2.1 Pinto compression expectations

[Fozzy48]

What compression should I be looking at from my 2.1 pinto engine.?

Cheers.

Fozzy

[Fozzy48]

So there's nobody on this forum that can tell me what compression I should be expecting from my 2.1 pinto. ?

Fozzy

[voodoo57]

Hang on a min...........

[voodoo57]

Call Penguin motors, i think they are Cambs based 01353 669345

failing that, go onto the Turbosports forum, plenty of advice on there, a lot depends on what size pistons and what material, ie cast? , what head etc.... not sure if Camshaft matters as much, but have a look and you should find your answer.

[colr6]

What's your reason for wanting to know Ian ? Compression pressures should all be within a tolerance of each other. If your trying to find a fault you may be better getting  cylinder leakage tester. You can buy them quite cheap off the likes of fleabay. using a compression tester it's a difference between cylinder pressure your looking for. If you suspect they are low then a leakage tester will tell you where it's leaking.

[deltamal]

According to the Haynes manual, the standard cylinder compression should be 185psi or above with no more than 20psi difference between the readings, guess that would be for a new build run in engine, personally I would want less difference between the readings! 

[Fozzy48]

3 hours ago, colr6 said:

What's your reason for wanting to know Ian ? Compression pressures should all be within a tolerance of each other. If your trying to find a fault you may be better getting  cylinder leakage tester. You can buy them quite cheap off the likes of fleabay. using a compression tester it's a difference between cylinder pressure your looking for. If you suspect they are low then a leakage tester will tell you where it's leaking.

Thanks for the replies.

I took the car for rolling roading yesterday. I was there for 1.5 hours with them telling me they would do some tests and checks first to make sure they weren't wasting theirs and my time and money. We left it there and came back 1.5 hrs later to be told there was a few issues. The main one being low compression. He's going to email me the data but readings were ranging from around 90psi to 105. I said should they be closer to 130 psi and he said nearer 170. 

So basically I came away £72 lighter and absolutely nothing done at all. He was saying that the fuel pipe from the pump was 8mm and somewhere changed to 6mm into the carbs. So that was stopping at least balancing the carbs up. I have to say I'm pretty annoyed. The pipes from the pump look the same size as that going into the carbs. It seems to me they couldn't be bothered to do anything on it.

So based on him saying it's low on compression by close to 50%, why does my car not feel like that  I drove it back up the motorway and apart from it not quite running as responsive as it should it certainly didn't feel like it was low on compression. I took it to noble motorsports that I've used before, albeit 15-20 years ago.

Fozzy

[Snapper]

I don’t see why 8 to 6mm would stop you balancing the carbs as that is purely a mechanical function done at idle.

compression pressure is dependant in a number of things but should be done with a warm engine, throttle open.

a 2.1 engine will give a little more than a 2.0, cam duration and overlap can reduce this

u think they are pulling your dangler, unless the engine was in danger of going bang any rolling road would at least run it up on the rollers and get a lambda Reading

[Fozzy48]

1 hour ago, Snapper said:

I don’t see why 8 to 6mm would stop you balancing the carbs as that is purely a mechanical function done at idle.

compression pressure is dependant in a number of things but should be done with a warm engine, throttle open.

a 2.1 engine will give a little more than a 2.0, cam duration and overlap can reduce this

u think they are pulling your dangler, unless the engine was in danger of going bang any rolling road would at least run it up on the rollers and get a lambda Reading

Well it seems it MAY be on the low side of compression if the readings are correct, but I'm gonna have to do some more checks on it. If I have to strip the engine then so be it.

To a certain extent I feel like I was fobbed off, especially the fuel pipe issue. But, if they can't tune it because of compression issues then I'll have to accept it and deal with it.

Cheers.

Fozzy

 

[Snapper]

You don’t need to strip the engine just yet, suggest you warm it up then compression check each cylinder with the throttles open.

the most important thing is consistency over all 4 even if low

then a spoon of oil down 1 bore and see if the reading goes up, if so do the same on the others.

if not swing the cam timing a few degrees (not many) see what the readings are

IMHO if readings are consistent and the car runs ok, try another rolling road and stay with the car

[Fozzy48]

3 hours ago, Snapper said:

You don’t need to strip the engine just yet, suggest you warm it up then compression check each cylinder with the throttles open.

the most important thing is consistency over all 4 even if low

then a spoon of oil down 1 bore and see if the reading goes up, if so do the same on the others.

if not swing the cam timing a few degrees (not many) see what the readings are

IMHO if readings are consistent and the car runs ok, try another rolling road and stay with the car

Yes mate, ofcourse I'll do all the compression tests before taking it apart. As it happens the engine will be coming out once I get moved to our new house. But not until I've checked it over as you say.

Cheers.

Fozzy

[mk2dk]

Hi Fozzy.

Did a compression test on my pinto last year. It has only done 1200 miles since a fully rebuild with new pistons etc etc, actually I think it needs more miles to be fully broken in, and the compression might  raise a bit. Engine warmed, throttle open, readings were 180 psi on all cylinders. Camshaft is a Kent Cam GTS1 294 deg duration.

When I build the engine I was aiming for 10.5 : 1

mk2dk

[Fozzy48]

4 hours ago, mk2dk said:

Hi Fozzy.

Did a compression test on my pinto last year. It has only done 1200 miles since a fully rebuild with new pistons etc etc, actually I think it needs more miles to be fully broken in, and the compression might  raise a bit. Engine warmed, throttle open, readings were 180 psi on all cylinders. Camshaft is a Kent Cam GTS1 294 deg duration.

