Hi Guys, I’ve decided to redo my 308 engine because it seems down on power, consumes a lot of oil, and I don’t know what its previous history is. This is a 1978 GTS with unknown mileage as the speedo was not working when I purchased it about 20 years ago. I have since put maybe 20k miles on it. I would like the new engine to have increased performance and to this end, I’m thinking of doing basically what Ferraripilot did on his 3.4L build. I'm looking at a 360 crank, Ti rods, custom pistons (10.5:1), larger intake valves, high lift cams, porting, programmable ignition, and reconfigured 40DCNF’s. I am told there are a number of similar 308’s running around today and I’m wondering what the owner’s experiences have been. I understand about half of these cars are using 308 rods and some are using 360 rods. Anybody care to share their long term experience living with them? Bill
I did a similar bui;d on my old GT4 and its was a revelation. Vastly improved performance. I was extremely pleased with the results.
more specifically, i did this: the “Hot-rod” P6 cams, four higher performance Weber 44DCNF carbs with 34 mm venturis; Euro 308 headers and a Tubi stainless exhaust, all putting the power to the ground through a lightweight aluminum flywheel with a new AP clutch assembly. most recently i changed out the ignition system to an mdi system that is programmable to 15000 rpm(currently set at 7500).
What Jason said........these mods will really wake a 308 up and transform the car. You may consider this route and be happy. I know you have lived with the lower performance for so long and are sick of it but going the stroker route may be an exaggerated overreaction to the other end......like going from a minivan that you are sick of getting passed by everyone and trading it for a sport bike. If you prefer a well balanced machine where power is still in line with the braking and handling capabilities it may be something to consider. Anytime you up the ante in one department you will find the other areas wanting.
To help with improved power I had brakes and suspension improved with Ferrari 355 front calipers and Koni coil-over shocks with adjustable spring collars, upgraded adjustable anti-roll bars, solid suspension bushings and Boyd 5-spoke 16″ dia. modular billet aluminum wheels My car out performs 308s, 328s, and 348s, along with out handling.
Well, there you go......I guess it is just a question of how much power Bill wants on tap and how light he wants his wallet to get as the stroker route will be a more costly endeavor. The power characteristics will change as well.....more stroke = more torque.
Thanks for the feed back. The engine/tranny was pulled a couple of weeks ago. It was transported to MWE in Ronkonkoma,NY. I took the Bridgeport to Port Jefferson ferry, with the engine and fixings were in the back of a pickup. Tear down revealed at least one broken ring and all valve guides were junk. My recently purchased 360 crank with Ti rods, were placed on the main saddles and spun with no clearance issues. The crank mags good, std/std. The sleeves were popped out and the O-ring surface on the block was found to be in good condition. All studs were removed from the block in preparation for boring the block spigots for the larger bore 328 nikasil coated aluminum sleeves. So the bore goes from the 308's 81 mm bore to the 328 liners with a bore of 83.3+ mm.The block spigots are enlarged accordingly. Both of my heads were found to be cracked. I found a set of euro heads, without the air injection features, but with matching cam covers. Bill
Sounds like it will be a beast! LA Sleeve had regular 308 sleeves when I was looking so may be worth a call for 328 sleeves.
I've been thinking about rebuilding a carb 308 gts upgrading it with a "sprint pack". Do you know where I can get the P6 cams, weber 44 etc?
Hi Bill, I wouldn't go too wild as it will be a lot more work to drive. The P6 cams may be too much for a fast road car. CAT cams have a few profiles and good prices. I would not waste time porting the heads, just clean them up and get a good blend into the bowls. Google this for some charts showing the torque/hp of the P6 cams (less torque under 3krpm) and discussions about the ports. forums/projects-rebuilds-modifications/13731-308-2v-head-porting If your engine builder can sleeve the old guides in place they will match the seats better than new guides (also cheaper and less risk of head damage. I have hundreds of stainless valves left if you need any (21-4N, tuftrided, stellite tips, $12ea) and also some viton stem seals left and a variety of cam gears incl. adjustables for the newer round-toothed HTD/GT2 belts. If you decide to get the CAT cams, let me know as I have a $50 credit with them you can use. Make sure your shop knows about the usual suspects (drill the blind hole in the bellhousing, drill the cam oil return, check 2nd synchro, diff seals etc.) cheers,derek
Hi guys, In the beginning there was the RR Merlin aircraft engine with hemi heads. Then Harry Munday did the Jaguar 6, also a hemi head. Then Harry did a cylinder head conversion for Ford 1.5 liter blocks and the Lotus Twincam (LTC) was born. I think this is when Jimmy Clark smoked the field at Nurburgring in a Lotus 23B sports racer. The Dino series engines followed with bore and strokes almost identical to the LTC, and a 2V hemi head. Then came the Cosworth BD series of belt driven 4V engines. Then cam the Quattrovalve. My base line cam at this time is Cat Cams 1700402. Int lift 0.423 in (10.75 mm); Exh lift 0.394 in (10.00 mm).This is the kind of lift I'm running on a bored and stoked Lotus twin cam. 190 bhp, 165 lbft from 1.93 liters. So 340 bhp and a broad band of torque is possible. This engine should be under carbed at red line, but I'm hoping it won't be particularly noticeable. I'm not trying to increase the rpm limit, just maintain it. We'll likely go for a bigger intake valve, bronze guides, seals, and reshaping the valve seat and area up to the valve guide. We'll port match the heads with the intake manifold. Some folks claim many Ferrari heads suffer from tapered ports, narrowest at the inlet manifold interface. We'll look for this. Some say only part of the intake valve curtain area is flowing, because of the upstream port shape, specifically the short side wall. Some have started with 208, small port heads (Michaelotto?) for greater freedom to reshape the inlet port and presumably better proportioned exhaust tracts could be shaped too. A larger intake valve should help here, but no adding aluminum material. I'll retain the discarded sleeves, pistons, and heads for possible flow bench work. I really hope the replacement heads are good. Bill
Why aren't there any pictures in this thread??? Speaking as someone who knows very little about this stuff, but is fascinated by it, pictures and more elaborate explanatiosn would be very muc appreciated.
