Planning A 302 Roller Motor Build

[BlackNotchBack]

I picked up a 302 roller motor from an AU XR8. I've run a compression test and can still see hone marks in the bores so Im planning on keeping the bottom end in one piece.

My plan is to build up the motor to put in my '66 coupe which will be used mainly on the street with some autocross, hill climb and track work thrown in.

Behind the motor I will be running a rebuilt T5 and tru trac 8" with 3.7 ratio.

Here's a list of parts I was intending on building the short block up with but would love some input.

Heads: Trick Flow 170 or AFR 165
Cam: Comp Cams XE270HR-12
Manifold: RPM Air Gap
Carby: Holley 650cfm Double Pumper
Headers: Hedman Long Tube 1 3/4"

I'm hoping for about 300hp at the rears. From what I've read anything too far over 6k is pushing factory rod bolts so I'd just set the limiter at 6200rpm.

Is there anything else i should be doing why the motor is pulled down or any parts that would be better suited to my application?

[boofhead]

You have a good plan. I would make 2 changes

1) I prefer the TFS TW 170 (or 11R) option of the two (and I have used a number of sets) the better way to go is to spend a little more and get the TFS TW 11R 190 street port. 56cc chamber and all set up with top gear for only a relatively small amount of extra cash.  Trust me on this.

2) The XE270HR-12 is a good choice with the TW heads (not so much with the AFR 165) though they are a 1.7 rocker required camshaft. I would get 1.72:1 rockers for a small extra lift brings it to .550 which will help.

3) Add in a spacer for the carbi on top of the air gap.

Otherwise, good selection of parts and will be a good engine - I know as the parts I suggest I know of a good engine that resulted.

[BlackNotchBack]

Thanks for that valuable info boofhead. Didn't realise TrickFlow offer a 190 head with a 56cc chamber.

Do you think it would be worth stepping up to the Comp Cams XE276HR with the bigger heads? It might struggle for piston to valve clearance required. It's probably going to lack a bit of compression as well. I think I've just answered my own question.

[GEOFF289]

Hi Justin,

Being a mechanical mug I have absolutely nothing to contribute to this discussion apart from suggesting you check out Boof's tech paper on engine building on the other forum - wwwdotmustangtechdotcomdotau - (putting the actual link on this forum doesn't work)

Geoff

[BlackNotchBack]

Found it. Thanks Geoff.

[boofhead]

Thanks for that valuable info boofhead. Didn't realise TrickFlow offer a 190 head with a 56cc chamber.

Do you think it would be worth stepping up to the Comp Cams XE276HR with the bigger heads? It might struggle for piston to valve clearance required. It's probably going to lack a bit of compression as well. I think I've just answered my own question.

Glad some have found the article - hope it helps.

Going to the larger head helps you run a smaller cam relative to what is required with a smaller head. For example, lets say you chose a Edelbrock RPM Head - so you have a lot less flow in comparison to the 11R 190. Then you run the XE276HR with the Edelbrock in an attempt to equal the XE270HR with the 11R 190. In other words you can go/keep/use a smaller cam size as you run a larger head. This helps streetability, idle and vacuum as well as mid range torque. You will find you will have a flatter torque curve so RPM recovery will be faster. You also have an RPM limit (due to stock rod bolts) while the larger cam will need more RPM (approaching 7k) to run at its best. Naturally you loose bottom end the larger the cam goes so my suggested setup keeps the bottom end reasonable. Lastly, you can move to a 347 with those heads and have a very nice engine so your future proofing your purchase. Hope this makes sense.

Edit: P2V will not be an issue with any of these cams with the Trickflow 170 or 11R 190.

[shaunp]

Thanks for that valuable info boofhead. Didn't realise TrickFlow offer a 190 head with a 56cc chamber.

Do you think it would be worth stepping up to the Comp Cams XE276HR with the bigger heads? It might struggle for piston to valve clearance required. It's probably going to lack a bit of compression as well. I think I've just answered my own question.

Yes and change the pistons, It may well have dished pistons now so you'll struggle with compression, I got a set of base DSS racing forged flat tops for Teacherspet's car from summit they are 3cc with plenty of valve clearance. Run 1.7 rockers and they will yield about 600 thou of lift with the 276 cam. I think they were around $300 US for the pistons.