When I build the engine I was aiming for 10.5 : 1

mk2dk

Thanks for that mate. It's certainly looks like I'm well on the low side.

Mine has an RL21 Kent cam and big valve head, so not sure how that would really affect my compression.

Fozzy

[mk1del]

Do another test or get a competent garage to do it , personally dealing with pintos over the years, I would expect  140psi just ok to  180psi good

Anything close  leave alone if runs good

[Snapper]

11 hours ago, Fozzy48 said:

Thanks for that mate. It's certainly looks like I'm well on the low side.

Mine has an RL21 Kent cam and big valve head, so not sure how that would really affect my compression.

Fozzy

The RL21 is an older version of the RL31 I have in one of my 2.1 engines.

longer duration cams with more overlap will reduce compression as the valves close later meaning compression of gas starts later as piston is further up the bore when both valves are closed.

This is why racey cams need more static compression.

If your engine is standard you will have lower compression test readings than the same engine with a standard cam

i run 10.7 on my RL31 engine and 9.7 on my FR32 engine

[Fozzy48]

10 hours ago, mk1del said:

Do another test or get a competent garage to do it , personally dealing with pintos over the years, I would expect  140psi just ok to  180psi good

Anything close  leave alone if runs good

I was talking to my mate other day about it and we agree like you and others have said to do more checks first which I do plan on.

It' gonna be into April that I get chance now as we should be moving house soon and I'll have me own garage.

Cheers.

Fozzy

 

 

[Fozzy48]

5 hours ago, Snapper said:

The RL21 is an older version of the RL31 I have in one of my 2.1 engines.

longer duration cams with more overlap will reduce compression as the valves close later meaning compression of gas starts later as piston is further up the bore when both valves are closed.

This is why racey cams need more static compression.

If your engine is standard you will have lower compression test readings than the same engine with a standard cam

i run 10.7 on my RL31 engine and 9.7 on my FR32 engine

The more I'm talking to people, the more I'm starting to understand that things like different cams can have an effect on compression, even if the timing is slightly out. I'm hoping it's' something simple like the timing or its been shimmed up too much therefore not closing the valves properly. 

Cheers.

Fozzy

[Fozzy48]

Here are the PSI's from the compression test last week. Still think he's talking  the round ones about the fuel pipe.

fozzy

[colr6]

So going by that he's done a cylinder leakage test as against a compression test. With the result the problem mainly lies in the head. First thing to do is off with the lid and check tappets. Then if you find the tappets to be ok, do a wet test as previously suggested and see what readings you get. That should give you a difinitive answer valves or bore.

[katana]

Well if they were any kind of ok mechnicks they should have been able to tell you where the leaks are - inlet valves, exhaust valves or rings. Those are pretty big %'s - normally see those with busted rings or holes in pistons! For gods sake you can hear the air escaping with those sort of leakdowns! I'd be getting a priest in to administer last rites when the head comes off!

[Fozzy48]

25 minutes ago, katana said:

Well if they were any kind of ok mechnicks they should have been able to tell you where the leaks are - inlet valves, exhaust valves or rings. Those are pretty big %'s - normally see those with busted rings or holes in pistons! For gods sake you can hear the air escaping with those sort of leakdowns! I'd be getting a priest in to administer last rites when the head comes off!

This is what I can't understand. Why would i not know when driving it that it lacks compression=lacks power. 

fozzy

[DT36]

With cylinder 2 & 3 being so low and at the same readings, it could indicate a head gasket leak across the bores. However, I'd then expect to hear air coming from the adjoining cylinder. 

As the guy hasn't given you any indication of where the air was leaking too, I'd be looking to do the tests myself after having checked the valves, as suggested by Col. 

Leak off test usually indicates the following:

Air at inlet side / carbs = inlet valve            Air at exhaust side = exhaust valve            Air at radiator = head gasket or cracked bore or head.                                                  Air in adjacent cylinder = head gasket.      Air at dipstick = piston rings/worn bores or hole in piston. 

[Fozzy48]

23 minutes ago, dt36 said:

With cylinder 2 & 3 being so low and at the same readings, it could indicate a head gasket leak across the bores. However, I'd then expect to hear air coming from the adjoining cylinder. 

As the guy hasn't given you any indication of where the air was leaking too, I'd be looking to do the tests myself after having checked the valves, as suggested by Col. 

Leak off test usually indicates the following:

Air at inlet side / carbs = inlet valve            Air at exhaust side = exhaust valve            Air at radiator = head gasket or cracked bore or head.                                                  Air in adjacent cylinder = head gasket.      Air at dipstick = piston rings/worn bores or hole in piston. 

Cheers for the replies guys. I'm gonna get some tests done as soon as I get chance.

Fozzy

[colr6]

Think those figures maybe slightly misleading, I've heard that engine run and TBH didn't sound to bad, certainly pulled ok on the road abeit from the passenger seat. Although Ian is experiencing poor starting when cold but that's it. A little more investigation into it by another party could prove fruitful and less expensive. On those sort of supposed leakages say down the bores it should be pushing fumes out the rocker cover like a chuffer train ! On the inlet side it would suffer with stand off to the extreme it would soak the filters.

[Snapper]

What sort of spec is the Head?

if standard I would first do a wet compression test, oil down spark plug hole on the worst cylinder and see if the compression increases.

are you able to do some mechanics yourself? If so you could pull the head off and check a number of things. 

Head gasket

Valve seats, upend Head and put methalated spirits in the combustion chambers to see if it leaks past the valve seats

you don’t say how long you’ve had the 2.1 or how many miles it’s got on it.