Barksavon
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| posted on 12/2/10 at 11:50 AM |
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Pinto Compression
Any Advice...I have just rebuilt a 2.0l Pinto engine for my Kit car.The engine came out of a G reg Transit, it's been rebored to +0.5mm with o/s
pistons fitted. The engine runs well but the compression seems low - 100psi on each cylinder when hot. Accordong to Haynes compression should be 145 -
175psi. I have read of low compression Pinto engines fitted to Transits, does anyone know whether 100psi is correct for a low compression engine and
is it worth putting the car on a rolling road to get the best out of it with such low compression. Thanks
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RAYLEE29
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| posted on 12/2/10 at 12:15 PM |
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Hi the transit was a low compression engine with a 1.6 cam not sure if the lower compression was acheived by using lower crown height or taller deck
height.
did you use standard pistons did you check the deck height did you check the cc of the combustion chamber what cam are you using
Ray
ps are you doing the comp test with wot?
[Edited on 12/2/10 by RAYLEE29]
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britishtrident
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| posted on 12/2/10 at 03:55 PM |
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If it has been re-bored it is unlikely to have low compression pistons, were you compression pressures taken with all the plugs out and the throttle
held wide open.
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Barksavon
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| posted on 12/2/10 at 05:30 PM |
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I think the pistons were standard and i've got a 2.0l camshaft fitted, i didnt check deck height or combustion chamber cc. Ive checked the
compression with a compression gauge that screws into the spark plug hole (1 plug removed at a time) but i didnt hold the throttle wide open when
doing the checks.
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jacko
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| posted on 12/2/10 at 07:17 PM |
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Remove all the plugs
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rusty nuts
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| posted on 12/2/10 at 07:40 PM |
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quote:
Originally posted by Barksavon
(1 plug removed at a time) but i didnt hold the throttle wide open when doing the checks.
Thereby lies a story!
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RAYLEE29
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| posted on 12/2/10 at 10:13 PM |
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ok to start redo comp test with all plugs removed and hold throttle wide open and crnk engine till guage stops going up do it for all four then squirt
a little oil down the plug holes turn over a few times and redo test
bear in mind that if the engines fresh then the rings wont be bedded in yet also when you built the engine what oil did you use to lubricate the
pistons nothing too good i hope as using too good an oil wont let the rings bed in properly
anyway do the retests and see what you get hope this helps
Ray
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Barksavon
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| posted on 13/2/10 at 02:30 PM |
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ok, thanks for the replies i'll re do the test as advised and see what i get
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RAYLEE29
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| posted on 14/2/10 at 12:27 PM |
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how did you get on?
Ray
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Barksavon
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| posted on 14/2/10 at 05:18 PM |
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Ray
not re done it yet, working today so not had chance, hope to do it in week so will let you know. What carbs you running your 2.1 Pinto on, if you dont
mind me asking. I've got one DHLA 40 on my engine at present but have got 2 carbs and a suitable manifold but it wont run very well with them
both on. Had the same problem with a 1.6 that was in the car last year, think its the jetting thats not right. Thanks for the advice with the
compression problem
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snapper
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| posted on 14/2/10 at 06:45 PM |
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Did you skim the head?
What cam are you using?
any cam with more duration than standard will show less compression on cranking because the inlet closes later so the piston is higher up the bore.
What gasket did you fit? a thinner 1mm gasket such as a Felpro will give 1/2 a ratio more, the Pinto likes compression but the pistons can only stand
10.5 to 1
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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RAYLEE29
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| posted on 14/2/10 at 07:19 PM |
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hi, my 2.1 is still in kit form
I will be using gsxr 600 carbs on a home made manifold when it gets to that stage
ive made the manifold and had them running on my mockup 1.6
cant really help with jetting or choke sizes for your carbs just ask on the forum someone should be able to give you a good base setting for twins
also check your cam timing as that will affect the compression too
Ray
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