A87 on a L20B?

[kgrantkey]

I have found a couple of bent valves in the u67 I was gonna use.They didnt lap in and closer inspection shows two exhaust valves are not gonna seal properly. I still have a good w58. Was just wondering what would happen tourque wise and overall performance if I put a good A87 on it. The l20b has been bored 30 over and I'm worried the small intake ports would hold it back from developing any HP versus the other (w58) head.

 

The A87 has been shaved to just below the Nissan stamp. My pistons are the concave L20B 30 over. You guys think the low end would pull better, or am I just waisting time?  I think it would suffer at high rpm but may be a stump puller?

 

Everything else is stock.

 

I also have the intake that fits the small intake ports. 

 

Should I just go with the W58 and larger Intake. Not worry about the exhaust runners in the w58?  Its just gonna be a daily driver that rarely gets driven.

 

 

 

PS the exhaust valves in the A87 are 1.30 so can;t swapp to the U67 with 1.38 exhausts

[wayno]

I have found a couple of bent valves in the u67 I was gonna use.They didnt lap in and closer inspection shows two exhaust valves are not gonna seal properly. I still have a good w58. Was just wondering what would happen tourque wise and overall performance if I put a good A87 on it. The l20b has been bored 30 over and I'm worried the small intake ports would hold it back from developing any HP versus the other (w58) head.

 

The A87 has been shaved to just below the Nissan stamp. My pistons are the concave L20B 30 over. You guys think the low end would pull better, or am I just waisting time?  I think it would suffer at high rpm but may be a stump puller?

 

Everything else is stock.

 

I also have the intake that fits the small intake ports. 

 

Should I just go with the W58 and larger Intake. Not worry about the exhaust runners in the w58?  Its just gonna be a daily driver that rarely gets driven.

 

 

 

PS the exhaust valves in the A87 are 1.30 so can;t swapp to the U67 with 1.38 exhausts

 

It's a tough call, fix the U67 right now, that would seem to be the cheapest way to go, big valves and large intake ports do count for a lot, even though it has less CR, it will still likely produce more power, second choice would be the W58 if it is a closed camber head(peanut head), for street use it will make no difference.

[datzenmike]

Swap the W58 valves into the U67... like a boss.

[kgrantkey]

Swap the W58 valves into the U67... like a boss.

 

That would be easy enough to do. I've got the u67 and the w58 each stripped down with the valves and all associated hardware placed in baggies labled for each port. My reluctance comes from having the w58 completely reworked at one of two good head shops here in town not too many miles ago.

 

If you read too many articles about keeping the valvetrain and  cam towers exactly as you find them.....I think I even read where someone said to never remove the cam towers or run the risk of premature failure. ..... Heck my engine should have blown up years ago if it's that dangerous.

 

 

I think I'll run the w58 ril I collect the coin to get the u67 reworked by one of the shops here in town I trust. Maybe even get one of those webbers that seem so popular.

 

If all the truck needed was the u67 reworked I'd find the coin but as with all or most 40 year old 620s its a matter of using my limited funds wisely. I still run drm brakes and they work great. I just have to keep them adjusted. I really want new shocks, and even though the tire are good and rims are fair I'd love to get some real pretty wheels and tires. The rubber seals and felt around the windows can cost an arm and leg..

 

I'm starting to get depressed,  I do love my Lil Hustler. :hug: :console:

[EricJB]

My 620 is an auto with 3.7 gears. So it never sees more than 5k any ways. And that's pushing it.

I have an l20 with a closed chamber A87. The head was roughly gasket matched to the L20 intake. Weber 32/36 and stock everything else. The cam is advanced to the #3 hole.

 

It runs really good and has a ton of torque. I don't think under normal driving conditions you will notice the difference in exhaust valve size.  

[datzenmike]

Thought you said two bent valves in the U67??? Just change the two valves. This has zero effect on cam towers or rockers, springs or retainers and lash pads. Just the valves you don't need to remove anything else to do this just the spring...

[wayno]

My 620 is an auto with 3.7 gears. So it never sees more than 5k any ways. And that's pushing it.

I have an l20 with a closed chamber A87. The head was roughly gasket matched to the L20 intake. Weber 32/36 and stock everything else. The cam is advanced to the #3 hole.

 

It runs really good and has a ton of torque. I don't think under normal driving conditions you will notice the difference in exhaust valve size.  

 

I noticed a difference with the small valves, but what I use that truck for is not normal conditions I expect.

[dr.feltersnatch]

 

 

If you read too many articles about keeping the valvetrain and  cam towers exactly as you find them.....I think I even read where someone said to never remove the cam towers or run the risk of premature failure. ..... Heck my engine should have blown up years ago if it's that dangerous.

 

 

the cam towers are line bored, so if you remove them it could cause them to be off slightly to each other, out of round etc. you can remove the cam from the towers easily just dont unbolt the towers.

[Sealik]

the cam towers are line bored, so if you remove them it could cause them to be off slightly to each other, out of round etc. you can remove the cam from the towers easily just dont unbolt the towers.

 

Machinists remove the towers for most head work....and I've done it many times with no issues.

