2 dr 610 Dirt track build, *now with video*

[GreaseMonky]

So before I get started I better introduce my self, I am Redbanner's older brother, the one that loaned him the wheels on his 710, aint i a nice brother.

 

 

Anyways, I have a Datsun 610 that I bought already as a dirt circle track car, and thats what I am doing with it its got an L20b in it now with a u67 head, and a stock ext mani, and stock intake, with a webber 32/36, anyways I was told its been balanced, and has Honda pistons??? anyone hear of this, and a lightened flywheel, not sure what the cam or anything is, and some other things,

 

 

 

I am wanting to maybe improve it some, I am limted on carb, I can only run a single two barrel, I can ad a header, and any size two barrel, I am wondering what a good cam would be I am letting off the throttle coming into the corner at 6500, and probably dropping down to 35-4ish so i need a higher rpm cam with some good power for exiting the corner, maybe a different head? I would like some more cc's so I am thinking about building another engine.

 

 

No for suspension, I wanna change the struts and shocks, whats a good brand?? its got a larger spring and strut on the right front and has been cut and welded by the balljoint to get more camber, and I need to get some more caster from the front, and maybe some camber and toe in the rear,

 

 

 

anyways thats a good start for now, I am sure i will come up with more stuff later thanks

 

 

by the way, I am looking for body parts for it, they dont have to be perfect

[GreaseMonky]

almost forgot, I wanna change all the suspension bushing out, where would be a good place to find those at? or a brand?

[NWOleman]

we need oics!

[datzenmike]

A '75 would have the intake and exhaust manifolds joined I would think like all the L20Bs back then. You should look and see. You can't remove just the exhaust because the intake won't work without it being attached. If going to a header you will need to get an intake from a later L20B. Maybe it's already been replaced. Cheapest thing is an L16 or 18 exhaust manifold. Basically it's a cast iron header.

 

The U67 head is good enough as is for now. Cam is up to you. If a dedicated race car not on the street then go crazy with it. Look for something with a power range in the 3,500 to 6,500 range. You will need much more than just the cam to make it work though. Stiffer springs and springs that will allow higher lift without binding should be used. bigger cam means bigger or multi carbs. If you are limited to carb size then a really really big cam can be avoided. The head can also be ported for increased flow. Every thing to do with the head, has to work together just like a symphony with porting, cam, springs, header, carb and intake matched and in tune. Change one thing and it affects everything else.

 

Biggest bang for the buck is to lower the rear end ratio. Easy and cheap. This will have your engine revving higher at the same speed.say coming out of a slow corner. Revving higher means your engine is making more power and doing more work than the guy beside you. Subaru makes a stock R-160 with 4.11 gears. R-180s also are stronger and will fit. I would look for an early 720 4x4 and get the R-180 front diff from it. Up to '83 they had a 4.375 ratio. Weld the internals so it's locked and both wheels spin.

[GreaseMonky]

A '75 would have the intake and exhaust manifolds joined I would think like all the L20Bs back then. You should look and see. You can't remove just the exhaust because the intake won't work without it being attached. If going to a header you will need to get an intake from a later L20B. Maybe it's already been replaced. Cheapest thing is an L16 or 18 exhaust manifold. Basically it's a cast iron header.

 

The U67 head is good enough as is for now. Cam is up to you. If a dedicated race car not on the street then go crazy with it. Look for something with a power range in the 3,500 to 6,500 range. You will need much more than just the cam to make it work though. Stiffer springs and springs that will allow higher lift without binding should be used. bigger cam means bigger or multi carbs. If you are limited to carb size then a really really big cam can be avoided. The head can also be ported for increased flow. Every thing to do with the head, has to work together just like a symphony with porting, cam, springs, header, carb and intake matched and in tune. Change one thing and it affects everything else.

 

Biggest bang for the buck is to lower the rear end ratio. Easy and cheap. This will have your engine revving higher at the same speed.say coming out of a slow corner. Revving higher means your engine is making more power and doing more work than the guy beside you. Subaru makes a stock R-160 with 4.11 gears. R-180s also are stronger and will fit. I would look for an early 720 4x4 and get the R-180 front diff from it. Up to '83 they had a 4.375 ratio. Weld the internals so it's locked and both wheels spin.

 

 

I will see if I can get my brother to post up some pics, I am not sure how to go about doing it

 

 

It has the seperate intake exhaust, and from what I believe a early ext mani, its got twin pipes on the colector end of it.

