So I’ve finally taken the engine out of our bus to sort out the oil leaks and give it a freshen up. While it’s out I’m looking to put on some 1641 barrels and pistons. Does anybody run these and what size cylinder head are you running with them. ?
Thanks is for that I’m running 040 heads twin port but have been advised to get bigger heads to make the 1641 barrels and pistons worth it
If you're going to get new heads then I would go up to 1776 and get the case machined to suit. There will be little/no appreciable increase in performance going from stock to 1641.
I went from 1600 to 1641, van pulled better, cruised at 60/65 on the flat no problem & climbed hills better.... I did rebuild the lot though from middle block up using same/existing heads etc but with new push rod tubes, seals & gaskets all round. Worth lapping valves in & resetting tappets
Yea I mean bigger valves. I believe the 040 is 35.5 x32 and the 141 is 39.3x33 The engine is stripped now and I’ve split the case. And I’ll do a full rebuild on it. The head are in good condition it’s just the barrels and pistons that need replacing seen as there isn’t much money between the 1600 and 1641 I thought I’ll just put the 1641 on. I will lap the valves when I start putting the heads back together.
That's why most people go for 1641 - the might as well factor. No harm in it. I chose 92 over 90.5 once purely because VWH had them at 50% off. I doubt it went faster but it was cheaper! Often people do report a marked improvement in performance from 1641 but they would wouldn't they? The ones they were replacing were worn out or they wouldn't have been replacing them... and they lapped the valves... and it's freshly torqued together so no head leaks. For a stock 1600(ish) bus engine, the bigger valve heads would only make an impression on your wallet.
May as well go 1641. Stock heads will do. After all the volume of air at 4000 rpm is only 4.6% more than stock going from 1585 to 1641cc. Carburettor(s) and exhausts probably have more effect than heads, although it seems new stainless steel valved EMPI heads with stock valves run cooler and give slightly better low end than stock... Although you shouldnt do it, the EMPI heads will pull from 25mph on the flat in 4th gear on my bus, where stock ones needed 30 mph on a 1641..(same exhaust and carburettor) max RPM about the same or slightly less .. trouble is if you go too far all that happens is you free up the engine to hit silly RPM .. my bus recorded 5700 rpm peak once.. 37mph in second.... shouldnt really push over 4000ish...
^this. Their engine was likely in a right state before they stripped it, hence the "improvement" once they'd properly adjusted everything. I wouldn't go with bigger valves on a stock van engine. You need to strangle it to get the gas flow up.
I will be putting a new stainless exhaust on her as I’ve spent a fortune on the empi rusty’s. I’ll go with that and take it from there. If anything it will be interesting when we go for the first drive.
I don't think you'll notice much difference, apart from new rings and barrels, and the engine set up properly. If you can find someone to do it, get a 3-angle valve job done. Then later, stick twin carbs on it to unblock the top end. That will make a difference.
1641 cylinder also give .5 point more CR. Have your valve guides check too. You will be amazed how much play your valves can have, and the engine still running "fine".
Playing with the compression ratio is something you may find you will be doing. On my previous engine the so called original heads in fact had their ' step' machined out and replaced with a steel spacer ring. On building these heads onto a new set of pistons and cylinders, the deck heigh was larger and the new engine noticeably less able to pull up a hill.. pre rebuild it was still in 4th, post rebuild it had to be in 3rd at the top of the same hill. So I looked at the measurements and realised the engine would still have 1mm between the piston and cylinder head at TDC. Pulled out the spacers and it went better. I believe some engine rebulder must have done this to clean up the maybe leaky cylinder heads, and also ensure the deck height and compression ratio were low enough that the engine was less likely to blow up during warranty. It did blow up about 4 years later but that was involving the head of a valve rattling around and a piston becoming rubble -'maybe shouldnt have run the stainless valves again - the heads did 50k miles the rest of the engine did 30k. The new valves are still in a box in my garage.
