34 replies to this topic

[zebigfatman]

Hi all, I have been building up my old 1275 for over a year now. Yesterday I came to run it and it worked but there seems to be a noise which I can't trace. It could just be the camshaft making the carb sound like that but I want confirmation from all of you experienced peoples.

Engine specs (if it helps)

1310cc
Kent 286 cam
1:5 roller rockers (set to 18 thou)
Ported head with oversized inlets
4 bolt center main cap
KAD flywheel.
Running single 1-1/2 su carb for testing

Changed all ht leads
Played around with the timing.
All the work was done by me and its my first engine build so I'm reluctant to put it in the car unless I know its OK.

Links to video

https://youtu.be/gzChIhWBcP4

As always, cheers for your help guys!

[zebigfatman]

Should also say, compression is good on all 4

[nicklouse]

quick question who built the engine?

[zebigfatman]

Me...

[Retroman]

Hate to say it but It does sound very knocky,

 

Have to say well done on cracking it up on the deck, not many of us do that.

 

Don't think it will be a cam / carb issue.

 

 

Did you have the block line bored for the 4 bolt centre main cap?

When you built it was the crank reground...?

Did you plastiguage the journals?

Was the crank checked for straightness?

 and did you get the oil pressure up before starting it?

How much oil pressure has it ?

[zebigfatman]

Its not a main cap as such, its a hat? I got machined up which sits over the top of the original main cap.

Crank is brand new/old stock from Minisport due to the old one having been reground to many times
Bearings are the standard ones (came with the crank)

I have fitted an electric oil pump which primes and pressurises the it to 25 psi before starting the engine, (got a proper pump as well). Oil pressure sat at about 60psi when running

Cheers for your help!

[Spider]

There is a noise for sure, but I don't think it too serious.

 

Check the rockers aren't tapping on the rocker cover, but I actually think it's a bolt in the clutch cover that's too long, eg, for the timing cover inspection plate or engine mount.

 

What type of Con Rods does it have?  A or A+ ?

[nicklouse]

i have to say I dont like the noise one bit. and i would not say it has anything to do with the cam.

[zebigfatman]

Pretty sure the rockers have clearance (said on minispares it is suitable) but will check.

Really hope my flywheel isn't getting carved up because it is a thing of beauty. But again will check, I have bolted on the mount to that side.

The rods are standard A plus, pretty much the only part of the engine (excluding the block) which hasn't been changed

[Steve220]

Were the tolerances on the crank checked before fitting/matched with the bearings? To me (amateur builder) it sounds like the valve gaps are too large.

[johnv]

worth trying without the rocker cover on .. mine made that noise when I tried fitting a metro turbo one

[minidaves]

duplex timing chain? modified the timing cover? also would say timinig is well out

[zebigfatman]

With regards to the crank tolerances, no they were not checked. I'm not even sure how you would go about that...

The valve clearances are 18 thou due to the 1:5 rockers. I did read somewhere on the forum that 18 was a good number for the cam-rocker combination, but happy to be corrected.

Will definitely try without the rocker cover on but won't get the chance till Saturday. Engine is at my mums and I am up to my eyes in an electronics's HNC

Anyhow thank you all, I have plenty to think about. Will post an update when I've checked out all the suggestions!

[zebigfatman]

Missed the timing post. Yeah, duplex chain and counter sunk the backplate. The timing cover is standard though. Does it need modifying?

[Steve220]

You should always check the crank tolerances during a build. Did you check for end float etc?