 

we are limited to only one carb, but we can run any 2 barrel, and holley makes a 500cfm, and a 350cfm, which is what alot of the other guys run, any suggestions on a cam profile? i have a cylinder head guy, so I am gonna try and pick up another head so I can have him start working on it, soon, I am racing tell the end of january, then I have about a 2 moth break so i plan on trying to have pasrts rounded up by then

 

its got a 3.9, rear gear now, in it, and seems pretty good, the tracks are short, 1/4 mile clay and we only run in second gear, not really enough time to shift with out loosing momentium, I can change my gearing a bit with tire size, right now I am running a 205/60/13, on a 13x8 steel wheel, with 2" back spacing, and i have a set of 185/50/13 if i wanna get a lower ratio

[RedBanner]

Post some pics of the struts , noaw!

[DISLEXICDIME]

I would. Find a 411 rear ens from a subaru and weld it like mike. Said.

As far as engines go. Are you running race gas or staying pump?.

 

if you are building a new motor look up jason grays engine specs.

http://www.newprotest.org/projects/510/jasonGray.pl

 

Now if your l20 is strong I would port the intake to 1.5 and add 44mm intake valves from a z car and unshroud the valves and run a 460 lift cam so you don't have to buy new springs and retainers. And don't forget to port match the in take to match the head. Is your distributor been recurved? is you cacum advance still working ? Or did they lock the braker plate?

 

As far as suspension. You can slot the cross member where the trailing arm mounts to the x member to adjust camber. As far as camber and toe. Byron on the 510 realm makes a nice set of camber and toe adjusting brackets he sells. Just search for suspension set up's that 68-73 510's use on the dirt the suspension is the same.

[Guest kamakazi620]

I will see if I can get my brother to post up some pics, I am not sure how to go about doing it

 

 

It has the seperate intake exhaust, and from what I believe a early ext mani, its got twin pipes on the colector end of it.

 

we are limited to only one carb, but we can run any 2 barrel, and holley makes a 500cfm, and a 350cfm, which is what alot of the other guys run, any suggestions on a cam profile? i have a cylinder head guy, so I am gonna try and pick up another head so I can have him start working on it, soon, I am racing tell the end of january, then I have about a 2 moth break so i plan on trying to have pasrts rounded up by then

 

its got a 3.9, rear gear now, in it, and seems pretty good, the tracks are short, 1/4 mile clay and we only run in second gear, not really enough time to shift with out loosing momentium, I can change my gearing a bit with tire size, right now I am running a 205/60/13, on a 13x8 steel wheel, with 2" back spacing, and i have a set of 185/50/13 if i wanna get a lower ratio

Avoid Using the holley 350/500 cfm carb Its TOO Big for a 2.0 liter!!! try a 38/38 weber Outlaw

[datzenmike]

It has the seperate intake exhaust, and from what I believe a early ext mani, its got twin pipes on the colector end of it.

 

This is good news. PO was going in the right direction. The exhaust (two pipe) is likely from an L16/18 which is good. You could separate the two pipes and run down and out to side of car unless rules say stock single pipe, then I would have a 2"-2.5" made. The intake is suspect as it may also be an L16/18 which are smaller port diameter and are 'restrictive' compared to the later '78-'79-and '80 L20B motors. Yes they have an EGR valve but very very easy to not use and or block off any chance of leaks.

 

we are limited to only one carb, but we can run any 2 barrel, and holley makes a 500cfm, and a 350cfm, which is what alot of the other guys run, any suggestions on a cam profile? i have a cylinder head guy, so I am gonna try and pick up another head so I can have him start working on it, soon, I am racing tell the end of january, then I have about a 2 moth break so i plan on trying to have pasrts rounded up by then

 

Holly is good with lots of easy swap and find parts.

 

As mentioned stock springs are limited to about .47" or .48" lift before the springs stack and bind. So you have a choice here. Use any cam but you like but be limited to this peak lift. Stock cam lift is .413" This will save you money in the long run but limit you also.

If getting a big cam get better springs and retainers that will go higher lift. Duration stock, is 248 with maximum torque at 3,200and hp at 5,600 RPMs. As a very rough rule, for every 10 degrees of increased duration on a cam the peak torque and hp rises about 500 RPMs. So a cam with duration of say 290 would move everything up about 2K or peak torque at 5K and top hp at wall over 7.5K! This means that the motor will need to be kept revved up quite high to make use of it and this is where a high numbered 4.11 or 4.375 rear end comes in.

 

 

its got a 3.9, rear gear now, in it, and seems pretty good, the tracks are short, 1/4 mile clay and we only run in second gear, not really enough time to shift with out loosing momentium, I can change my gearing a bit with tire size, right now I am running a 205/60/13, on a 13x8 steel wheel, with 2" back spacing, and i have a set of 185/50/13 if i wanna get a lower ratio

 

Going to 4.11s would increase the RPMs 5.4% and 112.2% with the 4.375s. As an example if using the 3.90 rear end and exiting the corner at 3,800 RPMs switching to a 4.375 ratio would find you coming out of the same corner at over 4,300 RPMs and much closer to your peak torque. The 'bigger' cam would allow you to rev well over 7K maybe even staying in 2nd.

