369 Cube Engine Build

[NZGTRA17]

Recently completed the build of the 369 cube shortblock to replace the standard Ford block based 347 that we ran last year. Bottom end is based around Scat H beam rods and 4.155" CP pistons.



Used a Dart SHP 8.2" deck block bored .030" over to 4.155". These blocks can go to 4.185" according to Dart but seems many US builders have gone as big as 4.2". Used a Scat 3.4" stroke 4340 forged crank and Romac balancer. Unfortunately the Scat crank I got could not be zero balanced (some can if counterweights have not been machined down by Scat at the factory) without using 10 slugs of mallory so we stuck with 28oz balance.



As is common with aftermarket blocks the timing chain clearance was tight, necessitating grinding of the block for clearance.......lots of pre-assembly checks pay off! To assist high rpm/G load oiling I have fitted a 3 quart high pressure accusump and plumbed it directly into the back of the block.



1/2" head studs, solid roller cam & lifters and metal shim type gaskets used.



Top end uses my previous Brodix 185cc runner CNC heads but now fitted with 2.08" Ferrea inlet valves. Comp Pacaloy springs and tool steel retainers. Topped of with Jesel shaft rockers. A watch out here is rocker to spring clearance. Lots of hand finishing required on the underside of the rockers to get the required clearance. Also lots of geometry checks to get the shim height correct for best alignment...........a few engine hours will tell on this one to see how guide wear pans out.



Dyno results as below with 369 graphed against the best of the previous 347's runs. 369 made a max of 436 rwhp and 422rwtq on a very conservative tune (we are running pump gas due race regs). Very strong down low from as little as 2500 and carrys through nicely to 6500. A big change from the 347 which was pretty much done by 5500 and lacked punch from mid straight on.



Still plenty of room to increase power in the future if required. The combo I have used can easily top 600hp with likes of 215cc runner heads and a Super Victor manifold. Albeit that rpm would need to increase to 7000 to achieve this.

We are contesting the NZ Endurance Racing Champs with the car this season and running 3 x 3 hour endurance races. Really looking forward to seeing how this new combo performs.

[Cobrafang]

Kel,

This looks awesome. I am surprised you appear to be still running the serpentine system. Gary Jones has gotten us off it and probably can produce a list of parts for your. KRC power steering pump and smaller lighter alternator...etc.

let me know.

-td

[NZGTRA17]

Originally Posted by Cobrafang

Kel,

This looks awesome. I am surprised you appear to be still running the serpentine system. Gary Jones has gotten us off it and probably can produce a list of parts for your. KRC power steering pump and smaller lighter alternator...etc.

let me know.

-td

Hi Tom, thanks it was a lot of fun to build. Had you had probs with the serpentine setup? Mine has been fine so far...........touch wood. We always use a new pre-stretched belt for each big race. I did replace the tensioner this time around as well as the waterpump to stave off any failures.

I am thinking that if I start to chase more power I will use an electric water pump and re-do the pulley setup at that stage. Any feedback on serpentine issues appreciated though in the meantime.

Kel.

[Werling]

I have a similar set up and have had two belts break, switched to goodyear belts and have had no problems since. I can't rember the make of the two belts that broke but most auto stores have there own brand of belts, now I only use the goodyear belts which are a little harder to get.

[NZGTRA17]

Originally Posted by Werling

I have a similar set up and have had two belts break, switched to goodyear belts and have had no problems since. I can't rember the make of the two belts that broke but most auto stores have there own brand of belts, now I only use the goodyear belts which are a little harder to get.

Todate I have used Gates belts and tensioners and have not had any issues with these.

We also loop a spare belt over the radiator hose and tie wrap it in place so that it can be fitted quickly in a race in event of a belt failure without needing to remove the radiator hose.

Kel.