3.5 - 3.9 v8 upgrade

Can you get some kind of stroker kit to up the CC a bit without having to rebore/line the block?

May be worth doing while you're there.

Lee

woss one of them?

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hmm. never knew they existed.

bit out of my price range though! a 4.3 stroker kit for a 3.5 isgetting very close to what i could pay for a full 4.0/4.6 motor..

From rimmers site:

Stroker Kits These kits enable you to enlarge the cubic capacity of your existing engine by increasing the stroke, hence the name 'stroker'. The kits comprise a brand new, high quality crankshaft, conrods and pistons (with bearings and piston rings supplied). The stroke is increased from the standard 3.5/3.9 engine?s 71.1mm to a massive 86mm, (longer than the standard 4.6 litre stroke of 82mm) giving a capacity of 4.3 litres on a 3.5 engine and 4.8 litres on a

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The 3.5 as fitted to the 101 is the early incarnation of the engine and has a different oil pump and dizzy to the later 3.5 (and 3.9). Certainly a dizzy from a late 3.5 will not fit the early one (I tried), and ISTR someone telling me that consequently the timing cover is different, along with some other components at the front end.

Alex

yeah, thats pretty much what i had guessed. i assume i can move the whole front end over from my 3.5 though?

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Have you thought about replacing the pistons, if you did you could go for higher compression ratio ones, I thing Rover Vitesses ones, which would be ideal if you spend most time on gas.

Gerald

I have thought about it - but Unless somebody can sell me a set of pistons for not very much it isnt going to happen! I'm hoping to make this a low budget engine swap! I wanted to buy some solar panels for the truck too...

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I'd take a leaf from Steves book ;-) there is no hurry so go the extra mile if it takes six months longer. You've not rushed so far and the truck is looking fantastic from where I'm sat.

Lee D

Was thunking today - since the bore size differs on the different v8's why do they all use the same heads? surely it means that different amount of 'head material' are 'exposed' on the larger bore engines.

Also - I guess i need a head gasket to match my engine capacilty (cylinder bore). So definately need 3.9 head gaskets rather than 3.5

Can you get tin 3.9 gaskets? cant see em at beamends.

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You'll get everything you need from Real Steel. Not trying to knock anyone else, but the stuff they supply is top quality and I've had no issues with them in all the years I've been rebuilding V8's.

Slightly different valve sizes, but it's not as if you're building a high-revving screamer of an engine. File the required cut-outs into the heads using a round file about 8mm diameter, use the new inlet gasket as a template. Either leave the outer 4 bolts from each head out completely, or fit them but only torque them to 20lbft. Any higher causes head gasket issues, you have been warned. I leave them out completely.

NO! Use composite gaskets, skim heads by 30 thou (from original) to restore compression. Repeat after me..... TIN HEAD GASKETS ARE UTTER CRAP.

As you say, swap over the complete front end. If the donor engine is a later "serpentine" 3.9, then you'll need a short spacer to go on after the front pulley, before fitting the pulley bolt. Turn one up, or buy one from RPI.

NO, NO, NO! They will make your new engine run excessively lean under load, and cause damage.

The required needle profile just isn't available for Strombergs, that's why I said originally to fit SU's and BAC needles, with an airbox.

Wimp.... ;-)

Badger. (Just in from Scottish Hillrally and absolutely shattered!)

they have so many exciting looking bits in their pricelist!

recommendation borne in mind! I tend to use beamends a lot for whatever i need now because they are cheap, local and i'd much rather support a business where i actually know the person running it!

I put em in last time (since that was how it came). will stick em in loosely as you say this time otherwise the hole will just get full of crud!

Getting them skimmed again will result in another bill though - if im getting work done i might as well get the unknown 3.9 heads skimmed and leave my good 3.5 ones alone.. Will be less 101 downtime involved too this way.

I dont think its a serpentine one. Not got any belts on but looks like it should take a normal belt.. This mean i dont need any extra bits?

Why cant they hack it? a single version of the same carb feeds my saab

I have now got a pair of SU's courtesy of mr Davies :) they need rebuilding though (i guess) and it looks like they need different elbows which means different LPG mixers..... RPI have a 4.6 101 on strombergs on their website -

wimp who is enjoying driving the truck after sitting looking wistfully at it far too much over the last 4 years! and wants to do so as much as possible this summer!

Ta badger :)

how wet did you get today? :) I got wet while actually sat in the drivers seat driving the 101!

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Tom Woods uttered summat worrerz funny about:

Blimmey you're really enjoying it aren't you... and I thought I'd got a problem ;-)

Ohh actually I may be lieing I seem to recall running Morph on them for a short while when the others were rebuilt.... vague recollection of fitting a new seal on the float chamber at the bottom. Either them or the ones which ended up on Percy anyhow.

