Slapping a OHV together

Tips and help requests for your cars mechanics. points gaps, timming settings all those sorts of things

Slapping a OHV together

Postby pbottomley » Tue Jul 30, 2013 8:09 pm

This should help folks a bit I think.... Assume all the grinding and boring has been done (easier said than done!)

So without further ADO

1/. Take a clean block, that had a re bore, and new cam bearings (in ideal world if needed new core plugs as well). Wipe everything dry and clean, make sure you have plenty of room and access to all side of the block.





I shall assemble the Crankshaft first so we start with the main bearings, rear main bearing first, making sure the tab is located the correct way around in the block (see the right edge of the bearing has a locating tab).



I then add the middle main bearings (note this has the thrust faces on the bearing, an automatic engine would have two of these. This is a manual engine so only one is used.



The last main bearings added and the Rear crank oil seal sat in place.





I now use a paste that graphite based to lubricate the main bearings. the principle is that this will hold lubrication in the engine for a short while once the engine is first started and protect the bearings whilst oil is being distributed around the engine at first start up. It never drys up and is so sticky it will not run away whilst the engine sits in storage.





The crank is then lowered into place with the rear crank oil-seal sat in its channel at the rear of the engine.



The front and middle main caps are then lubricated with the same graphite paste and placed into position on the block. They are not tightened down at this point.



The rear main cap needs a sealant along its edges to form a seal, i use sealant and only place a very small amount on the outside edges of the main cap. Be careful not to drop sealant into the engine block.





Then place the Main cap in place and tighten down, sufficiently to close and seal the cap in place.



The crank is now fitted and the rest of the engine can be built around it..
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Re: Slapping a OHV together

Postby pbottomley » Tue Jul 30, 2013 8:27 pm

Next comes the camshaft.

First we clean up the followers (there is a whole story on new or old, lets bypass that for now and just get on with putting it together) :goodideasign:

I put a drop of STP in the top of each follower, so that when it is pushed into place it assists lubricating the follower holes in the block.



Each follower is then lowered into place in the block (small hands required and patients for the ones under the oil pump support).



Wipe then clean and make sure no dirt is in the cam bearings, also clean the camshaft including the gear teeth for the oil pump. carefully slide the camshaft into the block, remember the bearings are easily damaged so its best to support the cam with both hands and slowly move it into place.





Once its in place, bolt on the cam plate, make sure you get it the right way around if its an automatic chain tensioner. the external chain adjuster type don't have a handed side.



NOt its time to Time the engine, its worth spending some time on this, as its very easy to be one tooth out and not realise it. I normally mark the tooth gear wheels and use a rule.



The difficult part is knowing if you have timed it 180 degrees out or not! First rotate the camshaft so that when the tooth gear wheel fitted the LOBES on the cam for cylinder one are not pushing the followers up. Then rotate the crank shaft till its at TDC, you should now find the two wheels fit the crank and camshaft and line up.

Once thats all in place you can fit the Chain tensioner (and at this point got bonkers as you realise the camshaft plate is the wrong way around and prevents you fitting the tensioner correctly! :angrywife:



Its out with the Torque wrench and 35pounds on the camshaft pulley bolt.



Next put a gasket and some sealant on the timing case cover and fit. make sure the case is level with the block before you nip it up fully.







Thats the crank and the camshaft in place. :D
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Re: Slapping a OHV together

Postby pbottomley » Tue Jul 30, 2013 8:35 pm

Next are the pistons. Its worth getting a good piston ring compressor and having some confidence in fitting pistons, as its very easy to break a ring by being weak about pushing pistons in place.

Starting at front of the engine (number one) I slide the first piston in place making sure i have the FRONT mark on the piston to the front of the engine! make sure you have first rotated the crank to the bottom of the stroke, as its not good to bash a con-rod into a crank at this stage.





using some of the graphite paste on the big end bearing rotate the crank towards TDC and engage the con-rod.



use some more paste on the con rod end cap bearing.



place the end cap in place and loosely tighten the two end cap bolts. make sure when you place the cap on the con-rod it is the right way around, the bearings have locater tabs and these should be placed together when fitting the caps.



Continue the same method for all pistons.
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Re: Slapping a OHV together

Postby pbottomley » Wed Jul 31, 2013 8:16 pm

Right here we go again... Last night we had two more pistons to fit, the oil pump and the sump to finish off the short engine.

So a quick push in the last two pistons, again making sure the marker tab is Forward and not backwards. Again tighten the nuts to the end caps loosely for now, and don't forget the graphite paste. (other products are available)





Its now time to Torque the Big end caps (25 pounds)



Its then time to Torque the Main Caps (different for various engines, in this engines case 55 pounds)

(Image to unload in due course)
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Re: Slapping a OHV together

Postby pbottomley » Wed Jul 31, 2013 8:25 pm

Right its that all important oil pump, and this is where most people make the mistakes. First rotate the engine to TDC on the number 1 cylinder.



Check that it is Number one at TDC and not Number 4, look at the camshaft and make sure the lobes are not pushing up the followers. If they are then its on TDC number 4, so the engine needs a 360 degree rotation.



Use a new gasket on the oil pump and slide it into place, then looking down the dizzy shaft hole make a note of the oil pump lobes.



This is a offset pump and the thin side of the oil pump should be towards the rear of the engine with the slot at 90 degrees to the block. We can see that this is not the case in the first fit.



I use a big old screwdriver slotted into the top of the pump, I then slowly withdraw the pump from the camshaft teeth, turn the screwdriver and re engage the pump. A few tries should get you to position the pump correctly. (remember NOT TO TURN THE ENGINE).



You should now see the slot is correctly positioned in the block and one can bolt it into place (20 pounds on the torque wrench)





The oil filler pipe is supported off the centre main cap using a small bolt, its now time to tighten this up.



Now we are ready to fit the sump.
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Re: Slapping a OHV together

Postby pbottomley » Fri Aug 02, 2013 4:56 pm

I forgot the head, so here is the head... its far far simpiler!!















Done... all ready to fit !!
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