[GreaseMonky]

This is good news. PO was going in the right direction. The exhaust (two pipe) is likely from an L16/18 which is good. You could separate the two pipes and run down and out to side of car unless rules say stock single pipe, then I would have a 2"-2.5" made. The intake is suspect as it may also be an L16/18 which are smaller port diameter and are 'restrictive' compared to the later '78-'79-and '80 L20B motors. Yes they have an EGR valve but very very easy to not use and or block off any chance of leaks.

 

 

 

Holly is good with lots of easy swap and find parts.

 

As mentioned stock springs are limited to about .47" or .48" lift before the springs stack and bind. So you have a choice here. Use any cam but you like but be limited to this peak lift. Stock cam lift is .413" This will save you money in the long run but limit you also.

If getting a big cam get better springs and retainers that will go higher lift. Duration stock, is 248 with maximum torque at 3,200and hp at 5,600 RPMs. As a very rough rule, for every 10 degrees of increased duration on a cam the peak torque and hp rises about 500 RPMs. So a cam with duration of say 290 would move everything up about 2K or peak torque at 5K and top hp at wall over 7.5K! This means that the motor will need to be kept revved up quite high to make use of it and this is where a high numbered 4.11 or 4.375 rear end comes in.

 

 

 

 

Going to 4.11s would increase the RPMs 5.4% and 112.2% with the 4.375s. As an example if using the 3.90 rear end and exiting the corner at 3,800 RPMs switching to a 4.375 ratio would find you coming out of the same corner at over 4,300 RPMs and much closer to your peak torque. The 'bigger' cam would allow you to rev well over 7K maybe even staying in 2nd.

 

 

Ok so use a holley, or no holley? I have thought about building another engine, and go for like a 2.2, or 2.4 with the l series head, with maybe a different head, with some port work, and larger valves,

 

 

If I am going to put a cam in then I will most likley change the springs and stuff out if I am gonna go thru the head then I am gonna do all of it. as far as reving how high can these engines go reliable?

 

as far as the exhaust I can run dual pipes, so if i go that route, what size pipe that way

 

The po only changed one side strut, and that was the RF, I do need to change the struts, and shocks, and I also wanna change all the bushings

[RedBanner]

Dear james,

I asked for pics, i know where you sleep.

 

Banner out.

[Digi7al Trauma]

[quote name=GreaseMonky' date='22 October 2011 - 09:52 AM'

timestamp='1319305976' post='565989]

I will see if I can get my brother to

post up some pics, I am not sure how to go about doing it

 

 

Dear james,

I asked for pics, i know where you sleep.

 

Banner out.

 

 

:lol: and dont threaten him, he "loaned" you wheels.. dont make him take them back :lol:

[datzenmike]

Ok so use a holley, or no holley? I have thought about building another engine, and go for like a 2.2, or 2.4 with the l series head, with maybe a different head, with some port work, and larger valves,

 

 

If I am going to put a cam in then I will most likley change the springs and stuff out if I am gonna go thru the head then I am gonna do all of it. as far as reving how high can these engines go reliable?

 

as far as the exhaust I can run dual pipes, so if i go that route, what size pipe that way

 

The po only changed one side strut, and that was the RF, I do need to change the struts, and shocks, and I also wanna change all the bushings

 

Holley is fine. Lots of them and parts.

 

L20B has a fully weighted crank which is good for high revving smoothness. The main bearings are wider than the KA24E and will support a lot of HP. Check the KA main on the right. They can get some monster hp out of the KA so imagine how tough the L series must be, left.

 

 

Did you ever meet Kieth Law? He was at Canby last year with his turbo L20B. Dynos 250WRHP and with a 4.625 rear end has to rev 7,500-8,000 to go 135MPH. I'm sure he has the stock crank rods in it. BUT it was built to survive this. Has high pressure, high volume oil pump for lubrication, extra filters and a massive oil cooler, big rad and electric fans. If you are serious about big hp you have to build the motor so it will survive. A stock L20B will rev as high as you want but stock oil and cooling system won't cut it. I would say a well set up engine with stock pistons to 6,500-7,000. Forged pistons should easily handle anything. I don't think a 2 bbl will make enough power to need custom rods.

 

Run the same diameter pipe that the manifold has. The cross sectional area of a 1" pipe is 0.785 sq in. If you double the diameter to 2" you don't get twice the area. Actually you get 4 times! A 2"pipe has a cross sectional are of 3.14 sq. in.! So a very small increase in pipe diameter makes a large difference in how much exhaust can go down it. Those two pipes normally are joined into one pipe of about 1 3/4" or so. Running those pipes separate will be plenty big enough.