[shaunp]

Think it was these https://www.summitracing.com/int/parts/dms-8720-4030/overview/make/ford

[shaunp]

I also agree with Boof, go with bigger heads, 11R or 185 AFR, you never know when you may want to drop a 3.4" crank in it and     then you'll have some heads that still work ok. I wouldn't worry about reving it. Drop some ARP rod bolts in it while its apart. Its little engine you'll have to rev it to get the HP

[BlackNotchBack]

Thanks for your input Shaun. I'm really trying to be as budget conscious as possible with this build. I know it sounds silly when I'm bolting $2500 heads onto a stock block.

How crucial would you consider changing the pistons to be if I were to run the XE270? Or would it be cheaper to have the heads decked?

Swapping out the rod bolts is a good idea if it means I can rev it harder.

[shaunp]

What I would do it build it once and be really happy, are the pistons flat top with 2 or 4 cut outs ?  I would personally freshen the whole thing and then you know you can hammer it and not worry, even if it means you have to wait a while longer. These engines dont wear much with the roller cam, and moly rings there is very little microscopic metal floating around. Resize the rods with some arp bolts, and some budget forged pistons, arp pump drive, and  good chain set, balance it. Then you know its pretty solid and its still a budget engine really. Use the bigger cam and 1.7 rockers cause now you can, make sure the springs can take the lift. 6500 should be no issue, to make power in a 302 you have to be able to rev it some. You could also get the cam ground on 110 centres or there is a Lunati voodoo cam I really like its a bit hotter and you would just use 1.6 rockers, I think it is called a 282. its got about 580 lift and pretty sure it is on 110 centres. is a really nice cam,  you really want 110 centres if you can get it on a carb engine.

[shaunp]

This is it but you got to give it compression, it will make a 302 nice and revy with a reasonable idle but some what choppy.

http://www.lunatipower.com/Product.aspx?id=1670&gid=289

or just go for the 276  comp which is also a good cam, grinding it on 110 centers makes it better. but run it with 1.7 rockers, I also like use 7/16 rocker studs and rockers as well. to stabilize the top end at revs.

[boofhead]

Some of the roller blocks had no valve reliefs - for example I help build up a SC 302 for gbx78 and being an 86 roller it has pure flat top (forged) from the factory - using the TSF TW 170 heads no issue with P2V with the performance cam that he installed.

One of the problems with the forum is sometimes there is to much information being supplied. I made my suggestions - spend the money on the TFS 11R Heads (the AFR 185 will very likely have P2V problems if you do not change to deep relief pistons plus the AFR 185 springs are of a lower quality/rating unless you get the competition upgrade to 8019 spring set). The TFS 11R 190 comes with upgraded springs standard, light 8mm valves, 2.05 intake valve, 7/16 ARP studs, lots of room so P2V is generally a non issue due to revised Valve position and angle. See all done and sorted with my one suggestion. Saves confusion. I suggest you stay with the original cam in your plan with the 1.72:1 rockers - you do not want to over cam the engine.

Stay with your current plan with my suggestions - it will turn out well.  I made suggestions knowing a number of issues will be avoided. I hope your not getting to confused.

[shaunp]

Boof I think its the HO engines that dont have the cut outs

[boofhead]

I do not keep fully aware of all of the combinations so your likely right. Thanks.
Pull the heads and see - I think the factory forged with reliefs with center dish is something like -7.5cc .
Any way regardless, compression will improve from the stock configuration with the 56cc - optionally deck the heads a little and with the smaller cam, aka 270, less compression is bled off (than the larger camshaft [276]). I agree a set of new pistons and rod bolts, more compression all helps but the costs grow. You then start thinking 347 (because it is all apart so why spend money restoring old rods and crank etc etc).  I think I will leave it there.

[BlackNotchBack]

My thoughts exactly boofhead. But I can more than understand where Shaun is coming from.

In an ideal world I'd give the bottom end a hone, bearings, pistons and rod bolts. However I can see the "why I'm here I may as well" mentality kicking in and I'll end up with $4k in a bottom end and be able to make enough power to put my T5 on borrowed time.

I'll keep with my original plan of using the stock bottom end running TFS 11r 190 heads and the XE270 cam ground with 110 degree between centres.

Worst case is that it doesn't make enough power or lets go. If that's the case I'll build another short and move whatever is salvageable across.

