Rebuild of a RV8 4.6 instead of the 3.9

General Chat About Engine Build

Moderator: phpBB2 - Administrators

Post Reply
Sir Shelby
Newbie
Newbie
Posts: 5
Joined: Fri Jan 17, 2020 11:18 am

Rebuild of a RV8 4.6 instead of the 3.9

Post by Sir Shelby »

Hello,

I am faced with a problem where at least none of the proffessionals seem to be able to help me. Eventually someone here alreday went for the same and might help me:
I am converting a RV8 4.6 for a Pilgrim Cobra where there was a 3.9 before.
Following basic boundary conditions are exisiting:
- 4.6 got equipped with an interim front cover in order to fire it via conventional distributor and have crank driven oil pump (new style of water pump)
- the 4.6 will be filled by a Holley Sniper EFI
- due to space reasons it will be equipped with v-belt instead of the serpentine belt

Now coming to my main problem:
The impeller of the newer style of water pump, driven by serpentine belt, turns into the wrong direction for my v-belt.
I tried to pull the impeller off in order to turn to the opposite side. Sadly this pressed metal sheet part is to weak to get it off.
Is there any water pump of the newer style available which turns the opposite direction or any idea how to handle this issue?
Please don't recommend the use of an electrical water pump. I would like to go for a semi-standard solution.
I am sure some of you already went for the same or a similiar modification and might have been faced with the same issue.

Thanks for any help.

king regards
Markus



jenand40
Getting There
Getting There
Posts: 159
Joined: Tue Nov 21, 2006 8:53 pm
Location: Burnham on sea, Somerset

Re: Rebuild of a RV8 4.6 instead of the 3.9

Post by jenand40 »

The water pump opposite direction on the serpentine engine is achieved by the routing of the drive belt, via an idler pulley, which also keeps tension on the drive belt.
If you cannot fit a serpentine belt then I would look into using a longer v belt and route it around an idler pulley, similar to the serpentine belt set up, to accomplish the correct direction for the water pump. There are two types of serpentine idler/tensioners, you want to use the flat face one, as opposed to the ribbed one so that it runs on the back of the v belt. It could also tension the v belt so it takes up any stretch.
Just my thoughts of how I would try and overcome this problem, whether it is possible requires further investigation.
Hope this is of helps.

DaveEFI
Gold Member
Gold Member
Posts: 4603
Joined: Fri Feb 26, 2010 4:27 pm
Location: SW London, UK

Re: Rebuild of a RV8 4.6 instead of the 3.9

Post by DaveEFI »

You could also keep the front of the engine as standard (assuming the water pump is the correct height) and go to programmed wasted spark with no dizzy. Which is a big improvement in both performance and even more, reliability.
Dave
London SW
Rover SD1 VDP EFI
MegaSquirt2 V3
EDIS8
Tech Edge 2Y

Sir Shelby
Newbie
Newbie
Posts: 5
Joined: Fri Jan 17, 2020 11:18 am

Re: Rebuild of a RV8 4.6 instead of the 3.9

Post by Sir Shelby »

Since I am working with a 285 degree cam, it won’t work with a programmed wasted spark system. I already considered that. But since you might get gas mixture into the bore even when the piston is down, you would for sure have endless nos. of failure ignitions.

Is there really nobody here who ever made such a conversion in the past? I can’t believe that.

Kind regards
Markus

minorv8
Knows His Stuff
Knows His Stuff
Posts: 571
Joined: Thu Nov 23, 2006 5:10 am

Re: Rebuild of a RV8 4.6 instead of the 3.9

Post by minorv8 »

I don't think that V belt works with the 4.6 pump. It is too narrow. The serpentine belt is wider and has thus more surface area to transfer the motion to the pulley. I believe that once you have enough load at the pump the V belt starts slipping.

I run a 4.6 with Real Steel Tornado cam. It is a healthy hydraulic grind, 224 deg intake and 231 deg exhaust @.050 lift. Something like your 285 cam. I have had wasted spark for several years. No issues whatsoever. Most engines nowadays have wasted spark unless they have coil for each cylinder.

What kind of space problem do you have ?

DaveEFI
Gold Member
Gold Member
Posts: 4603
Joined: Fri Feb 26, 2010 4:27 pm
Location: SW London, UK

Re: Rebuild of a RV8 4.6 instead of the 3.9

Post by DaveEFI »

Sir Shelby wrote:
Tue Mar 31, 2020 6:57 pm
Since I am working with a 285 degree cam, it won’t work with a programmed wasted spark system. I already considered that. But since you might get gas mixture into the bore even when the piston is down, you would for sure have endless nos. of failure ignitions.


Is there really nobody here who ever made such a conversion in the past? I can’t believe that.

Kind regards
Markus
Not too difficult to fit a cam sensor on the camshaft sprocket and go sequential.

I've not done what you want, but pal who did decided on an electric pump conversion.
Dave
London SW
Rover SD1 VDP EFI
MegaSquirt2 V3
EDIS8
Tech Edge 2Y

DEVONMAN
Top Dog
Top Dog
Posts: 1440
Joined: Sat Dec 13, 2008 2:46 pm
Location: Croydon UK

Re: Rebuild of a RV8 4.6 instead of the 3.9

Post by DEVONMAN »

It is possible to get double sided V belts which with a v pulley on the pump may work. Don't know what sort of length you need. By the way, flipping the impellor on the pump will not change the flow direction but will just be less efficient.
1950 A40 Devon Hotrod with 5.0 twin turbo RV8.
EDIS8 wasted spark, Holley Injection.
Been as far as the Moon and back in 57 years of driving. Same Car, 5 engine upgrades !!!


Image

User avatar
SimpleSimon
Knows His Stuff
Knows His Stuff
Posts: 620
Joined: Mon Apr 25, 2011 10:36 pm
Location: East Sussex

Re: Rebuild of a RV8 4.6 instead of the 3.9

Post by SimpleSimon »

Your uncompressed fuel in the cylinder wont be an issue just because your running a 285 duration cam with wasted spark :roll: in cam terms thats not huge, lots of us running more severe profiles and wasted spark with no issues :wink:
TVR Chimaera RV8 Mods & Megasquirt

Sir Shelby
Newbie
Newbie
Posts: 5
Joined: Fri Jan 17, 2020 11:18 am

Re: Rebuild of a RV8 4.6 instead of the 3.9

Post by Sir Shelby »

Most of the 4.6 is now converted.
It got T-liners, new pistons, stage 3 heads and the Interim timing cover with crank driven oil pump and bore for distributor.
Due to the much thicker timing cover, the pulley and damper of the 4.6 need to get modified in order to went forward.
Since this parts are really expensive I want to be sure to order the right ones.
Are the damper ERC5462 and the pulley ERR4866 the right ones or do I need different ones in order to get in line with the water pump?

Thank you very much for any assistance and help.

Regards
Markus

paul c
Getting There
Getting There
Posts: 265
Joined: Tue Mar 11, 2008 7:41 am
Location: Takaka New Zealand

Re: Rebuild of a RV8 4.6 instead of the 3.9

Post by paul c »

Is it the interim damper you are using? Usually that is used with the interim cover and a spacer on the longer crank. If necessary you could use spacers to get the pulley alignment correct.

Post Reply

Return to “Engines Area”