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 V4 with no oomph!
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TGO001
Starting Member

Spain
11 Posts

Posted - 01 Oct 2017 :  13:42:15 Show Profile Reply with Quote
Hi guys. Your thoughts please. Since buying my 72 V4 I have been disappointed with it's performance. So far I have fitted electronic ignition, weber 34ICH carb and Jetex exhaust. I have removed both heads and checked and lapped in the valves and checked the bores for wear (which were fine). Result? Nada, as they say here in Spain. It starts perfectly, runs smoothly but has no real power. I live in a hilly area and it really struggles uphill. It seems to run out of steam at higher revs. Any ideas would be gratefully received.
PS. Someone suggested that the timing wheels could be misaligned but would it run so smoothly if that was the case?
Thanks in anticipation .
Terry

Betsy67
V4 Fanatic

United Kingdom
247 Posts

Posted - 01 Oct 2017 :  16:10:19 Show Profile Reply with Quote
I had a similar problem, which was caused by a retarded ignition timing. Try advancing the timing a few degrees on the dizzy and see what happens.
The engine would start, tickover fine and would pull reasonably well. However if you wanted acceleration or climbing hills it would struggle.

Edited by - Betsy67 on 01 Oct 2017 16:13:23
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TGO001
Starting Member

Spain
11 Posts

Posted - 01 Oct 2017 :  20:49:55 Show Profile Reply with Quote
Shanks for your suggestion. Should have said that I have been up and down the timing marks but with improvement. Glad that it solved your problem, however
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TGO001
Starting Member

Spain
11 Posts

Posted - 01 Oct 2017 :  20:51:55 Show Profile Reply with Quote
Sorry. That should have read "with NO improvement"
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Mos6502
V4 Beginner

USA
90 Posts

Posted - 02 Oct 2017 :  03:37:41 Show Profile Reply with Quote
Did you do a compression test?
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UK_Sub
Moderator

United Kingdom
2103 Posts

Posted - 02 Oct 2017 :  09:20:30 Show Profile Reply with Quote
Perhaps the vacuum advance isn't working?
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TGO001
Starting Member

Spain
11 Posts

Posted - 02 Oct 2017 :  14:07:22 Show Profile Reply with Quote
Hi. Very grateful for your suggestions. Just been up to the garage and done a vacuum advance test. All ok there.
I don't have a compression tester but coming downhill with freewheel off, the engine seems to hold the car back really well. I'll have to buy one to do a definitive test though.I'll get back to you on that one.
Cheers from sunny Spain
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melle
V4 Guru

United Kingdom
2252 Posts

Posted - 02 Oct 2017 :  19:36:35 Show Profile Visit melle's Homepage Reply with Quote
This can be caused by many things... I would also suggest checking compression first, I think it's very unlikely that the timing is a tooth off. I assume it's a standard 1.5 engine? Do you know anything about its history/ mileage?

Was the engine dirty/ sludgy inside? How did you check the bores for wear? Visually or did you measure them as well? Did you also check the rings? Did you replace the distributor cap, rotor, plugs, coil and leads when installing electronic ignition? If not, did you make sure the coil is compatible with the ignition unit you installed? What plugs are you using and what is the gap? Have you checked the brakes? I'm sure I can think of a few other things if this doesn't help! (Like a worn cam, worn fuel pump membrane etc.)

When driving up a hill the throttle is pretty much fully open so there won't be any vacuum, so vac advance can be ruled out anyway. A burst vac pipe can cause an air leak though. Also the hose between the left hand side rocker cover and the pcv valve is notorious for leaks.

www.saabv4.com
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TGO001
Starting Member

Spain
11 Posts

Posted - 04 Oct 2017 :  13:20:57 Show Profile Reply with Quote
RESULT! Checked the PCV valve hose and found a small split. Made temporary repair by taping up and fitted new clips. It now drives like a different car. Many thanks guys, for all your suggestions and especially to Melle for hitting the bulls eye straight away. I can't beleive the difference such a small thing has made to the car. THANK YOU SO MUCH!
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melle
V4 Guru

United Kingdom
2252 Posts

Posted - 04 Oct 2017 :  13:36:29 Show Profile Visit melle's Homepage Reply with Quote
That's great to hear! I think John-Saab sells new ones.

www.saabv4.com
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72sonett3
V4 Fan

Spain
187 Posts

Posted - 12 Oct 2017 :  16:20:23 Show Profile Reply with Quote
quote:
Originally posted by TGO001
... Just been up to the garage and done a vacuum advance test.

No need to go to a garage to do that test... Take the dist cover off, and the vac hose off the carb and suck on it, then you should see the breaker plate rotate.

A compression test should show 10-11 bar.

quote:
Cheers from sunny Spain

Where in Spain are you? I am in the north east, near Girona.

--
'72 97
'77 96L conv.
'79 96GL (LPG)
'83 900i (LPG)
'95 900SE conv.
'99 9-3T

Edited by - 72sonett3 on 12 Oct 2017 16:30:11
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