Crossflow Build Advice

[Nath 1,975]

6 injectors and a throttle body?

https://www.youtube.com/watch?v=xxSI1QsIo8g

[wagoon 2,429]

For an extra 200 odd bucks I may as well get the good one... Spent more than that on alcohol last weekend so can't really get stingy with go faster bits.

 

That's it, you literally piss it against a wall or in a mates ear where as the engine will give you more joy for longer. BUT you also need to be careful especially when your engine is at the machine shop with this sort of attitude cause the bill can jump pretty quick when they ring you and need an answer on a part choice (ask me how I know ). You need to be able to trust the machine shop and the people selling/recommending parts are looking out for what you want and what suits your requirements and don't get caught up in a chase for horsepower. You will be very surprised has fast a $2500 rebuild turns in to a $4000 rebuild.

This statement is not aimed at anybody it is just what I have experienced in my build.  I think it is scary the number of horror stories where a machine shop has either doubled the bill price or done such a bad job that it has destroyed an engine

[ando76 4,354]

Yes it can get away very quickly if you let it - $200 here - $300 there.  I adds up but really if you want it - go for it. 

[Thom 6,654]

Never used one, but have wondered what they'd be like on a good streeter:

 

http://m.ebay.com.au/itm/191295208049?nav=SEARCH

 

 

In theory they sound good, but I am a little dubious.

 

 

A 4100 Autolite's the go (480cfm version)

 

I've used edelbrock's before and I love them, once you work out how to to tune one they are a very easy carb to use, just one thing if you use one you have to use a fuel pressure reg to drop the pressure down to 4 psi or you will have flooding and needle and seat issues

[Nath 1,975]

So been doing some more research... Had a chance to look at another build similar to what I'm after. Few question marks...

 

Roller rockers a good idea? Scorpion non-adjustable were suggested.

 

Am I really gonna see that much benefit from bore-ing it out 50 thou as opposed to keeping it standard? Is it worth the extra cost and loss of meat on a Crossy?

 

Need to decide on the carb soon - The choice seems to be between a 500 holley or a 465 (based on what a few people are telling me). Either is within budget so it's just a question of which one is better for the application I'm after. I'm not opposed to using an Edelbrock but unless it's gonna be heaps better I don't really see why it'd justify the extra stuff around. Want to decide soon though as I need to know which manifold to order.

 

Still need to decide on correct piston dish to go with the 49cc head job (Shut up unfamilia ) to fit in with the 10:1-10:5 target...

 

 

And for bonus points - stupid question of the day. How do I figure out which size bearing kits I need?

[matt_lamb_160 252]

Get a 4brl

 

Don't bore it more than you need to. No real advantage in going oversive.

 

For bearing and ring size, the machine shop will tell you how much they have machined.

[slydog 7,873]

 

And for bonus points - stupid question of the day. How do I figure out which size bearing kits I need?

 

After the machine shop measures it all up, inspects and decides what to do with it all.

[Nath 1,975]

Get a 4brl

 

Don't bore it more than you need to. No real advantage in going oversive.

 

For bearing and ring size, the machine shop will tell you how much they have machined.

 

After the machine shop measures it all up, inspects and decides what to do with it all.

Ahk that makes my life easier, thanks guys. Slydog gets the cookie though, he was in first.

 

Regarding the bore - That seems to be the general opinion. I guess the question I'm asking, is if there's anyone here who always makes a point of doing it to their crossies, or if no-one really bothers.

 

I will probably go the 4 barrel, have just been comparing the options.

 

Thanks fellas

[matt_lamb_160 252]

Yeah, he jumped in while I was editing damn it!! Haha.

 

3% increase in capacity (over standard) for thinner walls? I say not worth it.

[wagoon 2,429]

Sly ran scorpion rockers on his engine till the valves wanted no more part in the operation.

 

Only ricers overbore an engine these days

 

I pick the 2 barrel cause I'm happy to for go the dyno print out and 1/4 mile time slip wars. It's cool if that's what your building it for, just not for me

 

Went into the vault for you, 2.03 60's for both carbs mate!! the 500 was a good carb but the 600 vac had way more top end, 3mph is a lot with a carb change. 215/60 nankings 1280kg car

 

 

Jezz 2.03 60'!!! now I do 1.66 and I'm not happy!!!!

And this is why I pick the 500

 

And I will leave your head job well enough alone. But I would have thought that the machine shop would sort this out after they check your crank and rods then dummy assemble. Then do the measurements to get zero deck or just under and work out what piston is needed, at least that's what happened with my engine. Agree with the others on bearing kits etc as your crank might need to be ground if they find cracks.

[Nath 1,975]

Sly ran scorpion rockers on his engine till the valves wanted no more part in the operation.

Should be good enough for me then...

 

I will keep the rest in mind. Think I'll use the 4 barrel though.

[wagoon 2,429]

Keep in mind Sly used the adjustables so if your using hydraulic cam you need the non adjustables. But there is no quaility difference and you can buy a 6 cylinder set, extra saving bonus

 

Again dude what suits you is what suits you, so if you want the 4 barrel go that way. It's probably a smarter idea as you are much more likely to find cheap 4 barrel stuff than a cheap 500 holley and good design 2 barrel manifold. We all like/love/obcess over crossflows but that doesn't mean we all have to build the same thing

[Lord_fahrquhar 2,580]

6 injectors and a throttle body?