[boofhead]

I think the XE270HR-12 is good enough for your build though if your prepared to get a custom camshaft made then other options open up for no extra cost above doing the XE270HR-10 custom. For example, a
Comp cam custom for your setup made up of Intake lobe [13442] 219 @ 50 Lift .603, Exhaust Lobe [13475] 233 @ 50 Lift .596  using 1.6 ratio rockers ground on a 111 LSA ICL of 107. Ground this on a -9 (Steel core). Gain a bit of compression with a minor decking of the heads and all will be sweet.
Just an idea.

[shaunp]

Do you reckon the P-V will still be ok at 600 thou with stock pistons and TF heads?  To order it, work what you want and order it via summit for cheaper shipping rather then from Comp.

[boofhead]

Yep - I fully expect the P2V to not be an issue with that cam and the 11R 190s if installed in the right spot. The total lift is a non-issue as by the time the cam is at maximum lift the piston is way down the bore and moving away faster. With the short duration fast ramps it is less likely to cause P2V issues than long duration slow ramp camshaft. Naturally, you should check it all the same.

Note: A 20deg head such as AFR 185+ would have a far greater chance of P2V issues with stock pistons, hence no (usable) reliefs. The edge of a 2.02+ valve is closer to the piston just by the nature of the angle and wider valve.

[shaunp]

I can tell you from experience even the 165 small valve AFRs come real close to stock pistons with an XE 274 cam RF cam from memory the exhaust was the worst. But the Ex valve is the same size any how.

[BlackNotchBack]

Great advice guys, thanks. Just wondering the reason for such a big split in the inlet and exhaust duration (119/133) of the custom cam you've recommended boofhead?

What would you recommend taking the heads down to? 53cc?

[shaunp]

Great advice guys, thanks. Just wondering the reason for such a big split in the inlet and exhaust duration (119/133) of the custom cam you've recommended boofhead?

What would you recommend taking the heads down to? 53cc?

What do the pistons look like do you have the heads off, rather then guessing what comp you will have, you can then work out what you need to do.

[J.hatzivalsamis]

Great advice from the gurus interested in doing similar as I just picked up an EL  but want to know do you run electric fuel pump or mechanical and where to buy all the goodies? Happy New Year.

[boofhead]

Great advice guys, thanks. Just wondering the reason for such a big split in the inlet and exhaust duration (119/133) of the custom cam you've recommended boofhead?

What would you recommend taking the heads down to? 53cc?

SP is right - ideally it is best to know what pistons you have to deal with. Though just for reference a fairly normal 302 build with -3 relieves flat tops with 54cc heads will be just short of 10:1 compression. So it is a safe place to be given the unknown variables.

Good pickup on the cam recommendation so I can see your not only reading it your thinking about what is suggested - that is great. The heads do not need that much split ordinarily but like most choices there are compromises. So what I was looking for is to try and limit the duration to be similar to XE270HR-12 while providing more area under the curve which we archive with the faster later ramps which results in more lift. This will act as a bigger camshaft, especially mid range power with the lobes being tighter so overlap is increases (it will be 57 degs for the custom cam). Now the exhaust lobe is a different family and is a softer ramp rate with the purpose to release the exhaust at a slower rate rather than as one big woosh (tech term ) this purpose is so there is still energy in the exhaust flow so at the time of overlap it has (hopefully) just completed leaving a nice vacuum pressure drop to pull more air fuel. Because the exhaust is going out at a slower rate (the valve is restricting it) more time is needed. Hence longer split. Secondly slightly longer split does often tend to allow the RPM to go past peak HP further as the overlap is helped toward a higher RPM so the goal is a wider overall power range rather than a peaky power spike. You can go to far and have no energy left at all for the RPM your running to so little help during overlap. It is toward the limit that I would use and yes if I was going for peak HP I would not run such a wide split as I would want to time to overlap benefit at peak HP not past it to get the extended RPM range.

[boofhead]

Great advice from the gurus interested in doing similar as I just picked up an EL  but want to know do you run electric fuel pump or mechanical and where to buy all the goodies? Happy New Year.

I always prefer an electric pump with the regulator - you cannot control (as easily) the fuel pressure as well with a mechanical pump. Carbi's need a narrow band for the fuel pressure or you over whelm them. Also, when the car has sat for a while the electric pump fills the carbi fuel bowls with out the engine cranking. Saves long cranking periods when the car has sat for a while.

Note: EFI is always a high pressure electric pump.

I find summit racing has a great service, great custom support, easy website, good catalog and reasonable prices. There are lot of delivery method options and if you use ebay store you can get some delivery cost bargains from time to time. Other such stores for example Jegs are also options to compare prices.