I only went ack to the stroms because of keeping him as origional as possible (after ripping the gur out that is - ooopps!).

Lee

Do i not need different elbows for the SU's. Did you give me any of them? (lost in the back of the 2A at the mo!) If i need different elbows it means getting 2 more LPG mixers which is a bit of a pain.

You cant even see the carbs! :)

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I have a very vivid recollection that I cut the old ones - It's only the bolt hole that needed cutting to allow the bolt to go in where the elbow bolts on. In which case you will be fine :-)

The ones I cut are still (were) on Morph when he went with the origional carbs on. Not hard... quick kiss with the grinder.

It's all in the detail - though that spare wheel may have been a little un-origional too.... h'mmm ;-)

Lee

Indeed they do...... Especially those new heads........

A fair and commendable comment, I only recommended RS because I use them regularly and know the quality I'm buying. There's a lot of cheap stuff out there that I wouldn't touch with a dettol-soaked barge pole!

And you also get the better valve sizes too.

Ought to all swap over, including front pulley.

The carbs can flow enough air, the problem is how they add the correct ammount of fuel. Every engine type is different, due to compression ratio/airflow/valve timing/exhaust backpressure, so for a given mass airflow the vacuum level can be different. Because the Stromberg (and the SU) meter fuel via a tapered needle attached to a piston that is lifted by vacuum, the fuel flow can be different on 2 engines even though the mass airflow is the same at a given point, causing an incorrect mixture. From experience, the

It's possible that RPI machined down a set of std needles to give enough fuel for the 4.6, but it won't be producing it's full power potential as there is NO WAY that two 1.75" carbs flow enough air for a 4.6. The ideal for a 3.5 (for power, not torque) is twin 2", for chrissake!

Hehe, I understand.

I got very wet lying under a 90 replacing a front diff at 1am Saturday, after we'd turned down a metric carrier in a pre-roman lathe to take imperial bearings due the the owner not bringing a spare diff for the first time in umpteen years........!! Whilst there, I also replaced the crappy, incorrect mild steel bolts with proper high-tensile versions holding his right front swivel to the axle case as they had stretched somewhat during the day's stages .............. doh!

Badger. (Almost dried out now...)

I'm not listening... :p

Im a small business too! Got to do my bit!

OK. will use the 3.9 heads. is it going to come with composite gaskets as it is now? (assuming original spec) Not worth getting any more skimmed off if it is already composite? I shall probably just get them cleaned up and checked and skimmed only if they look crusty otherwise. Can probably get it done cheaply for cash if i go take them off this week :)

I just need to get the existing bloody front pulley off! Annoyingly the damper is slightly loose now (it started rattling till i put new nuts and bolts though) but it still wont come off fully!

Will have to order the right socket as discussed before and then get the local garage to have at it with the airline and then put it back on loosely for me.

OK, gotcha. Since i dont plan to run on petrol a whole lot (if ever!) for now (just LPG) i think i shall leave them how they currently are and swap over at leasure. Ive got the 02 sensor wired up so can easily keep an eye on it. Can i just sand the needles down or something to make it run rich? :-)

are details of the correct profile (or one that is better) available? could i get them made up? I've got a couple of saab carbs with right knackered needles that run rich all the time. might try them :)

RPI do sell a selection of stromberg needles. Might contact them and ask see what they say.

Having looked at my new engine he has actually included the complete wiring loom sans ECU and the fuel system is intact (just missing the fuel pump). So EFI might not be too far off! :) Am going to keep an eye on ebay for a new dissy (not included with the engine) and the ECU i need

Arnt roman lathes powered by slaves? :)

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so my current stromberg elbows will fit on an su if i give them a quick tickle with the grinder? thats what i like to hear! (and it makes a swap more viable)

I think there are even people with the correct number of rivets who have swapped over to SU's. :)

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In that case, hes a very naught boy, Traitors .... what have the rivet counters ever done for us. ;-)

Lee D

Good plan.

I've done this with SU needles, it's a long, slow process. You need to know where it's lean and ease a couple of thou off at a time with something like

Dunno, never found anythin myself, I just swap to SU's.

No harm in that.

Be careful as to what drive is required for your oil pump, most 101's I've worked on have had the early (pre-SD1) drive - the tang is on the dizzy not the oil pump shaft like the later ones and I don't think the drives are swappable between dizzys very easily. It's not summat I've tried doing in the last 15 years or so, so I may be wrong of course.

Yep, driver and navigator in our case! Well, they collectively broke it......... ;-)

Badger.