 

Just think of it as a big one barrel carb with six jets....

[ando76 4,354]

Personally I think the four barrel and the 465 is the go.  The smaller primaries will allow the thing to cruise along and not guzzle the juice, but when you want go you just bang the hammer down and you have all four venturi working. 

 

That way if you decide to change the cam for a big solid later on you can sell your 465 and bang on a 600 and you don't have to outlay for another manifold.

[Outback Jack 6,352]

^^ what he said^^

[Nath 1,975]

465 it is then.

 

Just in case you guys are interested I found a couple of pretty good youtube channels

 

 

Might not be so useful to you guys but gave me a better understanding of a lot of things.

[matt_lamb_160 252]

Agree with Ando, 1/4 mile times do not show the true disadvantage of the 500 Holley for street use.

[ando76 4,354]

I really like the progressive secondary 2 barrel holleys - thing is they are as rare as.  I know of 2 in existence up here and I have access to 1 but its a meth 350.

 

465 for the all round win IMHO. 

 

Mind you my mind is fried as I have been porting V6 Buick heads all day - yuk.  Yes I know but sometimes you have to do it to pay the bills.

[broken-wheel 659]

i had the progressive linkages on the 650 holley and I had to install it myself, pissed the 1:1 out and installed the new linkage, makes a bit of diff

 

see if you can find a beater holley and rebuild that, parts are dirt cheap for them and not much goes wrong with them so they are easy to rebuild, alternatively they now make a 600 4 barrel and has the fasts! aluminium base plate and all the things you normally change on a Double Pumper like AN fittings, sight glass, jet extensions etc. you find them on eGay for under 600 sometimes!

[Nath 1,975]

Food for thought there cheers guys. Was planning on getting a good condition second hand one. I've seen a few on gumtree (none in Sydney though )

 

Would a 600 be a little big for this application though?

[gerg 10,871]

Yeah 600 is a little big even for a mild 302. 465 is near perfect for your application. 390 would work too. Used on trucks a lot in the states.

[wagoon 2,429]

Agree with Ando, 1/4 mile times do not show the true disadvantage of the 500 Holley for street use.

I tend to disagree that the drag strip is not a good measure as it is known as the real world dyno for a reason. The 60 foot times indicates torque used to get the car off line, and torque is what is used on the street most of the time. And if there is no difference in 60 foot times between the 2 barrel and 4 barrel to me that indicates the 4 barrel made no difference until later in the run where the horsepower kicks in and the advantage of the 4 barrel sucking in all that extra air is shown. The 1/4 mile time and speed indicate both a horsepower and torque gain but the 60 foot time indicates that the gain was in the back end of the run. On the street you cant be winding the car out to 100+mph, that is why I used the track results as the example.

[broken-wheel 659]

keep in mind that with a good manifold like the AussieSpeed, if you don't open up the throats for a higher flowing head the signal is quite good and you can get away with a bigger carb, also whoever said they chew a lot of fuel can't tune them, they do not suck a lot of juice if tuned right, but I tell you what, it takes time and money to get it tuned right  and it's all done on the road with a O2 wideband. You can get them to run at 15:1 on 100km/h and crack open with a crisp response above that! With a progressive linkage you can dial in how much the secondary opens up as well, when I first tune the 650 i left the secondaries disconnected for idle, transition to mains, cruise, accelerator pump etc. You just need a lot of patience, gaskets, PV's, jets, air bleeds, pump cams, vacuum gauge and O2 Wideband. The Double Pumper is an awesome carb once you get to know it.

[broken-wheel 659]

I tend to disagree that the drag strip is not a good measure as it is known as the real world dyno for a reason. The 60 foot times indicates torque used to get the car off line, and torque is what is used on the street most of the time. And if there is no difference in 60 foot times between the 2 barrel and 4 barrel to me that indicates the 4 barrel made no difference until later in the run where the horsepower kicks in and the advantage of the 4 barrel sucking in all that extra air is shown. The 1/4 mile time and speed indicate both a horsepower and torque gain but the 60 foot time indicates that the gain was in the back end of the run. On the street you cant be winding the car out to 100+mph, that is why I used the track results as the example.

 

Drag racing is totally different man, too much torque off the line and you'll bag them up, a 300hp xflow will light up 275's at 4000rpm on the transbrake like there is no fucking tomorrow, it will fry the rear end with a clutch too! this is because you already got your total timing in by the time you're on 4000 RPM and the 2 barrel would already be maxed out at that RPM on a hot crossflow.

 

For street driven crossflows yeah the 500 is ok but it will fall over at over 4500, in a drag race you pretty much keep the pedal to the metal and use the timing curve to get out of the hole then add dots on the advance as you pass the 60foot then remove some timing as you cross the line or approach  your max rpm, I think I took out 1.5 degrees and gained 10hp at 6700, I found out once you reach the peak HP if you retard timing by 1 degree or 1.5 to 2 degree's you gain a little HP, I don't know why, i retarded to save the engine over the line but it added power and got me all confused

[wagoon 2,429]

And thats fine for full on race engines but the setup that was used in the times I used as an example were with a crossflow that is very close to the specs we are talking about. Theres no transbrake and 4000rpm launchs just a crossflow with a cam around 230@50 thou.

We are not talking about a drag car but a street car and everyone will point to dyno sheets and say see the 4 barrel makes more power. Yes it does make more power but not where you can use it on the street. That why I focused on the 60 foot.