it must be at least 3 years old - nothing obviously dodgy about it though.<br>
<br>
Cap, arm and leads (original spec) are all about 3 years old or 30k miles - I hope not to replace these as they cost a fortune!

<p></p><i></i>

[MaddMart]

Have to agree with the others, it does sound like the valve timing is out.<br>
<br>
As for compression test, whenever I've taking my cars to the rollers, this is the first thing they check.

<p>Martin<br>
<br>
<!--EZCODE LINK START--><a href="http://www.dolomitesprint.com/" target="top">www.dolomitesprint.com</a><!--EZCODE LINK END--></p><i></i>

[Toledo Man]

I know this might seem obvious but have you checked your dashpost oil level? It could affect you acceleration. The springs might need replacing as well.<br>
<br>
Always pays to check the simple stuff as well...

<p>Toledo Man<br>
<br>
1974 Toledo 2-door (currently a spares car for Snowdrop)<br>
1973 1500fwd (Baby Blue slowly being recommissioned)<br>
1971 1500fwd (spares car for Baby Blue)<br>
1983 Acclaim HL (Becky, my daily driver)<br>
1977 Dolomite 1300 (Snowdrop my other road going Triumph)</p><i></i>

[tinweevil]

Check also fuel delivery at both carbs. I used to get 35mpg but run out of puff at 85. Now I've removed the honking great lump of crud out of the front delivery pipe I get only 29-31mpg but get to motorway speed rather quicker <!--EZCODE EMOTICON START :D --><img src=http://www.ezboard.com/intl/aenglish/im ... /happy.gif ALT=":D"><!--EZCODE EMOTICON END--> <br>
<br>
Tinweevil

<p>1978 <!--EZCODE LINK START--><a href="http://www.triumphowners.com/704">Dolomite Sprint</a><!--EZCODE LINK END--><br>
1972 <!--EZCODE LINK START--><a href="http://www.triumphowners.com/754">Spitfire IV</a><!--EZCODE LINK END--><br>
1968 <!--EZCODE LINK START--><a href="http://www.triumphowners.com/705">GT6 II</a><!--EZCODE LINK END--><br>
1973 <!--EZCODE LINK START--><a href="http://www.triumphowners.com/755">Dolomite Sprint</a><!--EZCODE LINK END--><br>
39 anorak points on the Nicholas scale<br>
</p><i></i>

[MarkVeryard]

Back again - time for an update..<br>
<br>
1) Compresion - I bought a compression gauge yesterday, but there wasn't enough room to get the correct socket down the plugtubes! - it needed a larger socket than the spark plugs, so my spark plug tube spanner didn't help. I then removed the rocker cover and the plug tubes - still not enough room! Anyone know where to get a compression gauge to fit a sprint? - preferable usable without removing rocker cover.<br>
<br>
2) Valve timing - I checked this out, but am not sure if what I found was significant...<br>
<br>
With the crank pulley at TDC, the camshaft marks were very nearly aligned, though slightly out. I then turned the crank until the camshaft marks were perfectly aligned, the crank was then at 4 degrees to the AFTER side. Is this significant?<br>
<br>
Thanks again,<br>
Mark.<br>


<p></p><i></i>

[2F45T4U]

make sure your only turning the engine the way its supposed to. otherwise you put slack in the chain and it will appear as though the cam and crank are incorrectly aligned.<br>
<br>
But yer they should be at tdc together

<p></p><i></i>

[tinweevil]

Compression tester, <!--EZCODE LINK START--><a href="http://www.top-gear.net/product.asp?u=8 ... 3">Gunsons Hi-Guage</a><!--EZCODE LINK END--> fits.<br>
<br>
Tinweevil

<p>1978 <!--EZCODE LINK START--><a href="http://www.triumphowners.com/704">Dolomite Sprint</a><!--EZCODE LINK END--><br>
1972 <!--EZCODE LINK START--><a href="http://www.triumphowners.com/754">Spitfire IV</a><!--EZCODE LINK END--><br>
1968 <!--EZCODE LINK START--><a href="http://www.triumphowners.com/705">GT6 II</a><!--EZCODE LINK END--><br>
1973 <!--EZCODE LINK START--><a href="http://www.triumphowners.com/755">Dolomite Sprint</a><!--EZCODE LINK END--><br>
1980 <!--EZCODE LINK START--><a href="http://www.triumphowners.com/864">Dolomite 1500HL</a><!--EZCODE LINK END--><br>
39 anorak points on the Nicholas scale<br>
</p><i></i>

[MarkVeryard]

The Gunsons gauge is 14mm or 18mm - aren't the sprint plugs 12mm? - does this mean I need some sort of adaptor?

<p></p><i></i>

[Jon Tilson]

Gunson's thingy it was years ago...it came with 2 adaptors.<br>
<br>
The small one fits the Sprint amd also things like fiestas and anything else that takes the samller plugs...quite a lot of modern stuff does. It had an O ring and the ressure from screwing it in by hand was enough to seal it.<br>
<br>
On a Sprint 4 degrees out would be significant....<br>
Worth checking the TDC itself if you have a dial guage and the rotational direction must be right as Adam said<br>
becuase there is probably 5-10 degrees of backlash gont the wrong way.<br>
<br>
Jonners <br>


<p></p><i></i>