Initial engine break-in setup — running rough

Early Bay Forum

Help Support Early Bay Forum:

Moseley

Well-known member
Joined
Sep 15, 2013
Messages
1,479
Reaction score
42
Location
Worcester
Unless my eyes are deceiving me, that push rod looks fairly beaten up as a result of coming off the rocker arm - the tube is mushroomed at the end, and possibly looks bent? Also, the nut looks right at the end of its ‘slack’ travel on the adjuster compared to the others - points towards having had the gap set when the cylinder is not actually at TDC.

Is the push rod the same length as the others? Have you rolled it across a flat surface to check it isn’t bent?
 

ozziedog

Well-known member
Supporting Member
Joined
Jan 24, 2010
Messages
6,403
Reaction score
297
Location
East Brizzal
@ozziedog you're bang on here, the trouble I've got is that I'm now getting so excited after waiting so long to drive this thing that I'm starting to rush and squeeze jobs in during my lunch breaks while it's still light. Hopefully, there is no internal damage...
Should be ok, I’d just have a good look at the pushrod and roll it along something dry and flat like your kitchen work top. Might be a good idea to do it when the long haired general is out too ;) Then a quick wipe around with some kitchen roll. I’d pop the other side off too and then you can do the adjustment doing the opposite game. I’d put a few bob on that motor was only running on two cylinders. So give all the leads a little fiddle with on both ends and re set the valve clearances/ lash.:)
Ozziedog,,,,,,,, then we can get somewhere :)
 

Mechanoid

Active member
Joined
May 16, 2009
Messages
44
Reaction score
9
If you had a bent valve then you wouldn't get the correct cylinder pressure. Do a compression check on that cylinder. The other thing you could have done while the rocker shaft was out is to put a straight edge along the tops of the valve stems. If they are are all touching the straight edge, the chances are that the valve isn't bent. If No. 4 valve stem is below the others then it is most probably bent. However, do a compression test to set your mind at ease!
 

philstar

Well-known member
Joined
Dec 27, 2011
Messages
196
Reaction score
20
Location
Redditch
Year of Van
1971
Van Type
Panel van
After a short delay fixing the T4 I have now performed a compression test on the engine, and it's not good reading.

All cylinders are showing within less than 5psi variance, but only at 25psi
3TMRDXLvA9nkQYT8ZrdZLbazHjWZJoTuFFstaIwDj5Ym59m0CN3l-AMvVpif-tCwSqPF8burzsgrVMwY60HBnqxa2lgk3mXtcHoRa0kYxbgJLNaqJk5APXu10inKDfHejNSr6gE0j5tAsO_oe0C6Uf9MDDpTB2nKWN7HoUDXvmCcqJ3XtL_oxeZuYMCyZ4rAXkqwol1crCSod6Wo5h0THR9gi4S0fmpTJ26qxj0DmjuLG3FjeG6soL822Sz156Fh93v6jNirSaPZhptxr10awaM4rl1ye5w8q1WAVQJeQlqvUWQr2n2Ev1q2rsAdGXAW23IYNQul6RuishEV0sKlSZNOujUSMHkPU2PESRxUEWP3ZzzQt3J9Z4r7f3qWYbg2Kse0PPe1qH-t5bn9nHiXRKwcJWd7NQKnqy7AtFXjjTtNmS9x_IFq7sXBWBWwGGq5wfC-j3IGuHS1hlP3iytSNrNHsbcL2LawrtrIDpRHLoksuT8-VVDCpF5erUCRDYY-KS-mpDsiwbXKg-_7b24zaylRxK19rOdCxGWUdJCsoPw1rCbSmYkD00kpLGheJs6VzUUUyVD5qMz521UlMCF9XGefzt1MGUIbZkxBSzkQWU1K1kPBz4FKz40TeCOCyP4jGbDBSwwsjarT3lrAOytogNOIlnmF7Qu_A95EPodxamr7sKizg-7K7c3QA-6gMrzzDAcNHwSBNRRqwXRFYX7TY0UASvpUCYkEh-Xvs62B-OqkWNPih3TXMgMDMCh-TD-cpJ-0RAd6ynZzygfsYuThb0BgMnQPOo-ipWXQydp8JMptpoLp8IXivGJ3EiynUGLmeQxHZPyJG_ZZIzeHHBXs7h1SqG1BBbd2W_rxDbKj6Drld-CRM9Vrhju2tZ3RtfnlNeMKVjnOH8edej94MZZZhMzR58bo2kPkZepEi-tW1P-o-8a9SA=w1184-h1578-no

I tried a different connection on the tester and managed to get 50psi on cylinder #4 before running out of time, but even if this were replicated across the other three cylinders, 50psi is still too low for a brand new engine isn't it?

Assuming the tester isn't faulty, what are my options?

To confirm, this is a newly rebuilt engine (all-new top-end assembled by myself), end float is fine, standard 1600cc. It sounds great and revs freely (past a hesitant flat spot slightly above idle, as discussed earlier), there are no oil leaks. I haven't yet driven it on the road.

It does have an electric fuel pump so I might repeat the test again with this disconnected just to see if it makes any difference but I can't see it making up for nearly 100psi.
 
Last edited:

philstar

Well-known member
Joined
Dec 27, 2011
Messages
196
Reaction score
20
Location
Redditch
Year of Van
1971
Van Type
Panel van
I forgot to block the rear vacuum port on the carb which won't have helped things 🤦‍♂️

I have now re-assembled everything and got it running again and it does seem better, though there is a backfire if I rev it high and hard from idle. I have tried pulling off a number of times up a slight slope on my drive and it hasn't come close to stalling, so I think I'm going to fix the rest of the bits to get it road legal then get it insured and give it a road test.

If I'm still concerned I might take it to a garage where they can perform a more accurate setup.

I'm still not convinced about my butterfly valve/choke setup (Thread: Stepped cam set up) as it seems that even if I hold the cam fully open, the butterfly valve isn't quite vertical, and it is "loose", so I can then stand it up straight with my other hand.
 
Top