2G Considering a Rebuild

[4G63510]

I'm experiencing worrying low oil pressure on my 7-bolt Frankenstein build. I have an electronic oil pressure gauge, but I'm going to verify those readings with a cheap Bosch manual gauge. Assuming the engine is done, I'm looking to build a spare 2g 7-bolt block I have. I know everyone says crank walk is a myth or exaggerated, but I want to do my best to ensure this engine lives a long and rough life in my car. I've read Jack McGee's write up about his tricks to help ensure the 7-bolt lives a long time, but I was hoping we had something more concise with measurements or something a machine shop could follow. Maybe along the lines of what Jafro is doing with some of his stuff, but in written form.

I don't have high aspirations. 400whp max. I'm making 325whp in a 2300lb RWD Datsun 510. The 205 width 200TW tires can't cope with full throttle until 3rd gear. And that's rolling into it. I have a FP 68HTA V3 enroute to give better throttle response. My main drving is autocross and road course stuff, so response is my goal, not peak power. With that in mind, here's the plan (assuming I have to rebuild):

9:1 pistons
Basic rods (or some 156mm long rods if it's in the budget)
Prep the block (lots of questions here)
BC 268/272 cams (I already have BC valves, springs, and retainers)
That's about it. I just want it reliable. But I'd like to know what's the best approach to help ensure the time and energy is well spent. And money

Please don't post about putting in a 6-bolt, as that isn't helpful. Everyting I have around my current build is already 7-bolt and in my mind, it's a better platform.

 

[4G63510]

Here is one of those "tricks" I was talking about. Oil Passage mod
I'm considering doing this and installing EVO/6-bolt oil squirters.
I am NOT considering this a "fix" for potential crankwalk, even though it is in the Articles section.
I've already done the oil port mod. I have a 1G 7-bolt head, so it was designed for the 11mm ARP head studs I have. This may not have been necessary. I also have the Kiggly HLA regulator.
I have also done the oil filter housing pressure relief mod. It has helped with high oil pressure especially on cold days. I do have an EVO 3 oil filter housing as well.

I'd still like to see what else is being done. I'll keep searching, but suggestions are appreciated.

 

[IHeartMyHonda]

For what it's worth, I have been working on DSM stuff for almost 20 years and I've only seen spontaneous crankwalk once in person. I've seen it two other times, but those cars were missing the rear engine to transmission bolt that had been left out after a clutch job.

What year is your spare block from?

Is your oil pan baffled?

 

[4G63510]

For what it's worth, I have been working on DSM stuff for almost 20 years and I've only seen spontaneous crankwalk once in person. I've seen it two other times, but those cars were missing the rear engine to transmission bolt that had been left out after a clutch job.

What year is your spare block from?

Is your oil pan baffled?

I don't think my current engine has crankwalk, at least not yet. It's not showing the telltale signs. The oil pressure is worrying, so I'm exploring my options. I just want to make sure I do it right. It would also be great if we had a unified post or thread about "best practices" for building a reliable engine.

My spare is also a 95 style block like my current engine.

The oil pan is not baffled and is the stock DSM unit. I have a MM/D50 pan sitting here waiting for me to weld in an AN fitting for the oil drain. I'd like to do baffling, but I'm also having trouble finding DIY kits that meet my expectations on quality and price. That being said, oil starvation could have caused my issue, but I've never witnessed low pressure in any situation other than idle. Maybe I'm just seeing the beginning of a bigger issue and my gauges are warning me of impending doom.

 

[1990TSIAWDTALON]

Verify oil pressure with a "real" mechanical gauge before you get too worried. Some electric senders don't send the exact pressure to electric gauges, at least in my experience in trying them. I resorted back to a mechanical gauge for true readings on my cars, but they have been in all of my cars since back in the 70's
I hope the sender is just not giving you a true reading.

 

[4G63510]

Verify oil pressure with a "real" mechanical gauge before you get too worried. Some electric senders don't send the exact pressure to electric gauges, at least in my experience in trying them. I resorted back to a mechanical gauge for true readings on my cars, but they have been in all of my cars since back in the 70's
I hope the sender is just not giving you a true reading.

That's the plan this weekend. I've got a cheap Bosch gauge. I'm just waiting on an adapter so I can do that. I'm thinking this is the case due to the weird readings I'm seeing

 

[1990TSIAWDTALON]

I sure hope so!

 

[chrysler kid]

What oil pressure are you seeing?

Alot of the oil pressure readings have to do with oil temp. Are you seeing less than 5 psi at hot idle?

Usually worn out 7bolts will typically have excessive blow by, pushing pressure out of the dipstick from the bottom end blowby. A compression test may be a better indicator of wear than oil pressure, but it never hurts to rebuild an old motor better

 

[1990TSIAWDTALON]

As stated, if oil pressure turns out LOW on a known good gauge, it would be best to pull it NOW as apposed to waiting til it starts knocking. I am purposely NOT driving my White 90 GSX for just that reason. I have a fresh 6 bolt ready to go in so I don't want to kill a crank in the low oil pressure motor. This spring, my son and I will swap out motors and be able to drive a very spirited, mostly stock GSX again.

 

[4G63510]

I was seeing less than 10psi at idle when hot. But the needle fluctuates. (I have a video I might post) I'm looking at this as an electical issue with the gauge rather than actual low pressure. The needle will dip and then come back up. The mechanical gauge wasn't much more help. I think I need to clear out some air bubbles. I can see air in the line even with 20psi of pressure on both gauges.

I am going to pull the oil pan soon to swap in a RWD pan, oil pickup, and weld in a -10AN fitting for the oil drain. When I do that, I'll inspect the rod bearings and look for damage. If anything turns up, I'll pull the whole thing. As of right now, I'm treating this as a gauge issue, not an oil issue.

All that being said, is there any way we can make a sticky for "best practices/ tips and tricks" for rebuilding an engine? We have some very experienced people here and it would be great to get the best tips so we can keep these engines on the road instead of the engine stand.

 

[TheDude236]

All that being said, is there any way we can make a sticky for "best practices/ tips and tricks" for rebuilding an engine? We have some very experienced people here and it would be great to get the best tips so we can keep these engines on the road instead of the engine stand.

Not a bad idea tbh. Not sure who would want to bite since that would be a long ass tech article but it would certainly help.

 

[chrysler kid]

10psi is normal at idle for a stock 7bolt

Its abnormal if you have done the balance shaft delete. There are a few issues other than bearings that could cause low oil pressure like that on a balance shaft delete setup, oil pump pick up tube o ring, incorrectly installed BS delete bearing etc