 

Just use caution.......clean surfaces, towers in original position and then,   torque to 5-10-12lbs

...<....Confirm cam rotates without bind.

[datzenmike]

 

Swap the W58 valves into the U67... like a boss.

That would be easy enough to do. I've got the u67 and the w58 each stripped down with the valves and all associated hardware placed in baggies labled for each port. My reluctance comes from having the w58 completely reworked at one of two good head shops here in town not too many miles ago.

 

If you read too many articles about keeping the valvetrain and  cam towers exactly as you find them.....I think I even read where someone said to never remove the cam towers or run the risk of premature failure. ..... Heck my engine should have blown up years ago if it's that dangerous.

 

 

 

 

I'm starting to get depressed,  I do love my Lil Hustler. :hug: :console:

 

 

Having the heads reworked or rebuilt does not affect the valves. Take any two exhaust valves out of their baggies and put in the U67 head. Give a quick lap and you are good to go. Does not affect the rest of the valve train. Don't be depressed over this, it's an easy fix.

 

Preferably the cam towers should not be removed. If removed, put back in the same relation. The rockers (or cam followers) should also go back on the same lobe. All the rest springs, lash pads, retainers and valves don't matter much. I've swapped cams and mixed up rockers and nothing happens.

[ggzilla]

New valves only $15 at NAPA

[kgrantkey]

Swap the W58 valves into the U67... like a boss.

 

This is the most likely way I'll go.

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I don;t have the patients or experience to try and port a head.

 

With all the work involved just getting some of the rust under control and a few things needed elsewhere now is not the time to experement on the heads.

 

PS. Ever seen oneof these......I found it at an old speed shop with dust all over the package reduced to 10.00, I guess to get it out of the shop. It's as much an adaptor as it is a 1 inch high rise. Fits the stock intake perfectly.

[datzenmike]

Porting? I didn't either but found it fascinating to do..

[RTB]

I don;t have the patients or experience to try and port a head.

IIRC the modify your datsun book says the only thing you should really do to port your head is to match the gasket. Anything else will give you a very small return in power and cost a lot more. Plus if you have a die grinder you can gasket match yourself.

[kgrantkey]

IIRC the modify your datsun book says the only thing you should really do to port your head is to match the gasket. Anything else will give you a very small return in power and cost a lot more. Plus if you have a die grinder you can gasket match yourself.

 

Been using this on my air powered grinder. It works quite well except for any corner work,  I'm just gonna match the gasket and smooth a few casting rough spots.

 

 

It requires so much air to operate that I finally fixed the motor for my air compressor. I'd been using a spare with 1/3 less HP and a larger pulley on it.  It's back to kicking ass now!

[EricJB]

With a burr that fine, you will want to keep it dipped in wax or doused in WD40, or it might load up with aluminum. This is what I use. It looks like a pinion gear and throws flakes. No load up at all. Then a flapper, then some scotchbrite in a 1/4 inch cotter pin. And lots of WD40.

 

 

 

 

 

 

 

 

[kgrantkey]

With a burr that fine, you will want to keep it dipped in wax or doused in WD40, or it might load up with aluminum. This is what I use. It looks like a pinion gear and throws flakes. No load up at all. Then a flapper, then some scotchbrite in a 1/4 inch cotter pin. And lots of WD40.

 

 

 

 

You have probably done this more than once.  I just matched the ports to my gasket. I'd rather do too little than mess up a good head.  As I've said before this truck doesn;t get driven very much but She cranks right up every time I put the battery in it.

 

[RTB]

You also might want to match the intake manifold to the gasket as well. Otherwise that really wont make much of a difference.

[Parkinglotslider521]

Imho, i'd worry more about port/ valve size than the chamber. 

The more research I do, the more it seems that a small increase in airflow nets much larger gains than a large increase in compression. I know. Everyone is probably saying duh you idiot. But i was always under the impression that higher compression is the way to go.

Here's a nice little calculator to show horsepower increases with each mod done. seems pretty accurate. Fyi the L-16/18/20b is under Nissan not Datsun.

http://www.camquest.com/

[datzenmike]

I agree. Compression is a racing thing where even small amounts are important. Going from 8.5 to 9.5 gets about 3-5% increase in hp. It becomes less and less as he numbers go up because you are closer and closer to the ideal compression efficiency. Is 5 or 6 hp worth the extra cost of gas?

[ggzilla]

Is 5 or 6 hp worth the extra cost of gas?

 

Yes, because with higher compression, it will use less fuel going down the highway, and with higher octane fuel you can tune the engine for more advance and gain even more fuel economy. With higher gas prices, the additional cost of high octane is lower then the economy gains. Its a win-win scenario.

 

A perhaps better question is: Is 5 or 6 hp worth the extra cost of changing the head?

[Sealik]

For the price of gas up here....not good.....premium????...out of the question.

My theory was to increase the size of the engine (LZ23) and retain stock compression....8.5

More bang than the smaller LZ21/22 with the higher (9.5ish) compression??????

[datzenmike]

A jump of 1 point is maybe up to 6% hp increase. That's maybe, 6 hp per hundred.