Hi kiwiokie, Yup, I believe you are correct. But 4 valves in a hemi head? Hi derekw, I think I want to go with one of your round tooth form cam sets. What do you currently have? Valves and seals are also a possibility. Most likely, I'll go with bronze guides, they just work better. Viton seals? What valves do you have that are appropriate? I'm leaning toward the Cat Cams 1700402. I'd be happy to spend your credit of $50. Cat Cams has a couple of race spec cams, 1700406 and 1700407 that increase lift and duration. I think 1700402 is the better choice.for a street cam for my engine. I'm not sure how this compares to P6 cams. I suspect my choice has higher lift,but less duration? Bill
Bill. If you can wait until mid October I can bring the cams and the pulleys to the US which will save you some shipping and duties. The set of pulleys I have are 7075 hard anodized aluminum with a stainless steel eccentric pin if you want to fine-tune the timing. Otherwise there are 10 holes for the regular pin £600 for the set of six. I suggest you also get the valve springs from cat cams. They are softer as the originals were far too hard, that’s the reason for stuck accelerator stories of 10 K plus rpm and also why the valve seats get worn. Image Unavailable, Please Login Image Unavailable, Please Login
I only have the standard diameter valves-- 21-4N stainless, tuftrided and stellite tips. $12ea. Lee at SI valves has guides and valves and may have bigger inlets.
Bill, I found this quote on my engine rebuild blog from Rifledriver who has worked on these engines for years and knows his stuff: "The OE Ferrari guides had lousy concentricity up until the 90's. Put in modern guides that are true and grind seat to new guides and poof, no shim left. I have used machinists for years that put in under sized guides, indicate off the seat and bore the guide to the seat. Clean up the seat and you are done. Its more work but a lot less than replacing seats. For proper breathing the valves need to stand proud, not down even with the chamber. Otherwise they are shrouded at low lift and do nothing." This was the main reason I sleeved the guides-- and the kind recommendation of Stephan at RPM in Vermont. Many machine shops will have the 8mm tool and sleeves, plus the new sleeves are far better phosphor-bronze or aluminum bronze so will wear slower than the original bronze guides.
Hi kiwiokie, That's a great article. Do you have the rest of it? This Peugeot engine was incredibly advanced for it's time. I love to see how they did their 4V head and cam drive. Hi derekw, Are you saying the Cat Cams cams are soft relative to OEM Ferrari cams? I'm not sure I understood your point. I have to read your engine build post. Did you use the same cams? The replacement heads came in with their cam covers. These are early euro heads, so no provision for air injection, the 1-4 exhaust cam is not fitted with the air pump drive pulley or any provision for one. There is no provision for the exhaust port air injectors. The air injection system will not be reinstalled.The heads came from separate engines with studs and cam caps. The steel plug wire boot retainer sleeves are quite rusted on one of the heads. I think these just pull out. All 2V heads seem to use these sleeves, Ferrari part number 112903. Both heads passed a leak and pressure test. One head is 0.012 inch thicker than the other and chamber cc's appear to vary, probably because not all valves are at the same height. Some squaring up and equalizing is in order. It's not clear if all the seats can be reused yet. I'll be saving the cracked heads for now, perhaps to play with on the flow bench. Bill
Yes I used the same 402 CAT cams. The valve springs they supply are softer than the originals which were too hard. I think they might be Opel springs as I vaguely remember several people fitting softer Opel springs years ago that were a perfect fit.
