Holley Sniper

[David C]

Really useful information, thank you.

I have done a bit of reading about it and there seems to be general agreement that it's a good idea to have a post pump filter even if you are using a Hydramat.

I'm torn as to whether to go for the Hydramat. It looks brilliant if making a tank from scratch but since the Bristol tank has baffles and a sump I wonder how much advantage it gives. I think the size you have chosen along with how often the car is used will give a good few years before it clogs but I'm more inclined to let some of the small particles go through the pump and collect in a 10 micron post pump filter that can more easily be replaced. By no means a criticism of your choice. I may well decide on a Hydramat but haven't made my mind up yet.

My shopping list currently looks like this:

Sniper 2 550-510 3xx $1300
Hyperspark distributor 565-344 $400
Fuel pump 12-169 $490
Coil 556-153 $45
Filter 162-554 $120
Filter brackets 162-574 $45

Total $2400

These are not confirmed choices that will definitely work together, just the best I can do for now after a bit of on line research. I am waiting to see how well the overdrive gearbox conversion works. If it's a success I think the Sniper will follow soon after.

[Green411]

I used the Hydramat just to be on the safe side, as the stock tank baffles weren't designed for the needs of an efi electric pump. Haven't (yet!) used a post-pump filter, other than the one in the stock position near the Sniper (to disguise the conversion) which I forgot to put on the 'stuff used' list. It's a Vauxhall part and I can get the part number if you need it. I'm assuming in all this that David C is in the UK, btw.
My 411/3 has a 383 B block, so the distributor is UK driver's side, front, at 45*. I think the small block ones are like a traditional small block Chevy, in the middle, vertical, at back of intake manifold?
What transmission are you going to use David? A 4 speed o/d Chrysler one will bolt to directly to a 318/340/360 block I think, but an old 383 like mine needs an adaptor. In view of availability, need for an adaptor anyway, trans case size etc if I do get round to a trans swap then a mildly-built GM200-4R looks sensible.............(am a long way from deciding, but in any event I await the torrent of abuse from purists......)

[AndrewA]

David - if the Weiand inlet manifold causes too many issues am happy to look after it for a while......

[David C]

I am indeed in the UK.

I have gone for an A400 42RH transmission. It's a fairly straightforward bolt on replacement. Needs different flex plate and lower cover for torque converter. Also a small ear had to be removed from the block to get the starter motor to fit.
46RH are a bit easier to find and are a bit stronger. Most of the work is in modifying the gearbox crossmember and transmission tunnel. Article to follow...

The Poly engine in the 409 and 410 is internally balanced so works with the lock up torque converter without any modification. I think I previously saw that the 383 is also internally balanced but that would need to be confirmed. If so it should be fairly straightforward to bolt to a 46RH with a suitable adapter kit.

As long as the engineering is done well I don't see a problem with a GM unit. Wilcap make a suitable adapter. I think you will need an electronic adapter if the GM 'box is electronic.

It would be good to hear from others on the forum whether they would welcome an extra gear and better fuel economy or would be put off by non original gearbox. Also, once it's non original does it make any difference whether it's Mopar - developed from the original - or from another manufacturer.

[David C]

More on the Weiand inlet manifold on my 410-

For those who are interested or just need help to go to sleep there is plenty of reading on offer regarding inlet manifold arrangements, specifically square bore and spread bore. I believe 410 and 411 original manifolds were spread bore. The Weiand 7403 manifold is divided square bore. This means the Sniper should bolt straight up.
The question is whether I will get much benefit as square bore is better at higher revs but may lose torque at lower. The 42RH gearbox has a lower first gear which may offset this. I'm hoping that combined with decent tubular manifolds the improved breathing will give further improvement to fuel economy.

If it doesn't work out, Andrew is at the front of the queue for parts to make a fire breathing monster.

[Green411]

I was just reading through some earlier posts when I came upon Dezelsky's from June, when he was touring in Italy with his 411/4. I'd completely missed the photo he attached, and just had a look. Man, that is a pretty car! Perfect angle for the picture, and the combo of the wheels and colour really suit it.

[Green411]

Re David C's manifold intake manifold points, the Weiand design has got to be more modern (or perhaps less aged...) than the original mopar one? And I can't think why efi would need the help with fuel-atomisation of small primary bores. Am happy to be educated though if anyone knows different! Sniper is wet flow so surely avoiding the puddling of fuel in the intake matters more? The divided plenum should work ok - mine runs fine with a stock intake.
Re the transmission: I want my 411/3 to be easily(ish) returnable to stock in the future (dunno why, it just seemed important!) so part of the GM200-4R appeal is it's relatively small size. It's controlled via throttle-valve cable (like a TH700-R4) so no additional electronics to worry about - apart from TC lock-up. GM transmissions run by the ecu startd with the 4L60E and it's successors. Great trans, had one in my '95 Corvette. Additionally the 200's got a deep first gear and a lo-o-o-ong top gear. And thank you for not shouting at me for the idea of a foreign trans.....If I could find a separate conventional overdrive that fitted (not a Gear Vendors type) that would take the 383 torque then that would appeal too. Anyone got any thoughts?
You can all wake up now......

[David C]

I should really have said that the Weiand is a divided single plane whereas the original is dual plane. Supposedly the longer tracts in the dual plane allow the mixture to slow further and give a more dense charge at lower RPM providing higher torque.
Looking at the original manifold, one half turns through a right angle almost immediately on entering the manifold so common sense suggests more puddling on one side than the other. Since the Sniper only uses an O2 sensor in one of the downpipes I struggle to see how it can get the mixture just right in both banks. Hence I decided on a symmetrical manifold.

If reading this gives the illusion that I know what I'm talking about, please don't be fooled. I very much welcome input from anyone who can see through my waffle and tell me where I'm going wrong.

[Thor]

Life is too busy, but I have acquired a Sniper kit to put on the 318 Poly in my 409. I feel very sure that at the very least a transmission with a lock-up torque converter is required. A GM 6L80 would need an adapter but there are controllers for it. I've thought about a 42RH as I had a Dodge Dakota for many years with the Magnum 318 and 42RH (I think). But if you're going to the trouble of changing the trans and have the electronic outputs from a Sniper, it's relatively easy to install 6 or even 8 gears. I have no idea whether these fit under the Bristol floor without modification.