 

The car only turns in one direction so this is likely why the outside? strut was modified. Different spring rates can be run on the outside front and back. I know little about suspension tuning. There are probably books on it. Nascar cars do about the same thing. Poly bushings are ok but they are so hard they don't give much and will chafe (squeak) and wear faster. The ones for the tension bars will will actually restrict movement so much that the tension rods have been know to break suddenly. You can increase the dampening by emptying the strut hydraulic fluid and re-filling with thicker 20W motorcycle fork oil.

 

I don't know how much brakes are used but 290zx or 300zx struts can be substituted. These are shorter than the 610 struts by over an inch for the 280zx and maybe 2" for the 300zx and you get a vented rotor and monster calipers.

[DISLEXICDIME]

Its a dirt car runn solid bushings

[GreaseMonky]

Dear james,

I asked for pics, i know where you sleep.

 

Banner out.

 

 

And why havent you posted any pics, your not a very nice brother, I loaned you wheels.....

 

 

p.s., I know where your dattos sleep......

[GreaseMonky]

Its a dirt car runn solid bushings

 

 

Where do I find solid bushings?

[GreaseMonky]

Holley is fine. Lots of them and parts.

 

L20B has a fully weighted crank which is good for high revving smoothness. The main bearings are wider than the KA24E and will support a lot of HP. Check the KA main on the right. They can get some monster hp out of the KA so imagine how tough the L series must be, left.

 

 

Did you ever meet Kieth Law? He was at Canby last year with his turbo L20B. Dynos 250WRHP and with a 4.625 rear end has to rev 7,500-8,000 to go 135MPH. I'm sure he has the stock crank rods in it. BUT it was built to survive this. Has high pressure, high volume oil pump for lubrication, extra filters and a massive oil cooler, big rad and electric fans. If you are serious about big hp you have to build the motor so it will survive. A stock L20B will rev as high as you want but stock oil and cooling system won't cut it. I would say a well set up engine with stock pistons to 6,500-7,000. Forged pistons should easily handle anything. I don't think a 2 bbl will make enough power to need custom rods.

 

Run the same diameter pipe that the manifold has. The cross sectional area of a 1" pipe is 0.785 sq in. If you double the diameter to 2" you don't get twice the area. Actually you get 4 times! A 2"pipe has a cross sectional are of 3.14 sq. in.! So a very small increase in pipe diameter makes a large difference in how much exhaust can go down it. Those two pipes normally are joined into one pipe of about 1 3/4" or so. Running those pipes separate will be plenty big enough.

 

The car only turns in one direction so this is likely why the outside? strut was modified. Different spring rates can be run on the outside front and back. I know little about suspension tuning. There are probably books on it. Nascar cars do about the same thing. Poly bushings are ok but they are so hard they don't give much and will chafe (squeak) and wear faster. The ones for the tension bars will will actually restrict movement so much that the tension rods have been know to break suddenly. You can increase the dampening by emptying the strut hydraulic fluid and re-filling with thicker 20W motorcycle fork oil.

 

I don't know how much brakes are used but 290zx or 300zx struts can be substituted. These are shorter than the 610 struts by over an inch for the 280zx and maybe 2" for the 300zx and you get a vented rotor and monster calipers.

 

 

Well now that you have shown a pic, I guess that makes sense, I am gonna pull the intake and exhaust manifold tomorrow, and re set the valve lash, I will let you guys know what I find, and since my brother (Redbanner), is a big meany, I will try and get some pics up. Is there anyway to tell what cam, when I have the valve cover off?

 

 

On a side note, I want to build a crank case evac that ties into the exhaust, has anyone done this yet?

[Guest kamakazi620]

Well now that you have shown a pic, I guess that makes sense, I am gonna pull the intake and exhaust manifold tomorrow, and re set the valve lash, I will let you guys know what I find, and since my brother (Redbanner), is a big meany, I will try and get some pics up. Is there anyway to tell what cam, when I have the valve cover off?

 

 

On a side note, I want to build a crank case evac that ties into the exhaust, has anyone done this yet?

If your cam has a U20 cast in it it is stock

[datzenmike]

Also look for after market retainers and a spray bar.

[DISLEXICDIME]

http://designproductsracing.com/

[RedBanner]

Got a few picks

I dont know how bad this is in person. http://i1205.photobucket.com/albums/bb424/Noflagredbanner/496.jpg[/img

[RedBanner]

[RedBanner]

[GreaseMonky]

So I have done a little bit of research, and I guess the cam is the the same cam that Bills Datsun, runs??? talked to the previous owner, gonna try and find more info about the rest of the car?

[GreaseMonky]

Here is some pics

 

when i first looked at it