Air blowing from carbs

[ronhatch]

Hi all, I have rebuilt the engine on my TR4, new liners and rings,new head gasket, head has had new valves and seats and have been lapped, all the valve gaps are correct and are moving up and down  but I am getting air blowing out of the carbs ! I'm a bit stumped and would appreciate any advice. they are the original valve spring but they seem ok.

Regards

Ron

[harlequin]

Does it start Ron?

Cam timing maybe 

George 

[BlueTR3A-5EKT]

8 minutes ago, harlequin said:

Does it start Ron?

Cam timing maybe 

George 

You beat me to it George.

Edited August 9, 2024 by BlueTR3A-5EKT

[Rob Salisbury]

I'd be checking the cam timing, standard cam is 17-57-57-17, sounds like it maybe 180' out so blowing when it should be sucking.                                                                                  Cheers Rob

[ronhatch]

thanks for the replies, I thought it might be the cam but did not want to venture down that route until consultation, could I just turn the dizzy  and use the "second" TDC or will I have to take off the timing cover and reset timing chain ( which I'm sure I did  but the memory isn't what it was) but it feels like the inlet is open when it should be closed

Regards

Ron 

[BlueTR3A-5EKT]

35 minutes ago, ronhatch said:

thanks for the replies, I thought it might be the cam but did not want to venture down that route until consultation, could I just turn the dizzy  and use the "second" TDC or will I have to take off the timing cover and reset timing chain ( which I'm sure I did  but the memory isn't what it was) but it feels like the inlet is open when it should be closed

Regards

Ron 

Did the engine refurbish involve replacing the cam timing chain?  
 If so there is a chance it went back in the wrong place as there are often no defined timing  marks on most original engines cam and crank gears.

Moving the distributor could be done if the drive gear from cam to distributor is fitted in the wrong way.   But that only solves the ignition timing not the blowing out of the carbs.

To change the cam timing you only need to get the timing cover off.   Thankfully you are working on a TR4/4A which means you can see and get at the timing cover once the radiator is out.   Not as easy on a sidescreen car as the front apron needs removing.    
 

Double check the cam timing before you start ripping it to bits.    
Plugs out 
Find and confirm TDC of the crank with the timing mark on the front cover and crank pulley. Set to TDC 1&4
With the rocker cover off watch the  valves of cyl 1 &4 as you rotate the crank from 1/4 turn before TDC to 1/4 turn after.   At TDC 2 valves of one cylinder should be rocking.the other cylinder 2 valves will not be moving as that is on firing stroke.  Those moving should be With equal amount of open/close to each other.    This method is detailed in the service manual and is refined by adjusting the rocker clearances to a set size before testing the open closed with a feeler gauge at TDC

Edited August 9, 2024 by BlueTR3A-5EKT

[ronhatch]

thanks peter , I will take off the timing cover and start from there, I will go back to basics but I was hoping for a light bulb moment on something obvious ( and easy) that might have solved it. Part of the fun I keep telling myself as I grind my teeth , Thanks again for all the replies, I will start it tomorrow unless someone comes up with the easier fix 

Regards

Ron

[BlueTR3A-5EKT]

14 minutes ago, ronhatch said:

thanks peter , I will take off the timing cover and start from there, I will go back to basics but I was hoping for a light bulb moment on something obvious ( and easy) that might have solved it. Part of the fun I keep telling myself as I grind my teeth , Thanks again for all the replies, I will start it tomorrow unless someone comes up with the easier fix 

Regards

Ron

You are not alone Ron.   In 1972 I  did get my cam timing one tooth out on the first TR engine I rebuilt.   It ran but was flat until 3000 rpm then went ok.  

[Z320]

Stupido questione, perdonami:

engine is in the car, you want to start it with the electric starter?

Ciao, Marco

[ronhatch]

Hi Marco, there is no such thing as a stupid question my friend, thank you for your reply

engine is in the car and i want to start it

Regards

Ron

[Z320]

The engine sucks air in though the exhaust?

If the inlet valves open while the compression stroke

and the outlet valves open while the intake stroke

you can’t reverse this with a different dizzy setting.

[RogerH]

Hi Ron

The valve timing relies on getting#1 Inlet valve to TDC

However #1 inlet is actually the second valve along. 

The first valve is an exhaust valve.

 

Roger

[ronhatch]

Hi all , thanks for the replies, I now realise that the timing is way out. I don't know what I was looking at when I set it up but obviously the book was upside down !  I will reset today after proposing every scenario to my mates in the pub last night to get an easy fix. Strangely enough the solutions got more bizarre in direct relation to the amount of beer consumed, odd that 

Spanners at the ready to do a proper job like I should have done originally 

Cheers

Ron

[ronhatch]

Hi all, 180 out , I blame my wife , she must have brought me a cup of tea at a vital moment and distracted me , how thoughtless 

Regards

Ron

[harlequin]

48 minutes ago, ronhatch said:

Hi all, 180 out , I blame my wife , she must have brought me a cup of tea at a vital moment and distracted me , how thoughtless 

Regards

Ron

I hope your wife doesn't follow the forum otherwise that could be the last cuppa that gets delivered to your garage 

Good that you have found the answer 

George 

[BlueTR3A-5EKT]

16 hours ago, RogerH said:

Hi Ron

The valve timing relies on getting#1 Inlet valve to TDC

However #1 inlet is actually the second valve along. 

The first valve is an exhaust valve.

 

Roger

Pardon me Roger……

  Inlet fully open and crank set to a degree specification after TDC.   As specified by the cam grinder.      Standard cams are 110.    So inlet on no 1 pot fully open and crank set at 110 degrees after TDC on piston no 1

loop the chain and chain wheels on and attach

Rotate engine and check fully open at 110 again.  

Then check equal opening at tdc of both inlet and exhaust valves of that pot.

The method I use   https://macysgarage.com/cam degree.htm
 

 

 

[RogerH]

Hi Pete,

 not sure what you are getting at - my comment above is a little mistook I did a few years back.

I mistooked the first valve as the inlet - but it is an exhaust.

 

Roger

Edited August 10, 2024 by RogerH

[BlueTR3A-5EKT]

6 minutes ago, RogerH said:

Hi Pete,

 not sure what you are getting at - my comment above is a little stook I did a few years back.

I mistooked the first valve as the inlet - but it is an exhaust.

 

Roger

Ahhh fallen in now.   Old age creeping up